Brake Problems

[jimig1]

I have 4 wheel disk brakes. I can get the fronts to lock but the rears I can still move by hand. If you do a little pump the rear lock along with the fronts. I have bled 1/2 a quart of fluid through the rears so I don't think there is air in the system. The M/C is on the firewall so i should need residual valves. Could have an incorrect proportional valve like a disc/drum? I'm at a loss.

[mr48chev]

1. Do you a +


















1. Do

[mr48chev]

1. Do you have have a matched system designed for one car or do you have a mix and match system with front calipers and rotors for one vehicle, rear calipers for something totally different as they came with the axle and a master cylinder that may or may not match one or the other?

Mismatched calipers, brake lines that are the wrong size for the application, master cylinder bore that is the wrong size for the application or may have the lines hooked up to the wrong ports.

Unless you are just flat using the wrong method to bleed the brakes I'd think that you have the air out of them.

All brake systems have some sort of residual valves to hold a slight pressure in the lines. The old original systems had it built into the master cylinder and the drum drum master cylinders have a residual valve behind the seat for the brake line. That's that little rubber piece you see in the hole in the seat that has a little spring behind it. That is on factory rigs with the master cylinder on the firewall. Most modern systems have the residual valve and proportioning valves built into the combination valve that is usually a few inches from the mastercylinder.
It's bedtime as I have to get up at 03:00 for work.

[klutz51]

I would look at the proportioning valve, if you have a disc/drum it will effect how the pressure is transfered. I have a Corvette master and valve with 4 wheel disc and it works great. As stated by MR48 make sure all your components match 4 wheel disc set up.

[ls1man]

Make sure you bench bleed the master cylinder.

[jimig1]

I have a Corvette M/c the front calipers (82-87 camaro) and rear calipers (80-85 seville) are both GM metric calipers. The brake lines are 3/16".

[jimig1]

Originally Posted by ls1man

Make sure you bench bleed the master cylinder.

That was done.

[Speedbumpauto]

If those Seville calipers have the parking brake built in you have to adjust up the slack in the pads by ratcheting the P brake lever on the caliper or the P brake handle in the cab. The Lokar has such limited travel, IME, that it's hard to do. I have had horrible luck with those calipers in hot rod applications and will never use them again. In order to keep the rears working properly, you must use the P brake a fair amount and I, like many rodders, don't. Maybe I just don't know the trick. the other thing that can happen with those is, on some kits, they will mount with the bleeder screw at less than straight up which will leave an air pocket no matter how much you bleed them. I've had the best luck using a power bleeder at the MC and taking the caliper loose and rotating it so the bleeder screw is in the correct position for bleeding, then putting them back together. Pain in the kazootie pooper. I'll pay more for the shoe type parking brake system next time or just forget the P brake altogether and use the front calipers on the rear.

[mr48chev]

Good points there by Speedbump auto. I've seen more than one guy fuss about those calipers in hot rod hot rod applications even though they should be dead nuts reliable.

http://www.mpbrakes.com/docs/orig-gu...STRUCTIONS.pdf
Scroll down the page a bit and you see exactly what he was saying.

I'm not in the habit of setting the park brake in my later model Cad with rear disk and that may be why I don't think the brakes always work the way I would like.

[la hi]

I put power brakes in my 57 and unknown to me I put the rear lines to the front of the master and the front to the rear.
It took the garage finally, and they bleed and blead the lines then changed the lines around. That corrected my error. now the back and the front slide to a stop.