Brake Issue

DrexelSpivey · Jul 2, 2011

Whenever I have been in traffic for a long time, my brakes fail; pedal goes all the way to the floor, even if I didn't need them to creep along. After a stop and restart they work fine. What could cause this? ( Pads and Shoes are good)

TIA..

VAhasnoWAVES · Jul 2, 2011

im no expert...

but saying you were in traffic would lead me to believe your using them a lot. use builds heat. air expands more than liquid in these conditions. thats why we run brake fluid. i would guess you got air in the system. try bleeding it till all 4 corners run clear. if you dont regain pressure, the problem is elsewhere.

also, make sure your pads are seated 100%. one time doing a trail repair i didnt mount the rear one on the axle bracket properly. my peddle went strait to the floor.

PS - what year?

DrexelSpivey · Jul 2, 2011

VAhasnoWAVES said:
im no expert...

but saying you were in traffic would lead me to believe your using them a lot. use builds heat. air expands more than liquid in these conditions. thats why we run brake fluid. i would guess you got air in the system. try bleeding it till all 4 corners run clear. if you dont regain pressure, the problem is elsewhere.

also, make sure your pads are seated 100%. one time doing a trail repair i didnt mount the rear one on the axle bracket properly. my peddle went strait to the floor.

PS - what year?

It's an 88, and it was slow steady traffic, never touched them, just crept along at idle.. good thing I found out in slow going, was able to E brake..

techno1154 · Jul 3, 2011

I would look for fluid leaks first thing. Check the master cylinder for internal and/or external leaks as well each rear wheel cylinder and the front calipers.

By-the-way, if you were to release the pedal and applying it again would it hold? If you have an automatic transmission, be sure to put it in 'N' (neutral) before releasing the pedal.

magimerlin · Jul 3, 2011

X2 on checking for leaks and rebleading system to make sure all air is out. Also check the valve on the booster, the one way check valve for the vacuum from the manifold.

Matthew Currie · Jul 3, 2011

If no leaks, and assuming this is a conventional (non ABS) setup, it's looking like the master cylinder. You may experience this in light slow traffic first because you're not hitting the pedal hard. The rubber cups in the MC piston will expand under force, so when they wear, they'll fail first when gently applied, though still working when you stab the pedal.

heyhar · Jul 3, 2011

And, we've had a car-Sable, but MCs are similar-that performed fine, 98% of the time. It felt perfect, but would randomly go to floor. Of course, my daughter failed to tell me, till one day it scared her so bad she left it in a parking lot on her way to school, and I had to go get it. It felt fine until about the third time I needed to slow...right to the floor. A quick pump brought it back up, and a new MC solved it for good.

X2 0n Matthew's theory.

DrexelSpivey · Jul 3, 2011

Thanks all; no air in lines, no leaks, I'm just going to replace the MC, 291K and 23 years is probably a good lifetime for one...

magimerlin · Jul 6, 2011

Be a good time to do the dual diaphram booster as you are going to be taking the master off anyways. It was night and day difference when I did mine.

Brake Issue

DrexelSpivey

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VAhasnoWAVES

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DrexelSpivey

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techno1154

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magimerlin

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Matthew Currie

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heyhar

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DrexelSpivey

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magimerlin

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