hi there, could anyone tell me how much power and torqe the sti 6 speed can take? my car currentley has 360 bhp and 375 torque and i'm on my 3rd gearbox!

 

Six speeds should take around 450 500 all day long providing you changer gear properly rather than cracking it into gear all the time.

I went through 2 five speeds in 3 weeks on my classic. I swapped to a six speed and havent had a problem since.

Daz

 

cool, thanks for that,i'm planning on a new turbo which should take it over 400 bhp so i'll order a 6 speed.cheapest i've found is £2000+vat from grade a is that a good price? it comes with everything that's needed to fit to a classic.

 

try APi they will be cheaper

 

The works race car has 600 odd BHP, fistfulls of torque and it's been flatshifted all season... not broken yet.
(standard spec-c box)



Andy

 

When putting a 6 speed in a Classic do you have to put 6 Speed STI Clutch and Flywheel in?

I know you need:
The box
Gear Linkage
Prop shaft

Is that it?? (assuming diff ratios are the same)

 

Change the clutch ? Not unless you want to, the 5 speed set up will work fine. Ditto the speedo and so-on.

David APi

 

Cheers thought so, just wanted to check, was going to ring you tomorrow and check.

 

If you want a good gearbox read this:

https://www.scoobynet.com/drivetrain...onversion.html

I may be selling.

 

dont forget the extra weight a six speed will place on the car. (lots)

As an alternative PPG gearset, not an awfull lot of difference in price

 

There is to the price i just got one for 52 plate STI 6 speed with 39K for less than £1k.
Fitting shouldn't be to bad coz it's already booked in for a clutch and flywheel at the end of the month.


Is the Gearbox number different between a JAP and UK box??
I'm 99% sure it's a uk version, but would like to be 100% when i go to pick it up.

 

Yes check the tranny chart for correct gearbox identification

Warning the rear diffs are different ratios

Mark A

 

TY856 W N is UK

TY856 W B is JDM They don't interchange.

David APi

 

Cheers guys, i'm pretty sure it's a UK car from some question's i've asked, but i've asked the guy to confirm the gearbox number.

 

According to that web site this is how the uk sti 6 speed compares to the uk 5 speed

6 speed - 1st 3.636 2nd 2.375 3rd 1.761 4th 1.346 5th 0.971 6th 0.756
5 speed - 1st 3.454 2nd 1.947 3rd 1.366 4th 0.972 5th 0.738

This means 5th (6sp) is almost the same as my current 4th and the 6th (6sp) is actually a lower than my current 5th, so i will have a lower top speed with a six speed box.

Is this correct??

 

Yes. Assuming your diff ratios remains the same.

 

Is the web site accruate though???
It also says the front diff is 3.90 for all 6 speed sti box's (jap/uk/usa)

I thought the 6th gear would be slightly longer ratio than my current 5th.

 

The JDM ratios seem to be more popular for 6 speed conversions IIRC

 

Don't forget that the 6 speed cars run on 17 " wheels whereas the Classic is designed around 16" wheels. That is where the longer 6th gear comes from.

ALL 6 speeds use the 3.9 front drive ratio at the moment,JDM or UK/Euro type

The difference is the drop gear set up, asthe UK/Euro uses 3.545 rear ratio which is deliberately stepped down by the drop gears to reduce propshaft speed and the NVH [ noise Vibration & harshness ] that comes with fast rotating parts.

David APi

 

Cheers for the reply David, so as i'm going to be running the same size wheels (18" not that it makes much difference) with the six speed as i currently am with my 5 speed, my top speed is going to be slightly reduced and i going to be reving slightly higher at a given speed say 70mph.
Any idea how much the difference the difference in rpm would be??

 

Based on 225/35/18 tyres the top speed of a uk 6 speed box in 6th would be 171mph @7000rpm

Based on 235/35/18 tyres the top speed of a uk 6 speed box in 6th would be 173mph @7000rpm

Based on 225/35/18 tyres the top speed of a uk 5 speed box in 5th would be 175mph @7000rpm

So not really much difference worth worrying about.

 

Cool, i can handle loosing 4mph for not having to worry my box going bang all the time, not that much difference and i won't ever go that fast anyway.
I'm currently running 215/35 but will be running 225/35 on my next set of tyres.

 

Just as well then!