I've searched and I keep finding conflicting answers to my question. I'm swapping out the 10 bolt drum rear this weekend for a 9 bolt with the aluminum PBR's. I have the PV from the donor car (late 89 GTA) and it looks identical to the PV that I have in my 91. The thread pitches on all the fittings look exactly the same when I put the PVs side by side. I've read some posts that say all PV's were the same from 89-92 for disk/disk & disk/drum and that there is no need to swap them out. I've also read some posts that say I need to either swap the PV or add an adjustable PV. What to I HAVE to do? I'm all for not swapping it out if I don't NEED to. I also have the E-brake cables from the donor car, I'm guessing I need to swap those, right?

 

Anybody?


I'm heading outside to start the axle swap. I'll be checking in from time to time to see if anyone has any input on the need to swap the PV.

 

Earlier cars you needed the proportioning valve from the 9-bolt (I can't answer that question). Also if you have the parking brake cable for the 9-bolt you should be set to go.

 

Humm, seems like I read that somewhere too--Ed Miller, I thought--but I couldn't find any info (curiosity). Perhaps the thing to do is to try the system without changing the p/v and see how you feel about it.

JamesC

 

That's what I'll do unless someone chimes in with a definite answer later on today.

 

You will have to have a prop valve for the year car you have. 89 valves have different threads than 92s do. Been there and done that. The 9 bolt has different e-brake cables as well. If your car is a 91 then go purchase a 91, 4 wheel disc prop valve and you should be fine. They made several different prop valves from 82-92 and the threads were different as well. The PBR calipers on the 89 9 bolt were about the same on the 90-92 10 bolts so fluid volume should be the same.

 

Note the early/late designation:

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

The e-brake cables are self-adjusting, 90-92, IIRC, so the "tunnel piece" from an 82-89 car will be required--or another mod of some sort. I'm unsure about the e-brake handle.

PBR calipers, 89-97, are essentially the same, regardless of the rear end they came on.

JamesC

 

OK, I finished the swap today. I did everything but swap out the PV. I bled the rear brakes, but I didn't touch the fronts. When I drove the car the pedal feels kind of stiff, the fronts grab really hard when I stomp the pedal, but the rears don't seem to be grabbing very good.

Do I need to re-bleed the rear and then bleed the front to make everything even out?

 

Re bleed the rear you might still have some air.The same thing happend to me when I swapped my rear diff,so I went and re bleed the rear brakes and turned out I still had some air stuck in the lines.

 

I re-bled the rears this morning and took it on a 10 mile drive. Everything seems to be working great. It stops a lot better than it did on Friday when it still had the drum rear.

I did not change out the PV and everything is working just fine. The rears don't lock up, and the car doesn't nose dive. For once it stops pretty flat.

 

Sorry for not posting earlier. You may not need to change the prop but to be correct as designed you do. If it works well for you then don't. The props will look identical from the outside but are different internally and with thread pitches on the brake lines. The e-brake cable hook ups will also be different but you will only need the correct cables for your year car, with disc rears, for a 1991.

Ed

 

I did a similar swap when i got my car, though i wasn't lucky enough to get PBR. I switched to a Proportioning valve from a 92 with rear disc, but the 9bolt was from an 88. Then the rear disc calipers were shot, so i got new ones at autozone for cheap and that worked out fine. Rear disc, working e-brake. Definitely beats drums.

I took the e-brake cables off my old rear and put them on my 9-bolt, i believe.

 

I got the E brake cables off of the 89. They hooked right up to my car. The E brake works great and holds tight.

 

Glad to hear that it worked out........now after the 2:73's, how do you like the 3:27's ?

It gots to be better.......

 

It's like day and night....I LOVE IT!!! My car will actually launch now. And, I don't have to worry about burning up the clutch in traffic with the 2.73's anymore.

 

I knew you would. I've had a 2.73 rear for a short time with 5 speed and you know how that was. Even the 3.08 that came in my present car was not that much better. I would like your 3.27's as they give a good performance boost but are still very cruise [mpg] friendly. My present 3'73's are a little too deep for allot of x-way use for my taste. But I have a new set of 3.42's and HD Torsen when I get time.

Later........DM

 

read through the post i recently bought a 9 bolt with disc brakes, didn't come with the e brake cable or proportional valve.

my car is a 85 z28 with drum brakes.

do i need a different PV and can i use the cables from my original rear end for the ebrake?