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Old Aug 16, 2012 | 11:19 AM
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Rod-Tarry
Happily retired
 
Joined: Nov 2006
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From: Hampshire
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Originally Posted by scarnny
Hi folks I'm running 175x50x13 tyres and I'm using a standard t5 with a standard 3:6:1 cossie diff, the car is flat out at about 115mph at 6500rpm.
My question is would a 3:9:1 diff give me longer gears and a better top end or would it be to long and not pull top?
Any other ratios recomended for my set up? It would be nice to use 1st gear as its pretty non usable at the mo.
Also is the atb quaife diff a worth while upgrade?


Cheers andy....
Hi
Your maths dont add up.
175/70/13 with standard T5 5th (.8) & 3.6 diff gives 20.55mph per 1000rpm this is 133.6mph @ 6.5k rpm. Fitting a 3.3 diff would raise this to 146mph & a 3.9 diff lower it to 124mph.

Cheers Rod
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