I have had it. This fawkin 4-wheel disc setup is kicking my ass. These are the parts:
CJ booster w/pedal crank
GM dual diaphragm booster
Cadillac 4 disc master/Corvette 4 disc master(I have tried both)
79' Wagoneer front calipers
'85 Cadillac Eldorado rear calipers
All new lines and hoses
Wildwood Adj. prop valve
wildwood 2lb residual valves(2)

I have tried many different combinations using all of the above parts. I can now bleed a brake system with my eyes closed and one hand behind my back(there is no air in my system). I fully understand the adjustments on the Cadillac rear calipers and mine are adjusted properly.

My current setup is CJ booster w/pedal crank, Cadillac MC and Wildwood adj prop. The pedal goes to the floor and gets hard the last 1/2" of stroke.

I am ready to try anything at this point. Someone tell me your exact 4-disc setup and I will copy it. Or give me suggestions on my own setup.

Thanks,


Flame away! maybe it will keep my post alive.

i know you have tried everything but did you remove the little restrictor thingy from the master where the rear line attatches?

Those masters don't have built in residual valves. They are for 4 wheel disc....

Thanks anyway.

http://www.tsmmfg.com/Troubleshooting.htm

cool brake trouble shooting guide,one tip was to use a m/c with a smaller bore,who woulda thunk:eek: .

Did you remove the O-ring from the proportioning valve the restricts flow to the rear brake circuit?

http://www.pirate4x4.com/forum/showthread.php?s=&postid=612446#post612446

Good drawing here:

http://www.pirate4x4.com/forum/showthread.php?s=&threadid=59568

I have a similiar set up. Can put you through my windshield, if you'll buy me a new one...

I think your problem is not air in the system but not enough MC volume OR you are not getting full throw on your MC plunger due to incorrect linkage. Here is my setup and it will put you thru the windsheild.

MY MC is a Mid 90's GM 1-ton with 4 wheel disc brakes
Front calipers are mid 80's GM Dana 60 units
Rear are mid 90's GM 1-ton 2wd units
Stock CJ Prop. valve (unmodified)

I would go to the parts house and have them start pulling 1-ton units for 4 wheel disc brakes until you find one that will bolt up to your booster. With that you can ditch the residiual valve because the MC already has the correct valving for discs...

If it is getting hard 1/2" from the floor you are simply not moving enough fluid to fully activate the calipers..

Hope this Helps..

Hey TPI:
Are you using the stock CJ booster and pedal assembly? Do your rear pads drag at all? Everyone on here is always raving about how great the Corvette MC is, I don't understand. I will head to the pick and pull Monday and look for a 1-ton w/4-discs.

Thanks,
Tom

Tom,

I run a GM Hydroboost unit off of a 1-ton but that was because I run a pretty big cam and did not want low vaccum to effect my brakes. The booster selection will not affect how the brakes work it will only affect petal feel. I picked my MC up new for around 40 bucks so the pick and pull might be a waste of your time... I sure think your MC is just to small of a bore to work with your calipers..

Good Luck, here is a blury pic of my setup..

http://www.tpijeep.com/RJleftfront.jpg

I have the Vette master cyl , wago calipers and cadillac calipers in the back. It'll put you through the windshield.

Only problem I have is the damn wilwood valve leaks.

Other than that its good to go.

I am non power though.

I have the Vette master cyl , wago calipers and cadillac calipers in the back. It'll put you through the windshield.

Only problem I have is the damn wilwood valve leaks.

Other than that its good to go.

I am non power though.

Try going to a 10# r.p.v. it worked for me.

D-

That is exactly what I need to hear. I would love for the Vette Manual MC to put me through the windshield. So you are using a '68 vette manual MC, wildwood adjustable prop valve and waggy/caddy calipers. That's it? No factory proportioning or residuals? What kind of actuator rod are you using? Any help is greatly appreciated. I am about to lose it over these brakes. I have been working on them for close to 2 weeks with unsatisfactory results.

Thanks for the replies,
Tom

Originally posted by "D"
I have the Vette master cyl , wago calipers and cadillac calipers in the back. It'll put you through the windshield.

Only problem I have is the damn wilwood valve leaks.

Other than that its good to go.

I am non power though.

Likewise, cept for no prop valve. Your symptoms pretty consistent with air in the system. Maybe you have a leak? Not sure what to say. Could be air in the calipers? Is the rod in contact with the pedal fully off? Course I hate power brakes when Im troubleshooting cause it always feels like theres no brakes till the last little bit

I'll go back to the Vette MC tomorrow. I can make my rod any length I want. How high is your pedal in relation to the firewall? Does the Vette MC engage in the first 1" of pedal? I hope this works.

Later,

Wish the pedal height had some bearing for you. Im running em on a pre-amc CJ so theres nothing stock about the setup. Although if you want I'll measure on the morning. The pedals soft for about the first inch of travel then firms up quick. Just out of curiosity, what port do you have the front brakes connected to? The front port or the rear? That might start pointing to where the problem lies

I have the front brakes connected to the port closest to the firewall and the rear are on the port closest to the front of the Jeep.

Thanks,

For what it's worth I put my calipers on upside down once
(wrong side) :)
Kicked my ass for about 2 hours until someone gave me a helping hand pointing out my brain fart.

My Calipers are bleeder screw up.

Later,

My push rod is the same length as the stock one. I put a spacer to make up for the depth of the vette master cyl.

If i nail it the 35's lock up. Very controlled through out the braking range though.

I also am running my rear caliper upside down to get the E brake working properly. I bled them first and then installed them.

I for one think the master cyl is screwed up on yours. Mine worked greta for a few days and then the damn thing lost its bleed. I had to bench bleed it again an its been ok ever since.


Let us know what you find out.

After what Mike said and based on something I read on the Off-road BBS I swapped the front and rear connections on the master. It definitely made a difference. I am going to bleed the system and hopefully the problem is solved. I can't believe it was as simple as having the ports reversed. Thanks Mike, you are the first person to mention the ports. I am just glad I am on the way to a solution. It just didn't make sense that everyone else with the same setup had good brakes. It had to be the ports. I will update my progress later today.

i have been trying to keep up with this...especially since i've had some brake problems lately.


is it possible that the location of the push-rod pivot pin on the brake pedal arm changes location depending on what brake system and year the vehicle had/was?

what i'm getting at is maybe the pin on a 78 CJ with manual brakes is closer to top of the pedal arm than a 84 cj with power brakes...can anyone confirm or deny this?

i am going to check all of my pedal assemblies tonight (i have 3 or 4 extras laying around). if i find any variation, i'll let ya know.

matt

Matt, what you're talking about is pedal ratio. Yep its different for a lot of applications. Tom, I have the lines plumbed the opposite way you do now. What it tells me is that your rear lines are ok, fully bled and ready to go, and that the problem lies in the front lines :D

i have the stock YJ booster, 79 Bronco master, o-ring deleted from the proportioning valve, GM 1 ton front calipers, 1/2 ton waggy calipers on the rear. Pedal has a little mush at top but 1/2-3/4" down hold on tight. I can lock all 4 tires if needed.

Do you have a brake line that is balooning when you step on the pedal? Bad flexible lines can do that.

Mike,

Which way?

front brakes to front of MC or front brakes to rear of MC

P.S. My brakes are actually pretty good now. I am going to add the GM dual diaphragm booster next week.

Later,

Howdy!

Here's my set up and it works!

Front/Rear calipers are 3/4 ton Chevy Van on Bronco rotors. Stock 1982 CJ-8 mastercylinder, booster, proportioning valves.
Installed it all, everything worked fine.
My pedal starts firming up at about 1/3 way down and stoppes my shit quick!

Good luck i hope this info was somewhat useful.

Mrmacrro (FNG):beer:

Originally posted by tom85cj7
Mike,

Which way?

front brakes to front of MC or front brakes to rear of MC

P.S. My brakes are actually pretty good now. I am going to add the GM dual diaphragm booster next week.

Later,

Front brakes to the rear of the MC. Maybe there was just enough of a leak to suck in air and just moving them fixed it :D

Originally posted by tom85cj7
Mike,

Which way?

front brakes to front of MC or front brakes to rear of MC

P.S. My brakes are actually pretty good now. I am going to add the GM dual diaphragm booster next week.

Later,

Actually, I believe the MC styles change back and forth ...
Typically, the larger reservoir of the MC feeds the disc slaves as they hold more volume than the older drum style slave cylinder set ups.
I've seen later model MCs with equal sized reservoirs because their vehicle has discs both fore and aft ...
O'le Harold Off, locally, has made a good business of offering a dual diaphram "NavaJo" setup.
But don't get me started about him and his NavaJos ...

I have had it. This fawkin 4-wheel disc setup is kicking my ass. These are the parts:
CJ booster w/pedal crank
GM dual diaphragm booster
Cadillac 4 disc master/Corvette 4 disc master(I have tried both)
79' Wagoneer front calipers
'85 Cadillac Eldorado rear calipers
All new lines and hoses
Wildwood Adj. prop valve
wildwood 2lb residual valves(2)


except for the M/C (I used a 3/4 ton dodge, no residual valves) I have the EXACT SAME set-up as you. took me about a week and a half to trouble shoot it, and it came down to me ditching the propo valve. as soon as I got rid of it, all my problems went away. I locked the 35's up right outside my house and it made such a racket that a guy walking out of the pizza shop screamed and dropped his pie :D