i installed a 99 camaro rear a while ago now and i do notice that my rear wheels get alot more brake dust on them compared to the fronts.. i never changed the disk drum proportioning valve and i know thats the problem.. instead of getting the disk disk valve, can i put in an adjustable valve from summit? there is just one brake line running to the back right? anyone install this? can you fit it under the car and stick the **** through the floor somewhere for easy adjustments? and thinking (or dreading) cutting my lines and re-flaring them... is there a better flare tool than the crap i buy at pep boys? they really suck.

 

anyone

 

Subject discussed several times, try a search...

 

i did a search and saw the wilwood prop valve install. but i dont want to remove the stock valve just add another one to drop pressure down a bit. should work just fine but wondering if anyone else did it..

 

The reason you are seeing more dust on the rears is because the disc/drum prop valve is shooting 60-200 psi to the rear brakes first when you apply the brakes before even beginning to engage the front. It does this to overcome the pressure of drum brake springs and stabilize the vehicle in initial braking. Discs only need about 3-5 psi to initially engage the pads, and that pressure is controlled by the prop-valve. So you have a prop that is making the rear brakes do a lot more work, especially in light braking, that they were designed to. The disc/disc prop-valve is a bolt-in, no nonsense, pretty much guaranteed fix. I am one of the few strong advocates of OEM props for cars that are 99.9% street-driven in this forum, and thats my personal opinion. If you are truly racing the car on road courses regularly or have a system that is way different from stock it makes sense to go with an adjustable unit. If you are running OEM 3rd gen parts or using PBR calipers (1LE, LS1, C5) and haven't really messed with caliper volumes, stick to an OEM valve and you'll be fine.

 

ok thanks for the advice i will change to a stock valve but now i see there are different thread types and some wont work with others... i have a 87 firebird came stock with disk/drum and a 5.0 4bbl... now i have 99 camaro rear in it and the brake lines did all fit together when i did the rear swap... so does anyone know what prop valve i need? either part numbers or car years for junkyard hunting??... will a 4th gen valve work?

 

4th gens don't have prop-valves, they have ABS systems that control pressures. The differences in the prop-valves for 89-92 disc/disc cars is the thread size, early 89 cars had a different thread than later cars, and wether or not the car had the 1LE brakes. When I bought mine the dealer pulled-up 9 different part numbers so find the thread that lists the different part numbers so you'll know which ones are the 1LE or base versions. As for the fittings, I just got one of each of the 3 that were listed to make my connectors.

 

thanks for the help man i appreciate it.. so would a older(below 89) 3rd gen valve from any type of disk rear work? or should i look for the better brakes? (non iron caliper) in the junkyard...

 

According to Dan Burke, the lines are all the same (M1.0 tube nut threads) for 1982 - early 1989 applications, so fit shouldn't be an issue. Purchase a JY disc/disc valve and swap it in. Use a line wrench.

JamesC

 

No, you have a PBR caliper that has much less volume than the 82-88 iron calipers so stick with a PBR-sized prop-valve for an 89-92 car. GM still has them for about $100 each...

 

My bad (senior moment). If you're running a 99 rear, I assume, you have LS1 brakes, so Murco is correct about requiring another combo valve. Here's some info from Dan Burke's site about the 1LE upgrade that you may find useful:

14089496 1989 1st design: M1.0 tube nut threads (For 1982 - early 1989 applications)
10136840 1989 2nd design: M1.5 tube nut threads (Late 1989)
10136840 1990-'92: M1.5 tube nut threads.

JamesC

 

so i am screwed and need to change all my threads? to the newer style?

 

Since you have an 87, use the first design (listed above. Note the years). I used it my 85. It's a direct bolt-in.

JamesC

 

murcos just said that i should stick with a 89-92 style without iron calipers..i have aluminum calipers, and that would mean changing the threads... i do think the one that jamesC was talking about would be much better than what i have now. ??

 

The 89-92 (second design) won't fit your 87 because the thread size is different. As I memtioned, the first design, a 1LE combo valve, will fit 82 - early 89 cars without modification. The first design is the one I used on my 1LE conversion (PBR's front and rear).

JamesC