Well, thanks to all of you who provided info on rebuilding and upgrading the
LSD unit in my MK II Supra. Happy to report that the aftermarket LSD for a
Toyota 4x4 truck front axle, does indeed fit into our cars. I used a
TrueTrac 7.5" unit (same company makes Detroit Lockers), had to use Toyota
carrier bearings (part# 50066) maybe Archie can check on this part# to
verify. At any rate, this bearing fits our diff casing, and fits the
TrueTrac unit. I don't believe it is the same part as our original carrier
bearings. Sean at River City Differentials in Rancho Cordova, Ca. was just
awesome. He had the stock unit open and apart in maybe 5 minutes, sized up
the TrueTrac unit, decided it indeed would fit, had it installed in the
casing in less than an hour. I brought in a 3rd member from a Pick-in-Pull
yard with a 4.10 gear ratio for Sean to do the install. My orig rear end has
a 4.30 ratio. I'm looking forward to the slightly higher speeds in each
gear. Fortunately the engine is strong enough that the higher ratio rear end
is not a problem. I only had a chance for a fairly brief test drive, it was
about 11:30pm before I finished everything and I was pretty tired. Rear end
definitely hooks up better than before. Jumping on first gear from a right
hand turn use to result in quite a bit of wheel spin, not much forward
movement, felt like I had 500hp underneath. Now it seems to just steer and
jump forward. No dramatics. Looking forward to autocross this sunday to try
it out in a fast 2nd gear corner exit.
Cost of the LSD was $350 , carrier bearings $60, Sean charged me $40 labor
to set it up. Hardest part was getting the new 3rd member back onto the car.
What should have taken maybe 2 hrs ended up about 5 hrs. I just couldn't
get those darn 8 bolts on the diff housing to line up with the supports under
the car. Easy getting the 3rd member off the car though. Info follows:
TrueTrac gear driven LSD model# 911A342 , 27 spline
Toyota carrier bearings #50066 (may need to verify this) (90368-50006 ????????)
The old ring an pinion gear looked fine so reused it. Wanted to replace the
pinion and side seals but the parts I ordered didn't arrive on time. Could
always replace them later while on the car. The guy to call:
Sean
River City Differentials
3459 Sunrise Blvd #3
Rancho Cordova, CA 95742
916-852-7109
He says lots of customers ship him the 3rd members, he rebuilds, or replaces
the diff units, ships it out again. Something to consider if no dependable
diff shop in your area. I called around and most places acted like I was
asking them to walk on water. Randy's Ring and Pinion was one of the first
places I called, in the same area as Sean, and the shop foreman told me "we
don't do that." Lot of places just don't want to do anything thats not
listed in a book. Sean was not only willing to do it, he was actually very
knowledgeable. Told me the truck guys have been putting Supra LSD units in
the trucks years ago. Seems only right we can now enjoy the aftermarket
parts the trucks created
Compared to a $1000 Quaiff unit, or Torsen unit this should be similar. No
clutch plates to wear out, no rebuilding, good lock up. Some people have
told me if the car was generating lots of HP, the clutch type LSD units may
be better, although requiring rebuilding every few years. I think as long as
I'm not getting more than 300hp or 300 lbs of torque, this TrueTrac unit
should be fine. BTW, I put in Redline 75-90 gear oil, same stuff used in my
stock LSD unit. The TrueTrac doesn't need the friction modifier ingredient,
but shouldn't hurt since just helical gears, and the ring and pinion is
already broken in. If a new ring gear set, prob would use regular gear oil
for couple hundred miles for break in, then go with Redline. Any questions
just let me know !
Don L.
