Madddog

Well after reading up on the search results for the last 2 days, I'm more than a bit confused here...

OK, so I'm currently running an open 3.23 10-bolt drum rear. I picked up a 3.27 9-bolt disk rear complete last week for $100, albeit a very dirty and rusty one...guess buddy didn't know what he had. The rotors and cast-iron calipers obviously need to be replaced.

But I'm confused about the parts I'll be needing for this swap / upgrade (although Ed Miller and others have done a fantastic job documenting this). I want 89-92 PBR calipers, rotors from the same year (?), and will my 9-bolt backing plates work ? I think it was Ed who said that the 1LE upgrade would me MUCH easoer than the LS1 upgrade, fine with, I'm never at the track

I guess the backing plates are causing me the most confusion. And what year emergency brake cables should I order ?

Back to the search...

Bob.

JamesC

iTrader: (5)

The following link may shed some light:

https://www.thirdgen.org/techbb2/sho...hreadid=249098

JamesC

Madddog

What an excellent post, that's sticky material for sure.

Thanks to your 9- and 10-bolt backing plate comparison the difference is clear...since your upgrade was brake only and didn't include a 10 - to 9-bolt swap, I'm still uncertain if my existing 9-bolt backing plates (pre-89) will work with PBR calipers. Or maybe I'm just thick-headed...I've read so much about this swap that I'm starting to get all the info mixed up !


"As a matter of fact, the only difference in the 9- and 10-bolt rear ends, where PBR brakes are concerned, is the backing plates.

JamesC"

slowTA

iTrader: (1)

You're thick headed

Idealy you need the backing plates from a 9 bolt with PBRs. I've heard of someone making the 10 bolt PBR plates work with some kind of spacer.

Cast iron and PBR setups are completely different.

Madddog

Haha, I already knew about the thick-headed part My GF has already educated me on that one, and of course the ex-wife never lets me forget it.

Thanks, that helps a lot. I'll do a search for the part numbers, assuming they're still available.

So in addition to new backing plates, all I need is 89-92 PBR calipers, 89-92 rotors, and e-brake cables ? Hopefully I can source complete calipers up here for decent $$.

JamesC

iTrader: (5)

GM has discontinued the nine-bolt backing plates, but you might source them through Ed Miller. The ten-bolt plates are still available should you wish to modifiy the axel flanges on your ten-bolt (do a search) and build from there. By the way, if I recall correctly, Ed says that the 93-97 PBR's, though I bit different cosmetically, will also fit.

Your choices: use your nine-bolt rear with 89-92 nine-bolt backing plates and PBR's or modifiy the axel flanges on you ten-bolt drum and use 89-92 ten-bolt backing plates and PBR's.

JamesC

Madddog

Thanks, the search is on for backing plates, using my 10-bolt is not an option. It's open, the 9-bolt is "posi"...I've already chewed through 2 sets of spider gears on this open 10-bolt, now it sounds like there's play in one of the c-clips and my axle end keeps banging against the pinion pin. I'm tired of sinking $$ into this 10-bolt.

slowTA

iTrader: (1)

You may also have to look for the PBR caliper carriers. I'm thinking the calipers are like the 1LE/LS1/C4 setup where there is a cage that holds the pads and the caliper sits inside the cage also. I'm not sure if these will work with the newer 4th gen rear PBRs or not.

ebmiller88

iTrader: (7)

Hey guys...First off, we all know your pre-89 9 bolt plates won't work so we're done there.

As for e-brake cables, can't get them from GM so one of the sources I know you can get them is Napa, UBP P/N 94264. Here's a few pics of them compared to a set of factory GM ones I have. The UBP cables are obviously cheaper made but look to be fine to use...not a lot of options out there so we're stuck with them.

As for calipers, 4th gen calipers will work fine unless you have LCA relocation brackets on your axle, in which case you need to remove the big steel vibration thing on them or they will hit your brackets. Other than that one part, the 4th gen LT1 calipers are identical to 3rd gen '89-92 PBR calipers. And since the calipers are the same, the carriers are also the same. Additionally, the '88-96 Vette PBR rear calipers are of a similar design but don't use the e-brake like the 3rd gens do, and those calipers and carriers will also work, just without an e-brake.

Along those lines, guys looking to swap to LS1 rear brakes...C5 Vette rear calipers are the same as LS1 rear calipers and so are their carriers.

Let me know if you need help getting those 9 bolt rear backing plates, I know of a few sources, one being AndyZ28.


Ed

ebmiller88

iTrader: (7)

Forgot the cable pics but I'll have to Photoshop them first since they're too big to post.


Ed

dr_vlahos

iTrader: (1)

can someone please give me some advice??

I'm trying to convert my 1990 trans am 10 bolt drum brake to a disc brake set up without changing the entire rear end. I bought a 89 trans am 9 bolt disc brake (with aluminum calipers) rear end from a local scrap yard. My quuestion is: - can I use the backing plates from my 9 bolt donor??
- do I just do the same drum brake to ls1 conversion set-up article,(cutting the top of the drum backing plate and drilling new 2 new holes on top?
I want to use my existing 10 bolt rear end.
thanks so much
dr_vlahos

ebmiller88

iTrader: (7)

Yes, do just that and all will be OK. Just a note: your drum rear will have smaller center holes in the backing plates than the disc plates have to you MUST get the backing plate PERFECTLY centered so the brakes work right and are centered.

Ed

85irocz355tpi

You can clean up the 9 bolt and swap rear ends entirely U don't need anything except what u might break pulling the 10 bolt out. you'll also need a 4 wheel disc break master cylinder cause the valving is different between disc and drum. I've already performed this swap it's simple and the 9 bolt is stronger.

JamesC

iTrader: (5)

Check the following link for parts:

http://www.andyz28.com/3rdGen/reardisc.html

JamesC