This is probably a dumb question, but I cant seem to find a concrete answer to my specific question anywhere, and I have searched. I have an 89 Iroc originally 4 wheel disc J65 car. Awhile back I installed a C4HD front brake kit I was always under the assumption the 1LE, and J65 prop valves were the same. So I did not upgrade the prop valve. However I'm starting to wonder if the specific 1LE one is different. Which may explain my lackluster braking.

This is the one Ebmiller sells but what's misleading is it says 1LE/J65 In the description

http://www.flynbye.com/catalog/i40.html

 

There's no such thing as a 1LE valve. The front part of the valve is the same, the back circuit is specific to the PBR calipers. So if you have PBRs you have the "1LE" valve.

99% of the "1LE RARE" parts are just normal L98/LB9 G92 FE2 parts.

 

Im glad to know I'm not going crazyIll have to do some more digging and see what my issue is then.

 

You will need to change spring rate in the combination valve or get an adjustable one. I just did the swap with the rear adj. Wilwood valve and it stops awesome. I found a brake upgrade thread on here that explained everything and what spring to use in the valve. I will see if I can find it and link it.

 

https://www.thirdgen.org/forums/brak...e-upgrade.html

Here is the thread

 

"Need" is a bit of a stretch. You can modify the valve, but it's not at all a requirement.

If you read the threads about changing springs in the prop valve, the idea is that GM used an overly safe brake bias. By changing the springs or brake bias, you may make things better or worse. If you don't know how the system works, and what you hope to change about it, you probably shouldn't be making adjustments.

 

I did the swap and used the j65 valve. Car stopped ok. Put the adj. Valve in and yes it is a night and day difference. You are correct on know how. I personally like the adj. Route better and went that route to dial it in. I probably should have said want instead of need