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87 10 Bolt rear with 91 Disk backing plate

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Old 03-04-2018, 09:06 AM
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Car: 1987 Firebird Formula
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87 10 Bolt rear with 91 Disk backing plate

Hey guys, I've tried searching, I have an 87 10 Bolt all rebuilt that came with my Formula, and over the years I've collected parts I knew would be difficult to find until I purchased another ThirdGen, but I have a set of 91 Rear disk backing plates, can the axle flange be modified to fit the backing plate?

I want to upgrade to 28 spline axles, and a new carrier, so if the axles will not work, it's not a big deal.
Old 03-04-2018, 09:18 AM
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Re: 87 10 Bolt rear with 91 Disk backing plate

91 backing plates will bolt right on the 87 10bolt.
Old 03-04-2018, 09:22 AM
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Re: 87 10 Bolt rear with 91 Disk backing plate

Originally Posted by TTOP350
91 backing plates will bolt right on the 87 10bolt.
Even though the 87 flange is for a drum?
Old 03-04-2018, 10:12 AM
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Re: 87 10 Bolt rear with 91 Disk backing plate

No. Easier to get the "hassle-free" brackets from Fly-n-bye.

Otherwise you have to cut, drill, shim, and concentric ring the drum rear.
Old 03-04-2018, 10:41 AM
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: 87 10 Bolt rear with 91 Disk backing plate

Originally Posted by Kevman
Even though the 87 flange is for a drum?
Since it wasn't mentioned, I incorrectly assumed the 87 rear was a disc also.

I have cut and drilled to flange to make disc work on a drum rear b4. However, Drew is correct, the bolt on backing plates work very well. Used them a few years ago.

If you are interested in selling the 91 disc backing plates to offset the cost of the bolt-on brackets , let me know, may be interested .
Old 03-04-2018, 11:17 AM
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Re: 87 10 Bolt rear with 91 Disk backing plate

Originally Posted by TTOP350
Since it wasn't mentioned, I incorrectly assumed the 87 rear was a disc also.

I have cut and drilled to flange to make disc work on a drum rear b4. However, Drew is correct, the bolt on backing plates work very well. Used them a few years ago.

If you are interested in selling the 91 disc backing plates to offset the cost of the bolt-on brackets , let me know, may be interested .
Yes, I would be interested in selling them if I cannot after all use them. PM me, and I will dig them out of my shop.
Old 03-04-2018, 02:35 PM
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Re: 87 10 Bolt rear with 91 Disk backing plate

You can modify the drum flange to use the disc mounting plates, it just takes more effort than the aftermarket bolt-on mounting plates.

AndyZ28 offered the parts, but his website is currently down, and they cost as much as the no-hassle adapters from Flynbye. I'm in the same boat at the moment, NOS 91-92 backing plates, and a drum rear. Not sure which way I want to go yet.

These shots from the AndyZ28 1LE CD show what has to be modified.












Old 03-04-2018, 09:16 PM
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Re: 87 10 Bolt rear with 91 Disk backing plate

The following 10-Bolt FAQ has a lot of info on brakes, to include the drum/disc axle interchange, master cylinders, combination valves, e-brake cables and so forth:

https://www.thirdgen.org/forums/tran...-10-bolts.html

After modifying the flanges, the following conversation write-up should prove somewhat useful:

https://www.thirdgen.org/forums/faq-...iscs-89-a.html

JamesC
Old 03-05-2018, 09:01 AM
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Re: 87 10 Bolt rear with 91 Disk backing plate

That Fly N Bye performance is dangerous for my bank account.

For $84 USD I can get the kit for 1LE brakes, so I may sell the ones I have and go that way.

I also discovered they sell the hubs and caliper mount for 2010 Camaro SS front rotors, which with my parts store discount could be worth while.
Old 10-28-2018, 03:56 AM
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Re: 87 10 Bolt rear with 91 Disk backing plate

Originally Posted by Kevman
That Fly N Bye performance is dangerous for my bank account.

For $84 USD I can get the kit for 1LE brakes, so I may sell the ones I have and go that way.

I also discovered they sell the hubs and caliper mount for 2010 Camaro SS front rotors, which with my parts store discount could be worth while.
Hey Kevman, I am local to you and have a lathe and bridgeport in my home shop. I can probably save you a bit from ordering from the states. Cheers!
I can make hubs etc. I have an 87 T/A myself.

Last edited by rgauder; 10-28-2018 at 04:02 AM.
Old 10-28-2018, 02:40 PM
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: 87 10 Bolt rear with 91 Disk backing plate

Originally Posted by Kevman
That Fly N Bye performance is dangerous for my bank account.

For $84 USD I can get the kit for 1LE brakes, so I may sell the ones I have and go that way.

I also discovered they sell the hubs and caliper mount for 2010 Camaro SS front rotors, which with my parts store discount could be worth while.
Let me know about the factory backing plates
Old 10-28-2018, 03:50 PM
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Re: 87 10 Bolt rear with 91 Disk backing plate

Originally Posted by TTOP350
Let me know about the factory backing plates
I think this is what he is talking about:

http://www.flynbye.com/catalog/i30.html
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