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Smoking Brakes - Need some suggestions for trouble shooting

 
bigb_1925
I love my Chevy Chevette!
Posts: 9
Joined: 08/09
Posted: 08/29/09 05:59 PM

I've got a 64 Impala with smoking brakes and I'm looking for help in diagnosing the problem.

I've currently got a manual disc-drum set up.  I recently replaced the worn out master cylinder (drum-drum) with a manual disc-drum (deep cup, large disc/small drum reservior).  While replacing the MC the peddle push rod seemed to be too long and I had to resort to partially bleeding the rear brakes to allow the MC spool to engage.  The pedal is very stiff and the MC spool is depressed even if I don't step on the pedal.

After about 100 miles of use, the rear drums started smoking.  I thought that the drums just froze up.  So I pulled the drums, cleaned the backing plates and replaced the shoes.  I thought that it was really odd that the drum that was acting the worst came right off.  I didn't have to struggle with prying it off.  It was almost like the brake had never been hung up.

I found upon my test drive, that now both front and rear brakes are smoking and it feels like the brakes are on while trying to accelerate.

So, I'm now thinking back to the new MC and the push rod.

Do I need a shorter push rod?  What is the acceptable amount of compression of the MC when the brake pedal is not compressed.  If the push rod needs to be shorter, can I modify my existing  pushrod (cut to length and grind)?

Is there a check valve in the MC that is not releasing pressure on the brake?  Does this need to be removed?

Ideas on this cause would appreciated.

Mike  

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zman123
Everything in my driveway’s a Chevy
Posts: 537
Joined: 06/08
Posted: 08/30/09 06:53 AM

Shorten the pushrod between the pedal and the MC, There should be NO compression of the MC piston prior to putting your foot on the pedal, even a little slack.  

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bigb_1925
I love my Chevy Chevette!
Posts: 9
Joined: 08/09
Posted: 08/31/09 03:26 PM

Thanks.  I'll try that tonight.  

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bigb_1925
I love my Chevy Chevette!
Posts: 9
Joined: 08/09
Posted: 08/31/09 05:30 PM

That did the trick.  Thanks for the advice.  

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