How much ftlbs/bhp Can a 5 speed box take !
 

I have a bit of a dilemma.
The previous owner has gone through 2, 5 speed boxes with the current set up of 400 ftlbs/ 400bhp approx.
Was that because he was a bad driver, or cant a 5 speed box take that kind of torque.
So my dilemma is do i replace the clutch because it is starting to slip @ a cost of approx £1300. Or do i replace the gear box for a 6 speed conversion @ a cost of approx £3000, which i cant afford just now !

400 ft/lbs is WAY more torque than Id expect a Classic five speed to cope with. I think that 320-340 ft/lbs is more like it.

It's a funny thing the common thought is 320 is the top end for a uk or earlier sti box where the later 99/00 sti seem hold out a little more around 340. Still
some have gone at the standard level where others have run the likes of md321h on them and are stil going strong. If I were you I would fit the 6 speed and be done with it yes they are not cheap but are cheaper then a ppg and from what I have seen are almost bullet proof so once fitted you will be able to forget about it

hmmm I know of a 5 speed that eventually let go at in excess of 550bhp & 500lb/ft

Speak to engine tuners owner alan jefferies as he is running a 5 speed box and its lasting well at circa 450 i think and thats competeing the car

and the rest....

5 speed chocolate gearboxes. bite the bullet time i'm afraid

Some are brilliant; but others struggle at under 300 ft/lbs... Id fit another cheap five speed for now and start saving up. Hopefully if you favour it a little itll last until you can fit a six speed. £3,000 sounds steep: are they getting dearer? David O'Brien at API used to be a reasonably priced source of JDM six speeds transmissions btw.

Simon

It's a newage though and with normal use should be ok at 400lbsft

6 speed boxes are not easy to get hold of ...... demand is outstripping supply.

You will be looking at about £2500 to £2750 for a jdm dccd 6 speed with everything to fit from a breaker, and a bit cheaper if you manage to find a private sale.

If the present gearbox is good but the clutch is on the way out I'd consider replacing the clutch but with a six speed clutch. This is what I did and have an 03 wagon with similar power. It'll keep your costs down and retain the balance of the drivetrain. Speak to API, they did the buisness for me.
Trev

Now the jdm dccd 6 speed i don't know much about this box ! Is there a big difference in the uk spec 6 speed box ! Oh and thx for all your help so far guys, i am leaning towards the 6 speed box.

I will give API a call tomorrow, Thx Trev.....

The Jap 6 speed box really needs a 7th gear for motorways LOL

Shaun

I was led astray by the Classic 'Wagon avatar... :D

My remarks do refer to Classic transmissions, but my advice to call David O'Brien still stands.

At the moment the car is running
2.5 short block
fully forged
20g Andy forrest custom turbo
Ecutec
Sti head
Greddy fuel pump & pressure regulator
full 3" s/s exhaust

Still say ft a 6 speed and the forget about it, give it beans when you want and not have the fear that in the back of your mind that if you did it in a used 5 speed it may break, what's the point of not being able to use all your cars potential for fear of breaking something as you gave it to much. Best bit of advice I was given was simple and that was to BUY, FIT and FORGET in any mod you do

Good advise stevie.
I always buy the best.
Its just money is tight just now.
So i will have to wait and buy the right box.
HOW DIFFICULT IS IT TO REMOVE & REPLACE THE BOXES AND DRIVE TRAIN.