MG Sports Cars

engine swaps and other performance upgrades, plus "factory" and Costello V8s

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louebird
Louis Realmuto
Long Island, NY
(3 posts)

Registered:
12/21/2017 12:40PM

Main British Car:
1980MGB 3.9 Rover

Torque specs for MGC drive shaft flange?
Posted by: louebird
Date: December 21, 2017 01:59PM

I'm replacing the original 3.90 rear end in my 1980 MGB with a 3.30 MGC unit. The original 'C' flange is slightly larger and has a different bolt pattern. After installing the 'B' flange on the 'C' housing, what is the correct amount of torque used on the flange nut?

I've been told that the 'C' units use a regular spacer as opposed to the collapsable washer used in the 'B' units. There is plenty of info out there for the 'B' rear ends but I can not find anything pertaining to 'C'.

Any information would be greatly appreciated. Thank you, Lou


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5379 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Torque specs for MGC drive shaft flange?
Posted by: BlownMGB-V8
Date: December 21, 2017 08:14PM

I've seen a 135-140 spec and a 90 spec (Glen). If you have a crush spacer you might start out at about 80 and go in 5 or 10 lb increments, checking to be sure the pinion bearings haven't tightened up any. If not and you get to 140 I'd stop there. If they do, stop immediately, back off and torque to the next lower increment and check again. Hopefully at that point your preload will be within reason.

Use a sealant on the spline and loctite on the threads.

Jim


louebird
Louis Realmuto
Long Island, NY
(3 posts)

Registered:
12/21/2017 12:40PM

Main British Car:
1980MGB 3.9 Rover

Re: Torque specs for MGC drive shaft flange?
Posted by: louebird
Date: December 22, 2017 12:54PM

Jim, Thank you for the response. The question now is "do C rears use crush or just a regular spacers?" I'm getting conflicting information and I don't have a MGC manual because I've never owned an MGC.

Thanks again, Lou


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