scooby_will

Hey all im looking at going down the route of the 2.5 sti bottom end with high power so am thus looking at fitting a 6 speed to my classic to handle power

Now i know you will need the gearbox, propshaft, differential, and gear selector, clutch and flywheel but will i need to get modified half shafts for front and rear or will the 6 speed ones fit straight on and will i need to get the propshaft modifed? thanks all

Fat Boy

existing 5speed clutch and flywheel will work ( assuming they're man enough for the planned power)

scooby_will

they wont be man enough no, with 450hp and more torque they defo wont, would a 6 speed clutch and flywheel then be needed as the 2.5 sti bottom end will match to this.

Fat Boy

Preferably but depending on waht torque you're running you'd probably need an uprated clutch anyway.

I'm running 450bhp on an AP organic, but I'm only running 380ft lb torque (2 litre)

scooby_will

yeh thats the difference then, the 2.5 is alot more torquy than the 2.0 so will be much more than the what a normal clutch can handle

dazdavies

iTrader: (22)

Having done this very conversion several times, I can confirm the following.

Depending on your car's origin.

If your car is a UK car then you can get a six speed from a UK STI and it will swap straight over as the classic rear diff with match the final drive of the gearbox i.e 3.54.

Clutch wise if you go six speed clutch you'll need to get the six speed flywheel which will also mean you need to swap to a six speed starter motor.

There are plenty of aftermarket 5 speed clutches that will cope with all but the most powerful applications.

I'm in the process of building a 600/600 classic that will be using a 5 speed clutch and flywheel, regardless of what gearbox I use (probably a six speed)

As for the drive shafts that depend on your year of six speed. If it's a non DCCD then your 5 speed shafts will fit.

Aztec Performance Ltd

iTrader: (234)

A 5 speed clutch and flywheel will fit the 6 speed box, but as the 6 speed clutch is some 10mm bigger, it will be able to handle more torque than the equivalent 5 speed version - some 20% more going by the data I have on clutches here.

Take a look at the clutches we have on the GB which would be ideal at that output:

https://www.scoobynet.com/group-buys...ml#post8465353

Bob