brakes locking up

brakes locking up - 07/16/13 08:10 PM

hey guys just restored a 71 duster has drum brakes all around.power booster or brake fluid is exspanding.it has tti headers .anyone ever had a problem with the distribution block getting to hot?all 4 brakes are engaging after the car drives for a wile.but releases after its cooled dowm.thought about making a sheild.????
thanks

Posted By: Challenger 1

Re: brakes locking up - 07/16/13 09:32 PM

I'm pretty sure it is not the fluid getting hot and expanding.

Try loosening the 4 nuts that hold the master cylinder to the booster and see if that will allow the brakes to release.

Be sure the drums brakes are adjusted properly and that you have the shoes installed properly.

Posted By: RapidRobert

Re: brakes locking up - 07/17/13 01:58 AM

seperate the M/C and the booster & measure how much clearance you have between the round nub on the end of the pushrod & the bottom of the piston recess (want ~.060"). For a quick check shorten it & see if that fixes the problem. If you get too much clearance you wont have enough pedal reserve (pedal too close to floorboard when brakes are applied)

Posted By: MILFORD MOPARS

Re: brakes locking up - 07/24/13 12:41 AM

yep tried that .tti tells me my m.c. is not venting???
I did shorten the rod and it did not help.maybe the booster is not releasing after it gets hot?? could the pads be installed backwards and create heat?

Posted By: Andrewh

Re: brakes locking up - 07/24/13 01:29 AM

or the booster is bad.
seen a lot of posts on that lately.
there is an internal check valve that if it goes back can draw the pedal down.
This will cause your brakes to engage while driving.

See if you have the same problem with the booster capped so you don't draw vacuum.

Posted By: Challenger 1

Re: brakes locking up - 07/24/13 07:01 PM

Quote:

yep tried that .tti tells me my m.c. is not venting???
I did shorten the rod and it did not help.maybe the booster is not releasing after it gets hot?? could the pads be installed backwards and create heat?

Yes

Posted By: 68HemiB

Re: brakes locking up - 07/24/13 07:37 PM

FYI:

In drum brakes, the shoe with the longer and/or darker friction material goes toward the rear.

The shoe with the shorter and/or lighter friction material goes toward the front.

Posted By: RapidRobert

Re: brakes locking up - 07/24/13 07:44 PM

I still think the prob is in either the booster or the M/C especially if all 4 corners are locking

Posted By: 68HemiB

Re: brakes locking up - 07/24/13 07:50 PM

Quote:

I still think the prob is in either the booster or the M/C especially if all 4 corners are locking

Absolutely. My FYI was simply a reply to the "shoes installed wrong" comment. I personally do not think that is the O.P.'s problem.

When locked up:

1. Separate the mc from the booster slightly to see if they unlock. If that unlocks them, look to the rod length or booster or check valve.

2. If it doesn't unlock them, crack the hydraulic lines at the master and see if there's trapped pressure (in which case it's a mc issue).

Posted By: RapidRobert

Re: brakes locking up - 07/24/13 08:22 PM

Quote:

Quote:

I still think the prob is in either the booster or the M/C especially if all 4 corners are locking

Absolutely. My FYI was simply a reply to the "shoes installed wrong" comment. I personally do not think that is the O.P.'s problem.

Yeah I was directing my post strickly to the OP

Posted By: chromedome426

Re: brakes locking up - 07/24/13 08:55 PM

My guess is a faulty booster allowing engine vacuum to apply the brakes. Next time it happens, pull the vacuum hose check valve out of the booster to see if it will release the brakes.

Posted By: MILFORD MOPARS

Re: brakes locking up - 07/25/13 02:35 AM

yep I did pull that vacuum line off wile the car was warming up.but it didn't free up.when I backed the m.c off a little it freed up
ive backed they adjustment in and lost peddle but still builds up pressure.took the booster off last night.found a little corrosion.im going to clean it up and see if that works.
thanks guys