my cj7 was purchased with the corvetter master cylinder already installed, i have 1 ton axles with disc brakes on the front and rear, and braded steel brake lines. when i apply the brakes the pedal travels very far before you reach any pressure and then you have to press it all the way to the floor to get enough brake pressure to stop, this might be a simple fix, im not sure. if anyone has some input or knows where some literature is on this setup i would appreciate it.

1st thing I would check is brake line routing. The front port is for the rear brakes and the rear port is for the front. Are they plumbed correctly? Next, have you bled the brakes? could be some air in the system. Those are the first 2 issues that come to mind and are the easiest to fix.

I initially went with a corvette mc and it never worked too good. I went to a hydroboost and never looked back.

x2 on the hydroboost, but my hydroboost from Vanco uses a Corvette mc ..... other than the two suggestions to check plumbing to make sure the bigger res is plumbed to front brakes and the small res to rear, and bleeding, the mc just might be shot altogeter. or if the system really filled up with air for some reason you might have to bench-bleed the mc....

Still using my Vette master on the CJ. Mine is a non booster setup and plumbed correctly.

Chevy 1 ton calipers front, Chevy 3/4 ton rear, 38s and lock em up with out even thinking about it.

Corvette master, with original CJ power brakes on 1 ton axles is never going to work well enough to make anyone happy or safe. Ditch the booster or go hydroboost as mentioned above.

the corvette master was never enough for my jeep. pedal would go almost to the floor before building pressure.

a 1 ton master fixed that problem.

what 1 ton master did you get?

hey Van, its me out in Guam... maybe you remember... the hydroboost is the best, well almost the best, upgrade to my rig since I started building....

Now would you please make a hydroboost kit for 2002 Dodge Dakota before the crappy brakes in that thing kill me....


Corvette master, with original CJ power brakes on 1 ton axles is never going to work well enough to make anyone happy or safe. Ditch the booster or go hydroboost as mentioned above.

I'm using a 1975 chevy 1 ton 2wd manual brake master cylinder. It pretty muched just bolted right in with no mods and works great. I'm running a 60 up front and 70 in the rear with 39.5's with disc's all around.

i have a 7 with same setup and it SUCKS. fixing to go w/ hydraboost

x3 or 4 on the Hydroboost. I went from the manual brakes Corvette master to a new Vanco setup. The manual brakes behaved exactly how you describe. Took the full travel of the pedal to get any pressure.

Now running a big Vanco unit, scout front brakes, and rear disks w/ caddy calipers. Locks up all 4 37" Claws at any speed.

Tips for your setup:
- Bleed, bleed, and bleed some more
- If you have the stock prop valve, make sure you are bleeding it correctly
- Check the travel of the piston in the Master vs. the travel of the rod on the pedal. Entirely possible that your MC is set up for a different ratio.

I'm using a 1975 chevy 1 ton 2wd manual brake master cylinder. It pretty muched just bolted right in with no mods and works great. I'm running a 60 up front and 70 in the rear with 39.5's with disc's all around.

yup, pretty much what I did except I used a dual diaphragm booster from master power brakes.

just make sure the 1 ton master comes from the non-hydroboost truck application (ie shallow hole).

GM 60 front with stock GM 60 calipers (3 3/8s pistons), 14b rear with 3/4 ton GM rotors and GM calipers (3 1/8 pistons) stock '73 C3500 master (1 1/4in piston), master power brakes CJ dual diaphragm booster with adjustable pushrod, and a disc/disc proportioning valve.

It is very easy to lock up the 42s, and in first gear/low range (65:1) automatic, I can easily stop and hold the jeep in gear, even while cresting a steep ledge or drop off. I also run an rv low stall converter so the engine is really pushing on the drivetrain. All with one foot, of course:D

Big master cylinder piston volume to supply plenty of fluid to fill all the calipers (to minimize pedal stroke) and a big powerful booster (either dual diaphragm or hydroboost) to provide the needed assist to actuate the master and stop the vehicle with minimal pedal effort. Makes for an easy day of wheeling.

http://www.mpbrakes.com/uploads/products/bm1402_large.jpg

expensive, but worth every penny. They ship it with a corvette 1 1/8 master which would work with 1/2t axles, but for 1 tons, you need to swap the master out for the 1 ton version mention above to get the 1 1/4 master. It's a direct swap and even the lines match up.

hey Van, its me out in Guam... maybe you remember... the hydroboost is the best, well almost the best, upgrade to my rig since I started building....

Now would you please make a hydroboost kit for 2002 Dodge Dakota before the crappy brakes in that thing kill me....

Of course I remember you, just because we don't list it on the site doesn't mean we can't make it. We make hydroboosts for just about every vehicle out there. You may need to take a couple measurements for me but that's about it.

I must be missing were he said he had a power brake setup. Fairly important info if you ask me.

If you did not do the install yourself,you need to go through and check that everything was done properly to start with.
1- Check your brake line routing,be sure the lines go to the proper ports on the master. COST $ 0

2-Make sure that the stock cj proportioning valve has been removed from the system. At best that valve was for front disc rear drums. It will never let you reach the proper line pressure to the rear discs. Drums are usually around 450 psi. Discs generally require more than twice that. COST $ 0

3-Make sure that the brake rod going into the back of the master is the proper length. An original cj manual brake,brake rod needs to be lengthened 5/8" COST $ 0

4- Do you have the correct MC for your application. Corvette had 4 whl manual disc MC's and 4 whl power disc MC's. COST $ 0

5-Check your pedal ratio. Manual should be about 6 or 7 to 1. Power 3 to 1

In other words check out what you have before you start throwing $ at it.
Do a search on here for" cj7 corvette master cylinder"and you will get plenty of info.http://www.pirate4x4.com/forum/showthread.php?t=594475&highlight=corvette+master+cylinder+cj7
http://www.pirate4x4.com/forum/showthread.php?t=554383&highlight=corvette+master+cylinder+cj7

thanks for the info, im going to check that out.

One more for the bench bleed. The Corvette MC i run in my yj was a bitch to bleed (69 vette 350 power brakes 11/8?? bore, think manual was 1" bore so check that,as said above, u might not have the volume), i was at it for a while, like 20 min or better. However, my brakes with stock yj booster are very powerful. Im running dodge 1-ton front calipers, chevy 3/4 rears with 2002 dodge rotors on the rear (13 inch) and i can lock up the 38.5s at 30 mph like nothing, all 4 of them and not even push on the pedal hard, there is a fair bit of travel in the pedal but its nowhere near the floor. Without the travel it would be pretty hard to modulate this things brakes i think.

x10 for the stopping power with the vanco kit with little effort.. the 405/70R20 tractors on my rig weight 165lb each and the 20" steel wheels I think are 65 lbs each. you can do the math. I have very short pedal travel, generally just use the very tip of my boot to exert pressure during "ordinary" trailing and with a stomp on the pedal its an instant dead stop even on steep decline.

I have nothing against the Vanco kit. The reason his kits work so well is he builds his kit for what you have. If you do what he says his kit will work great no 2 ways about it. It would work well for this guy if he wanted to spend the money. If he doesn't,then he needs to figure out exactly what he has,then research what he needs to correct it. The Corvette MC works great if the entire system is matched up properly and put together correctly. This guys problem right now i believe, is he is not sure what he has or whats been done to it. In turn without us knowing this it is difficult if not impossible for us to help him. my.02

your right, i dont know exactly what i have, so this weekend im going to check it all out and figer out exactly what everything is and whats been done.

your right, i dont know exactly what i have, so this weekend im going to check it all out and figer out exactly what everything is and whats been done.

That is really probably the best. Definitely the cheapest.

i just dont understand why when someone does something they dont do it right, or to where it functions safely and properly, like i said i bought it with this setup on it so im kinda in the dark to everything. but thanks everyone for the help so far, hopefully i can figure out all my componets and get this figured out. if i cant get it done with the parts currently on it, im callin vanco back and ordering hydroboost.

Ive used the vette master cylinder on several rigs ( no booster) and one thing I had to do each time was extend the rod from the pedal to the cylinder 1 inch and it solved my problems. I like this set up and will continue to use it....

i just switched my cj5 to boost assist only 120$ for cylinder booster and bracket from pirate jack in nort carolina works and fits great

you may have just hit the nail square on the head ~ the rod may be too short .... if it is there is no fix except to make it the proper length. whatever the problem is its not the vette MC standing alone, all car MC's should be as good as the vette

Ive used the vette master cylinder on several rigs ( no booster) and one thing I had to do each time was extend the rod from the pedal to the cylinder 1 inch and it solved my problems. I like this set up and will continue to use it....

I used a manual only vette master on my cj on tons. It worked great.

Extend the rod and it should work. nhgpnut posted the correct list of what to check.

I went with a Scout duel booster 8 3/4, and a 68 vette mc for power brakes. Running 77 Blazer calipers on all 4 wheels with a disc/disc prop valve. A little adjusting the pushrod. Stops my jeep on 37s with little effort, it also clears my mc2100 carb on the 258. Everything bolted right up