71 disc drum brakes issue need help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Critterman71 · 01-28-2012, 07:46 PM

I have a 71 Chevy Longhorn with power Disc and drums with with all original equipt. I am having trouble finding my problem. every time I stop the rear brakes lock up under normal pedal pressure. I can stop the truck if I ease down on the pedal but if I hit the pedal normally it always locks the rear. The booster has been tested as well as the master cylinder and the front calipers too and rear wheel cylinders and all lines. NEED HELP> Thanks Critterman71

BuiltwithIvy · 01-28-2012, 07:55 PM

do you have a proportioning valve?

CaptRMW · 01-28-2012, 08:39 PM

If you haven't already pull the rear drums and check for a seal leaking differential grease or a cylinder leaking brake fluid on the shoes.. Roger

Critterman71 · 01-28-2012, 08:46 PM

Thanks for the direction but I have check that also cylinders are excellent and no seal leaks thats why this is so baffling to me. I am now wondering about the prop valve but I am unsure how to test it for my issue, and or if it can be adjusted. Thanks so much for your reply. Keep truckn.

01-28-2012, 07:46 PM	#1
Critterman71 Registered User Join Date: Nov 2008 Location: Lansing Mi Posts: 642	71 disc drum brakes issue need help I have a 71 Chevy Longhorn with power Disc and drums with with all original equipt. I am having trouble finding my problem. every time I stop the rear brakes lock up under normal pedal pressure. I can stop the truck if I ease down on the pedal but if I hit the pedal normally it always locks the rear. The booster has been tested as well as the master cylinder and the front calipers too and rear wheel cylinders and all lines. NEED HELP> Thanks Critterman71

01-28-2012, 07:55 PM	#2
BuiltwithIvy Registered User Join Date: Oct 2011 Location: Ithaca NY Posts: 251	Re: 71 disc drum brakes issue need help do you have a proportioning valve? __________________ "To speak of the art of one loom, the art of one river, the art of one tractor, or the art of one automobile is not preposterous; it is to point to the size and importance of the gap between general knowledge and situated knowledge" - James C. Scott 1969 C10 - http://67-72chevytrucks.com/vboard/s...d.php?t=492064 1930 Tudor Sedan

01-28-2012, 08:39 PM	#3
CaptRMW Custom Sport W/T Join Date: Nov 2010 Location: Tarpon Springs,Fl & Annapolis,Md. ....................Quaint drinking villages with a fishing problem Posts: 898	Re: 71 disc drum brakes issue need help If you haven't already pull the rear drums and check for a seal leaking differential grease or a cylinder leaking brake fluid on the shoes.. Roger

01-28-2012, 08:46 PM	#4
Critterman71 Registered User Join Date: Nov 2008 Location: Lansing Mi Posts: 642	Re: 71 disc drum brakes issue need help Thanks for the direction but I have check that also cylinders are excellent and no seal leaks thats why this is so baffling to me. I am now wondering about the prop valve but I am unsure how to test it for my issue, and or if it can be adjusted. Thanks so much for your reply. Keep truckn.



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