Differential Ratios Correction

[Alan Critchley]

Amendment:

Could anybody tell me the best differential ratio for a Tiger Cat with Sierra Running type diffential unit. The engine seems to be revving excessively through the gears, ie (50mph = 2500 RPM).

At present i have a 3:9 differential unit. Would a 3:6 reduce the high revving?

Sorry for the mistake in details

Alan

[mikelr]

Alan.
Suggest you speak to Graham/Duncan at Chester Sportscars,they will give you a difinitive answer. Cant help you myself, but probably someone else on here will have the knowledge.
Mike

[paul]

Alan a 3:9 should give quicker acceleration and a 3:68 give a better top end. I had a 3.68 on mine with a type 9 5sp box and 70Mph should be around 3000rpm (depends on how accurate your speedo is though!)
What is the car revving at 70Mph in 5th gear? this will give us a better idea. I'd guess a 3.92 diff would be around 3150rpm, but that is a guess.
Hope this helps in some way