Q's 91z28

Have searched and I'm more confused now. I have a 91 Z28 with rear drum brakes that I'm converting to LS1 disk brakes. The rearend is out of a 2000 Z28. What proportioning valve do I need to ensure that I get proper pressure. The stock valve does not and will not work ( I tried yesterday). I have seen that the 1LE valve will work but I want to make sure that its the right one. Also, can you pick one up at local parts store like Autozone...etc. FYI, I have also done the LS1 disk brake upgrade up front. Any info would help guys.

JamesC

iTrader: (5)

You can purchase the correct 1LE valve from Ed Miller. http://www.flynbye.com/catalog/c17_p1.html

The valve has been discontinued from GM. You won't be able to purchase from an auto parts store.

JamesC

Q's 91z28

This is what flynbye.com says
'90-92 1LE/J65 Proportioning/Combination valve NEW
Correct prop valve for installing 1LE/LT1 PBR J65 ('89-97) rear discs on your '90-92 year F body.

--I have the LS1 brakes from a 2000. Will this still work? The way I read it, its for brakes up to 1997.

Guest

lets back up for just a second so I can get some info.

You said in your opening statement that the valve you have will not work because you tried it- can you explain further what the problem is you are having? Was it fitment, bias issues?

Also, what pads are you running both front and rear (brand/compound-ie- Hawks HPS, PFC ceramics, Wilwood E, Q, T etc)? I need fronts AND rears if different or the same.

Dean

Guest

You are still online but I guess not seeing this post. I have to get going so I will give a generic response.

The factory offered 3 different combo valves-
1)disc/drum
2) disc/disc non 1LE
3)disc/disc 1LE

All increasing in rear bias. The rear drums needed the least pressure due to leverage on the mechanism of the shoes. THe non 1LE had a little more rear pressure due to the disc needing more pressure to exert force BUT the front and rear calipers were proportioned as such not to need as much pressure for bias balance as the sportier large 1LE fronts did with the 1LE rears.

IMPORTANT NOTE: These bias' were all factory determined with 3rd gen brakes on 3rd gen cars with there wegiht bias, tire sizes,etc accordingly.

You are asking about putting 4th gen brakes on a 3rd gen weight bias with a third gen combo valve. You might be better suited using an in line adjustable prop valve if you now have too much rear pressure, or going to the 1LE valve if you currently do not have enough rear pressure.

Ninety-One

I don't mean to hijack your thread, but I'm having a similar problem, all I swapped was the rear end, and the rear brakes feel as if they aren't working. What proportioning valve do I need for a 91 RS that I swapped to a 9 bolt disk brake rear end(cast iron calipers). The car was previously drum brakes.

JamesC

iTrader: (5)

The normal 84-89 valve used on four-wheel disc cars with Delco-Moraine calipers (iron, single piston). The number 2 that Vetruck mentions above.

JamesC