As per my other thread, my gearbox went bang on sunday! got the box out and it's stripped third gear, I'm rebuilding the box using another box i've got but removed due to a shuddering problem under hard acelleration. the first troublesome box was out of a wrx car which had a damaged transfer casing, a gearbox specialist made one good box out of the wrx box and the uk box out of my 96 uk car which had a dodgy sychro on first. When the shuddering couldn't be resolved i removed the box and uk rear diff and replaced it with a complete rebuilt wrx set up inc rear diff, which has now destroyed itself!
My plan is to use the gear kit, selectors, front diff and front casing of the first box and use the transfer box of the second wrx box and retain the wrx rear diff?
Just need some help on the ratio side of things? I'm assuming i need to retain the crown wheel of the wrx box (37 teeth) and matching pinion and use it on the front diff of the first (supposively rebuilt uk) box replacing the crown wheel (40 teeth) and pinion in the good gearset?
Also on inspection of the first box that shuddered there seems to be what looks like foam/rubber deposits coming out of the centre diff? could this of been caused by the wrong drop ratios being used in the rebuild and ruining the centre diff?
Sorry the post is so long but this is difficult to explain fully!
Thanks in advance for any help. Neil.

 

Just thought i'd update this thread, I did manage to successfully rebuild the damaged wrx gearbox using the gearset including motion shafts and front casings from the original suspect box which i'm now pretty sure had the wrong front drive ratios resulting in the failure of the centre diff. Just kept the cwp and transfer case from the wrx box that destroyed third gear. Dismantled carefully, gave everything a thorough clean and re assembled methodically with plenty of syntrax.
Drove the car yesterday and i'm glad to say it's perfect!
If you've destroyed your gearbox and know your way round a set of spanners it may be beneficial to have a go at repairing it youself? I'd gladly help anyone attempting it as much as i could.
Neil.

 

Do you take any pictures of the transmission while it was disassembled? I have a front differential that is shot. I'm trying to decide whether or not it's worth the effort to rebuild, or if I should just weld up the center diff, cut the axles from the joint at the hub up to the differential, and leave it RWD.

 

Yes i did mate, changing the front diff isn't to difficult? although it does require removal of the box then removal of the rear transfer case and splitting the two front half casings? If you take your time and are methodical i think you'll find it isn't as difficult as you think?

 

Well done mate sounds like the hard work paid off.....

when i brought my WRX 5th gear was a little bit crunchy but just thought seeing as i hadnt driven an impreza before maybe i wasnt pushing the clutch properly.....

took it to my mates garage and left it there for a week and went on holiday, came back and he explained that he was changing all the fluids, got to the gear box, went to drain it and there was no oil in it, can you belive it......

ive learnt a lot buying this car, ie what to look for in the future...

the synchro has gone in 5th and slightly in 1st

dont know weather to buy the bits and do it with my mate (works for nissan and has re built boxes for many nissans) or buy a second hand box?

Although could end up with other problems with that one

can i ask where you source the bits? and any photos would be really appriciated,
Many thanks

Regards
Anthony

reading_anthony@hotmail.com

 

Hi mate,

To be honest i think you'd be better off repairing the box you already have if your mate has the facilities? As long as the lack of oil hasn't damaged any of the other parts? Buying a second hand box can be a bit of a lottery although some places may give you a short warranty but you'd pay more.
I'm not entirely sure how the gear sets come apart but i'm pretty sure some of the gears have to be pressed off and back on to the motion shafts? although fifth and first gears and syncros are either end of the shafts and may be a fairly simple job? If you start a thread on here you may get some more definitive advise on how the gear sets actually come apart? As for parts i had a suspect donor box so didn't need any bits? just used what i needed out of the donor box cleaned all the parts thoroughly and re assembled it with sytrax gear oil and used a good quality liquid gasket on all the sealing faces? (loctite)
As far as i know the fifth and first gear sycros on the gear sets i removed are good and were replaced when the box was reconditioned a couple of years ago? so if you do decide to repair your box i may be able to supply you with the bits you require? I'll send some pics of the box disassembled as these may help you out?
Cheers Neil.

 

Neil thanks for all that, send me those photos and i will let you know, chances are i will have those bits off you.

thanks again for taking the time to reply mate.

cant wait to get my scobby back into great shape.

Regards
Anthony

 

HI NEIL
WONDER IF YOU CAN HELP I HAVE A GEAR BOX THATS HARD TO SELECT 2ND THE BOX WAS IN A RB5 THAT WAS FRONTED AND WAS IN SECOND WHEN THE RAILING CAME TOWARDS HIM IN SLOW MOTION, ALL OTHER GEARS GO IN SMOOTHLY.
ALL BEST
SLAB

ps just noticed the caps was on sorry

 

Have you checked that you have the correct rear diff fitted as a centre diff issue could well be caused by incorrect drop gear ratio's resulting in a mismatch.

You can use a 752 or 754 transfer case on either a 752 or 754 main gear case as long as you dont mix and match between transfer cases. There are also two types of drop gears on the 754 cases, one uses taper bearings and one uses a roller bearing similar to those used in the 752 box. You need to make sure you are matching everything up. If you are not 100% sure what ratio your rear diff is I would suggest taking it out and removing the end plate and counting the teeth to eliminate any doubt about a mismatched rear diff being the cause of your issue.

If you are using a 752 transfer case and need a set of 1:1 drop gears I have a spare set, I also have a spare set of 1:1 754 drop gears with roller bearings, if you need them let me know

 

piccys anyone

 

does anyone know if its much grief to fit a LSD to a TY754VN2AA gearbox?
anyone up for doing it?
cheers
carl
hampshire

 

DIY Box Rebuilds can get messy. Iv tried and done ok bu its never the same as a guy with 10 years experience doing it for you. Lol

 

I've stripped down the box all clean, just waiting for some new oil seals. As I'm fitting a different diff I'll have to re align the crown and pinion gears. This is how I've been told to do it. Turn the star shaped nuts around the drive shaft housing to pinch up the tapers on the diff then undo one side. and tighten the other until it goes tight against the pinion gear then back both adjusters by three notches. Well that's the theory anyhow!

 

I have a good front diff, no crown or bearings a centre diff plus the output casting with taper drop gears out of a 754, free to a good home!