Hey there. I have a 9bolt 4.11 rear end with the australian PBR calipers I am trying to swap into my 88 Iroc. I have the 9bolt in and everthing bolted up.

The problem is the offset on the rotors seems to be wrong. They look to be the right rotors but when I put the calipers on it seems to be pulling the rotors inward like toe in.

I bought this setup used and am using the rotors that came with the rear end. The rotors seem to be about 11.5" diameter, I was under the impression that they should be 11.86" or something like that. Any help or suggestions would be greatly appreciated.

Does anyone know the correct p/n for the rotors that should be on this?

I am not 100% what this rear end came off of. I think it may have been an 89 but I cant remember if it was a Camaro or Firebird...

Thanks

Outside Diameter 11.665" (typically rounded to 11.7").

Check RockAuto or any other parts store. For PBR's you need the 1LE and/or performance version.

9- and 10-bolt J65 braking systems, Camaro or Firebird, use the same components--either Delco-Moraine iron calipers with 10.5" rotors (82-88) or PBR alum calipers with 11.7" rotors (89+).

JamesC

Thanks for the reply. So presumably I have the rotors I have on there are the 11.7" for the delco moraine system. I have a bunch of different sets of rotors on order at the moment so hopefully one of them will work.

What is the difference between the 89+ PBR's and the 1LE PBR's?

If you have 11.7, they're for the PBR system.

Nothing.

JamesC

Pictures of the 9-bolt 11.655 dia rotors and the aluminum PBR calipers (1989 rear).

Are you sure the calipers are moving freely on the mounting pins?
That was one issue I had when I did the rear-axle switchover.

Good-luck,
kk

Thanks for the help guys. The rotors I had were wrong and after ordering about 5 pairs of rotors finally found the correct ones. For some reason napa was the only place up here (canada) that had them. Now I just have to figure out why the brakes are so loud. Sometimes they sound like a drum singing on a brake lathe and it is LOUD...

Mine were doing the same thing. If your running the old rubber lines back there chances are they are collapsed or starting to anyways causing the calipers to not fully release. I went braided stainless and my brake noise went away...either that or the car is too damn loud now for me to hear it LOL.

I am using braided lines but they did come used with the setup I bought. But it seems to make the noise mainly just under light/normal braking. Not under hard braking.

if its a very early 89 9bolt brake setup with the dust shield, its prone to making those noises.
the bracket is kinda flimsy

It does have the dust sheild. Did the later ones not come with dust sheilds? I will look into this as a possibilty.

A bit more info on the problem:

The noise is more frequent when the brakes have warmed up, mainly under light to normal braking pressure, I guess at lower speeds like when rolling up to a stop sign or coming to a stop etc and a bit of the noise when taking corners at low speed without my foot even on the brake. The noise comes from both sides, not always necessarily at the same. I think the right rear might be a bit more apparent/start hearing the noise from that side first usually.

It does seem to be a bit better now that I have gone through a tanks worth of gas since putting them on but I doubt this noise is going to go away much more than it has already.

Some were equipped with the shield, others weren't. It may well be the year as TTOP suggests.

Are you using new brake pads and did you bed them?

JamesC

I am using new raybestos pads. I also did try bedding them as best as I could for driving on public roads + it has been wet out here the last few weeks. Also I do not have the correct proportion valve so i could definitly use some more braking power from the rears.

I will try removing the dust sheilds next time the car is in the air to see if that makes any difference. Are they just bolted on at the back/inside??

Dust shields were spot welded on my 9-bolt.

damn. might be getting out the grinder then...

i just tossed a set of raybestos pads for just those kinda noises. went to OEM original and noise went away.

where in BC?

Im in Vancouver on the North Shore