Evo 1 gearbox options

[cliffy101]

Hi I have a Evo1 running 400bhp and 500 torque. While on the rolling road 4th gave way this is the second time in the last 12 months that 4th has gone. This box was rebuilt and hadn't much miles on it.

Anyone have any options as to what I should be looking to do?
I have another box there but dont want to just throw it in only for it to go again soon. I have a trip to the ring coming up so I want to try get something that will hold out.

It doesn't do much road miles just a few track days and a few 1/4 mile runs.

Thnaks for any help in advance

 

[JakeMac]

I'd be on the case of who ever rebuilt it, clearly they missed something. You should also have a warranty on the work which is normally mileage related

 

[JakeMac]

That is however alot of torque for a standard box, dog gear internals would be ideal but there ££££s