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7.5 to 8.5 rear swap

Stuff like brakes, frame, springs/shocks, tranny's, etc. etc.
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307 Regal
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7.5 to 8.5 rear swap

Postby 307 Regal on Wed May 04, 2011 3:29 pm

My car has a 7.5" rear end. How much of the suspension would be compatible with an 8.5" rear end? Do I need the control arms from the 8.5"?
N/A T-Package '87 Regal (Y56) Street/AutoX Cruiser
'76 Buick 355 V8 "5.8L" / 200-4R (shift kit) / 7.625" 3.73:1 LSD
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eversmann79
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Re: 7.5 to 8.5 rear swap

Postby eversmann79 on Wed May 04, 2011 3:53 pm

from a gn or 442 rear?
think all you need is 1" shorter driveshaft.
correct me if im wrong

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Chris Van
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Re: 7.5 to 8.5 rear swap

Postby Chris Van on Wed May 04, 2011 4:06 pm

Direct bolt in.... If you are getting the 8.5 out of a donor car just MAKE SURE you get the driveshaft too. You will need it too....
If not.... I have just what you need....
83 Olds Cutlass
85 Olds Cutlass
71 442. W-30

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307 Regal
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Re: 7.5 to 8.5 rear swap

Postby 307 Regal on Wed May 04, 2011 4:14 pm

eversmann79 wrote:from a gn or 442 rear?

Not sure. I haven't called on it yet.

Chris Van wrote:Direct bolt in.... If you are getting the 8.5 out of a donor car just MAKE SURE you get the driveshaft too. You will need it too....
If not.... I have just what you need....

*noted.*
N/A T-Package '87 Regal (Y56) Street/AutoX Cruiser
'76 Buick 355 V8 "5.8L" / 200-4R (shift kit) / 7.625" 3.73:1 LSD
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JBreu
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Re: 7.5 to 8.5 rear swap

Postby JBreu on Wed May 04, 2011 4:50 pm

Direct bolt in, only you will need to have your shaft shortened 1". BTW, How much you getting it for??? 8)
1984 Monte Carlo with sbc 388 stroker ( dynoed 514hp) 700-r4 , 12 Bolt w/4:10
Old Chevy's Don't Die, They just get faster!
Best ET to date : 12.20 @110 Mph All Motor
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307 Regal
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Re: 7.5 to 8.5 rear swap

Postby 307 Regal on Wed May 04, 2011 5:39 pm

JBreu wrote:Direct bolt in, only you will need to have your shaft shortened 1". BTW, How much you getting it for??? 8)

I was just about to call the guy. He has it listed for $400 which I'd assume isn't bad for an 8.5 posi if it's in alright condition. While I'm talking to ya, how much did it cost to get that 12 bolt in your Monte?
N/A T-Package '87 Regal (Y56) Street/AutoX Cruiser
'76 Buick 355 V8 "5.8L" / 200-4R (shift kit) / 7.625" 3.73:1 LSD
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JBreu
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Re: 7.5 to 8.5 rear swap

Postby JBreu on Wed May 04, 2011 6:50 pm

307 Regal wrote:
JBreu wrote:Direct bolt in, only you will need to have your shaft shortened 1". BTW, How much you getting it for??? 8)

I was just about to call the guy. He has it listed for $400 which I'd assume isn't bad for an 8.5 posi if it's in alright condition. While I'm talking to ya, how much did it cost to get that 12 bolt in your Monte?

$400.00 is a steal, even if it's an open differential...I bought mine on E-Bay a few years back for $800.00 and it cost like $150.00 to get her shipped up here from Indiana....then something like $250.00 or sop for the 12 bolt swap kit (upper/lower control arms) from UMI performance.... 8)
1984 Monte Carlo with sbc 388 stroker ( dynoed 514hp) 700-r4 , 12 Bolt w/4:10
Old Chevy's Don't Die, They just get faster!
Best ET to date : 12.20 @110 Mph All Motor
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307 Regal
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Re: 7.5 to 8.5 rear swap

Postby 307 Regal on Wed May 04, 2011 7:47 pm

JBreu wrote:
307 Regal wrote:
JBreu wrote:Direct bolt in, only you will need to have your shaft shortened 1". BTW, How much you getting it for??? 8)

I was just about to call the guy. He has it listed for $400 which I'd assume isn't bad for an 8.5 posi if it's in alright condition. While I'm talking to ya, how much did it cost to get that 12 bolt in your Monte?

$400.00 is a steal, even if it's an open differential...I bought mine on E-Bay a few years back for $800.00 and it cost like $150.00 to get her shipped up here from Indiana....then something like $250.00 or sop for the 12 bolt swap kit (upper/lower control arms) from UMI performance.... 8)

Was the rear from an A-Body? I'm just curious because I've (technically) got access to a 12 bolt from a '71 GMC Sprint and ever since I saw your car on here I've been kicking the idea around..

EDIT: might be kicking that idea around a bit more. Got a hold of the guy and the 8.5" is already gone. :blam:
N/A T-Package '87 Regal (Y56) Street/AutoX Cruiser
'76 Buick 355 V8 "5.8L" / 200-4R (shift kit) / 7.625" 3.73:1 LSD
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JBreu
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Re: 7.5 to 8.5 rear swap

Postby JBreu on Wed May 04, 2011 8:03 pm

From an "A"body car.....All 66-72 A Body cars will work with our G-Body cars.......You will need the 12 bolt swap kit though, and the 66-67 A body cars are a lil narrower then the 68-72 cars....BUt with the proper backspacing on your wheels, you would be ok !! 8)
1984 Monte Carlo with sbc 388 stroker ( dynoed 514hp) 700-r4 , 12 Bolt w/4:10
Old Chevy's Don't Die, They just get faster!
Best ET to date : 12.20 @110 Mph All Motor
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Re: 7.5 to 8.5 rear swap

Postby pontiacgp on Wed May 04, 2011 8:11 pm

I have the 8.2" 67 chevelle rear and like JBrue said it's more narrow than the 68 and up...it's 2.5" wider than a G body rear and 2" narrower than a 68 and up A body...I'm currently putting disk on the back and it looks like an F body calliper bracket with 1980 Seville rear callipers with the parking brake will work...I just have the get the flange on the axles trimmed to fit into the F body rotor
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