UpInTheLex

iTrader: (5)

There are fitment problems on the differential snout where the flexable rubber coupling meets the driveshaft.
The bolt circle on the Supra differential is slightly larger than the SC's.

I have a 1995 SC 400 auto and I installed a Differential from a 1994 Supra TT auto.

The Part number for the flexable rubber bushing for the SC400 is 37511-24010. $150
The part number for the TT supra is 37511-30020.

When I first installed the differential I was able to strech the old coupling to fit and it worked ok, altough after 20,000 miles I noticed vibration and premature failure of the part. The rubber bushing(coupling) is cracking from stress and I believe it is a source of slop in the driveline.

So i'm at a loss. Should I machine a new coupling from aluminum with hardened steel inserts that matches the bolt circle of each side? How do i ensure that it is balanced so I don't introduce more vibration to the drive line? How much will the part cost to manufacture? Should I disassemble the entire diff and change the snout back to the SC type? Or should I get a driveshaft from a TT supra? and who says that it'll bolt to the front of the transmission.

Anyone else encountered this problem or have any advice? I'm all ears. I can't believe we haven't heard of this fitment problem before.

Supra Dr

iTrader: (14)

you have a few options:

cheap way out is to switch the flange on the diff back to the NA flange. i did this
on a n/a supra so it should work for you. DONT over torque the pinion nut or you
will change the preload/pinion depth.

you can also get a custom 1 piece driveshaft w/ metal flanges & eliminate the rubber.
try searching user turbob6, he has 1 & i remember a thread w/ pics. PHR
www.powerhouseracing.com did his car & they do sell the shafts complete.

john

UpInTheLex

iTrader: (5)

John Thanks for the quick reply.

What I'm going to end up doing what you said first. I'm going to swap the flange off of the SC differential. I just removed the supra one using a 1 3/8 inch socket. (36mm wouldn't fit because of the thick walled socket wouldn't fit inside the flange) My SC differential is in California right now and I'm in Maryland

The junkyard across the street has the flange I need on a 94 SC400, so i'm going to see if i can borrow the flange until I get back to Cali and can send them mine.

Moral of the story. When swapping differentials between Supra Turbo and SC's it is not a bolt in operation. You must change the front pinon flange by removing the 35-36mm(can't tell which) nut and installing the new one to the correct torque.

John or anyone else know the correct torque spec on the pinon nut and the correct procedure for the install?

Supra Dr

iTrader: (14)

haha, this will sound hokey. but i use a torquewrench to loosen the nut.
put a alignment mark on the nut & pinion gear. (i use whiteout - drys quick &
wont wipe off) i also have a adjustable spanner to hold the yoke from spinning.
i dont think the parking brake is strong enough to hold it.

i start low say 125lbs, & go up in 5lb increments till it breaks free. the reason
is the actual spec is a window to set the proper pinion depth & bearing preload.
there is a crush washer/spacer that is a use once part inside. too loose & the
pinion gear can walk around. too tight & the preload/pinion depth has changed.
so in theory, if you reinstall the nut @ the same torque nothing will change.

i reuse the nut (which has the index mark) which your not supposed too.
a small dab of blue lock tight corrects for the reuse & wont back off.

i've used this method for years when replacing pinion seals too. its a bit of
a PIA, but it wont hurt the diff down the road. the lazy tech way is to spin the
nut off / on w/ a air gun. but then the diff takes a poopoo down the road &
everyone but me wonders why. the right way isnt the easiest.