Current gearbox is ****ed (code TY752VBCBA from my MY98 WRX Wagon). I know very little about gearboxes and all I need to figure out is can I buy pretty much any classic Impreza box or do I need to find an exact or near match? I've looked at the very handy webpage that shows all the correct engine and gearbox codes, but the thing I have trouble with is once you start talking about diffs and ratios. I just want to know what will be a straight fit and not make anything weird happen with the gearing.

For example, I'm looking at a 62k mile UK MY00 box, but will this be OK or do I need to get a Jap box?

 

dont think it'll fit the only other box thats the same is a 97 98 legacy

 

Cheers. So what other boxes WILL fit? I've figured out that the boxes pre-99 are all a 752 prefix and post 99 are a 754, so presumably this signifies a major change. I just need to know if they are directly interchangeable as TBH I'm not all that keen on paying £300 - £400 for an early 90's gearbox. I'd rather have something from this century (or close to it!) if I'm going to have to buy one...

Is it simply a case of making sure the ratios and final drive are the same, or will there be problems with bolt patterns etc? If it's just a case of matching the gearset, there seem to be loads of alternative versions listed e.g. 3AA, 4AA as a Scoobynetter kindly PM'd me just now. But then if they all have the same gearset, why do they have different codes?

Help!

PS It's running around 300bhp at the moment, so maybe that is also a consideration? I don't intend going much further with tuning it, but I do drive it quite hard around the back roads...would a later 754 series box be harder wearing?

 

The 754 series is deemed stronger and better developed.
You must run the same diff ratios front and back, but the jap boxes have a different final ratio out of the box to the UK ones.
The best way is to buy a box with it's matching rear diff. They are simple to fit, just hard work!

Not also that the Sti/RA (especially) are short ratios and are best suited to the high revving jap engines (about 8000 rpm) and that the UK turbo's run a lot lower red-line, about 6500rpm.

Putting an RA box to a UK turbo engine would make the car a pig to drive , all revs and gearchanges and screaming down the motorway at 80 mph.

The real expert is David at Welcome to the API website who will guide you without bullsh!t.

Gearbox/diff removal/instal is very hard work! (done mine 3 times)
Graham

 

Hi Graham - thanks for popping in. For once I've entrusted the job to a garage rather than swotting up and doing it myself, so I don't need to worry about how hard it is. You've explained it pretty well, but I'm still only just getting to grips with this thorny subject, so just to confirm:

The front diff is an integral part of the gearbox, between the driveshafts?

The rear diff must run the same ratio as the front - otherwise the front and rear wheels will run at different speeds?

As I never rev it over 6500 anyway, and enjoy quietness and fuel economy (most of the time LOL), it's best to stick to a WRX/STi or a UK box?

A late classic 754 box WILL definitely fit but I'd need the rear diff to go with it? Would it need a matching propshaft or are they all the same?

Is there anything else I'm forgetting? The box I'm looking at picking up is from a MY00 UK Turbo.

 

With a UK turbo engine i would stick to the UK box/diff.

You are right in what you say, about the diffs.
The props for classics are all the same.

Getting a garage to do the swop is a very good idea!

You should fit a new clutch while it is off though.

An Sti clutch would be good as they are very tough handling 300bhp etc.

Good luck with it!
Graham

 

David APi

 

Correction accepted!
An auto in an Impreza turbo...what a waste (imho that is), but I don't think they do one??
Graham

 

Come on Graham you know you're talking to the great coracle here.

WRX Impreza as an auto is actually a nice car to drive. I could certainly live with one if I had to. Acceleration is fine because of only four gears and whilst not stunning, is certainly very acceptable.

Rumour has it that Andy Forrest is going to convert his 900 hp monster to auto next year. He is getting older so it'll probably help him.

David APi

 

I think he 's got it in the garage..

Will be calling soon to spec the Type R box.

Just waiting for the Capital Approval from the Finance Director.

 

So, looking at it the other way round, I should stick with a Jap box for my Jap import WRX and not bother with the UK box. Which I've just found out doesn't come with the diff anyway. Although if anyone wants the TY754VN1AA with 60k miles on it for £225, it's there for the taking as clearly it's not going to work with mine.

The clutch was an AP organic job that has only done 30k miles anyway, and apparently it's still got plenty of life in it. I'm replacing the release bearing though as that is still the original which has done 120k miles.

Just out of interest, is there anywhere that lists all the UK gearbox codes for comparison. Just strikes me that it might be easier to pick up a UK box with the right final drive ratio if such a thing exists.

The only thing I can find at the moment is the right code that I need and supposedly fresh from Japan with under 30k miles on it, but that's £450 which seems a lot tbh. Am I being unrealistic in not wanting to pay over £300 for a second hand gearbox?

 

Lots on eb@y.
£100 box = scrap
£400 box = last a long time!

That clutch will be great for ever, I hillclimb hard on mine for 3 years now with lots of dump-the-clutch starts.

The is a giant listing of all the box numbers; I have a hard copy in front of me as many others do.
Will try to remember the source or pm me your fax number and I will fax to you if you wish.
Without it you are working in the dark.

Graham

 

Well I think that's decided it then...the low mileage import from Japan with the exact right code gets the vote and I've just managed to scrape the £450 together.

I'm very pleased with the AP so far, it's had no trouble coping with the higher power since it was remapped and it feels pretty normal. Coming from my previous car which needed a 4-paddle cerametallic to handle drag starts, but was a pain in traffic, the AP is great.

Don't have a fax machine at the moment, but thanks for the offer. At least I know who to ask if I have gearbox hassles again!

Cheers!

 

Neil yhm David

 

There are loads of boxes that will fit straight onto your car. Have a look here and note the numbers in the T.R. and F.D. column, they stand for transfer ratio and front diff ratio.

As long as the replacement box has the same TR and FD as yours it will fit straight on, be it TY752 ot TY754.

HTH

 

Very useful, many thanks everyone