pontiac rear with lt1 brakes

[Ishmael]

I'm doing the C5/lt1 conversion on my 68 firebird. I'm not sure how I will do that on a pontiac (non c clip) rear. Has anyone done that? Every add I see for rear brakes says they are only for c clip rears. Noel at Touring Classics said it was going to be a problem but that he's had other customers who have done it. Its an 8.2 with the half circles cut out of the pumkin cover - pontiac for sure. Even if you haven't done it do you know what I should do? I can't see how it should make a difference but the manufacturers certainly seem to thinks its an issue.

[Apogee]

Scott, your '68 Firebird should have the 2.75" RW507 ball-bearings on the axles and they should protrude about .105" inches (the thickness of the drum backing plate) from the face of the housing end if I'm not mistaken. I'm thinking that it might just be an offset issue with some of the aftermarket LT1 type brackets that won't allow them use the same bracket for both the BOP and the c-clip variants. It could be as easy as adding a Ø2.75" x .105" counterbore on the backside of the c-clip brackets so that they mount flush with the housing and still positively retain the bearing...or it could be a lot more involved. I'm just thinking out loud here, not having a LT1/C4 kit in our repertoire to reference.

There are also several variants of the BOP axles, not the least of which are the SET9 tapered roller bearings that came on certain BOP's and O-type housings. That might be another reason why the aftermarket sort of avoids it...you never really know what you've got until you pull it apart and look at it. Speaking from experience, we've had our fair share of struggles in the past with those applications. Maybe it's time to revisit them in ernest.

Tobin
KORE3

[Ishmael]

I don't really want to get rid of the rear because it is supposed to be as strong as the 8.5. I'll have to start looking for someone who manufactures a bracket while I look into the bearing issue you pointed out which I think is correct.
thanks

[ponchopwr70]

I have wilwoods, what I did was make spacers that go behind the axel retaining plates.

[Ishmael]

I have wilwoods, what I did was make spacers that go behind the axel retaining plates.

Did you take any pictures or could you diagram if for me? What thickness did you use? Obviously it affected your back space right? Anything info you could give would be helpfull.

[ponchopwr70]

I didn't take any pictures. What you need to do is measure the thickness of the old backing plate, then measure the thickness of the new backing plate/caliper bracket. You subtract the two and thats the thickness of the shim you need. I had some stock that I turned down to the od of the bearing and cut a slot to fit it in between the old retention plate and bearing. Then just bolt it up. It won't change backspacing because the axel is still in the same place. All this is doing is pushing the retainer farther out.