6 Speed Gearbox
 

Just bought a 2004 WRX Wagon, was wondering is there a Six Speed gearbox that fits straight in without big modifications.
Thanks

your front drive shafts will match either the UK or JDM bugeye/blobeye 6 speed. I know you can use a 6 speed clutch on a 5sp box but not sure the other way around.
The propshaft/diff/ rear drive shafts/drums would all have to be changed to match up.
Trev

It's the other way around I thought, you can use a 5 speed clutch setup in a 6 speed gearbox housing as the 5 speed is a smaller diameter. But you can't use a 6 speed clutch in a 5 speed gearbox housing as it's too large.


Generally speaking you'll need the full conversion kit as Trev says. Expect to pay £1.5k for parts with fitting on top.

API fitted a 6 speed clutch to my 5sp box when the 5 sp clutch wouldn't hold the power I was running. It looks like it works either way but the starter motor would have to be changed for the 6 speed clutch.
Trev

This is not what I have been lead to believe for years.


https://www.scoobynet.com/drivetrain...speed-box.html


But does seem to be something API have been doing for some unknown reason. Seems like a lot of pointless work as a good 5 speed clutch with uprated friction plates & pressure plates will hold very high power very well indeed.


My original 72k mile 5 speed clutch is still holding 350bhp 381lb/ft and has done for the last 40k miles.


I wouldn't want to grind the bell housing to make the larger 6 speed clutch fit when an uprated 5 speed is more than adequate.

I was unaware of any grinding done to make the 6 speed clutch fit.
It's clear from the supplied thread it was something David may have been doing, wether or not he did it to my car I have no way of knowing.
He recommended it as a solution to the failure of their 5 speed uprated clutch, supplied and fitted at the time of an engine build they did for me, that's fitting the 6spd version of the same clutch. This was all free of charge. It's ok to talk of uprated 5spd's but from there it would have quickly increased costs to me and possibly a harder action.
I feel conversations on clutches are pretty futile, as there are to many variables, you deal with what you have.
What was done worked and at the time that was good enough for me.
Of course this doesn't answer any questions for the OP.
Trev

I have an old 63 beetle and there is a similar process grinding the inside of the gearbox housing to fit a 200mm clutch instead of a 180mm clutch. Been done for years on old VWs so nothing new really. It's not done very often as it's a hell of a lot of work rather than the alternative option of uprated 5 speed clutch.


The Exedy organic uprated 5 speed clutch has an almost standard OEM pedal feel and holds a LOT of power over the standard unit. Most people go down this route as it's not that expensive. But whenever fitting a new clutch you should either get the flywheel re-faced or replaced. So with doing that it can work out £500+ for parts. It's possible API fitted a complete used 6 speed assembly to your car to save money?


Whatever fitted, if it holds power fine and drives nicely then job done! :)

The Exedy 5speed was rated below the API uprated or Heavy Duty 5 speed as they called it then (2009) which was in my car, so with the gearbox in mind, sensible options were limited. Power was around 380hp/440lbs then. The 240mm just gave more area contact without changing the action, so the right decision in my case. If David had some grinding done he never said.
Trev

Think you're right Trev, at those kind of power and torque levels even the Exedy 5 speed might be pushing it. Sounds like the right decision then! Sounds like a fun car! :)