Question about brakes grabbing - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BP68 · 09-13-2011, 11:04 PM

Hey all,

I have a 68 with but my cab, brake pedal, booster came off a 72 that had power brakes. The master cylinder came from my buddy who got it new for his 71 with power brakes from CPP I think. It has been a while.

Anyway, when I first started driving the truck, the rear was locking up bad. Found out I had a leaking alxe seal. Got that fixed.

Brakes work great from inital push to about just over 3/4 of the way down.
But once I hit that last 1/4 to bottom of travel, brakes seem to lock up. I think it is the fronts locking.

So press pedal and feels right till right before end of travel than the grab hard. Any ideas on what could cause this. Could the wrong prob valve cause this? The prop valve is supposed to be a disc/drum unit, but it was one my bodyman had and installed, so I cannot be 100% sure. Just seems weird all is good till right when you reach end of pedal travel.

thx for any help/suggestions.

MADMIKE · 09-18-2011, 05:24 AM

Quote:

Originally Posted by BP68

thx for any help/suggestions.

Do you know what size the rear wheel cylinders are, the front caliper size, and which MC size you have.

A stock type combination valve can only do so much for proportioning the brakes correctly. If the bias is wrong from the start there isn't much to do to fix the problem until the components are sized correctly.

BP68 · 09-21-2011, 11:37 PM

Quote:

Originally Posted by MADMIKE

Do you know what size the rear wheel cylinders are, the front caliper size, and which MC size you have.

A stock type combination valve can only do so much for proportioning the brakes correctly. If the bias is wrong from the start there isn't much to do to fix the problem until the components are sized correctly.

I got my wheel cylinders and calipers from advance auto parts as listed for a 72 C10. The MC is from CPP for a 71 I believe.

I am thinking my best bet is going to be to just add a adjustable prop valve to my front line so I can dial it in. Just wondering if I was overlooking something simple.

faribran · 09-22-2011, 12:23 AM

...but would u want to add the adjustable prop valve to the FRONT line?

09-13-2011, 11:04 PM	#1
BP68 Registered User Join Date: Jun 2006 Location: Olive Branch, MS Posts: 824	Question about brakes grabbing Hey all, I have a 68 with but my cab, brake pedal, booster came off a 72 that had power brakes. The master cylinder came from my buddy who got it new for his 71 with power brakes from CPP I think. It has been a while. Anyway, when I first started driving the truck, the rear was locking up bad. Found out I had a leaking alxe seal. Got that fixed. Brakes work great from inital push to about just over 3/4 of the way down. But once I hit that last 1/4 to bottom of travel, brakes seem to lock up. I think it is the fronts locking. So press pedal and feels right till right before end of travel than the grab hard. Any ideas on what could cause this. Could the wrong prob valve cause this? The prop valve is supposed to be a disc/drum unit, but it was one my bodyman had and installed, so I cannot be 100% sure. Just seems weird all is good till right when you reach end of pedal travel. thx for any help/suggestions. __________________ 68 C10 Shortbed Fleetside 06 Chevy Ext Cab Fleetside 03 Grand Prix GTP My build thread http://67-72chevytrucks.com/vboard/s...d.php?t=269999

09-22-2011, 12:23 AM	#4
faribran Registered User Join Date: Jul 2005 Location: AL Posts: 1,828	Re: Question about brakes grabbing ...but would u want to add the adjustable prop valve to the FRONT line? __________________ "

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