Blown gearbox again!

[Mr T]

I have a modded tt supra that has blown 2 gearboxes in 3 months since I fixed No 1 boost controller vacumn pipe, I turned the boost down to 1bar after rebuilding the gearbox (new input and lay shafts and bearings) but Bang no gears again. This car has been raced in Japan and there are no signs of previos gearbox repairs prior to me buying the car. It has a twin carbon OS Girkin clutch & flywheel for the 5 speed so it has been used with a 5sp before. Does anyone Know of any other reson for the 5sp gearbox to sheer the teeth of two shafts other than to much power? ie misalingned propshaft,lightened flywheel etc Please Help. cannot aford to put a 6sp box in as I am selling the car in October.
:help:

[slick]

Totally confused, sorry. You've got a 5sp Manual MkIV Twin Turbo Supra?? Or have you blown a 6sp box and since tried to replace it with a 5sp in said car?

[Mr T]

It is a late 1993 5 speed, 3l Twin turbo from Japan, manufactured by Toyota as described. I've blown the same 5sp gearbox the same damage to both (new Toyota parts used for first repair)
The car was bought modded. the BHP is unknown.
it has HKS intake,HKS blow off,HKS exhaust and de-precat pipe,HKS boost controller, HKS piggyback ECU,HKE fuel pump,Thurst intercooler (big) and pipes, OS Gekin twin carbon clutch and lightened flywheel. Cams ,injectors etc. I've not looked yet but all this conected to a standard (factory fitted) 5 speed (blown) gearbox. I would fit a 6sp but the clutch is different and the propshaft,diff and possiably the driveshafts and hubs.

[Martin F]

The MKIV TT never came with a 5 speed box. Are you sure your car is a MKIV ?

If so it maybe an NA to TT conversion where somebody has left in the 5 speed box.

[Mr T]

Can you imagine the feeling of blowing your gear box up and then finding out you,ve been ripped off with a n/a conversion.
A personal visit to the seller is now requied!

[Martin F]

Go to this site http://mkiv.supras.org.nz/specs.htm scroll down a bit and use it to checkout your vin details.

Your vin plate should be on top of offside wing under bonnet.

[Mr T]

I did cheak it after reading your reply and it is a conversion job. I bought it with my heart as it is modded to eveything i wanted and more, all it lacked was the 6sp gearbox but with seeing loads of 5sp TT,s for sale I thought the later supras had 6sp.(mine is L reg)