Drivetrain help / info

[323GTR]

OK, a little bit of a strange one this, due to the 323GTR having a weak gearbox, that can't handle power, a friend of mine is in the process of adapting a gearbox from an EVO IV / V / VI to fit his car. As far as I know, he has the gearbox, rear diff and propshaft, and has a rally prep company doing the work. The problem he has at present is that the kit he has came from a GSR, so he has the AYC. Trying to make the AYC work would be a nightmare, so he's hoping to fit the RS diff. The question is, is it as simple as just getting the RS rear diff, or does he need an RS gearbox too? I have heard that the ratios are different between GSR and RS? Do the RS internals fit in the GSR casing, or does he need the complete unit need to be from an RS? I suspect he will need to make the EVO diff fit, or can he stick with the Mazda one and just get a custom prop? Does anybody have experience of anything similar?

Also, what is the front / rear torque split on an EVO, and what LSDs are fitted as standard (centre / rear / front)?

OK, this may upset a few of the EVO purests, but the EVO has the strongest drivetrain out there, and seems to be the only option to handle the 400+ HP he has at the moment. The Mazda box has a fundamentally weak design, and even upgraded ones can't take much over 300HP for long periods, so this swap seems the only way to go. Any help is greatly appreciated, as if he makes this work, i'll be doing the same to mine! I appreciate you guy may or may not have done anything like this, but any thoughts or insite you guys can offer may save us a load of hassle.

[Laurence_EvoIV]

I can't answer all the questions there but I can chip in a few thoughts.

The RS diff has it's own propshaft, with a different joint to the diff than the GSR. The driveshafts are also different. I don't see any mention about the driveshafts so I don't know what you are intending to do about that.

The RS and GSR gearbox are fundamentally the same just with different ratios. As far as I am aware, you can bolt a RS or GSR propshaft to either gearbox.

I would recommend that you use the RS diff and RS propshaft if you can.

The type of diff fitted to each Evo depends on several things and is not simply a case of Evo X has blah, it depends on the type (GSR or RS) and then whether those parts were actually fitted at the factory or whether they ran out and used something else!

Good luck.