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MG MGB GT V8 Factory Originals Technical - 3.07 or 3.9 differential ?

Hi,
I have a 75 gt v8 conversion, 3.5 ltr 5 speed rover vittesse,with a standard 3.9-1 differential [first gear not needed].
Apart from my first gear back what other gains would i have with the correct 3.07-1 differential?
Or are there any benefits from keeping my standard back axle?
I know that 3.07 crown wheel and pinions are available, has any body had any experience of fitting one of these to a standard axle, is it a d.i.y job or best left to a specialist?
Thanks for any information.
Graham.
Graham

Graham,
You really need some experience to set up a rearend properly; lots of the adjustments are done by feel. You have to have the right amount of preload and all that or it'll get expensive real quick. The beauty is, these guys don't charge much to do it right, about 60-70 pounds in your case.
Best, Joe
Joe Ullman

Graham-
The biggest advantage of installing a 3.07:1 ratio is not only do you get your 1st gear back, but 1st gear will be so low that it'll be great for creeping along in heavy stop-and-go traffic. If you wish to, 2nd gear will still be low enough that you can start off in 2nd gear and thus reduce the need to shift. Also, RPMs out on the motorway will be considerably reduced, thus improving fuel economy, lowering noise levels, and extending the engine's lifespan. However, as Joe Ullman said, the preload is critical. Get it wrong and it can get real expensive. Since you've never done this before, turn the final assembly over to a professional.
Steve S.

Graham,

Also consider a LSD and I would leave it to a specialist.

Prices are interesting Mike Satur is offering them a £332 wheras B&G are £680 but from Quaife (good price if it includes LSD).

The problem in the past with these diffs has been whine.

Paul
Paul

Joe, Steve S, Paul.

Thanks for information guys, looks like i will be going for it, but getting it set up proffesionally.

Just wondered, will it make it quicker as well as faster with the 3.07-1, can't get my head round it,
thanks again guys.

Graham.
Graham

Graham-
You don't get something for nothing. You'll get a bit less acceleration (not that you'll ever miss it unless you live for sprint racing), but a higher top speed and easier cruising out on the motorway, with better fuel economy as well.
Steve S.

Your 1/4 mile time will be a couple of tenths faster with the 3.07, it's the best ratio.

Dwight.
Dwight McClain

This thread was discussed between 16/09/2001 and 20/09/2001

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