I am have a problem with my rear brakes locking up under moderate to heavy braking. The car has the entire front disc brake system from a 71 Monte Carlo installed and it is a big improvement over the drums.

I have done all the norm things, adjusted the rear shoes, emergency brake cables and still have the same problem. I have an adjustable prop valve in the rear line and it is almost completely closed. I am now considering removing the hold back valve (original) from the front lines to see if this would help. I am thinking it may be restricting the flow to the fronts too much. Is this a good idea or will I cause more problems by removing it?

Thanks for your suggestions.
Greg
68 RS coupe, 275 horse 327

Are you using a combo valve from the Monte, or a '69 proportioning with seperate metering valve?

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1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
All sheetmetal is NOS GM
See my NEW webpage at: http://www.geocities.com/compuboy007/

That's a good point. If you got the distribution block off the Monte, it might be a combination valve. If so, you shouldn't need the extra prop valve on the back or the metering valve on the front.

Try turning the prop valve adjuster the other way.
David

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Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327 original owner. 69 Camaro Vintage Racer, 65 Lola T-70 Chev SB Can-Am Vintage Racer

Thanks for the replys.

I am using the combination valve and hold back valve that came off the Monte Carlo. I added adjustable prop valve in an effort to solve the lock up issue, it didn't help.

I do remember reading on this forum that GM started using a combination valve in place of the separate parts around 1970 or so. I assumed since these parts are all orignal to the 71 Monte, that the combination valve is just a distribution block and place for the brake light switch. Is there any easy way to tell them apart?

Thanks again for your help.
Greg

I bet you are correct in your assumption. If you pulled all of the parts off the same car, they were engineered to work together. The only other thing I can think of is that your metering valve might need to be rebuilt, or at least disassembled and cleaned out. There is a company that can rebuild the valve. Do a search in the archives, it's been mentioned before.

A combination valve will have a rubber covered push button on one end.
Regardless of what valve you have. A manual adjust proportioning valve should be able to take care of the balance issue.

It's been a while since I fooled with one, but, I think the more you turn the handle clockwise, the the higher the rear pressure will go.
You should back it off to lower rear pressure.
The handle screws down on a spring, the spring determines the "cut in" pressure of the prop valve. Once the cut in pressure is reached the spring rate determines what the rear pressure will be in relation to the front.
David

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Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327 original owner. 69 Camaro Vintage Racer, 65 Lola T-70 Chev SB Can-Am Vintage Racer