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MG MGB GT V8 Factory Originals Technical - V8 Diff Ratio

I am currently fitting a Rover 3500 motor and a Toyota Cressida (Celica) 5 speed gearbox to my rubber bumper MGB.
I can't get a W58 box which has a top gear ratio of 0.78 in this country so I will have to make do with a W55 which has a ratio of 0.85. To compensate for this I would like to fit a Diff with a better ratio than the standard 3.9 say, 3.0. Does anyone know of a diff that would fit without too much modification?
Chris Barrow

Chris,

the easiest way is to use an axle out of a C, that comes with 3.3 or 3.09 ratio (take care, some had a 3.7 as the B with automatic gearbox). I used a 3.3 and a LT77 Rover 5 speed and it works very well.
A friend has bought a GTV8 last year, converted by Dave Wale and it came with a shortened version of the Rover SD1 axle with a 3.08 ratio.
I also heard from a Ford Capri 3.0 axle used unber a B V8 but have no further Information upon this.

May be some old Mitsubishi Chelica rear ends will work too?

Ralph
Ralph

I'm using a Ford/Currie 9 inch 31 spline axles and rear disks (Ford Explorer) with a small drum parking brake all supplied by Currie Enterprises. The housing is available in aluminum as well.

http://www.currieenterprises.com/

The Aussie dollar is pretty strong against the US dollar now so this may be a bargin you can't walk away from.
Michael S. Domanowski

Forgot to add my rear diff. ratio is a 3.00:1. I'm using a T5 World Class transmission with I believe a 0.78 final gear ratio and 15/50 series inch tires. At 80 mph I'm only turning 2650 rpm and I get over 25 mpg at that speed.
Michael S. Domanowski

Chris,
Aside from the diff fitted to the MG C most diffs for ratios in the 3.00 range are for larger vehicles so you may have very few options.

Perhaps a 4WD may be an alternative or maybe the 3.08 fitted to the Holden Commodore range imported to SA from Australia for a number of years in the mid 80's.

They all used a Borg Warner 3.08 diff and some had Limited Slip as well. Normally known as 4 pinion as opposed to the standard 2 pinion.

Pete.
Peter Thomas

Many thanks for all the information. I will have to look for something locally as the cost of importing anything into this country is prohibitive. Unfortunately MGC cars are like hen's teeth in South Africa, and I have yet to find a local engineering shop who do things like shortened axles. There are quite a number of old Rover SD1s around. I will see what I can find, and whether the expertise to shorten it is available. Thanks again to all for your input!
Chris Barrow

This thread was discussed between 09/11/2007 and 12/11/2007

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