Diff question

i have checked my vin and apparently i have a ao1a diff as i have the letter a on my diff. But im confused as im supposed to have air vents in the diff? Which im pretty sure i dont after looking at it closely.

Does anyone have a picture of the lsd and normal diff together? Im trying to work out which i have and how hard it is to fit lsd to a n/a if it is even worth doing etc. Ive just done a diff oil change and had a fair amount of metal stuck to the diff drain plug so am wondering if i should be getting ready to change it.

If you find the 4.083:1 A01B LSD from the prefacelift SZ-R, that is a straight swap with the current 4.083:1 A01A open diff that you have.

If you want to change to an LSD and don't want to spend a long time looking for the A01B, search for an A02B. It is the 3.769:1 LSD from a TT Auto. Same 8" casing but requires the flange to be changed as it won't mate with the W58 manual box otherwise.

Unfortunately I don't have pictures for you or anything.

If you find the 4.083:1 A01B LSD from the prefacelift SZ-R, that is a straight swap with the current 4.083:1 A01A open diff that you have.

 

If you want to change to an LSD and don't want to spend a long time looking for the A01B, search for an A02B. It is the 3.769:1 LSD from a TT Auto. Same 8" casing but requires the flange to be changed as it won't mate with the W58 manual box otherwise.

 

Unfortunately I don't have pictures for you or anything.

Ive heard changing to the tt auto one screws up gearing on the n/a?

Is it possible that someone has changed my diff as i dont have these breather holes? Im guessing i should wait for some tech pictures before i state that though.

Ive heard changing to the tt auto one screws up gearing on the n/a?

 

Is it possible that someone has changed my diff as i dont have these breather holes? Im guessing i should wait for some tech pictures before i state that though.

Being a 3.769:1 ratio as opposed to your current 4.083:1 ratio will give you different speeds at the same rpm in gear to what you have now.

I made the change from A01A to A02B (W58 5 speed manual hooked up to the GTE TT engine) back in June and have suffered no issue. If anything my fuel economy has probably improved!

I've changes my diff on my na, i smashed 3 na diffs so upgraded to a tt one which I belive was auto and its exactly the same

I've changes my diff on my na, i smashed 3 na diffs so upgraded to a tt one which I belive was auto and its exactly the same

Ok thanks. So im looking for a tt diff or a n/a lsd diff. What price should i expect to pay. Very low mile lsd are available from japan for £280 so im guessing around 150?

Bang on, yes 150

Bang on, yes 150

sweet thanks. So it is the ao2b im looking for ideally. This will be a diff from a auto tt turbo?

Also still looking for pictures to check which diff exactly i have.....

Left - Diff B fitted to pre-facelift manual J-spec 2JZ-GTE and all UK spec TT's.

Right - Diff A fitted to all other Supra models.

http://img210.imageshack.us/img210/2994/supravsoarerex8.jpg

TRD do LSD's to fit both casings

41301-JA800 TRD LSD - Diff B

41301-JS402 TRD LSD - Diff A

Left - Diff B fitted to pre-facelift manual J-spec 2JZ-GTE and all UK spec TT's.

Right - Diff A fitted to all other Supra models.

 

http://img210.imageshack.us/img210/2994/supravsoarerex8.jpg

 

TRD do LSD's to fit both casings

 

41301-JA800 TRD LSD - Diff B

41301-JS402 TRD LSD - Diff A

Ok thanks. What do people mean when they say open diff? Looking at this im pretty sure i have the one on the right. Which would make it the non lsd one.

Ok thanks. What do people mean when they say open diff? Looking at this im pretty sure i have the one on the right. Which would make it the non lsd one.

You say you have an A01A diff.

The first A means you have the 8.5" crown wheel, meaning you have the smaller diff, ie the diff on the right of the picture.

The 01 is the final gear ratio of 4.083.

The final A means the diff is the open type, as opposed to the TorSen diff, which would be present if your diff code had a B at the end.

An open diff basically means it isn't a limited slip (TorSen being a basic type of LSD).

The only LSD insert worth fitting is something like a Giken or a TRD plate type one. The Torsen type was pretty useless when new, buy a 100,000 mile plus used one and I doubt you'll notice any difference, save to your bank account.

The only LSD insert worth fitting is something like a Giken or a TRD plate type one. The Torsen type was pretty useless when new, buy a 100,000 mile plus used one and I doubt you'll notice any difference, save to your bank account.

Chris, the TRD & OS Giken offerings - do they work with the 'A' case smaller diffs or would the B03B and different driveshafts etc. be required? As I mentioned above I had my A01A break and replaced with an A02B but wouldn't mind something better down the line once I get going on drivetrain and engine upgrades.

Both makes are available for both types of casing. I have new side bearings and drive shaft seals at a good price, for the small casing, which you will need if you fit an LSD section.

Ok that is good to know! Thanks Chris, I'll be in touch (hopefully in the not too distant future!)

SteveL has a Giken diff already cased and good to go in the sales section mate.

This is something I need to sort before doing some trackdays next year, the lack of LSD is annoying.

SteveL has a Giken diff already cased and good to go in the sales section mate.

Wow, yer i was looking at the standard supra one that ive seen go for around £150. Spending £1300 would be my entire car budget blown.

It is honestly not worth the hassle to fit the Torsen type diff. You would see better traction by spending the extra budget on top of the range tyres when you next need to change them. Or replacing your dampers.

Chris, I have ebach springs on yellow Billies, but still struggle. Is the oem LSD not even worth a look for the occasional track day? If Im pushing hard on B road corners I sometiems end up with lots of wheel spin and smoke from one wheel but not a lot of traction.

Can only imagine this would be worse on track.

The Eibachs are too low, you are into the "daft" part of the rear camber curve under power. The OE LSD was a waste of time new, trust me. It will be even more a waste of time when it's old. You need a plate type LSD on track. The TRD one is OK, and v=can be modded to be good, with expensive machined parts. The Giken is as good as it gets outside hydraulically controlled active LSD's. Brilliant in build quality and operation. Best thing you can buy for a serious MKIV. I can supply at a discount. I can modify, overhaul and supply ALL spare parts for it, from a washer to a casing. AFAIK there are no separate spares available for the TRD LSD.

Its a shame your along way from me otherwise I would drop the car in for a proper setup. In the short term would a decent alignment place be able to correct the camber so there is more grip when the power kicks in?

Tbh Im not a fan of the springs, fitted by previous owner and its a very hard, crashy ride.

It is honestly not worth the hassle to fit the Torsen type diff. You would see better traction by spending the extra budget on top of the range tyres when you next need to change them. Or replacing your dampers.

Ok thanks for the reply. I will just get a spare standard diff just incase anything happens to mine. I have V expensive tyres on now anyway and fairly new oem shocks, so perhaps there are other areas i should be looking at too.

It's nothing to do with the static camber, it's the dynamic (in use) camber change. When the MKIV is lowered beyond a certain point the rear (in particular) gains a huge amount EXTRA negative camber as the car squats down under power, or rolls in a corner. Lowering very much actually increases roll forces, due to the change in roll centre position. Race cars are able to run super low because all the suspension pick up points on the chassis and uprights are changed. Put simplistically they move all the pick up points UP on the body / chassis, not shorten the springs. A MASSIVE job. I have done it on Elans, starting with a bare Spyder chassis with no pick up points installed, and on a Volvo 240, by weeks of maching special bits and bobs. I have also done it on an MR2, but the man hours involved is horrendous.

Ikeya (sp?) sell some rather iffy looking bits and bobs to restrain roll centres on lowered Supras, not sure how good they are.

The lousy camber curve of the MKIV is why ultra low profile tyres don't suit the car, like 19 inch tyres.