Help Rear Diff

[philw99]

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 August 28, 2018 by philw99 (see edit history)

[Scooter]

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

[Frank Bullitt]

What is your current rear tyre size?

 

Are you talking about the the smaller 200mm diff or the larger 220mm diff?

Edited August 23, 2018 by Frank Bullitt (see edit history)

[James]

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.

[philw99]

Thanks for all the information guys has really helped.

 

Does anyone know if i could change the internals of my A01A Diff to an LSD (Cusco or KaaZ) with a final drive from something else? like a Lexus GS300 or GS430 maybe?

[Frank Bullitt]

So you are using the smaller 200mm diff?

 

I believe most ring & pinion sets are interchangeable between the 200mm diffs.

 

What tyre profile are you running as this will change the ratio.

[philw99]

Sorry.. yes i'm running the 200mm diff 100%.

Glad you said they're interchangeable, just need to find one that fits then find someone who's willing to swap it for me

 

Tyre on the back is 275/35/18 (Currently)

[Frank Bullitt]

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 August 28, 2018 by Frank Bullitt (see edit history)

[philw99]

Mr T ?

[Ric]

Toyota

[philw99]

Getting confused if i should be looking for Toyota Part codes or Lexus part codes, thats all. (assuming they are different)

90% sure Toyota don't make them anymore for the Supra.

 

So maybe a Lexus Part code of 41201-80445 for the SC430 might be worth investigating?

Edited August 28, 2018 by philw99 (see edit history)

[Frank Bullitt]

Lexus is just the posh part of Toyota

 

For the 3.266 final gear ratio you want 41201-19645

Edited August 28, 2018 by Frank Bullitt (see edit history)

[philw99]

Thanks pal. Will get prices on 41201-19645 tomorrow

[Frank Bullitt]

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 August 28, 2018 by Frank Bullitt (see edit history)

[philw99]

Found one, Diff from a SC430 2004 Auto done 74 thousand miles. Looking on here http://japan-parts.eu looks to be the correct part code of 41201-19645.

Fingers crossed it's right

[Frank Bullitt]

You can count the teeth on the ring & pinion to make sure it’s correct. If you divide the number of ring gear teeth by the number of pinion gear teeth it will give you the ratio.

[philw99]

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?

[philw99]

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

[Frank Bullitt]

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.

[Frank Bullitt]

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.

[philw99]

Frank new question about this Diff, the bolts don't appear to fit from the old one:

https://imgur.com/a/p1TmVsK

 

Only taken one bolt out so far, not sure if you can see from the picture but it's too small. Not sure if bigger bolts will fit through the driveshaft?

[Frank Bullitt]

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.

[philw99]

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.

[Scooter]

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?

[philw99]

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.