1.6T wrc wheelbase/dimensions regs.

[Zico]

Xtrac rear differential don’t even need an auxiliary hydraulic pump for handbrake operation.

Here is a brochure of the S2000 version.

http://www.xtrac.com/pdfs/532%20SUPE...FFERENTIAL.pdf

Thanks OldF, I remember Mazda being the 1st to use it in the GrpA 323 ?. I'd always assumed it was a clutch within the centre diff.

[OldF]

Thanks OldF, I remember Mazda being the 1st to use it in the GrpA 323 ?. I'd always assumed it was a clutch within the centre diff.

I don’t know what systems earlier grp A cars used but if I’m remember correctly, by the end of 1995 all the grp A cars had an active centre differential, which could be controlled in such a way that when the hand brake is pulled, the centre differentials clutch was not activated.

Xtrac gearboxes used in S2000 have a centre differential as an option. The reason why it’s not used I think is weight saving. The lack of a centre differential doesn’t ruin the cars car's driveability that much that it would be worth using.

[Mirek]

I think it's not because of weight. In my opinion it's more likely because of power loses which are rather important with less powerful normally aspirated engines of S2000 cars. My estimation is that it can save 10-15 Hp.

The other thing is that mechanical center differential is not that useful for car handling as active one.

[OldF]

That must be the case.

In a Mitsubishi evo 9 dyno graph the max power from the engine was 202,7 kW (276 PS) and the max power from the wheels 170 kW (231 PS). The difference is 45 PS which 16 % of the power from the engine.

Assuming the losses in all three differentials are the same, with one differential less the power on the wheels would increase by 15 PS.

Maybe I know remember why they don’t use a centre differential.