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Drum to Disc Rear End Swap Worth Doing?

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Old Dec 6, 2011 | 07:55 PM
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85FBTranam's Avatar
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From: Ontario, Canada
Car: 1985 Pontiac Trans Am
Transmission: BW T5, Hurst Short Throw Shifter
Axle/Gears: 3.70 Posi
Drum to Disc Rear End Swap Worth Doing?

Does anyone have any opinion on whether a swap from a drum rear end to a disc rear end is worth doing. The existing rear end is a 1985 BW 9 Bolt with drums. The doner rear would be a 1988 BW 9 Bolt with iron calipers.

I have a new BW Posi and 3.70 ring and pinion. Better to swap the rear and put the new Posi and gears in the Drum or Disc rear end.

Aside from the fade issues with heat on the drums, is it actually worth it to do the full swap?

Thanks for your thoughts.
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Old Dec 7, 2011 | 02:16 PM
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Base91's Avatar
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From: Georgetown TX
Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: Drum to Disc Rear End Swap Worth Doing?

Depends on what you want to do with the car. If it'll just be a DD or occasional cruiser it's probably not worth the effort. You could spend the money on something more appropriate. If you want to race it, even only now and then, it would be worth doing.
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Old Dec 7, 2011 | 05:33 PM
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From: Florida
Car: 1987 Black IROC-Z (SOLD)
Re: Drum to Disc Rear End Swap Worth Doing?

Only decent swap for the rear would be The 11.655 dia rotors & aluminum PBR calipers. Iron calipers are junk in my opinion.
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Old Dec 7, 2011 | 05:36 PM
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From: Canada Halifax NS
Car: 82' Trans Am
Engine: 383
Transmission: t-56
Axle/Gears: 3:73
Re: Drum to Disc Rear End Swap Worth Doing?

It's worth doing. But like DJP87Z28 said buy the good stuff..
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Old Dec 7, 2011 | 08:05 PM
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85FBTranam's Avatar
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From: Ontario, Canada
Car: 1985 Pontiac Trans Am
Transmission: BW T5, Hurst Short Throw Shifter
Axle/Gears: 3.70 Posi
Re: Drum to Disc Rear End Swap Worth Doing?

I hear alot of mixed opinion on the iron calipers on here. What are the issues with them? Hard to adjust? Lower braking power than the drums?
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Old Dec 7, 2011 | 08:17 PM
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Car: 85 Z28 T-Top 36mm sway & wonderbar
Engine: TPI L98 350 W/85 Vette Stage II ECM
Transmission: W/C T-5, alum drive shaft
Axle/Gears: 9 bolt posi, 3:27, PBR's, BB LS1's
Re: Drum to Disc Rear End Swap Worth Doing?

I did just that and the parking brake does not work as well on the PBR disc brakes. I had to change prop valve, new parking brake cables, rotors, calipers, etc. Check out my signature and albums link to see pics of the rearend that I did the work on. The drums will keep the wheel cleaner and the E-brake works much better.
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Old Dec 7, 2011 | 08:27 PM
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85FBTranam's Avatar
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From: Ontario, Canada
Car: 1985 Pontiac Trans Am
Transmission: BW T5, Hurst Short Throw Shifter
Axle/Gears: 3.70 Posi
Re: Drum to Disc Rear End Swap Worth Doing?

Thanks for the input and links. I am not totally sold on the iron calipers, other than for looks. Need to make up my mind on either installing the new posi and gears into the drum rear end, which would be way easier!
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Old Dec 8, 2011 | 07:30 AM
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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: Drum to Disc Rear End Swap Worth Doing?

The old style Delco-Moraine calipers have a poor reputation on TGO, which may not be totally merited (my car was equipped with them for a while and in my experience they were fine). With new calipers and/or the 'fix' kit in place and with regular use of the parking parking, I doubt you'd have issues.

http://members.shaw.ca/crussel/recalls/86c28/86c28.html

JamesC

Last edited by JamesC; Dec 8, 2011 at 07:36 AM.
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Old Dec 8, 2011 | 05:47 PM
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85FBTranam's Avatar
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From: Ontario, Canada
Car: 1985 Pontiac Trans Am
Transmission: BW T5, Hurst Short Throw Shifter
Axle/Gears: 3.70 Posi
Re: Drum to Disc Rear End Swap Worth Doing?

Thanks for the link JamesC. The axle that I have is an 88. Regardless, I have remanufactured calipers, I would assume that this "fix" has already been applied? Any way to tell?
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Old Dec 9, 2011 | 09:53 AM
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JamesC's Avatar
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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: Drum to Disc Rear End Swap Worth Doing?

Originally Posted by 85FBTranam
I have remanufactured calipers, I would assume that this "fix" has already been applied?

Any way to tell?
I would assume so.

Not that I know of.

JamesC
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