Center diff lock up happen much?

[tremmor]

I've got a few issues with my gb.

Have just got a good old 96 GX legacy. It had a few wasted syncros so I found a replacement gearbox and put it in over the weekend. Replaced it with the same NZ new gb with hi/lo and (presumably) the same output ratios. Apparently it is an identical replacement but haven't done my own check.

Dropped the car off the hoist after doing the change and pushed it out of the shed (well, tried). Could only push it so far (3meters) before it got increasingly difficult to the point that i couldn't push it. Took it for a shot drive up the gravel driveway and could hear the wheels skittering over the gravel. So, I reversed back to the shed and jacked up the front. One of the front wheels skidded as the weight came off and i got a bit of a sinking feeling that there was some diff wind up going on.

Initially assumed that the gb and rear diff ratios must not be matched but then thought that the center diff should deal with that (at least for a while).

Last night i jacked up the rear wheels and then got in the car and put it in 1st and slowly TRIED to let the clutch out. It would have pulled its self off the jack before spinning the rear wheels. Same thing when i jacked up the front - the wheels that were off the ground did not spin - just felt the engine load come on and the car inch forward.

Basically got the symptoms of a welded center diff. Did a bit of research and found that these have a viscous coupling in the center diff. Has anyone had experience of these things seizing up?? Or maybe someone has welded it up in its previous life.

The gb was empty when i got it. Filled it with 80W gear oil (not the 75 that is recommended in the oil book in repco).

Have got a warranty on the gb so can (reluctantly) take it out and swap it if need be but wondering if there are any more things to check/ideas out there.

Cheers

[DRFVDR]

my guess would be the rear and front diffs are of different ratios = BAD

and NO the centre diff will not take care of it.

[tremmor]

Yeah - wouldn't expect the centre diff to last very long - but still would have thought that I'd be able to push it out of the shed even with different ratios.

Something that I noticed tonight - I wasn't able to turn the left front wheel with the car in neutral and the wheel jacked off the ground. It would just turn through a few (5 or 10) degrees as the back lash in the system was taken up. I would have expected the rotation to run through the front diff, then through the centre dif, and then through the gb input shaft, allowing the wheel to spin.

Any other ideas?

[jacsmiley]

sounds like its going to have to come out man it may be the correct replacement but sounds like something is very wrong

i'd get the gb number off the bell housing and check that ref against the ref on you roriginal gb. theres gb charts on here. you may have the same gb but for a different spec car. eg: 4.111 ratio diffs all round. but the new gb you got may have 4.444 ratio center and front which wont suit the 4.111 at the back. even tho it came out of a legacy gx

[tremmor]

OK - have got a replacement centre diff on its way. Apparently its an easy install (just remove the a**e end of the gearbox and substitute the old with the new).

Old GB number TY752XGBAA

New GB number TY752XRAAA

Neither number features on the list - Google doesn't know much about them either...

Cheers for the comments in any case guys.

[DRFVDR]

Make sure that the rear and front diffs are the same or else u will lunch another centre diff

[jacsmiley]

 DRFVDR said:

Make sure that the rear and front diffs are the same or else u will lunch another centre diff

yes. you need to know if the new gb has the same final drive as the old one first. if the center diff was the cause of the binding then thats a straight forward swap. but if it is because the front and rear final drives were different then you will have the excact same issue after you change the center diff.

[tremmor]

Ok, cheers guys. I see if Alex at Highbrook Automotive can shed some light on what diffs this new gb is likely to have in it - and what diffs the old one has.

I guess that if i'm going to pull the old gb apart then i could have a crack at replacing or relapping the syncros in it and just put it back in again... Bit of a stuff around though. Has anyone attempted this? I'd imagine its pretty intense.

[tremmor]

Just out of intreset - the replacement gearbox had a seized centre diff (presumably the viscous coupling had seized). I have put the old gb back in and am putting up with the average syncros.

[Koom]

Could you not put the good centre diff onto the box with the good syncros?