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

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Old 07 March 2010 | 08:31 AM
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Default 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 !
Old 07 March 2010 | 09:06 AM
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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.
Old 07 March 2010 | 09:42 AM
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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
Old 07 March 2010 | 09:52 AM
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hmmm I know of a 5 speed that eventually let go at in excess of 550bhp & 500lb/ft
Old 07 March 2010 | 10:19 AM
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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
Old 07 March 2010 | 10:22 AM
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and the rest....
Old 07 March 2010 | 10:34 AM
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5 speed chocolate gearboxes. bite the bullet time i'm afraid
Old 07 March 2010 | 10:37 AM
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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
Old 07 March 2010 | 11:21 AM
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Originally Posted by GC8
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 newage though and with normal use should be ok at 400lbsft
Old 07 March 2010 | 11:24 AM
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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.
Old 07 March 2010 | 11:28 AM
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Originally Posted by EH52WRX
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 !
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

Last edited by trevsjwood; 07 March 2010 at 11:30 AM.
Old 07 March 2010 | 11:34 AM
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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.
Old 07 March 2010 | 11:37 AM
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I will give API a call tomorrow, Thx Trev.....
Old 07 March 2010 | 11:39 AM
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The Jap 6 speed box really needs a 7th gear for motorways LOL

Shaun
Old 07 March 2010 | 12:13 PM
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Originally Posted by trevsjwood
It's a newage though and with normal use should be ok at 400lbsft

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

My remarks do refer to Classic transmissions, but my advice to call David O'Brien still stands.
Old 07 March 2010 | 12:20 PM
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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
Old 07 March 2010 | 12:33 PM
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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
Old 07 March 2010 | 12:40 PM
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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.
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