SC400 differential

[rohsc400]

What is the special thing about SC400 93 differential?
A reputable repair shop offered to replace the differential mechanism in my SC400 and then baked off and said only the Lexus dealer can do it because of complexity.
Any idea why is it so?

 

[Blizzy]

The dealer is the only place to get shims to adjust backlash and pinion depth to ensure that the gears and meshing just right.

If your differential unit is starting to struggle and you are in need of a swap, you might call Titan Motorsports. They often have gently used Limited Slip Differentials from the 93-98 Supra Turbo. The LSD from the Auto TT is a direct swap, and it would likely be cheaper than sourcing a new differential unit from the dealer.

If you already have a differential unit and just need a shop, I would try another reputable shop. If I can rebuild a differential without a shop, only hand tools, and a couple fine measuring devices, then surely you can find a shop to do the job. Once the correct shims are ordered, the differential is no more or less complicated than any another.

 

[rohsc400]

Thanks a lot! Much appreciate your answer.

Can you tell me what can happen if the shims are not correct?

Also, anyone knows a good reputable shop that can do such job in central New Jersey?

Does it make sense to buy a used differential from e-bay?

Thanks!

 

[Blizzy]

Thanks a lot! Much appreciate your answer.

Can you tell me what can happen if the shims are not correct?

Also, anyone knows a good reputable shop that can do such job in central New Jersey?

Does it make sense to buy a used differential from e-bay?

Thanks!

You need a dial indicator to check the backlash between the gears and some Prussian Blue or Red Lead to check the gear contact pattern. Shims are required to correct both (shimming the carrier to correct backlash, and shimming the pinion to correct contact pattern).

Incorrect backlash will cause a whine at speed, a nasty grinding noise at speed, or a clanking noise upon braking or accelerating. Incorrect contact pattern will grind the ring gear and pinion gear down, leaving shaving in the differential oil.

In either case, you can easily destroy your ring and pinion if the backlash and pinion depth are not shimmed appropriately.

I have no idea of a reputable shop to do the surgery. You might look in the yellow pages for a transmission or drivetrain shop. In all likelihood, they could get the job done quickly and easily.

 

[rohsc400]

Thanks a lot again!