lomas the great

im having problems with my gearbox
ive got a my99 uk turbo boost to 345bhp
the uk box blow 2nd and 3rd, so i had a jdm wrx box fitted witch is lower ratio to the uk box.
The problem is the center diff has broke after 2 weeks and now its at the garage.
Im having the uk 5th put in the jdm box for longer 5th gear and thought the center diff from the uk box would fit the jdm box but it does not.
would the gears fitfrom the jdmbox to the uk box casing witch would mean i can use the center diff again

Splitpin

I vaguely remember this, and some discussion with you over whether you had the correct ratio rear diff to match the JDM 'box. If the centre diff expired after a fortnight, that would suggest that you didn't.

You are also trying to mix and match components from a 754 case UK box and a 752 WRX one, which as you've found out will cause compatibility problems. How far you can mix them is anyone's guess but I'd suggest even if you get it to work, you're wasting your time with this solution.

TBH you are largely throwing good money after bad trying to get the 752 box (or the bits from it) running as, given the amount of power (and presumably torque) going through it, it will probably sh*t itself again within a fairly short period of time, leaving you sat there having to shell out again.

If you want a solution that will last a bit longer you should be looking either at a 6MT (which you ruled out last time), or maybe a newage UK WRX 'box, and some training for your right foot.

lomas the great

a 6 speed box is well out of my price range
im having the work done for peanuts at a very reputable garage so its worth a try.
the wrx box that was fitted was supplied with the rear diff so that was not the problem
all im asking is will the gear set from the jdm box fit in the uk box as the 5th from the uk fits the djm.
them i will just change the rear diff over again

Splitpin

You may have fitted the diff that was supplied with the WRX box. If it did itself that quick, suspicion would be that you were supplied the wrong diff. Did you strip it and check the ratio?

DavidAPi is the one to tell you whether you can transplant the internals from the one case into the other, although in the absence of any other information I would work on the basis that you can't, because you'll run into lash issues, at the very least, and likely reverse idler problems too.

The thing to remember with a six speed, or indeed a stronger 5MT, is that you've already shelled out a bit on a gearbox that lasted a fortnight, and peanuts or not, the outlay is continuing.

99greenwagon

iTrader: (39)

sorry to hijack but what 5MT box is stronger? are u refurring to the sti 5 speed from a v5-6? if so,is it a like 4 like swap?

Splitpin

No was talking about a box from an MY03-04 UK spec WRX

99greenwagon

iTrader: (39)

oh right,so is this a direct swap replacement for the oe uk my99? just swap the box and job done?what is it capable of?(power/torque?)

Splitpin

Yes. Can't remember whether you need to swap over the speedo head and sensor loom after a certain MY but even if you do that's a 5 minute job.

That's the wrong question to ask, because there isn't an exact answer for it. It's not like there's a specific torque level that gearboxes are fine below, and will instantly screw up above. Exactly how long they last depends on the amount of torque being put through it but also, to a huge degree, on the amount of mechanical sympathy exhibited by the driver.

Consensus seems to be that the newage ones will handle more abuse for longer than the classic 754's, which is the important point.

lomas the great

had my car back yesterday
turns out the place i got the new gearbox from suplied me with the wrong rear diff.
not good, it had stripped the center diff.
so i had the box fixed with parts from my old uk box.
the bits didnt match but the garage i used was a gearbox pro and made all the diffs match and used my uk 5th in my lower ratio jdm box.
can not fault mikeanics in congleton cheshire.
£485 for complete rebuild and it was not strate forward be any means

99greenwagon

iTrader: (39)

that sounds pretty good,lets hope it lasts for u mate.