rear disc conversion

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Feb 17, 2009 | 09:07 AM

transamice

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Joined: Apr 2005

Posts: 490

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From: Hamilton ON Canada

Car: 87 GTA t-top

Engine: L98 350 w/RMT

Transmission: 700R4

Axle/Gears: 9 bolt BW 3.45

rear disc conversion

I have an 87 GTA with rear drum, I got a rear axle with PBR disc brakes from an 89 GTA.
Can I use the 87's axle and change the mounting bracket, calipers from the disc axle or do I have to change the whole axle?

Feb 18, 2009 | 06:49 AM

JamesC

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Joined: Aug 1999

Posts: 19,282

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From: Lawrence, KS

Car: Met. Silver 85 IROC/Sold

Engine: 350 HO Deluxe (350ci/330hp)

Transmission: T-5 (Non-WC)

Axle/Gears: Limited Slip 3.23's

Re: rear disc conversion

Quote:

Originally Posted by transamice

I have an 87 GTA with rear drum, I got a rear axle with PBR disc brakes from an 89 GTA. Can I use the 87's axle and change the mounting bracket, calipers from the disc axle or do I have to change the whole axle?

You'll either have to mod the drum's axel flange or purchase a conversion piece from Ed Miller: http://www.flynbye.com/catalog/i30.html

You'll need to proportioning valve whether you do as above or swap years entirely.

JamesC

Feb 18, 2009 | 07:59 PM

transamice

Thread Starter

Member

Joined: Apr 2005

Posts: 490

Likes: 1

From: Hamilton ON Canada

Car: 87 GTA t-top

Engine: L98 350 w/RMT

Transmission: 700R4

Axle/Gears: 9 bolt BW 3.45

Re: rear disc conversion

I have the brackets from the 89 axle though, 4 bolts and they come off.
Just didnt know if I can use the same brackets on the 87 axle, will save me from switching the whole axle and changing gears again.

Feb 18, 2009 | 08:54 PM

ebmiller88

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Posts: 6,420

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From: Fort Mill, SC, USA

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

Re: rear disc conversion

You can modify the drum flanges to accept the disc backing plates and you'll be fine, similar to how you would modify the drum flanges for LS1 rear discs. Or just get the conversion plates. Please note you'll have to have the drum axles turned down to fit inside the '89 discs or buy new ones for a '93-97 which will install over your drum axles.

Ed