I am need of some advice regarding gearbox/diff options. I am currently having a engine built which will be running 450 Bhp+ and quite high torque and i dont think the standard box will take it. What are the best options for it? Its a WRX Sti RA so no DCCD. Also will the standard diffs be ok running that much power and torque?

 

Based only from what I have understood on many threads on this subject, it seems it is all about the use of the car (road only, road track, dragracing) and the ££££££££££.

For the first use: A simple 6 speed with it's diffs and the larger clutch = £1500 + fitting
For the 2nd use: As above! Use an AP organic 240mm clutch(u need the flywheel)
For the 3rd use: Dog box, straight cut or semi helical, ie Possum Bourne, or full on box ie Modena from Town End Garage = £4500 + fitting. This option uses the 5 speed case, ie you old gearbox. AP clutch.

Hope this help
911

 

Its having a lightened and balanced flywheel and a paddle clutch anyway. And its mainly for road use

 

A nice 6 speed it is then!
APIDavid has some in stock would you believe! These used to be mega rare a few months ago...They do weigh a lot more though.
Perfect for the road.
911

 

What sort of price do you think i am looking at for a 6 speed?

 

The going rate is about £1500 for the box, the rear matching diff and the (shorter) prop. You need the shift mechanism too. Almost everyone sells this combo.
There are other considerations, ie linking the analogue speedo to the electrical box sensor, but several people here know how to overcome these trip wires.
Just ask them to help you!
Remember you can sell your box/diff to help offset the cost.

Just call David at API, most helpful man.
911

 

Will a 6 speed be strong enough though?

 

There is no clear answer to that.
Change gear without the clutch (Real Drag racing!) and the 6 speed will die. If you need to do that then a Modena dog box is the only option; it is designed to do it, AND still needs rebuilding!
Hard road/track driving using the box as intended I would think would be handled easy with the 6 speeder.
The occational b*lls-out standing start with 450 bhp would test the 6 speeder etc etc.

I hill climb my Stiv3 hard, and I'm careful on the road, always use the clutch, but i do dump the clutch at 5000 rpm, have done in racing for 2 1/2 years, and the stock Sti box is sound as a pound!
I would fit the 6 speeder to get, better box, larger clutch, and peace of mind that I might drive it home after a hill climb!

911