CR box and 3.73.1 differential

[S6 Devil]

I have managed to find a 3.73.1 differential at a great price so am now thinking of changing my RR Tuscan to a CR box.

Would it be possible to have my standard gearbox remanufactured to a CR box?
Can you recommend someone to do this?

Has anyone, who has done this mod got any information on what sort of difference I am likely to see/feel? Is it really worth doing?

[glow worm]

I have a 3:73 diff without a CR box and find it really good, just smooth... I suggest you try the diff without a changing the gearbox ratios..see if you like it.. May save you time and money.
John Reid is the best ex TVR gearbox man to speak to about your diff and gearbox work.. http://www.readmanracing.co.uk/

I changed the diff mainly to get rid of a "shunt" at low revs/high gear and put the older 4 flange Dana Spicer hyrdatrak with shorter prop shaft. Changing the ratios was an obvious improvement at the time, and does give more accelleration (not that it was slow before !!)

I have been told that CR boxes did cause premature transmission failures!!

Edited by glow worm on Friday 15th June 09:56

[S6 Devil]

glow worm said:

I have a 3:73 diff without a CR box and find it really good, just smooth... I suggest you try the diff without a changing the gearbox ratios..see if you like it.. May save you time and money.
John Reid is the best ex TVR gearbox man to speak to about your diff and gearbox work.. http://www.readmanracing.co.uk/

I changed the diff mainly to get rid of a "shunt" at low revs/high gear and put the older 4 flange Dana Spicer hyrdatrak with shorter prop shaft. Changing the ratios was an obvious improvement at the time, and does give more accelleration (not that it was slow before !!)

I have been told that CR boxes did cause premature transmission failures!!

Edited by glow worm on Friday 15th June 09:56

Thanks Keith, I hadn't thought of just swapping the diff. I will have a word with John and maybe get him to overhaul the diff that I have. Cheers!

[Robertjp]

CTS will overhaul your diff for under £300 too - i looked into it myself when considering buying a used one.

[Whitey]

did your RR Tuscan not have a 3.73 diff as standard?

[S6 Devil]

Whitey said:

did your RR Tuscan not have a 3.73 diff as standard?

No, it was a standard car but has had an S spec engine fitted with big bore exhaust.

[jcpgasoline]

I have a 3.73 diff on my Tuscan which was originally coupled with the wide ratio box. I have just replaced the wide ratio box with a close ratio box because I found that the TVR Power 4.5 SS I have in my car was just too much for 1st and 2nd gear with that gearbox/diff combination. In other words it was VERY easy to lose traction in 1st and 2nd and even 3rd. And that's with sticky R888's on.

Anyhow, first impressions of the new set-up are that it makes the engine's power more usable in 1st and 2nd gear in particular. Better traction because there's now slightly less torque at the wheels due to the higher ratios in 1st, 2nd & 3rd. Acceleration is still mental (60mph in 1st, almost 100mph in 2nd!) and I still have to treat the loud pedal with respect.