brakes "90" GMC 1 ton van, repaired,still locking

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  #1  
Old 04-02-03, 03:20 PM
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Angry brakes "90" GMC 1 ton van, repaired,still locking

Hi Guys

Replaced front passenger brake caliper that was locking. Front fine now back brakes begin to lock. Replaced both back cylinders + lines and bled . All in terrible condition. Right rear still locking. Auto adjust on both wheels seems fine and turns easy. hardware on back wheels looks good and functional as do shoes. During all these steps after replacing front caliper, both back wheels would lock individually at one point or another.

Whats next??

Thank you

Rob
 
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  #2  
Old 04-02-03, 07:34 PM
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I would check if you van is equipped with proportioning valves. If it is equipped with one its time for an adjustment. Also make sure you lines are clean and getting even flow to every wheel.
 
  #3  
Old 04-03-03, 04:41 AM
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Wink brakes "90" GMC 1 ton van, repaired,still locking

Thanks weldgod

I am not familiar with this valve. I see that it has one. The lines off master lead to it. Can i adjust this simply or do I need detailed from manual?. This is my friends van hence no manual.

All the best

Rob
 
  #4  
Old 04-03-03, 05:41 AM
Joe_F
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I'd pitch the valve. They are fairly cheap through GM and this is a common failure on these vans.

Also, I would change both rubber caliper flex lines for safety as well. Common problem too.
 
  #5  
Old 04-04-03, 05:37 AM
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"90" GMC 1 ton van, repaired,still locking

my friend,

one more q?

Any electronics before valve that could be at fault or are connections to fail safe censors??

Thanks a bunch
 
  #6  
Old 04-04-03, 05:37 AM
Joe_F
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If the van has rear wheel ABS, sure.
 
  #7  
Old 04-07-03, 12:17 PM
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Angry brakes STUMBLE "90" GMC 1 ton van, repaired,still locking

Hi again

We just spent 2 1/2 hours at dealer. We have the proportion valve but the anti-lock portion of the valve is discontinued and no longer available in this van as determined by the dealer. He had no answers for us(very helpful though). Any thoughts on this application as is with the old anti-l unit? apparently this was one of the first out for that period and is attached to the valve by the same bracket a bolt and brake lines. It has a four prong connector. The dealers did not even know what it was. The factory did not, but a Mech. on duty recognized it. Can this be discontinued if it is a part of our braking problem? Is it likely to cause the condition we are having and if so can we fix that part or use some other from a different year or make? We are not to concerned with the ABS on this van.

Thanks

Rob
 
  #8  
Old 04-07-03, 01:12 PM
Joe_F
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A couple of things:

1) See if the aftermarket has rebuilt ones. Try A-1 Cardone (sold through most parts stores)
2) Have the dealer's parts dept fetch the part # and put it on their locator service to see if any turn up anywhere at another dealer. In turn, your dealer can order it from that dealer.
3) A used unit is a possibility, but is a gamble.

If the dealer has been helpful thus far, see if they will go the extra mile for you. They seem like they are on the right track.

The hardware may "look" good but is likely wasted. Change it and don't gamble.
 
  #9  
Old 04-08-03, 01:50 AM
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I Agree
 
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