Modified 10 bolt backing plate for 9 bolt
#1
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Car: 1991 BandittII Firebird
Engine: 5.7 HSR
Transmission: 700R4
Axle/Gears: 3.27 9 bolt
Modified 10 bolt backing plate for 9 bolt
i bought a 9 bolt disk for $75 last summer.off course it's my luck that it's a 2.77 gear and out of a 88 Z so it doesn't have the PBR calipers it has the crappy iron calipers.so i started to do some research as to what i needed to do to put the PBR calpiers on this rear end.through my almost endless searhing it was mentioned that the 10 bolt backing "may be" modified to be used on a 9 bolt rear end but i never found anything else about using the 10 bolt backing plates.i called the local chevy dealerships parts department.the 10 bolt backing plates were only $15 apeice so i ordered the backing plates thinking if they didn't work i was only out around $30.i picked them up yesterday and took them home and marked them up as to where they needed to be modified.i took a trip to work to use one of our horizontal milling machines.i brought them home and mocked them up and this what it looks like.
#2
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This link, which is on the FAQ board, might have proved usedful:
https://www.thirdgen.org/techbb2/sho...hreadid=246768
JamesC
https://www.thirdgen.org/techbb2/sho...hreadid=246768
JamesC
#3
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Car: 1991 BandittII Firebird
Engine: 5.7 HSR
Transmission: 700R4
Axle/Gears: 3.27 9 bolt
that page is refrenced on a few dozen different threads and it was helpful but it doesn't go into any detail on modifing the 10 bolt backing plates for use on a 9 bolt.
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Car: '88 Iroc, '91 RS, and a '70 RS
Engine: 5.7 TPI; 5.0 TBI; ZZ4/T56 on the ag
Transmission: A4, A4, slated to be a T56
I don't know if I'd trust those elongated holes to keep the bracket in place.. just MHO.
Ed
Ed
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Car: 1991 BandittII Firebird
Engine: 5.7 HSR
Transmission: 700R4
Axle/Gears: 3.27 9 bolt
i agree and i'm not going to trust them.my plan is to make a template of the hole pattern then weld the holes up and redrill the new hole pattern.
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Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Originally posted by Apeiron
Probably could have just swapped them left for right and drilled 4 new holes in each.
Probably could have just swapped them left for right and drilled 4 new holes in each.
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Car: Yes
Engine: Many
Transmission: Quite a few
if you have a welder and some copper round stock, you could stick a copper 3/8" bar in the 'good' part of the hole, and weld up the rest.
then again, they were only 30 bucks. like others said, just swap the left for the right, and the holes will fall in new material, with no problems 'ovaling' holes.
then again, they were only 30 bucks. like others said, just swap the left for the right, and the holes will fall in new material, with no problems 'ovaling' holes.
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Car: 1992 Camaro RS 25th Aniversarry Edition
Engine: 305
Transmission: TH-700-R4
Axle/Gears: 10 bolt with 3.23's and SLP Posi.
Originally posted by 91banditt2
why would you want to use copper?
why would you want to use copper?
#12
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Car: 1991 BandittII Firebird
Engine: 5.7 HSR
Transmission: 700R4
Axle/Gears: 3.27 9 bolt
i did what Apeiron had suggested and flipped them around and drilled new holes.i still welded in the old holes so it wouldn't look like swiss cheese.
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Car: 1988 Trans-Am GTA
Engine: 5.7L TPI
Transmission: WC-T5
Axle/Gears: BW 3.27
also, i can't tell in your picture, but the mounting holes for the PBR calipers need to face the REAR of the car or the will interfear with most of your suspension, it almost looks like the yolk is peeking out from behind there so i just wanted to make sure you knew that.
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Car: '87 GTA hardtop, '86 IROC hardtop
Engine: 385 DFI, 350 carb
Transmission: T-56, T-5
Axle/Gears: ls1 torsen 10-bolt, 9-bolt disc
You can still get the 9-bolt plates from GM, I just ordered a set this morning. they only list them for '90 model year, at least that is what my friend at the chevy dealership said when he tried to look up an '89 model year.
thanks
Luke
thanks
Luke
Last edited by luke j; 03-22-2006 at 06:57 PM.
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Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Originally posted by luke j
You can still get the 9-bolt plates from GM, I just ordered a set this morning. they only list them for '90 model year, at least that is what my friend at the chevy dealership said when he tried to look up an '89 model year.
You can still get the 9-bolt plates from GM, I just ordered a set this morning. they only list them for '90 model year, at least that is what my friend at the chevy dealership said when he tried to look up an '89 model year.
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Car: '87 GTA hardtop, '86 IROC hardtop
Engine: 385 DFI, 350 carb
Transmission: T-56, T-5
Axle/Gears: ls1 torsen 10-bolt, 9-bolt disc
That is what I thought also, but he said they where for a 7.75 ring gear rear end. I guess I will have to wait and see what I get. I may have spoken too soon I guess.
thanks
Luke
thanks
Luke
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Car: '87 GTA hardtop, '86 IROC hardtop
Engine: 385 DFI, 350 carb
Transmission: T-56, T-5
Axle/Gears: ls1 torsen 10-bolt, 9-bolt disc
I just called him this morning and had him order them, I should have them tommorrow or monday morn. I will post the part numbers when I can. I really hope they are correct, but I now have my doubts.
thaks
Luke
thaks
Luke
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Car: '87 GTA hardtop, '86 IROC hardtop
Engine: 385 DFI, 350 carb
Transmission: T-56, T-5
Axle/Gears: ls1 torsen 10-bolt, 9-bolt disc
yup they are 10 bolt brackets, same part numbers as above. The computer listed them for 7.75 ring gear diffs. I have brackets now anyway. I wil just swap side to side and redrill. are there any bigger brakes that will fit with these brackets?
thanks
Luke "spoke too soon" Johnson
thanks
Luke "spoke too soon" Johnson
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