LSD problems after gearbox rebuild (MR2 turbo)

[anthonym]

I've just had my freshly rebuilt gearbox re-installed in my car and the LSD, which was fine prior to the rebuild, is now fuct . It's a clutchpack style aftermarket LSD (unsure of brand) and it's now binding horribly at low speed/low load when turning corners, mainly LH bends, but RH also, to the extent the car judders violently accompanied by a loud clonking noise.

I'm wondering if anyone knows what might have caused this? As noted the LSD was not doing this prior to the rebuild, I used exactly the same oil as well. The people who rebuilt the box of course say it couldn't possibly be anything they have done. Is there any special proceedure required when fitting a clutch pack LSD? I know the rate can be adjusted, but this wasn't done.

Also can anyone recommend a thoroughly competent gearbox rebuilder?

[vvega]

did they wash/clean the lsd ??

some lsd's like auto use water based "glues" to hold the fiction matter in place

if a water based akalide "like i have at home" was used to clean the box it could have well damaged the lsd clutch packs

there are no specal "from normal diff" method to install a lsd
so thats not really of a concern

to me it sounds like a incorrect axel lenght or fiction material issue

this is going off teh fact that you say they havent ajusted the diff in any way

thats about all i can say withou hering the problem first hand

oh one other possibility
maybe a bolt got droped into the spider gear part and has lodged making it effectively a locked diff

hmmm
well im all out

v

[Stu-]

Have they pulled the diff apart and possibly adjusted the pretension? Thats about all I can think of.

[10k 20v]

i'm with vvega on this one. another suggestion thou is maybe the clip for the axle has broken and been lodged in the spidergears or clutch packs somehow? apart from the pretension being adjusted

previous experiance with lsd's has always led to the wrong oil causing the problems you have described. (i know you said you have used the same oil)

[anthonym]

Thanks for the replies guys . Thinking about it the diff is acting as though it's locked, but the problems occur only at very low speed, low load, with no load (car in neutral) there is no problem. When the tension releases the noise sounds bad enough to be gears slipping (that's actually what it sounds like). There's a remote possibility it could be the axles, which were changed, but then they worked fine with my second 'box which also has a clutch pack LSD. Guess I'll find out for sure when it comes out again .

One more question is it possible to inadvertently change the preload (sorry I have no experience with this sort of thing)?

[vvega]

nope not to change preload

now for the intersting bit
you replaced the axels ??

lsd and no lsd ones are diffrent lenght
and when installed they "bind" on the hexagnal bar in the centre(the bar is thicker than the flatish 4 spider centre)

the other option is that teh axels are of a different gen box

there are 2 distently diffrent boxes
and the ofset of the center of the lsd is diffrent
i could well be you have inavertantly used the wrong ofset axels and they are causing the unit to bind in the centre

but to be honest it really sounds like it has some debres in the spiderunit
that would make a nasty cruching noise


if the paks have been exposed to water the fiction materail will alos be making a bit of a mess

be good to hear what when wrong when you find out


v

[anthonym]

nope not to change preload

now for the intersting bit
you replaced the axels ??

lsd and no lsd ones are diffrent lenght
and when installed they "bind" on the hexagnal bar in the centre(the bar is thicker than the flatish 4 spider centre)

the other option is that teh axels are of a different gen box

there are 2 distently diffrent boxes
and the ofset of the center of the lsd is diffrent
i could well be you have inavertantly used the wrong ofset axels and they are causing the unit to bind in the centre

but to be honest it really sounds like it has some debres in the spiderunit
that would make a nasty cruching noise


if the paks have been exposed to water the fiction materail will alos be making a bit of a mess

be good to hear what when wrong when you find out


v

I have 2 late model (dual cone syncro yada yada) boxes, both with aftermarket clutchpack LSDs (which may be different), and 3 pairs of LSD axles. I don't know what brand the diff that's in the car now is. The other one (that just came out) is a TRD, and dosen't have the hexagon bar (has a solid center with a hole in it) and I'm using the axles that were working fine with that (because they were newer, and since they were both LSD axles I assumed they were the same). The 3rd pair of axles also worked fine with the LSD that's now having issues.

Nevertheless, I suspect a rotating hexagon binding on an axle would produce the exact symptoms I'm experiencing, which is more like gears slipping than crunching, so this is the first thing I'll be checking, thanks .

[anthonym]

Took the axles out yesterday and inspected them, they are the same as the axles (late model 1994-5 vintage) that were fitted to the LSD when I got it, but different to the axles I used when I put it in my race car (RHS 5mm longer IIRC, both sides with much shorter splined portions) which are 1990 vintage. However, I have used these axles with late model LSD gearboxes for a long time without any apparent problem, the LSD that's giving problems was used with these axles for about 500km and wasn't thrashed particularly hard. There is no damage to the LSD in the spline area and no evidence of the axles binding, the LSD appears to be TRD, it has a flat center with a small hole in the middle.

Anyway I swapped the early model axles in and tried it and the problem remained, so the box is now out of the car waiting to be stripped down.

Interestingly it transpires that there is no problem when the car is cold, it only starts binding up after it's warmed up.

[vvega]

if it was a viscous id say its rooted :S
but its not so
maybe a bearing ??

v

[fivebob]

Has it gone back into the same gearbox housing?

Sounds like it may need re-shimming as the clearances appear to be a bit on the tight side, so that when it warms up and the metal expands there's not enough freeplay causing the clutch pack to lock up.

Got any instructions/diagrams?

[anthonym]

Has it gone back into the same gearbox housing?

Ahem, no. I gave the rebuilder 2 boxes and he's used the case from the one that had the standard diff in it. Both were late model boxes though.

Sounds like it may need re-shimming as the clearances appear to be a bit on the tight side, so that when it warms up and the metal expands there's not enough freeplay causing the clutch pack to lock up.

Got any instructions/diagrams?

I've got the Japanese instructions for a TRD LSD, which do include a diagram, I can't be 100% sure that the problematic diff is TRD though.