I got a stumper here........

I´m running disc brakes all the way around, using in the rear exactly the same setup as in the front. You´ll likely laugh, but they´re calipers from a VW bus. They grip REALLY well.

But I´ve a small problem. After a couple of uses, like maybe 10 times, the rear calipers begin to drag on the discs. It´s kinda gradual, but gets to the point that first gear, together with a GRS 2 style t-case and 4,88 diffs have a hell of a time pulling it along. The only way to get going again is to get out and open one of the bleeders on either back wheel to let a small amount of brake fluid shoot out. Then I can go for a while until the situation repeats itself.

I´m using a master cylinder out of a Ford Ranger. The proportional valve and most all of the tubing is original. The front wheels are piped seperately directly from a tee on the master cylinder, while the rear is common until it splits on top of the rear diff.

Any ideas, other than driving around with a pint of brake fluid, a flashlight and a 7 mm wrench???...:^)

Im not home and dont have my manual in front of me but how are you dealing with the stock proportining valve. The sotck set up has a funky loopback system from the rear that sense volume/flow or somthing klike that. Im wondering if your brakes that are working so great are flowing too much fluid and the prop valve is thinking you have an open circuit (ie leak) and disrupting flow. Dono just an idea.

-yag

Originally posted by billj
I got a stumper here........

I´m running disc brakes all the way around, using in the rear exactly the same setup as in the front. You´ll likely laugh, but they´re calipers from a VW bus. They grip REALLY well.

But I´ve a small problem. After a couple of uses, like maybe 10 times, the rear calipers begin to drag on the discs. It´s kinda gradual, but gets to the point that first gear, together with a GRS 2 style t-case and 4,88 diffs have a hell of a time pulling it along. The only way to get going again is to get out and open one of the bleeders on either back wheel to let a small amount of brake fluid shoot out. Then I can go for a while until the situation repeats itself.

I´m using a master cylinder out of a Ford Ranger. The proportional valve and most all of the tubing is original. The front wheels are piped seperately directly from a tee on the master cylinder, while the rear is common until it splits on top of the rear diff.

Any ideas, other than driving around with a pint of brake fluid, a flashlight and a 7 mm wrench???...:^)


forgive me for asking the obvious questions..... you are sure that the calipers themselves aren't the problem?

ie: the pins that the pads slide on corroded/bent/full of grit etc.
or what about the pistons/bores of the calipers?
until i rebuilt both the front calipers on one of my motorcycles c/w new o-rings etc, they would drag so badly you couldn't turn the wheel by hand. that solved all my probs.
:)

Naw, they´re freshly rebuilt. And it seems that both rears hang up equally. Moreover, I can relieve the pressure by opening either of the two rear bleeders, it makes no difference which...

:question: :question: :question:

Originally posted by zukipuke
Im not home and dont have my manual in front of me but how are you dealing with the stock proportining valve. The sotck set up has a funky loopback system from the rear that sense volume/flow or somthing klike that. Im wondering if your brakes that are working so great are flowing too much fluid and the prop valve is thinking you have an open circuit (ie leak) and disrupting flow. Dono just an idea.

-yag


I made no changes whatsoever in the proportional valve plumbing. I´ll look into this... Thanks:) :)

I believe most of brake systems that are designed for drums have a residual pressure valve that is designed to keep the drums from backing all the way off after each use to minimize pedal throw. If you don't remove them after a disc conversion, the calipers will build pressure and "ratchet" down on the discs and drag. I had this problem with my Scout.

hey Bill, whatya using for parking/E-brake? just curious.:emb:

Originally posted by scwafish
I believe most of brake systems that are designed for drums have a residual pressure valve that is designed to keep the drums from backing all the way off after each use to minimize pedal throw. If you don't remove them after a disc conversion, the calipers will build pressure and "ratchet" down on the discs and drag. I had this problem with my Scout. Scwa is on the right track. With rear disc conversions on a Toy, poeple have had this problem... If I were you, I'd start looking in the system to see where it might occur. The easiest fix on a toy is a FJ80 master cylinder, since they come with rear discs.

It will probably be either in the master cylinder (where I *think* the toy one is) or in whatever prop. valve you are using. Search the Toy forum for rear disc info, or maybe the whole BB, and see what other people have done to fix this problem.

I don´t "think" that there´s anything to retain pressure on the master cylinder. At least externally, there´s nothing special at all, just a simple casting. Could there be something INSIDE?? It´s a MC off of a Brasilian-made Ranger that came with ABS.

As far as the proportional valve, it´s Suzuki stock. I didn´t touch it, except to bleed the air out.

I´ll search the Toy list to see what I can find out. Thanks for the tip...

Originally posted by UZI 9mm
hey Bill, whatya using for parking/E-brake? just curious.:emb:


Right now, I don´t have an e-brake. I already know that´s irresponsible, so please, no flames necessary...

I´m looking to build one to mount on the t-case, using motorcycle or go-cart brake parts. I´d definetly would prefer a mechanical system, but I´m having trouble finding a cable actuated caliper. For my needs, I COULD use hydraulics (obviously a seperate system from the main one), as I don´t use my E-brake for parking, only as a secondary stoppoing system...

Originally posted by scwafish
I believe most of brake systems that are designed for drums have a residual pressure valve that is designed to keep the drums from backing all the way off after each use to minimize pedal throw. If you don't remove them after a disc conversion, the calipers will build pressure and "ratchet" down on the discs and drag. I had this problem with my Scout.


"Ratchet" is a good description of the problem. What did you do to fix it on the Scout?? Where are these "residual pressure valves"?? TIA

Originally posted by billj



irresponsible, so please, no flames necessary...


no worries-everyone else here is irresponsible, too.



I´m looking to build one to mount on the t-case, using motorcycle or go-cart brake parts. I´d definetly would prefer a mechanical system, but I´m having trouble finding a cable actuated caliper.

poke around at the Trail-tough web site, there is mention there of calipers from certain years (1982's?) Subaru sedans that incorporated an E-brake in with the main calipers. these are used for their Samurai rear disc brake conversion kit. (if you could at least find something like that where you are to look at. many Subaru's in Brazil?)
it may give you an idea or two.:) :beer:

Not hardly any Suburus here in Brasil...:( Caddies are even rarer...

D'OH!:(
hmmm. what about "Wilwood" they make little mechanically actuated calipers. expensive though, i think.

hmmm. what about "Wilwood" they make little mechanically actuated calipers. expensive though, i think.
You mean this?? wilwood spot caliper (http://www.precisionbrakescompany.com/wilwood_mechanical_spot_caliper.html)

It is a vaiable option, just need to fab a mount.
You should be able to find something similar a little cheaper though. Too bad the caddy/olds calipers are like gold and getting hard to find... What about cannibalizing one of the newer model cars, alot of them have rear discs with e-brakes?

"Ratchet" is a good description of the problem. What did you do to fix it on the Scout?? Where are these "residual pressure valves"?? TIA

On my Scout it was in the MC right were the hardline threaded into the MC.

Originally posted by StomperZUK

You mean this?? wilwood spot caliper (http://www.precisionbrakescompany.com/wilwood_mechanical_spot_caliper.html)

It is a vaiable option, just need to fab a mount.
You should be able to find something similar a little cheaper though. Too bad the caddy/olds calipers are like gold and getting hard to find... What about cannibalizing one of the newer model cars, alot of them have rear discs with e-brakes?


damn:eek: they're not nearly as expensive as i actually thought they were.:) cool. thanks again, dude:D

Yep there is a small valve that keeps a small amount of pressure to the rear drums. If you havent taken this out that would explain your problem.

Turned out to be the 5 mm of preload I put on the MC piston. I chopped the extra length off the actuator extension and...

PROBLEM SOLVED!!!:D :D :D

Thanks for all the help!!!:D :D

:beer: :beer:

i am having problems with this also...i didnt do anything but put a mc with the 4 wheel disc on the jeep....i am having the same problems as the first guy to post..


where is the residual? how do you remove? thanks

Originally posted by PurdueYJ
i am having problems with this also...i didnt do anything but put a mc with the 4 wheel disc on the jeep....i am having the same problems as the first guy to post..


where is the residual? how do you remove? thanks


I already like this Newb, cuz he searched first, then asked questions...;)

To your question, what I did was to install a Ford Ranger master cylinder on the Zuk booster. It´s almost a direct bolt-on, requiring only a minor drilling out of the two mounting holes, an o-ring on the M/C and an extention to the booster actuation rod. It was this actuation rod that created my problem...

When I made the new rod, I made it too long and this created a constant pre-load of the M/C. I removed the M/C, chopped around 8 mm off the actuation rod to eliminate the pre-load and put all back together. Solved the problem!!!:)


BTW, welcome aboard, ya Noob!!!:flipoff2: :flipoff2:

Its your stock proportion valve get rid off it and get a wildwood
manual adjust, set it and be done. my O2

of course i did a search...dont want you guys to hate me right off the bat...haha...i really care about you guys and want you to love me :flipoff2: :flipoff:

anyways...i changed my MC though...still have the problem...let me ask you this...how do you know if the push rod is too long?

the MC just fit right on perfectly...it wasnt like i had to push on the rod to get it to go on....does that mean the rod needs lengthened?

where exactly is this residual valve at? built into the MC? or the distribution block under it?

What master cylinder are you using? The stocker or a rnager like bill did? that might help em figure this out for you. ;)

loose the residual pressure valve (like you have been told)and when you are through GO TO YOUR ROOM.....................:D akisan

your on your HONOR...............:D

78 Mercury Marquis with 4 wheel disc and hydroboost Master Cylinder...

i did the F350 one...but the resevoir for the rear wasnt any bigger...this one had a bigger front and rear resevoir and the push cylinder was the same bore as the F350 one...this was also a bolt up to my YJ...no grinding or drilling...



bobaki...thanks for the advice on the residual pressure valve...but if you are gonna try to flame me then why dont you read my last post...then open your mouth...

"where exactly is this residual valve at? built into the MC? or the distribution block under it?"

thanks for repeating someone...helps a ton...now can you answer my question so that maybe i can act on your advise :flipoff2: :)

How long did the actuator rod end up being?

I am in the process of the same mods, and will be geting to that part just after Chrismas. the info would help me ALOT!

as for a emergency brake setup, I am looking at line lockers AND a driveshaft disk system (ie. Spydertrax)

but also looking at the '80-'82 Subaru sedan rears. the problem I have is getting parts here in Detroit Mi. for Inports :(

Thanks for any info you could send me.
mark

you feel warm ?must be the weather,if I were to flame you there wouldn't be a doubt.................:D the valve is back by the fuel filter,where the lines split off to the axel

dang...this is confusing me...bob...you say get rid of the residual valve...and that its back by the fuel filter where the lines splits...is that the actual block on the axle where the one line splits to each side? or is it something else? just trying to figure this out adn i dont seem to be getting very far...flame me

Originally posted by PurdueYJ
dang...this is confusing me...bob...you say get rid of the residual valve...and that its back by the fuel filter where the lines splits...is that the actual block on the axle where the one line splits to each side? or is it something else? just trying to figure this out adn i dont seem to be getting very far...flame me

Hey purdueYJ,
It would probably help if we knew exactly WHAT VEHICLE you are asking about. :flipoff2: According to your sig. you don't list a ZUK. Could you be asking about one of your HEEP's? :shaking:

Being that this is the SUZUKI tech section, most could reasonably assume you are asking about a SUZUKI vehicle.:D

If in fact you are asking about a Samurai, the stock proportioning valve is on the inside of the passenger side frame rail, just toward the rear of the t-case, can't miss it, has BRAKE lines connected to it. Some have completely removed it and replaced it with a direct connection and hooked up a wilwood prop. at the MC.

There on the m\c ,a small brass fitting with only about three pounds of back pressure made for disk calipers! look at the line nearest the fire wall there should only be one of them if you have one at all ! (american junk brakes) zuk's criss cross thier brakes (one front on a line ,one rear) thus having two porportioning valves back at the rear.88 and older.

but also looking at the '80-'82 Subaru sedan rears. the problem I have is getting parts here in Detroit Mi. for Inports :

subaru leone `82-`90 has e-brake in FRONT cylinders:eek:

Originally posted by Orionn
How long did the actuator rod end up being?

mark

Sorry I haven´t responded sooner. I was away at a 4x4 event for the weed-end. Our first attempt at a Brasilian "rockcrawling" competition. I didn´t compete this time, only helped with the organization. Was quite sucessful, but it rained like a mo-fo and kinda fawked up the obstacles......:p :(

Anyhoo, I don´t remember exactly the length of the actuator rod, but it´s nothing more than a M5 Allen screw, 40 mm long, IIRC, with a M5 lock nut.

Just set it up so that there´s around 5 mm of free play between the actuator rod and M/C when it´s mounted up. With a vernier caliper or depth gauge of some type, determine the distance between the M/C mounting surface and the hole in the M/C plunger where the actuator fits. Then adjust the actuator rod to be 5 mm less than this. After ensuring that everything is correct, put a little Locktite on the threads and also tighten down the locknut. Double insurance is good here, cuz if the actuator length changes for any reason, your brakes could fail.......

Not good......:p :eek:


HTH

sorry...mine is a jeep...

but i did the newbie thing and searched...this seemed like the post that had to deal with my same problem....jeep or PUKE i figured i could find an answer in here


so its a jeep....91 yj...you know where the residual valve is? thanks guys...kosta

Samurai's have a "cross" system (1 line out of the M/C goes to 1 front & 1 rear, the other goes to the other f/r) the RPV in these must be in the proportioning valve. On a typical (American) F/R proportioning systems, it is a little disc hinkey under the flare nut going to the rear port of the M/C. Just remove the nut & pull it out. I would look for the same thing under the Samurai's nuts going to the rear brakes. As far as finding the Sub cals, look here: RockAuto (http://www.rockauto.com) they have a great parts search engine with pics (sometimes) and part numbers (dumbasses). I'll bet they will ship anywhere. MIKE

Damn, you think that the guys/gals on Junk Yard Wars ever have these kinda probs?:flipoff2: :flipoff2: :flipoff2: