Going 3/4 ton d44 and d60 w/ 3/4 ton front Chevy discs, what kinda master cylinder should I upgrade to? This is for a 99, but I doubt my stocker has what it takes :laughing: I "hear" 90s E350 van maybe? or ??

Going 3/4 ton d44 and d60 w/ 3/4 ton front Chevy discs, what kinda master cylinder should I upgrade to? This is for a 99, but I doubt my stocker has what it takes :laughing: I "hear" 90s E350 van maybe? or ??

I believe you need to run a early style booster to use that master cylinder. Search for YJ brake upgraded master cylinders and you should find your answer. Possibly a WJ master will work with the new style.

I can't remember what year E350 (i thought it was 80s) but thats what i used... I also had 4 wheel disks...

It bolted right up to my 93XJ booster (had to bore out the master cylinder holes just a tad bit)

Going 3/4 ton d44 and d60 rear, w/ 3/4 ton front Chevy discs, what kinda master cylinder should I upgrade to? This is for a 99, but I doubt my stocker has what it takes :laughing: I "hear" 90s E350 van maybe? or ??

I have an 01 XJ, ford hp d44 front & d60 rear, 3/4 ton dual piston ford front calipers. I would like to hear a deffinitive answer to this too. What bore size works best 1 1/8, 1 1/4 or what. I've read threads that say get a 1984 E350, 90 Vett, Crown Vic, etc. Or is the VanCo hydroboost the way to go?
Anyone here actually have first hand info on what works best? Especially with the 97-01 dual diaphram booster.

OK, there is a TON of info on Pirate, and elsewhere discussing MC up grades. XJ/ZJ/TJ/WJ, or whatever jeep, newer than 1995 uses a dual-diaphragm booster that needs to seal against the MC; accordingly, MC upgrades for early (pre-96) models do not apply to post -95 models.
I've read elsewhere on this forum that the '99 Dodge 1500 pickup will fit the latter boosters--in the case I'm citing, it was a 2001 TJ Sahara. Seems you only need to lengthen the push rod 3/8 inch---meaning replace the stock push rod with a 1/4-fine thread grade-8 bolt, with the head cut off.

I've used a WJ master in my old 89 and will swap one into my 92 soon. Pretty easy to do. I added a Wilwoods ADJ. Brake Propotioning valve and a factory firewall spacer. Plus I removed the O-ring from the OEM valve. Worked great to the previous POS ABS brakes that I had!

I don't think the WJ MC is much of an upgrade; I'm pretty sure the piston is not greater than 1". Upgrades are generally needed to deal with the addition of larger brake calipers than stock. For instance, the early "vette" and Mercury Grand Marque MC's have 1.125 bores, compared to the XJ 15/16 bore, and are used to add needed fluid volume when going to 1/2-ton or larger brakes found on older FSJ's or Chevy trucks. These MC's won't readily seal to the double diaphragm boosters used after '95 in Jeep vehicles. The WJ MC would, but again, it doesn't solve the volume requirement. As I recall, the '99-2000 Dodge MC has a bore of 1-1/8 or 1-3/16--quite a bit larger than the WJ, and it's intended for 4-wheel disc applications.

The WJ MC is no different than the 97-01 XJ, ZJ, TJ. There was a thread on NAXJA by 53guy IIRC that stated the bore sizes ect. But it seemed as though the Dakota has a bore size of 1.125" which is about perfect for 1/2-3/4 T brakes. The Ram 3500 MC has a bore size of 1.25 which is a bit too stiff for anything shy of 1 ton calipers.

I don't think the WJ MC is much of an upgrade; I'm pretty sure the piston is not greater than 1". Upgrades are generally needed to deal with the addition of larger brake calipers than stock. For instance, the early "vette" and Mercury Grand Marque MC's have 1.125 bores, compared to the XJ 15/16 bore, and are used to add needed fluid volume when going to 1/2-ton or larger brakes found on older FSJ's or Chevy trucks. These MC's won't readily seal to the double diaphragm boosters used after '95 in Jeep vehicles. The WJ MC would, but again, it doesn't solve the volume requirement. As I recall, the '99-2000 Dodge MC has a bore of 1-1/8 or 1-3/16--quite a bit larger than the WJ, and it's intended for 4-wheel disc applications.

So are you saying that with the WJ booster that the 99-00 dodge MC will seal and bolt up no issues?


I have a 90XJ with the WJ Booster and master and now currently in the install of the 60 front with dual piston capiper and the 14 bolt rear with K20 calipers and have been wanting to lookin to this sooner then later.

Well I am personally in this whold MC issue right now,... D44HP & 9" combo with Chev 1/2ton calipers in all four corners,..stock master could only slow it if you pumped it up,.. tried a 4wheel disk WJ MC,.. No luck same result,... so I am in a bind I even tried yoinking the stock proportioning valve ,.. I can't stop the ol'best on the 35's and new diffs :(

I didn't start the thread, but here it is.... And yes, the WJ MC is the same size and part number as late model XJ's.


http://www.naxja.org/forum/showthread.php?t=903864

I wouldn't say that the Dodge upgrade is AWESOME, but it does a lot better than before. Its a tad stiff pedal, but I have a hunch that the break pedal might be longer in the dodges and if XJ's were shorter, it'd have a harder pedal feel. I haven't done the research on that part yet.

So are you saying that with the WJ booster that the 99-00 dodge MC will seal and bolt up no issues?


I have a 90XJ with the WJ Booster and master and now currently in the install of the 60 front with dual piston capiper and the 14 bolt rear with K20 calipers and have been wanting to lookin to this sooner then later.

Basically since a WJ is no different a newer XJ MC (according to previous post in this thread) then a 99-00 Dodge 3500 should bolt right up? I wonder this only b/c I have a HP60 and 14 bolt w/ disc all the way around going into my rig and i know i'm gonna need to figure some shit out when it comes to stopping power.

For you guys too lazy to go to the link to get all the info...here's the cliffnotes...


1999 Jeep Cherokee MC, M10-1.0 M12-1.0 lines 1" bore MC

http://partimages2.genpt.com/partimages/357150.jpg


1999 Dodge Dakota and Durango MC, 1 1/8" bore, M10-1.0
M12-1.0 lines

http://partimages2.genpt.com/partimages/357565.jpg

1999 Dodge Ram 1500, 2500, 3500 MC 1 1/4" bore, M10-1.0 M12-1.0 lines

http://partimages2.genpt.com/partimages/71012.jpg
http://partimages2.genpt.com/partimages/71011.jpg
http://partimages2.genpt.com/partimages/357343.jpg


The Van and Wagon models have a 1 1/4 bore, but appear to have a shorter MC, so I don't know how useful they would be for our application.

http://partimages2.genpt.com/partimages/357579.jpg

The 1998- March 2001 dodge trucks have the same MC. The went to a larger bore after March of 2001 it appears and they had a different line size on the earlier MC's, but the bore was the same at 1 1/4". I think that the best bet for us is going to be the 1998-2000 MC's, but I think the only hurdle is going to be the resevoirs. I haven't had a chance to look at the durango or the dakota MC's yet, but they might be a better option if you only need a small upgrade in volume with their 1 1/8" bore. I'll run over to Napa and have them pull one so I can look at it and I'll get back to you, but it looks like you might not need an adapter for the Durango and the Dakota MC's, but we'll definately need one for the Ram MC.


Next post....

Ok, just got back from Advance Autoparts and the Durango/Dakota MC is virtually identical to the Jeep XJ MC. It has a different resevoir and resevoir roll pin tabs, but the mounting holes for the MC are identical as well as the push rod spacer. If you only need 1/8" more fluid volume (or if the 1 1/4" bore is too large for you resulting in a hard pedal) this is the best swap I think. If the resevoir fits under your hood that is. Swapping the XJ MC resevoir and the Durango resevoir is not doable as the spacing isn't correct.



Just for reference, it appears that up until 1999, the E-350 MC has two options, below 9500lbs GVW has a 1 1/16" MC and above 9500lbs GVW has a 1 1/8" MC. Correct me if I'm wrong, but that's what it appears. 1999 and newer has a few options and I'm not going to get into them, but they were mostly 1.3.....+" bore MC



next post....

Alright, the resevoir for the Durango, Dakota, and Ram are the same part number and are obviously, the same resevoirs. For the following, refer to the pictures above if you get lost. For starters, the Dodge is a bit wider of a resevoir. An XJ resevoir is about 3" tall by 5" long and 3.75" tall if you include the cap. The Dodge resevoir is about 3" tall (3.75" with the cap) and about 5" long. Seems like it will fit, however, you have to take into consideration the angle that it's mounted at. The Dodge resevoir is not designed to be mounted at an angle, so it is about 3" tall from tip to tip where as the XJ resevoir is more of a triangle shape. So what is missing on the XJ resevoir on the bottom, you can pretty much add to the top front and that's how high it's gonna sit. The part that may save us is the cap on the Dodge. It's designed with the cap towards one end, so it we mount the cap to the rear (giving us less resevoir space and therefore less fluid....might be enough, might not...) it might clear the hood. If the cap is mounted towards the front, you can get more fluid in there than required if you wanted, but you might not clear the hood. It's all still going to be trial and error, but we'll find out soon enough.



next.....

Quote:
Originally Posted by Speed_racer
"From what Ive read, go WJ. "



To be totally honest, that doesn't help this thread much. The WJ's have a MC with a 1" bore, no greater than a late model XJ. This brake stuff is so muddied up with contradicting info.....Grand Cherokees are pretty much only good to the guys looking for different proportioning valves. The difference between the XJ and the WJ (and ZJ for that matter) is the proportioning valve. The MC is the same between the two and the booster really doesn't do much in the way of volume; only pedal effort. So if you're looking to upgrade and early XJ with a single diaphram booster, that's a complete swap in my book, going to a WJ or ZJ brake system.....However, if you've upgraded axles and have therefore increased your piston size and volume, you'll need not only a prop valve change, but a larger MC as well. I appreciate you're input in the matter and yes, a WJ swap is an exellent option with only upgraded rear disc's and not a whole shooting match like a few of us have done.


Next....

Its VERY close, but it fits just fine in a 1999 XJ with the resevoir cap in the front. The Durango/Dakota MC/resevoir will fit a tad better as it's missing about 1" of the length as the Ram MC and they take it out near the firewall, so the resevoir is pushed back closer to the firewall than the Ram's (which is downhill and will move it further away from the hood). So freakin A it works. Now its just a matter of putting a spacer or whatever I need to get the pushrod to work as well as deciding if I need the 1.25" bore or if that will be too much fluid for me. I sure hope not. We'll see as soon as I figure out what this spacer needs to look like!


next...

Well, after much thought, I decided to go and swap out MC's with the Durango instead of the Ram becasue of the pushrod issue as well as I thought that it would be almost too much fluid with 1/4" larger piston size. My brakes are stiff now and will stop me really fast, however, they do not lock my tires up which is good, but won't hold the Jeep when powerbraked. I have a feeling that the 5.13's might be a bit much for my brakes when I'm hitting the torque converter stall limit, but I'm overall happy with the swap. It couldn't have been easier, pull the old MC off, put the new one on, bleed everything. By the way, I have an XJ prop valve body with a ZJ piston and spring minus the O-ring if that helps at all. Any thoughts on the swap?

Pic's...leaving them where they are...go look and see...

Good work, excellent post 53guy...

yup yup...any time.

Just thought I'd add that according to napaonline.com, the '99 Dakota, 1.125 bore MC (2-wheel disc) has the same part number as the '04 Dakota, which has 4-wheel discs. The part number is TS 102967--re-built MC.

Lots of info, thanks for the effort 53guy.
However, your post doesn't indicate what size brakes/calipers you are running. I'm running the 3/4 ton large Ford dual piston calipers, and D60 drums in the rear. I believe I need a 1.25 bore MC that will seal to the 01 XJ dual diaphram booster, and a proportioning valve for disc/drums.
So from your post, it appears I need the 1999 Dodge 3500 MC. Is that correct?

Thx.

53GUY, not clear on the conclusion of your upgrade. Did you install the Durango 1.125 MC? You stated that "my brakes are stiff now, and I can't lock them up--", is this after the MC install?
Also, if you did the Durango install, what mods, if any, did you do to the push rod going into the MC?
Thanks
Good wright-up

Lots of info, thanks for the effort 53guy.
However, your post doesn't indicate what size brakes/calipers you are running. I'm running the 3/4 ton large Ford dual piston calipers, and D60 drums in the rear. I believe I need a 1.25 bore MC that will seal to the 01 XJ dual diaphram booster, and a proportioning valve for disc/drums.
So from your post, it appears I need the 1999 Dodge 3500 MC. Is that correct?

Thx.

Go to the link, it says it there, but anyhow, I'm running Waggy dana 44 front and a dana 44 rear with disc's, so figure they're both 1/2 ton gear. Yeah, I'd try the Ram MC. They do bolt right up (if I remember correctly, the ram didn't need any work to bolt up, but I could be mistaken. Just compare the Durango one with the ram one when you buy them to be sure) but you'll need to fab up a spacer. I never got to do the spacer, so I'm no help there....sorry.




53GUY, not clear on the conclusion of your upgrade. Did you install the Durango 1.125 MC? You stated that "my brakes are stiff now, and I can't lock them up--", is this after the MC install?
Also, if you did the Durango install, what mods, if any, did you do to the push rod going into the MC?
Thanks
Good wright-up


I did install the Durango MC and yes, after the MC install my brakes are a bit stiff....they stop very well, but I cannot lock them up like you can in a stock xj. The Durango MC requires NO mods to the pushrod, only bending the stock lines around a bit. Because you're throwing a new MC on, you might have to adjust your brake light switch, but that's no big deal and takes a second under your brake pedal. If anything, I'd say that I have slightly too much volume for my brakes, but like mentioned before, it might just be a break pedal issue.

So my XJ is an 1989 with a D44 and (" with Chev 1/2 ton brakes in all four corners,.. maybe its the lack of coffee in my system but I am still unsure on which MC I should run in mine so I can stop... and I am also now without a proporting valve,.. so will that effect anything with the MC swap?

what is a master cylinder?

So my XJ is an 1989 with a D44 and (" with Chev 1/2 ton brakes in all four corners,.. maybe its the lack of coffee in my system but I am still unsure on which MC I should run in mine so I can stop... and I am also now without a proporting valve,.. so will that effect anything with the MC swap?

The MC's that I posted really wouldn't apply to you much at all. They are for the NEWER XJ's with dual diaphram boosters. I've done about zero research on the early model XJ's, but from brousing I think that the E-350 would be a good choice for you. I don't know what that would entail, but look around here and on NAXJA and you'll find tons of info on them.




what is a master cylinder?

Refer to post 13.....:flipoff2:

I have Chevy 1/2-tons on the front and Cadillac metrics on the rear of my '88 Cherokee. I upgraded to a MC from a '76 Mercury Marque, with hydro boost brakes. It's meant for 4-wheel disc applications, has a 1.125 bore, bolts up without mods to it or the booster, and the ports are on the same side as the stock MC, so no brake line mods required. I did have to use an adapter on one of the lines--the ports are the same size/thread, but swapped front/rear, and I adjusted the stock push rod for optimum length.
http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=101603&Description=Brake+Master+Cylinder+-+Remfd

Well I am personally in this whold MC issue right now,... D44HP & 9" combo with Chev 1/2ton calipers in all four corners,..stock master could only slow it if you pumped it up,.. tried a 4wheel disk WJ MC,.. No luck same result,... so I am in a bind I even tried yoinking the stock proportioning valve ,.. I can't stop the ol'best on the 35's and new diffs :(

Here's my experience, for what it's worth.

I have an '88, with a HP44 and Chev 1/2 ton calipers, and Explorer discs in the rear, and I have an '89 with HP60 with Chev 1/2 ton calipers and Explorer discs in the rear. Both rigs have the later model ('96+) dual booster and master cylinder, no modifications to the proportioning valve, and both rigs stop well. The upgrade to the dual diaphram made a difference. I can't lock them up, I'm running 37's, but the brake pedal feel is good and it stops quickly.

It looks like the Chev calipers you have in the rear are a little bigger than the Explorer calipers, so that might be an issue needing more fluid capacity. Are you just running out of pedal? Sure it's bled real good? A smaller bore master cylinder will provide more pressure, but less volume, while a larger bore will provide more volume but less pressure. So, there needs to be some sense of what the problem is to determine how large a bore is needed in the master cylinder. If you still have the original booster, upgrading to the later dual diaphram will be an improvement.......maybe all that you need.

Nice info all. I am looking at this now. My '90 with HP44 and 9" with all ford disks and drums stops lousy. I'm running out of pedal. I have readjusted and bled everything several times I have the original booster. I am thinking of changing the MC. So will the ford E350 work in this application? Why this over the dodge? If they have the same bore and the dodge bolts up doesn't that make it easier? Thanks for the help.

Nice info all. I am looking at this now. My '90 with HP44 and 9" with all ford disks and drums stops lousy. I'm running out of pedal. I have readjusted and bled everything several times I have the original booster. I am thinking of changing the MC. So will the ford E350 work in this application? Why this over the dodge? If they have the same bore and the dodge bolts up doesn't that make it easier? Thanks for the help.

Its not a matter of what brand or type, its a matter of what booster you have as to which one to use. The dodge will bolt up to a dual diaphram booster where as the E350 will "bolt up" to the single diaphram booster. The dual diaphram booster has a built in angle on the mating surface where it bolts to the firewall making some MC's unusable becasue of hood cleance....although not so much with the MC, just the resevoir. Also, be aware that pretty much anything with the dual diaphram booster and without the XJ resevoir (which you can't reuse on any of these), the resevoir will be mounted at an angle, making the front pool have less brake fluid and the rear be almost overfilled. Just something to watch for and keep on top of brake ware and fluid levels because you won't have as much fluid.

As far as if the e-350 will work in your application...yes, but stay with your single diaphram booster. If you have a dual diaphram booster, the dodge will work. Then its up to you to decide what size bore.

I started messing with this a while ago, got frustrated, and put it on the back shelf for a while.

My XJ is a '94, which was the changeover year for the dual-diaphragm booster. I've got a D60 front with the 3/4-ton large single-piston calipers, and 14ff rear with the 1/2-ton caliper conversion.

First thing I did was the E350 MC, because we had one laying around. Not even close to working on the newer style booster.

Next, I got the Dodge 2500 MC, which ALMOST bolted right up to the booster. I had to file the inside edges of the holes slightly to fit it down over the studs on the booster. This looked promising until I went to close the hood, and the reservoir didn't clear. Oops.

At this point I put the ZJ 4-wheel disc MC back on, bled everything through, and now it stops. Pedal feels really mushy and goes to the floor (almost) but it's a fluid volume issue at this point. Luckily the calipers are big enough that it still does a good job of holding on hills and stopping in general (even with the 39.5s), but I'd like to do something better in the near future as wheeling season is starting up again.

Does anyone have anything conclusive as to what would work best here? I still have the Dodge MC laying around so if there's a smaller reservoir that works I could try that...or if anyone has the same caliper setup on the Durango MC I'd give that a shot as well.

OK here is my whole diff swap/brake issue story:

I cam across a D44 HP and 9", rebuilt them with the help of my buddy took 2wd chev calipers from a 1/2 ton modded the backing plates to fit on the 9" flanges, swapped in some Chev knuckles on the D44 to accept the chev calipers butt still use the ford rotor and hub assembly,.. so now I have 1/2 chev in all 4 corners,.. Now,.. Diffs in , lines in, all ready to go blead the system and all feels good pedals firm,.. pop in the fuel cell and fire it up,.. as soon as I have the engine running pedal pressure drops to the floor,... bleed again,...and again, swap in a 4 wheel disk Grand Cherokee MC,.. same result,.. yoing the proporting valve ,... tried without it,.. still same result,.. if your rolling can't stop it until it slows to a crawl,..and you have to pump it a few time to stop it won't even come close to locking it up,... so needless to say I missed an event due to my oversight :( so now I need to find a MC to make enough pressure to even engage the rear brakes,.. I want to get this thing road safe next week,..and frankly the brakes are whats holding me up,.. so I'd love to find the best MC with little to no brake line mods,... now do I need to put that proporting valve back in or just go with the MC straight up and what type? My truck is a 1989 XJ

Jenssen, the answer to your question is in this thread!

OK here is my whole diff swap/brake issue story:

I cam across a D44 HP and 9", rebuilt them with the help of my buddy took 2wd chev calipers from a 1/2 ton modded the backing plates to fit on the 9" flanges, swapped in some Chev knuckles on the D44 to accept the chev calipers butt still use the ford rotor and hub assembly,.. so now I have 1/2 chev in all 4 corners,.. Now,.. Diffs in , lines in, all ready to go blead the system and all feels good pedals firm,.. pop in the fuel cell and fire it up,.. as soon as I have the engine running pedal pressure drops to the floor,... bleed again,...and again, swap in a 4 wheel disk Grand Cherokee MC,.. same result,.. yoing the proporting valve ,... tried without it,.. still same result,.. if your rolling can't stop it until it slows to a crawl,..and you have to pump it a few time to stop it won't even come close to locking it up,... so needless to say I missed an event due to my oversight :( so now I need to find a MC to make enough pressure to even engage the rear brakes,.. I want to get this thing road safe next week,..and frankly the brakes are whats holding me up,.. so I'd love to find the best MC with little to no brake line mods,... now do I need to put that proporting valve back in or just go with the MC straight up and what type? My truck is a 1989 XJ


Do you have a dual diaphram booster? I would never run a single (pre like 95) again. Just the boster helps alot. Allows more pressure. If you do have a dual I would start there. I have the dual ford front calipers and K20 rear's and will be trying the stock WJ booster and MC without the prop valve, like it is now. I dont run a prop valve and have never had issue of locking up rears, but that was with the 8.8 rear disc and stock 90 front xj D30 stuff.

Well after reading over the past week about this, I found the ram 1500 MC new with res. for 68$ delivered. SO I did that in anticipation of the stock WJ stuff not being enough fluid for the D60 front ford dual piston calipers as well as the K20 rear's. I will come back later in the month and post the outcome. I have to get the front end in first.

How about posting where you got "--I found the ram 1500 MC new with res. for 68$ delivered." That's the best price I've heard of.

How about posting where you got "--I found the ram 1500 MC new with res. for 68$ delivered." That's the best price I've heard of.

http://www.usautoparts.net/

bump for tech info

So has anyone in this thread made any progress with replacing their MC in a 97+ XJ? I have my D44 installed in my 01 XJ with the large Ford dual piston calipers. I am at the point where I need to buy/install a new MC. I guess I'm going to try the Ram 3500 MC.

So has anyone in this thread made any progress with replacing their MC in a 97+ XJ? I have my D44 installed in my 01 XJ with the large Ford dual piston calipers. I am at the point where I need to buy/install a new MC. I guess I'm going to try the Ram 3500 MC.


Next, I got the Dodge 2500 MC, which ALMOST bolted right up to the booster. I had to file the inside edges of the holes slightly to fit it down over the studs on the booster. This looked promising until I went to close the hood, and the reservoir didn't clear. Oops.


Try it and let us know how it works out.

Well after reading over the past week about this, I found the ram 1500 MC new with res. for 68$ delivered. SO I did that in anticipation of the stock WJ stuff not being enough fluid for the D60 front ford dual piston calipers as well as the K20 rear's. I will come back later in the month and post the outcome. I have to get the front end in first.

Well let it be known that the dodge 1500 master does NOT bolt up or even close enough to elongate the holes to bolt up. Not to mention the pushrod tube in the master is not present on the dodge.

I guess I will go get the durango and see if thats a bolt on.

This tread turned out to be like so many.. So much wrong info or people just saying what they "heard" or "read" and theres bogus info within. Sure hope to find a MC that bolts to a WJ booster.

1999 Dodge Dakota and Durango MC, 1 1/8" bore, M10-1.0
M12-1.0 lines

http://partimages2.genpt.com/partimages/357565.jpg
..

Umm bogus info????

Straight from Wagner brake web site.
New Master Cylinder
15/16" MC134437

https://mfr.activant.com/mfrserv/app/FMO2/bg_lookup_process.jsp?action=bglookup&partnum=F134437

For instance, the early "vette" and Mercury Grand Marque MC's have 1.125 bores, compared to the XJ 15/16 bore,.

Well wagner says that the 1990 Vette is a 7/8" bore?

great thread guys. **increased pedal travel when going to larger calipers is the thread topic. I just wanted to add an opinion for the guys that need more braking with stock calipers.

I was wondering why no one has addressed the issue of fluid and brake pads. At highway speeds, where we need good braking the most, it does not matter how hard the caliper is able to squeeze the pads on the rotor, the problem is heat.

When we are running heavier wheels, larger rubber and have extra equipment on our rigs, rotors glow red with heat. Stock pads build up gas, heat, and brake fade is almost instant. Fluid boils and causes pedal fade also.:evil:
Good Performance pads don't gas or fade like stock, or even "Gold, Premium, Auto Parts best". Sport rotors(slotted, or drilled) will de-gass stock pads well, but aren't needed as much when running good pads.

I would go for a good set of pads before swapping out MC's.

"78 Corvette MC, power brakes: http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=101749&Description=Brake+Master+Cylinder+-+Remfd
'99 Dodge Durango: http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=102967&Description=Brake+Master+Cylinder+-+Remfd
'99 Dodge Ram 1500: http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=102867&Description=Brake+Master+Cylinder+-+Remfd
You need to know the year and application for the components--no one said anything about a '90 Vette.

"78 Corvette MC, power brakes: http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=101749&Description=Brake+Master+Cylinder+-+Remfd
'99 Dodge Durango: http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=102967&Description=Brake+Master+Cylinder+-+Remfd
'99 Dodge Ram 1500: http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=102867&Description=Brake+Master+Cylinder+-+Remfd
You need to know the year and application for the components--no one said anything about a '90 Vette.


well it Was mentioned up in the early treat post that a 90 vette was the upgrade.

As for the napa listed bore sizes. Thats interesting. I dont know which to believe, a auto parts store listing or a manufacture of the master cylinder.

PS not saying that in a derogitory way. Just seriously I dont know which to believe.

Right from my company. We make just a crap load of MC's and the durango is 15/16"

https://www.dormanproducts.com/cgi-bin/vm91corp30r/item-dtl.w?sid=0x01a39991&item=M134437&icrid=0x0081d1ad&clt=hwrap1&vsrch_str=&vsrch_brand=&vsrch_cat=&st_amount=&end_amount=&start=&vfrom=&prev=&vnext=&category_list=:0

And here is the 99 Ram MC 1-1/4"

https://www.dormanproducts.com/cgi-bin/vm91corp30r/item-dtl.w?sid=0x01a39991&item=M390426&icrid=0x0081d22e&clt=hwrap1&vsrch_str=&vsrch_brand=&vsrch_cat=&st_amount=&end_amount=&start=&vfrom=&prev=&vnext=&category_list=:0

I hear you, Lookin4fun, I've also read until I'm dizzy, trying to sort out the "fact" from "hear-say". The Napa on line site says one thing, and evidently Dorman lists the Durango at 15/16--in direct conflict with Napa, and the experience of others (53guy). Like I said, you need to know the year and application before zeroing in on a possible upgrade. Example, the '78 Vette came with power and non-power brake applications; the power brake application has the 1.125 bore, while the non-power assist MC has a smaller bore. Also, how many times have you gone to a parts house looking to replace a stock part, only to have the parts guy tell you what you have didn't come off your Jeep? It's certainly happened to me, more than once over the years. When some one says they actually bought and installed something, again like 53guy, I have to accept that it's probably true. The only way I could argue with that kind of "evidence" is to have done it myself, and know it won't work.

Ok guys i put a new MC in my dakota with is the same as the durago. I will measure it for you guy just tell me what exact part i need to put the ruler on. I will post the pictures.

I got all excited about the possibility of using the '99 Durango MC--1.125 bore. Then someone stated on another forum that a mfg tech guy told him it was a step bore, with the 1.125 being the small section. Can anyone verify this? If so, what's the step ID? And does it mater any way?

Ok guys i put a new MC in my dakota with is the same as the durago. I will measure it for you guy just tell me what exact part i need to put the ruler on. I will post the pictures.

Well, the mounting flange, distance from hole to hole.
Diameter of the bolt holes.
Diameter of the end of the master cylinder that fits into the booster.
Diameter of the bore/piston if that is possible.
Not sure what else if anything is needed.

Well, the mounting flange, distance from hole to hole.
Diameter of the bolt holes.
Diameter of the end of the master cylinder that fits into the booster.
Diameter of the bore/piston if that is possible.
Not sure what else if anything is needed.

Well only #1 and poss #2 is really all that important.

The durango and dakota both have a "severe duty" option I found. If you go to most auto parts stores they only list teh reg ole one for 00% of those out there. Of which are a 15/16" bore. The SD ones though have the mentioned stepped bore with the 1-1/8 small size, large I didnt write down. That part number is A1C132967 or 13-2967.

I go down to kragen today to get mine after work, they had to order it. New with res was 68$. I will post as to what I find.

AS I understand it, the newer (post '80s?) step-bore, or "quick take-up" MC's are designed for "quick take-up" calipers. These calipers have a different piston seal that pulls the piston back inside the caliper bore ~.080 after each application of the brakes. The idea is to increase gas mileage by reducing caliper drag. The 2-step MC's have a valve in them that reacts to high pressure, resulting in the fluid from the larger piston being "vented" to the reservoir after the pads make contact with the rotors. On initial application of the brakes, the larger volume (lower pressure) from the the big piston flows past the smaller piston, "quickly" moving the piston into contact with the rotor. As the pressure builds upon contact, the valve in the MC vents the large piston fluid into the resivoir, and the high pressure from the smaller piston is used to apply the stopping power. How this design will work with non-quick take-up calipers needs to be understood. It may be just the ticket for retrofitting larger calipers onto older trucks.

Do you have a dual diaphram booster? I would never run a single (pre like 95) again. Just the boster helps alot. Allows more pressure.

Excuse my ignorance but how can you tell a single VS a Dual diaphram booster?

The difference between the two is the length: Here's a '90 single diaphragm http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=NBB&PartNumber=5474071&Description=Power+Brake+Booster+w%2fo+Master+Cylin der and here is a '94 dual diaphragm http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=NBB&PartNumber=5473192&Description=Power+Brake+Booster+w%2fo+Master+Cylin der

I am 95% sure mine is the single in the 1989 Cherokee I have I will have to check it out at the storage yard to see for sure so if I run the ___year E350 MC sans the proporting valve I should be ok is what the concencious is,..?

The '89 XJ came stock with the single diaphragm booster.
The E350 MC that fits your booster is meant for disc/drum applications. I'd use the '76 Mercury Marquis unit intended for hydro boost; it's 1.125 bore, intended to be used for 4-wheel discs, and does not require any grinding to fit. The fittings are on the same side as the xj. One line from the combination valve connects without any change, and the other requires an adapter. Easy as pie, and should work fine with your 1/2-ton brake calipers. http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=101603&Description=Brake+Master+Cylinder+-+Remfd

THANK-YOU-THANK-YOU-THANK-YOU-THANK-YOU-THANK-YOU-THANK-YOU! I plan on attacking it sunday so hope all ges well , now I am sans proporting valve that will be ok correct?

More than likely OK. If you find your rear wheels locking up before the fronts, then you probably should either install a ZJ combination valve (one meant for 4-wheel discs) or an adjustable proportioning valve in the rear brake line.
Good luck. Please document what you did and report back.

More than likely OK. If you find your rear wheels locking up before the fronts, then you probably should either install a ZJ combination valve (one meant for 4-wheel discs) or an adjustable proportioning valve in the rear brake line.
Good luck. Please document what you did and report back.


WILL DO! Saturday or Sunday is the day to get it back on the road! Its been MIA since July1st weekend :( Then its just a matter of making the motor happy :)

ALL RIGHTY! I called Partsource and in Canuck bucks the MC is $40.89 before discount (Fenco PN M1603) for a 1976 Merc Marquis w/ 4 wheel disk brakes and hydro-boost ,.. it should be in tomm so hopefully this weekend I can drive my Heep after 9 months!
Thanks again and I will get some pics and info on the swap

good topic... free bump

Jenssen, get back to us on results, or add your results to the "new" MC thread.

Jenssen, get back to us on results, or add your results to the "new" MC thread.



OK Guys the 1976 Master Cylinder fits like it was made for the Jeep,... awesome,..:smokin: :D had to yank the lines a bit to fit into place and man o man is it bigger,..PICS to follow,... now after bleeding the system AWESOME brake pressure,... but alas as I drove it the system lost pressure,..odd I know pump it up and whammo mucho brakes,..
So as I was bleeding the rear passanger side I noticed a weird sound,.. it was like blowing through a blade of grass,.. I think I have one bad caliper in the rear that may be backing off a bit as when you pump it up its ok,..
Now I am running Chev Front calipers in all 4 corners and didn't think that would be an issue so back to the Jeep tonight to try two new rears,...

-So the coombo for brakes to date is
-4 Chev Front calipers in all 4 corners
-1976 Ford MC w/ Hydroboost
-Stock Lines
-braided lines in place of flex hoses,..
-no proportining valve

Any insight on the pressure drop?:confused:

OK Guys the 1976 Master Cylinder fits like it was made for the Jeep,... awesome,..:smokin: :D had to yank the lines a bit to fit into place and man o man is it bigger,..PICS to follow,... now after bleeding the system AWESOME brake pressure,... but alas as I drove it the system lost pressure,..odd I know pump it up and whammo mucho brakes,..
So as I was bleeding the rear passanger side I noticed a weird sound,.. it was like blowing through a blade of grass,.. I think I have one bad caliper in the rear that may be backing off a bit as when you pump it up its ok,..
Now I am running Chev Front calipers in all 4 corners and didn't think that would be an issue so back to the Jeep tonight to try two new rears,...

-So the coombo for brakes to date is
-4 Chev Front calipers in all 4 corners
-1976 Ford MC w/ Hydroboost
-Stock Lines
-braided lines in place of flex hoses,..
-no proportining valve

Any insight on the pressure drop?:confused:


Well can you elaborate more all in one post as to what exact: Booster, MC and calipers your running? in 76 theres a few different MC I would think, as well as chevy calipers, and no mention of what booster at all?

Thanks

-M/C Fenco PN M1603 for a 1976 Merc Marquis w/ 4 wheel disk brakes and hydro-boost
-1980's Chev 1/2 2wd Front Calipers in all 4 corners
-Booster - Factory XJ http://partimages2.genpt.com/partimages/78217.jpg

-M/C Fenco PN M1603 for a 1976 Merc Marquis w/ 4 wheel disk brakes and hydro-boost
-1980's Chev 1/2 2wd Front Calipers in all 4 corners
-Booster - Factory XJ

Well almost got the exact fitment lol

What yr and type (if you know dual or single) booster is it?

Updated: See pic

Lookin4fun, I suggest you re-read this whole thread; the answers to your questions have already been answered. "--The '89 XJ came stock with the single diaphragm booster.--". "-- I'd use the '76 Mercury Marquis unit intended for hydro boost; it's 1.125 bore, intended to be used for 4-wheel discs, and does not require any grinding to fit--"
http://napaonline.com/masterpages/NO...linder+-+Remfd

So back to my loosing pressure dilema,... do you think a rear caliper backing off due to being a used junk yard piece could be at fault?

Lookin4fun, I suggest you re-read this whole thread; the answers to your questions have already been answered. "--The '89 XJ came stock with the single diaphragm booster.--". "-- I'd use the '76 Mercury Marquis unit intended for hydro boost; it's 1.125 bore, intended to be used for 4-wheel discs, and does not require any grinding to fit--"
http://napaonline.com/masterpages/NO...linder+-+Remfd

if you re read too much you come to the same conclusion as so many MC/Booster/Caliper/WC threads come to. Too much partial info and not enough all in one post info. Thats why I asked for the exacts for his working setup. Why knows if at somepoint he or anyone else for that matter, didnt swap Boosters or such.

Its just nice to get the exact fitment of what actual Fit together.

And still dont know if thats a single or dual in his post, but hey you can only expect so much over the internet huh.. Nice picture though, kinda looks like a power booster thats for sure. which well if you have a new one and you can hold in it your hands and just compare with the same exact front view then I guess you can see if its what you got. But what yr and model sure would have been alot more informitive and reduce future error by others.

So back to my loosing pressure dilema,... do you think a rear caliper backing off due to being a used junk yard piece could be at fault?

well as I see it there is only a few possibilities

there is air in your brake system somewhere, did you bench bleed the new mc?... keep bleeding.

or you have a leak, have someone stand on the brakes while you crawl around looking for a drip.

your brake fuid is contaminated...is there a chance you mixed different types of fluid.

or you have a bad connection at the mc or distribution block that is sucking in air...

did you eliminate the residual valve that was there for the original drum brakes?

Don't know what else it could be, but I'm no expert.

if you re read too much you come to the same conclusion as so many MC/Booster/Caliper/WC threads come to. Too much partial info and not enough all in one post info. Thats why I asked for the exacts for his working setup. Why knows if at somepoint he or anyone else for that matter, didnt swap Boosters or such.

That's why I started the other thread. :D

Funny, the more I drive around on mine, the more I like it. About 120 miles so far on 39.5s with the large single piston front 60 calipers, 1/2-ton GM calipers in the rear, '95 ZJ master cylinder and prop valve (from one with 4-wheel disc), '95 ZJ dual-dia booster. Brings it down hard enough from 60 MPH that everything in the back flies forward and hits the back of my seat. As I drive it around more I'm less motivated to try and sift through all this crap and find something that might be only marginally better. :shaking:

Adding a 2lb inline check valve to try and correct my brake issue,...

Jenssen, what year calipers? Newer calipers are "low drag" design, meaning, the pistons retract further into the pistons and require a "quick-take-up" MC to work. GM went to this design in the '80's. Also, you don't want to put any residual pressure valves in your XJ brake system. You need to determine why you're loosing pedal. Do you know if it's the front or rear circuit, for sure? Clamp each flex line at each caliper, one at a time, and test for pedal firmness. If one moment you have a firm pedal, then the next moment it goes to the floor, and there's no sign of leaks any where, that indicates an internal leak in the MC. Clamping off your calipers should help diagnose what component is failing.

Jenssen, what year calipers? Newer calipers are "low drag" design, meaning, the pistons retract further into the pistons and require a "quick-take-up" MC to work. GM went to this design in the '80's. Also, you don't want to put any residual pressure valves in your XJ brake system. You need to determine why you're loosing pedal. Do you know if it's the front or rear circuit, for sure? Clamp each flex line at each caliper, one at a time, and test for pedal firmness. If one moment you have a firm pedal, then the next moment it goes to the floor, and there's no sign of leaks any where, that indicates an internal leak in the MC. Clamping off your calipers should help diagnose what component is failing.

Unfortunatly I am not sure what year the rear calipers are,..80's Junk-yard parts as is my whole truck,..but as a side not the front and rears "look" the same but the rears have a fine thread bleeder screw,..
Now the system pumped up works like a hot damn but when I bled the rears I could hear the PS rear caliper sqeeking like it was backing off alot so I may just swap out both rears for ___year Chev truck,.. as they are used. Now I was told by my Mechanic friend at a 4x4 shop they ran into this with Jeeps and 4 wheel disk conversions before ergo the 2 lb check valve to keep a little pressure on the rear,... I can try the vise grip test on the fronts as I have yet to put the braided line on there but the rears are all stainless lines,.. no visable leaks on the MC or on the lines or calipers :$

Is it possible that you are using newer low-drag disc brake calipers, with an older non-quick take-up master cylinder?

Quote:
Several carmakers use fast-fill or quick take-up master cylinders. These cylinders fill the hydraulic system quickly to take up the slack in the caliper pistons of low-drag disc brakes. Low-drag calipers retract the pistons and pads farther from the rotor than do traditional calipers. This reduces friction and brake drag and improves fuel maileage.

If a conventional single-bore dual master cylinder were used with low-drag calipers, excessive pedal travel would be needed on the first stroke to fill the lines and calipers with fluid and take up the slack in the pads. To overcome this problem, fast-fill and quick take-up master cylinders provide a large volume of fluid on the first stroke of the brake pedal.......

See full article here: http://books.google.com/books?id=5rW-ppyB_ugC&pg=PA75&lpg=PA75&dq=master+cylinder+caliper+piston+drag&source=web&ots=farCdcpBtj&sig=I_sD5ruqaFucQUIdlPje35ZLC_g

Is it possible that you are using newer low-drag disc brake calipers, with an older non-quick take-up master cylinder?

Quote:
Several carmakers use fast-fill or quick take-up master cylinders. These cylinders fill the hydraulic system quickly to take up the slack in the caliper pistons of low-drag disc brakes. Low-drag calipers retract the pistons and pads farther from the rotor than do traditional calipers. This reduces friction and brake drag and improves fuel maileage.

If a conventional single-bore dual master cylinder were used with low-drag calipers, excessive pedal travel would be needed on the first stroke to fill the lines and calipers with fluid and take up the slack in the pads. To overcome this problem, fast-fill and quick take-up master cylinders provide a large volume of fluid on the first stroke of the brake pedal.......

See full article here: http://books.google.com/books?id=5rW-ppyB_ugC&pg=PA75&lpg=PA75&dq=master+cylinder+caliper+piston+drag&source=web&ots=farCdcpBtj&sig=I_sD5ruqaFucQUIdlPje35ZLC_g

Very possible as the rears have a fine thread newer looking bleeder,.. unlike the fronts which use a coarse thread,.. so what year Chev trucks had the old style not the low drag?

Pre '80s for sure; I'm using 1976 Chevy 1/2-tons on the front, and '85 Cadillac on the rear, with parking brake (these don't use the low drag calipers).

Tech to the top BS to the bottom...

Tech to the top BS to the bottom...

Is today like a posting spree for u or somthing?

theres obviously not a mod thats moving or deleting bs threads so he is moving up all the threads that actualy belong here , by doing so the stupid noob threads move down to the bottom and to the next page.

thanks for your effort TJP, they should make you a mod so you can move the bs threads to the noob forum

Is today like a posting spree for u or somthing?

Just doing a clean up on the forum since there isn't a moderator to do it.

I just get disgusted with this forum looking like JU. I want to see this forum grow into the best place to find hardcore tech on the net. There is the non-hardcore jeep forum for newbie ?'s. NAXJA is also a great source for info.

This forum was meant to be for hardcore tech, there are more than enough other forums that the "what tire is best" or "which 3" lift should I buy" around to get those ?'s answered at.

This is for the guys how fab there own parts and think outside of the box.

Think of it as an advanced college level forum. You have a grade school question ask it at JU... A question in between those is where NAXJA or the JeepForum fits in.

Now back to the regularly scheduled programing....

Just doing a clean up on the forum since there isn't a moderator to do it.

I just get disgusted with this forum looking like JU. I want to see this forum grow into the best place to find hardcore tech on the net. There is the non-hardcore jeep forum for newbie ?'s. NAXJA is also a great source for info.

This forum was meant to be for hardcore tech, there are more than enough other forums that the "what tire is best" or "which 3" lift should I buy" around to get those ?'s answered at.

This is for the guys how fab there own parts and think outside of the box.

Think of it as an advanced college level forum. You have a grade school question ask it at JU... A question in between those is where NAXJA or the JeepForum fits in.

Now back to the regularly scheduled programing....

Ok that makes sence. :D

Since a few of you mentioned wanting the Vanco system but the $ hurts (and I know it does). For $6.00...

http://www.pirate4x4.com/forum/showthread.php?t=576622

I have a 1999 or 2000? durango mc on my zj and it is 1 1/8. I think when I was going through mc's at the parts store the 98 durango and older had smaller bores. I have ok brakes with my stock ZJ mc but the pedal went nearly to the floor, now it is nice and firm. I run chevy 1/2t front and isuzu rear calipers.

Reedzj--a little more info please? Year of ZJ? Any mods required to bolt-up Durango MC?

I have a 96 with stock booster. It was an easy bolt on swap. I am not positive on the year of the master cylinder but I think it was a 1999durango from Napa. I will try to find the part number for you.

Adding a 2lb inline check valve to try and correct my brake issue,...

Any updates yet?? I'm running the exact same setup as you are (92 booster, Chevy calipers F/R) and waiting to see what happens! I'm looking at the 69 Vette Master, but want to see what your results are first!!

Any updates yet?? I'm running the exact same setup as you are (92 booster, Chevy calipers F/R) and waiting to see what happens! I'm looking at the 69 Vette Master, but want to see what your results are first!!

Well It's crunch time ,.. It's Monday night and I NEED the Jeep as soon as Wednesday, So I ordered 4 Fenco 76 Chev 1/2 ton calipers, the check valve (JIC) and have already installed the new MC so I am gonna swap in 4 brand new calipers (no low friction) bleed and test te system,.. if need be the check valve will go into the rears,.. keep posted for pics of the MC swap and such,..

Thanks again!

BTW: What do you think customers will say if I roll up in this on a sales call for for a Equipment Company,... hehehehe I just got a new job so the ol girl may be doing sales calls!

http://i7.tinypic.com/24cul3t.jpg

Ok is there anything else I may be overlooking on brakes that pump up ok but loose pressure after driving? I want to make sure I have all the bits to do this one last time. Could anything else be messed up? Front to back reversed lines wise? Vacume issues? Anything small and easily overlooked? Vac diaphram??

Ok is there anything else I may be overlooking on brakes that pump up ok but loose pressure after driving? I want to make sure I have all the bits to do this one last time. Could anything else be messed up? Front to back reversed lines wise? Vacume issues? Anything small and easily overlooked? Vac diaphram??

Yes, call me.

Thanks for the insight Sir! I will try the ideas you had starting with the caliper bleeding techniques first!
1- Skid old calipers
2- Re-Bleed system "properly"

What does "skid old calipers" mean?

I think perhaps he means Flip old calipers.

I think perhaps he means Flip old calipers.



Nope I meant skid'em and replace with new units,.. I don't want anymore variables,..and for $22.00 for a reman it makes me sleep well,.. :smokin:

clean up

JENSSEN, any update? Other then that calipers, any ideas? I'm getting ready to do this, just want to see if I'm going the right direction.

JENSSEN, any update? Other then that calipers, any ideas? I'm getting ready to do this, just want to see if I'm going the right direction.

Aything yet?

Aything yet?

Yup! Properly bled the rears and installed new rear caliper,...and WOW they work well now,.. now just have to put the rear lines to the right portion of the MC and do the same to the front LOL I have them bassackwards,... give me a day or two but its all coming together,... and I can hold back the jeeps motor now floored! more to follow

Any body know what the threads are on a 1990 XJ MC. I have a brand new 85 E350 MC sitting in front of me and it has 7/16-24 and 3/8-24 threads.

'90 XJ MC=7/16-24 and 1/2-20

Well I am glad my only thread in here lasted this long haha

I gues I was lucky when it came to my axle swap. When I did my 60 front 70 rear in my ZJ I didn't have to change the MC and it will lock all 4 tires up no problem. However I am in this boat with my Scrambler. I can't seem to get this thing to stop for shit, seems like I only have back brakes. It has a 60 front and a 14 bolt rear. Good thread, thanks for the info.

'90 XJ MC=7/16-24 and 1/2-20

Thanks for the info. Looks like I am going to have to run new lines.

Ok I am seriously wondering if my vacume booster that the MC bolts to is shot,.. I never had the greatist breaking even with the old combo and the pedal always was rather low,.. is it worth trying to swap?

Hoping I dont have an many issues are you have been, but it looks like I'm off to a good start!! :shaking:

Why dont these 2 look anything alike? Is this what your Merc. Master looked like?
http://www.schwabdesigns.com/jeep/MCs.jpg

Yeah it looked very simular to my stock one just way larger over-all my stock MC looked different but mine is also a 1989

Ralphxj, what year of XJ do you have? If it's newer than '94, you probably have the wrong MC for your application.

Bubba,... what happens when the vacume booster s**ts the bed?

Jenseen, one way to check the booster is to push the brake pedal, hold pressure, then start your engine. Your foot should drop a couple of inches, indicating the booster is assisting you in pushing the pedal. A loud hissing, or no movement would indicate the booster is doing nothing.

Ralphxj, I'm not absolutely sure, but your MC looks like it is intended for a dual-diaphragm booster. If so, the Mercury MC probably won't work on your booster; it wont seal correctly were it bolts to the booster, resulting in a vacuum leak.
Looks like Jeep started using dual diaphragm boosters in '92 for ABS applications.

Yeah it pumps up nice and hard off and drops down when I start it,.. so I guess thats out,.. maybe I try some brand new calipers JIC in the front,.. or try reversing the lines,..


Does it matter if which line goes to front or back off the MC with out the proporting valve in it?
Currently the big tank is on the rears and the small on the front,.. and its with that 76 Ford MC,..

Generally, the rear reservoir, which feeds the primary piston, feeds the front brakes, since your front brakes are your primary brakes. Remember, when you apply pressure to the MC's push rod, you are directly applying force to the first piston, and applying force to the second piston with the compressed fluid from the first. If the first circuit fails, the primary piston must move out until it physically hits the second piston before the second piston moves. By then, most of your pedal travel has been used up.
I'm using the Mercury MC, and have the rear piston actuating my front calipers, the same set-up as used with the stock MC. You specifically mentioned the "larger" reservoir. The reservoirs on my Mercury MC are, in fact, not exactly the same size, but the difference is minor. The difference in reservoir size of most 2-wheel disc MC's is significant. I assume you are using the 4-wheel disc MC?

Yeah its just that the rearmost resevior is or somehow was connected to the rears and the fronts are well off the front,..I can lock the rears on the gravel , not the fronts,... now I have brand new calipers in the rear and older ones in the front I may just swap new fronts on to be safe and reverse the lines,..

insight?

ok so I have a 2001 wj master and booster in my Xj right now. I just put in a 44/9" with 1/2ton gm fronts and rears. I bought a dakota/durango mc from napa . I had to elongate the hole for the master to fit on the booster but no the hole in the booster is too small to allow the MC to fit all the way on. Any ideas? i was under the assumption that people were bolting the dakota MC to the late model dual booster with no problems. Do you think that the booster i have is too new?

Thanks for the help,
Adam

Ralphxj, I'm not absolutely sure, but your MC looks like it is intended for a dual-diaphragm booster. If so, the Mercury MC probably won't work on your booster; it wont seal correctly were it bolts to the booster, resulting in a vacuum leak.
Looks like Jeep started using dual diaphragm boosters in '92 for ABS applications.

Mine is from a 92 with ABS! So your saying its probably a dual diaphram boaster?? Is there an easy way to tell by looking at it?

I guess I'll have to do alittle research as to what MC I need now! I hate my jeep sometimes! :homer:

Adam90xj, a search over at NAXJA, or Pirate tech may have saved you a head ache.
Robertk (NAXJA) stated the Durango/Dakota MC wouldn't fit his WJ booster--he didn't give years, but stated the bolt pattern was too narrow on the MC, and the MC's snout was too big.
On the other hand, 53guy (Pirate) reports the 99-03 Durango and RAM fit his 99 XJ booster. Only problem with Ram MC was reservoir hits hood.
It appears the nose of the Durango (again Pirate) MC is 1.900, while the nose of the WJ is 1.730, which of course, implies the Durango won't fit the WJ booster. I got this info from a recent Pirate post by lookin4fun.
How about taking some measurements off your stock MC and the Durango MC, and posting them here so others can avoid the same problem? The various od's of the snouts, and bolt patterns.
ralphxj, looking at a picture on NAPA.com, the '92 booster with abs has three "orifices" on the front (engine side); one for the MC, one for the vacuum line, and a third hole that looks the size of the vacuum fitting. The XJ only has two "orifices", the hole for the MC, and the vacuum connector. Look at the Napa site: http://napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=NBB&PartNumber=5473192&Description=Power+Brake+Booster+w%2fo+Master+Cylin der
Ralphxj, how about adding to the MC data base and measuring the od of the snout and bolt pattern on your '99 MC? Measure each change in od, and note where the change is in relation to the mount flange.

Ok thanks. I'll take some measurements today. I have a 95 wrecked xj and i'll see if that has the dual booster and see if that will bolt up. Thanks for your help.

And btw. The wj res. is taller than the durango res. that i sourced from a used parts place so hood clearance shouldn't be an issue on mine. perhaps the wj booster mounts at a different angle than the xj boosters?

Adam

As I recall, it was the combination of the Ram reservoir and the booster mount angle that resulted in hood contact; seems the Durango MC is shorter, so no hood contact.

Ok here is what I found out about mine. 1992 XJs with ABS have a dual diaphram boaster, and use the same Master as the newer XJs and Grands. That Master is 1in rather then the 15/16 like the non-ABS ones.

I am going to start with just a new master, thinking maybe mine was just shot!?! If that isn't the case, I'll then try a Ram Master and see if that makes a diffrence.

Ralphxj, do you still have the ABS system hooked up? I've read bleeding ABS brakes requires a different approach; however, I can't say what, since I've never dealt with them.
Also, looking at the picture of dual diaphragm booster used with the '92 ABS system, there seems to be an additional connection to the booster. Is that true?

Ralphxj, do you still have the ABS system hooked up? I've read bleeding ABS brakes requires a different approach; however, I can't say what, since I've never dealt with them.
Also, looking at the picture of dual diaphragm booster used with the '92 ABS system, there seems to be an additional connection to the booster. Is that true?

I have removed all the ABS stuff, will try to use the stock MC and just not have the ABS stuff, hoping it all works the same! We'll see what happens. It very well could have been air in the ABS system they I couldn't get out, thats VERY possible!

As far as an "additional connection" I'm not sure how many the others have, but mine has 2. One is a line coming off the manifold, and the other is a electical connection. Thats all i have, one air line, and one electical.

Would be interesting to know what the electrical connector is for. It's either in input control, or an output signal. If it's an input control (???), what affect would there be on your brakes if it wasn't receiving whatever input it needs? Would be nice if some one could enlighten us on ABS systems in a Cherokee.

Still looking into the wiring on my Booster! I have been looking over my FSM, and haven't found what I want yet! I'll update with the info when I find it.

JENSSEN, any info on your brakes?

(Tech to the top!!)

I have removed all the ABS stuff, will try to use the stock MC and just not have the ABS stuff, hoping it all works the same! We'll see what happens. It very well could have been air in the ABS system they I couldn't get out, thats VERY possible!

As far as an "additional connection" I'm not sure how many the others have, but mine has 2. One is a line coming off the manifold, and the other is a electical connection. Thats all i have, one air line, and one electical.

For what it's worth, mine is a '94 with ABS and the dual diaphragm booster. This was my stock setup:

http://www.phatserver.net/~chris/recent/disc6.jpg

This is the booster and MC that I used from a '95 ZJ with 4-wheel discs:

http://www.phatserver.net/~chris/recent/disc4.jpg

Here's what came off mine:

http://www.phatserver.net/~chris/recent/disc8.jpg

and the much-simplified current setup I am running (but with booster hose attached):

http://www.phatserver.net/~chris/recent/disc9.jpg


When I had that setup on my D30/D44disc arrangement, I just used a small brass T-fitting (NAPA part number 5200 if I remember right) on the front output from the combo valve, and used that to distribute to each front wheel. I junked the ABS pump and module and the new booster didn't have that electrical connection on it. I don't know what it did. Pretty sure I just pulled out the ABS lamp too.

Now I'm using that exact same setup on my D60/14ff setup with the large single-piston front D60 calipers and 1/2-ton GM calipers in the rear, and the more I drive it the less I'm tempted to fawk with it. I drove for about 10 miles in western MA traffic over the weekend and locked up the 39.5s several times with no issues. The pedal is slightly soft but doesn't max out.

Thanks, thats exactly what I wanted to hear!! According to Napa's computer, my Master was the same as the ZJ's with discs. They were both 1in bore Masters.

Hoping to get mine figured out in the next week!!

According to Napa's computer, my Master was the same as the ZJ's with discs. They were both 1in bore Masters.

That may be true, but as you can see the reservoir on mine looked totally different. Also IIRC the pushrod depth was set differently so I ended up swapping the booster and master over as a set just so I didn't have to mess with it.

Yeah its just that the rearmost resevior is or somehow was connected to the rears and the fronts are well off the front,..I can lock the rears on the gravel , not the fronts,... now I have brand new calipers in the rear and older ones in the front I may just swap new fronts on to be safe and reverse the lines,..

insight?

how did they work??