Hi all.. 85 T/A. replaced all hard lines to rear. Brake light came on. Re-centered prop valve (very tough to move that thing.. therefore think its gunked up.. previous owner let brake fluid get very dirty) brake light out... more bleeding.. brake light back on.. trying to shop for replacement combination valve but can't find correct one. Only find standard thread .. my brake lines are metric. Tried Rockauto, summit, jegs, etc.. can anyone help with finding this part? Thank you thank you

 

Never seen a new one for our cars, don't think they exist in the aftermarket. Never seen a rebuild kit either which blows my mind.

 

yep. my prop valve was gunked up all right... so the shuttle thing inside was getting stuck and restricting flow to one end of the car.. did not want to re-center due to not being able to move freely.. really wish i could find a new prop valve that would take the metric bubble flare lines that my car has.. i've got a brand new PV-2 i guess i'll try to install.. still deciding if i should try to source adapters to go from the metric bubble-flare lines to the standard inverted-flare ports on the PV-2 prop valve.... or just cut the ends of the lines and re-flare them with the standard inverted-flare ends... anyone have any thoughts on this? thanks.

 

I think Hawks sells reconditioned ones, maybe a little pricey, but you can pretty much name your price when you have something needed and the only ones available. Otherwise go to the thirdgen parters or ask if Hawks themselves have one they can take off thats cheaper. HTH...

 

Thanks called hawks today they're gonna see if they have one.

 

What about just cleaning it up with some parts/brake cleaner? Aren't all the pieces there/in good enough shape to just clean it?

 

This might be the way to go.. Hawks isn't coming up with a compatible replacement.. I'm a bit surprised by that. I will actually try cleaning it.. hopefully the seals aren't damaged.

 

Hawks is still looking for a replacement for me.. cleaning my prop valve is not proving too successful. Have it soaking in carb cleaner for several days now. Still can't unstuck the shuttle thing in the bore.

 

It would take some researching but the combo valves were a GM parts bin part, probably not unique to the f-bodies. Maybe the ones below could work if not just to scavenge parts from. Personally I'd put in an adjustable unit, more work yes but you could control the bias front to rear.
1982, 1983, 1984, 1985 CADILLAC NOS ELDORADO/SEVILLE BRAKE PROPORTIONING VALVE | eBay
1982 - 1985 Camaro Firebird Brake Proportioning Valve 4 Wheel Disc Brakes #1 | eBay

 

I think every GM prop valve was tuned to the vehicle to create the brake bias they were looking for. Even Camaros of the same year came with different prop valves depending on suspension, tire, brakes package. The external housing is probably GM corporate, but the internal parts (valve rod diameter and spring rate) varied by application.

Each prop valve (combination valve) has a two letter code stamped on the body. That tells you what internals are inside and relates back to how it's tuned. You need to find a valve with the code you want so it behaves like it should.

Some of the valves are similar and you can swap out with a different spring to get the outcome you want, but you have to know what you're doing. I created the following thread to help people learn how to do that, https://www.thirdgen.org/forums/brak...ng-torque.html

That thread should be a sticky but our moderators aren't good at recognizing valuable content and would rather have stickies that tell you to do a search before you ask questions.