Diff for 3.5 SDi Vitesse

[BAZ]

I have a 2.88 LSD from a XJS Le Mans and am getting a variety of views re mating it with the 3.5 SDi Vitesse engine and gearbox (5 speed). I don't intend to race it and haven't yet thought about wheel size; but the Jag ran on 15" rims and I'm not sure what the standard wheel size was for the Rover.

Advice please

[TINKA]

Hi Baz, I am afraid to tell you that 2.88 is to tall for a RV8 unless it has been tuned to give a lot more power than the standard 165 bhp. The problem you will find when the car is complete, is that it will be ok in the first 4 gears but 5th will be practically a waste of time. The thing about Cobras is that they are about as aerodynamic as a brick, so once you are at cruising speed you will have to push the loud pedal a lot more just to maintain your speed, and that is going to use a lot of fuel. The choice of diffs you need to choose between is 3.54 or 3.31, the 3.54 will give the best acceleration and the 3.31 will give more relaxed cruising ie. lower rpm for an easily maintained speed. :7 :7

One good point is, that if your box came from a Vitesse that is good news, as they are a stronger box than the standard LT77. :tu :tu

Sorry for the bad news and good luck Martin

[RichardG]

Baz,

FYI the Vitesse ran a 2.84 diff (unlike the standard SD1), produced ~190bhp and had, if I remember 205/60 15 wheels. Now, the vitesse was good for ~130mph and was a heavy car. The SD1 was quite aerodynamic for its time, but a cobra's going to be a lot lighter! Having said all that, if you're able to get another diff - go with the accepted wisdom of a lower diff ratio. I'm going to use my 2.88 lsd but then I'm running a auto. Good luck whatever route you go.

[TINKA]

Hi Baz, if you want a better response to this post, could I suggest you post it on the Tech tips section in the main forum.

Martin :tu :tu :tu :tu