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Help Rear Diff


philw99
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Wondering if anyone could help me? looking at putting together some options for a new limited slip diff for the Supra.

 

The cars current form is a 1999 JZ80 GE that was originally an automatic however has been converted to a manual with a BMW 420G gearbox.

Gear ratios are out and need to be changed. I believe the auto diff is currently about 4.0 and the final drive gear needs to be changed to 3.2 or 3.7.

 

How could i source a 3.2 final drive gear? (Seen you can't buy them new anymore) Also what options do I have for changing to a limited slip diff

 

Would I have to have the current diff rebuilt with a 3.2 final drive and new LSD internals?

Can you use any other Diffs parts?

 

Thanks

Phil

Edited by philw99 (see edit history)
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http://mkiv.supras.org.nz/specs.htm

 

NA diff is 4.083 (49/12)

TT auto diff is 3.769 from one more pinion tooth 13 (49/13)

 

If you could get a small case TT manual diff it would give you 3.266 (49/15) but these are perhaps hard to find?

 

Some more info here

https://www.clublexus.com/forums/performance-and-maintenance/866276-diff-gear-ratio-help-needed-46-vs-48-tooth-ring.html

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You can change your current small case diff to the A03B from a facelift twin turbo manual/auto. That is small case, 200mm, 3.266:1.

 

Check your VIN plate to see what diff is currently fitted. The most common are:

 

A01A - 4.083:1; small case 200mm; open

A01B - 4.083:1; small case 200mm; LSD

A02A - 3.769:1; small case 200mm; open

A02B - 3.769:1; small case 200mm; LSD

A03B - 3.266:1; small case 200mm; LSD

B03B - 3.266:1; large case 220mm; LSD

 

There are others as well, but those are probably the most common. The A01B and A03B being less common than the A01A & A02A/B.

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If you are wanting to run a “true” 3.2 then a 35 profile will make a 3.266 ratio 3.2 ratio.

 

You need the ring and pinion from a 98-00 Lexus GS400, 98-00 Lexus SC400 or a 02-05 Lexus SC430 and depending on the price being asked for said item you would be much better off ordering a new OEM set from Mr T.

 

E2A

 

If you change profile and increase it to 40 it will change the ratio to a 3.07.

Edited by Frank Bullitt (see edit history)
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No problem, expect it to be £600+ for a new set.

 

Also try,

 

TCB - Ask for Paul Pridham - http://www.tcbparts.co.uk

 

Inchcape Toyota Oxford - Ask for Steve Manley - https://www.inchcape.co.uk/dealerships/toyota/oxford/

 

Don’t forget to mention the forum and any chance of a discount.

 

Overseas (Japan) you have,

 

Impex - https://en.impex-jp.com

 

Amayama - https://www.amayama.com/en

 

Just remember if you go international you will have duty to pay so buying within the U.K. may work out cheaper.

Edited by Frank Bullitt (see edit history)
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  • 2 weeks later...
  • 2 weeks later...

I'm reading on multiple forums that is will just bolt right in e.g http://www.mkivsupra.net/vbb/showthread.php?339635-Diff-upgrade-options

 

Means that I can just send this one away and get an LSD added, if that's the case.

Think I might fill it with Diff oil first and test it out make sure it feels right with the 420g gearbox. Can't decide

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Frank know you said about taking the diff apart and counting the teeth, do you think this video shows it's a 3.2 final drive?

 

Also do you think the SC430 diff will fit on the Supra N/A? It looks the same?

 

Im not sure. The ratio might be stamped on the crown wheel, take the cover off and have a look.

 

Yes, the diff will fit.

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I'm reading on multiple forums that is will just bolt right in e.g http://www.mkivsupra.net/vbb/showthread.php?339635-Diff-upgrade-options

 

Means that I can just send this one away and get an LSD added, if that's the case.

Think I might fill it with Diff oil first and test it out make sure it feels right with the 420g gearbox. Can't decide

 

At the very minimum I would open it up and make sure the insides are in good condition before fitting it. I would be looking for any excessive play in the bearings, checking all teeth and ring gear.

 

Then fill it with a good quality 75W-90 oil, fit it and take it for a run.

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  • 3 weeks later...
  • 1 month later...

I've not taken the original diff out yet, just one bolt and that didn't fit on the new Diff. The pic is the new Diff with a bolt from my NA Supra.

The new plan is to take the final drive out the new Diff, use that in the original diff from the NA. Also going to get a LSD added hopefully.

 

Sorry for the late reply I have been away. I’m confused looking at the photo, are you saying you have taken the diff out and can’t put it back? I also hope this has been sorted.
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Phil if it's the side/driveshaft flange then these whole bits can be levered off. With the diff on the floor Ie without driveshafts bolted on don't undo any other bolts and then gently prise/lever off the flanges. You can then do the same on the current diff and fit them onto the new one?

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I've not taken the original diff out yet, just one bolt and that didn't fit on the new Diff. The pic is the new Diff with a bolt from my NA Supra.

The new plan is to take the final drive out the new Diff, use that in the original diff from the NA. Also going to get a LSD added hopefully.

 

Sorry for the late reply I have been away. I’m confused looking at the photo, are you saying you have taken the diff out and can’t put it back? I also hope this has been sorted.
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