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Discussion Starter · #1 ·
Greetings All,

I recently picked up a 69 C20 in Colorado as a working project truck. Just to keep me busy in the evenings. She's pretty rough, but I love these trucks and I'm looking forward to restoring it as a driver.

I have recently fully restored 72 GMC Jimmy 4WD, I did most of the work myself other than paint and electrical. So I'm no mechanic, but I know enough to get myself in trouble...

That said - I have a mystery problem on my newly acquired C20 project. The previous owner installed a front disc conversion, and I cant drive more than 8 miles without the front brake pressure building up so bad that the front discs eventually lock up. I can then wait half an hour, let it cool, and It'l drive again but only 5-8 miles again.

I replaced the front proportioning valve. I was wondering if that could be faulty.

Has anyone seen/heard of this type of problem before and diagnosed it ?

Cheers in advance for any help !

James.

PS - shiny truck and also broken truck pics below.

Shiny truck


Currently broken truck (previous owner responsible for road-runner decal - might keep it)
 

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We had a similar problem wi th my dad's '57 chevy with a disc brake conversion. With his, the brake pedal was not coming up enough to release the pressure in the front lines. We could put a foot under the pedal and lift and it would release. Ended up being a spring problem under the dash. Fixed that and no more problem with sticky brakes.

Sent from my SM-G900V using Tapatalk
 

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Discussion Starter · #4 ·
Thankyou Cozwurth. The link from techinspector1 suggested inspecting for a similar kind of issue. I might go check that out tonight and see what I find.

I have replaced almost every part of the brake system - so if it ends up being a pedal adjustment I will probably have to laugh at myself for all the hours already invested ! Thanks again.
 

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Discussion Starter · #5 ·
Resolved thanks guys. Turned out to be a combination of both brake booster pin, and pedal adjustment. Both needed adjusting out. Took it for a 10 mile drive and so far so good. Thanks again.
 
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