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MG MGB GT V8 Factory Originals Technical - Diff ratios....


I am wanting to increase my diff ratio to bring up the revs as I am currently doing just over the 100 MPH mark when I hit 7200 in 3rd.... Although great, it is just too fast to be able to enjoy 2nd and 3rd to their best on most roads!

I have a Salisbury axle running a standard 3.9 ratio and would like to switch to a 4.3 - 4.8 reducing that 100mph to around the 80 mark!

I have done a bit of research and am new getting the impression that no one makes this ration crown wheel and pinion for the Salisbury but it was available for the banjo.

Due to again MORE work and cost, I am loather to start to replace the complete axle for this. Does anyone have any ideas of how I can increase the ratio? Didn’t know if possible a Sherpa Van might have run on the same etc or if anyone has one of these in a box in their garage?

Any info as always greatly received

Cheers
Ed
Ed Braclik

Is this a V8 or four banger? 3.9 is to tall for a V8 to begin with. I not sure about raising it from there, it may make the almost un-drivable in anything but racing conditions.
M Mallaby

Ed, saw your post on the B board. Sounds like the last answer might be what you're looking for, but perhaps some of our fellow V8 types will have an answer. Probably from the Brits or Aussies though, as we here in the US didn't get much else in the way of BL vehicles, especially any with smaller engines that would have had the ratios you're looking for. For us here in the States the answer would probably be a complete swap of rear axle to something like a Ford 8" or Chevy 10 bolt which have tons of ratios made for them, both factory and aftermarket. The same should apply over there to something that would work, perhaps the Ford unit in the old Cortina or such.
Bill Young

Ed, what engine/transmission are you running? 7200 RPM is up there. If you are running low enough horsepower, you can switch to the older tube type MGB rear with the "pumpkin" center that's easy to take out. From there, watch the MGB racing boards (maybe post a message) asking for 4.56 or so gear ratio from a race car. I have seen a number of these at club meets (like the KC All British). It's not uncommon to see several at each event. Since you are in the UK, I would think they would be even more plentiful.

Sounds like you want to be shifting a lot.

What kind of engine life do you expect with running such RPM's? Ever miss a gear?

Richard
Richard Morris

This thread was discussed between 26/01/2007 and 28/01/2007

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