More Questions about CJ Brakes

[dbesade]

Okay,

Stupid question, I have installed a new master cylinder, bench bled it, installed it, all new rear brake lines, and new shoes and wheel cylinders in the rear drums.

After that I did more adjustments on all 4 drums and bled them 3 times. I still have very little stopping power, barely enough to keep it stationary in reverse. I would like some suggestions at this point. I'm thinking brake booster at this point.

Thanks

-Dave

[Mudrat]

Did you ever resolve this problem???? I'm still down 100+ posts from vacation and travel ...

Pat

[dbesade]

Nope

[Mudrat]

Well,
CJ's were made for years without boosters (actually a lot of cars were too!), but they had a large plunger in the MC for pressure.

Did you replace the brake lines?
Is it possible there is debris in them?
Have the new MC seals failed allowing leak by? (I've actually had that happen with a new Chevy MC on my K-10 )
Have you checked your proportioning valve? (left inside frame rail by the clutch bell crank)
When you nail the brakes – does it steer to one side (uneven braking)?

Lets see if we can work though this one – might be of use to others as well ….


Pat

[Trailbst]

If you have a brake booster, is there adequate vacuum to it. Does the vacuum valve still work properly?

[dbesade]

Okay,

There is no leaks in the Master Cylinder, I checked when I was bench bleeding it. Have checked again, no leaks past the seals. I did replace the rear brake lines, I bled them before I attached them to the drums so there wouldn't be any debris.

When I nail the brakes they do nothing, a slight stopping sensation but nothing more. I have to pump frantically for them to work correctly. How would I check the proportioning valve?

My CJ Has Stock power drum brakes. I have a booster on the way already, the one on my CJ is stock, as is/was ALL the brake parts.

-Dave

[pyagid]

I bled them before I attached them to the drums so there wouldn't be any debris.
-Dave

Did you bleed them again after they were attached? If not you will have air in your lines they need to be bled after attached to the wheel cylinder

-Paul

[dbesade]

Yup. Bled all around 4 times.

-Dave

[Mudrat]

Okay,

There is no leaks in the Master Cylinder, I checked when I was bench bleeding it. Have checked again, no leaks past the seals. I did replace the rear brake lines, I bled them before I attached them to the drums so there wouldn't be any debris.

When I nail the brakes they do nothing, a slight stopping sensation but nothing more. I have to pump frantically for them to work correctly. How would I check the proportioning valve?

My CJ Has Stock power drum brakes. I have a booster on the way already, the one on my CJ is stock, as is/was ALL the brake parts.

-Dave

Frantic pumping to stop still sounds like an air build up or a bypass leak somewhere and you have to pump the pressure up

Your not leaking anywhere are you - well, I mean your BRAKES aren't leaking anywhere -right?

Do you nose dive any at all - even a little? Like the front is trying to grab and the back is just along for the ride?

If Yes, then it sounds like it's more in the rear brakes? If so check shoes and adjustment first, then the hydraulic actuators. (New, used, rebuilt?)

If No: then it sounds like the problem is at or before the p-valve and is affecting both front and rear brake presure. Either the MC, the 2 lines to the p-valve, or the valve itself. Check out the MP Brakes FAQ. They don't tell me how to test the P-valve, but do provide this tid-bit...
Q: What are the symptoms of a bad residual valve?
A: The brakes will be very spongy and you will need to pump the pedal to get good brakes.

Check this Trouble Shooting FAQ also ...

Does it get hard when you pump?
Is it a really soft peddle that hits the floor?
After it's hard, does it leak down under pressure?
And we are only talking brakes here



Hope this helps

Pat

[dbesade]

Hey,

OKay some background is in order I suppose. This was my dads hunting rig back in Florida. The Previous owner before him was the Original owner of the Jeep so it hasn't passed many hands.

Since my dad has had it (about 4 or so years) it has had piss poor brakes. When he finally shipped it down to me I have done my best to correct the problems as they come and have been fairly successful. The tub itself is in pretty damn good condition for its age, just needs a new floor, side walls are immaculate as is the frame. It came from the factory with 4 wheel power drum brakes.

Now when I finally busted a brake line I decided to replace the entire rear (from the prop valve) half of the brake lines. I also installed a new Master Cylinder and installed new Wheel Cylinders and adjuster kits in the rear drums. When I pulled them off and did a good inspection, I realized the entire brake system was stock, from the factory stock. The wheel cylinders were leaking, the hardware in the drums was backwards (which explains the zero wear on the shoes which were also coated in Brake fluid).

So over 2 weeks in-between work and school I replaced the adjuster parts, shoes, wheel cylinders, brake lines, and master cylinder hoping it would at least boost the brake power. I am going to replace the Booster as well as its pretty damn rusted and gone.

----

Now,

I have NO leaks anywhere in the brake system, I have been watching. So I'm guessing from the information you posted there is still air somewhere in the system.

When I slam on the brakes at low speed the jeep does nose dive a little. Before all this work the rear drums were adjusted all the way in (on purpose) so they were not in touch with the drum as the wheel cylinders were fscked anyway and I didn't have the time to fix it). So the front brakes were doing all the stopping.

Most of the time when I slam on the brakes, nothing happens until I start pumping. When it does stop I hear a slight groan from the rear brakes and slight rubbing from the front.

It doesn't get very hard when I pump with no engine power and when the engine is running its very very very very to the floor with pinky finger soft.


P.S. I'll fix the picture in the mod forum :)

-Dave