MA46 w/MK2 LSD problem

[bajallama]

Alright I have a MA46 celica supra rear in my kp61 starlet. I chose this rear end for its low cost, greater width and ease of part availability(differential perspective). I recently replaced the factory 3.73 open diff with a 4.10 LSD unit out of a MK2 supra. However after about a month the LSD pooped and it acted as an open diff. I pulled the diff and shimmed the clutch packs with proper steel shims at the thickness of .020 on each side (.040 total). After about two weeks driving, no complaints. Now after about a 40 mile drive I get off the freeway and noticed a chattering/ grinding sound on turns. Went to a parking lot and did slow speed circles and the chattering got worse. It seems as if the clutches are grinding and popping loose, but also other odd noises will mix in there. I let the car cool down completely, then started her up and drove away and no more chatter! However once the diff warmed up after about 20 min of driving, the symptoms started again. I thought it was the fluid, which was Lucas 80-90 and they say no LSD additives required. So I today changed it to Sta-Lube 80-90 GL5 with hyploid, again it said perfect for LSD units, so i didn't by that extra tube of LSD addy. Well it still does it, maybe not as bad but it does it, only when its warmed up however.

Just need some input on this. Axle bearing maybe? should I try some additive? carrier bearing? carrier retainer came loose maybe? I'm lost

here is a pic of her:

[thechuckster]

i always use LSD-specific oil for LSD diffs

not sure what you get in the US, but I've used something like this:
http://www.penriteoil.com.au/product...ls/limslip_140
(they also have a multi-grade limslip oil: http://www.penriteoil.com.au/product...imslip_85w-140)

[bajallama]

here is what I have in there now:
http://www.crcindustries.com/auto/co...?PN=SL2473&S=N
It's LSD specific.

Do you always use a 85w-140? cause possibly if I run a denser heated weight, it might fix it. Factory said 80w-90 but that might be the issue.

[thechuckster]

i just used the heaviest stuff I could buy on the day (and have always used penrite oils in engines/boxes/diffs). My cars have mostly done lots of highway duty so i figured something that stayed as sticky as possible despite heat buildup would be ideal.

The limslip goop is blue, very sticky and stinks something fierce. Would be ideal for hazing recruits & new employees (takes forever to get out of your hair).

I would have gone for a diff-specific oil rather than a gearbox oil that also suits diffs - can't backup that with any sound reasoning - i just wanted to fill it and then ignore it until it started to fiercely whine.

Wilbo666 rebuild a F-series diff (i think) - might be worth sending him a PM on how he shimmed it up?

[bajallama]

Ya makes total sense to use diff specific lubricants. It just sucks cause even though I live in the Los Angeles, there are no stores anymore that sell specialty lubricants over the counter (If there are they are super hard to find), Autozone and generic auto parts stores are rare to find with even standard gear oil in stock, its amazing, no one works on their own car anymore. I found on some LS1 forums, a lot of GM RWD vehicles have similar problems and I guess MK3 supras too and they use the FORD LSD additive and supposedly shuts up the diff. Thanks a lot for the help though, ill try to special order some penrite over here or see if amsoil makes something similar.

[thechuckster]

Maybe try a parts store that specialises in off-road gear for diff oil?

[Celica RA45]

it might pay you to buy a trd lsd unit for it as spare parts for these lsd are getting harder to find .and when i had mine i had nothing but problems with them till i changed to a trd unit ,hey its just 1 idea

[allencr]

...pulled the diff and shimmed the clutch packs with proper steel shims

New friction disk/s & clutch plate/s? Then were the old ones checked for flatness?
How were they prep'ed, glass & wetordry? It's SOP or should be to soak'em.
They don't get a chance to to get oiled up again like all the motorcycles & automatics with wet clutch packs that get to open & close.

I'd guess that you'll have more luck with an LSD additive/friction modifier then with different brands & types & viscosity.

[bajallama]

These LSD's are a dime a dozen, I find one or two everytime i go to the junkyard. So if it breaks I'm not too worried, just a pain to get them out of those mk2's.

Ya, never really thought of an off-road shop.

allencr - The clutch plates looked brand new when i pulled them out, it was out of an auto supra, so not much abuse. wear over all the clutches was hardly anything, still had the rough surface and oil grooves on most of the faces. Weir Performance has a rebuild kit for these which is just basically new brass, shims, and heavier springs, but since mine looked so good I thought I would just shim it for now. I'm not sure what you mean by prepped, are you saying from the factory? I think ill run a modifier first, then opt for the thicker 140. I'm pretty sure they are continously oiled hoever, since they do sit in the oil bath and the clutc plates are grooved for oil flow. Have you had luck with any specific modifier, i.e. Ford or GM products?

[pandaah]

i doubt 140 will shut your diff up.. I go thru alot of oil at work in different vehicles and yeh 140 is thicker but 80w90 is fine for lsds if it says so on the bottle..

Id be taking it out and reinspecting check for signs of wear due to the banging around, check the crown wheel and pinion for damage etc.. Check everything thoroughly cos you can try.. Put i think your pissing money against the wall with modifier and or new oil

[allencr]

...what you mean by prepped, Have you had luck with any specific modifier, i.e. Ford or GM products?

So they are flat & clean & smooth, for new or used, and if not then smooth'em & take the glaze off the old ones. Deburred. Tabs & slots smooth?
Disks soaked in oil for hours if new, and assembled new or used, with Lots of oil too.
No modifier experience, I'd like the lube pure & don't care about a little chatter and consider a chatter problem as a clutch surface problem and not a lube problem.
No motorcycle or auto trans wet clutches have ever chattered as far as I know, yet a dry clutch can chatter if it gets some oil on it. Go figure.
Good luck.

[bajallama]

Well, I tried the Motorcraft Friction Modifier and it fixed it. I was super suprised that the little bottle would work, but drove it home from school and did some figure 8's in a parking lot and the chatter disapeared. Took the car to the track yesterday and no problems at all, it locked up fine. Oh and that stuff stinks soo bad. Do not get it on your clothes