LSD v non-LSD

[threesixty]

Opinions? I am picking up a parts Supra with a F302(non-LSD) to replace my AILING F283 (LSD) and I am wondering what differences I will notice?

[Norbie]

Less traction and more wheelspin... pretty obvious I would have thought?

[threesixty]

Well, yes obvious! I guess my question is, is the better gear ratio (MPG) and newer diff worth replacing? Or should I wait. Is it THAT big of a difference?

[Supra Bob]

Well, if your not pushing alot of extra power out of your supra, then I would think if you want to improve the mileage, then go for it... However, if your planning on building your car up any, I would keep the lsd.

A third option you have is tearing apart the non-lsd and putting the ring and pinion gears into your LSD rear...

[threesixty]

Well, I have a 7M, and I do plan on pushing more power. I would keep the LSD, but it's making all kinds of noises. It cries when it's cold on the first go around, and on launches the tail end kicks hard to the right. So that probably means that switching the gears over is pointless? Yes? No? I don't know much about them, I've never looked inside one!

[SilverMk2]

Assuming your existing LSD even works you'll have a harder time accelerating out of corner and when taking off. Going from the 4.30s to the 3.73s will cut your cruising RPM way down. Say at 3000rpm in 5th you'd go from 65mph with the 4.30s to 75mph with the 3.73s, plus your speedo will read way slow as a result. I don't think you'll see a huge MPG increase (maybe 1 or 2 tops). I did the same swap about a year and I love it. Freeway cruising is much more enjoyable this way. You will lose a little snap off the line, but if you like a balance of driveability with performance you won't regret it. You might want to wait and get a LSD 3.73, however, you can install something like a Truetrac in the nonLSD diff. You might have to someday if you break the factory LSD.

[Flyin' Hawaiian]

360, this is just a shot in the dark here, but when was the last time you changed the oil in the lsd? I know it seems kinda basic, but when friction modifier hasn't been put in an lsd rear end, or the oil hasn't been changed in a long while, you'll get all kinds of noises from the diff. For a few bucks, I think its worth a shot to just replace the oil and see how it behaves.
If it still makes noise, then you'll have to rebuild it or slap the open diff in. Just to clarify, the Supra lsd diffs all make a bit of noise, as their gear teeth are cut a little straighter than other mfg'rs, even my rebuilt diff with all new seals, gears (4.10 and love 'em!), and shims still give a whine at around 75mph, but nothing near what it was before the rebuild.
FWIW, a complete rebuild with new gears will cost ya in the neighborhood of $350~450...
Chris

[WadeT]

I'm at this very crossroads. I currently have 280k+ a non-LSD (IRS it's called) that's getting very noisy. The last 40k+ miles have been with a 7mgte so I feel that is very strong and simple unit. The LSD has more moving parts and I'm concerned about it's longevity with a 300+ rwhp 7mgte. The IRS has held up well and it's likely I'll be replacing the stock 4.30 IRS with a 3.73 IRS.

[Norbie]

You're getting a bit confused here. IRS stands for Independant Rear Suspension; LSD stands for Limitied Slip Differential. Non-LSD diffs are more correctly known as open centre differentials. IRS and LSD are mutually exclusive, ie they are completely different things. Note that all Mk2's have IRS while only some have LSD's.

The only extra moving parts you'll find in an LSD are the clutch packs, and when these wear out it doesn't stop the diff from working - it simply starts to behave like an open centre. There is no difference between the LSD and non-LSD centre in terms on strength or longevity.

HTH

[WadeT]

You're getting a bit confused here. IRS stands for Independant Rear Suspension; LSD stands for Limitied Slip Differential. Non-LSD diffs are more correctly known as open centre differentials. IRS and LSD are mutually exclusive, ie they are completely different things. Note that all Mk2's have IRS while only some have LSD's.

The only extra moving parts you'll find in an LSD are the clutch packs, and when these wear out it doesn't stop the diff from working - it simply starts to behave like an open centre. There is no difference between the LSD and non-LSD centre in terms on strength or longevity.

HTH
*sign*
I'm quite aware of the fact that all MKIIs are IRS but I was quoting the fakn TSRM for it's labling of NON-LSD section as "IRS".

As far as the comment about LSD and non being of equal strength might be true but that the time during the 1980s many car companies were having problems with LSDs. That is the main reason why the old man bought the '85 with non-LSD. And I have yet to see a MKII with a stock rearend that is pushing the kind of mileage mine has, not to mention being turned by a 300rwhp 7mgte.

[Supra Bob]

Wade,

I'm not too far behind with 262K on the original rear... (and the LSD still works nicely I may add :) )

[Norbie]

I don't know what the TSRM says, but my comments above are still valid - IRS refers to the suspension, not the differential!

Re the LSD, I'm sure some car companies have had problems with their LSD's but in this case the diffs are mostly the same whether LSD or non-LSD. That is to say the ring and pinion, which carries most of the load, is identical in both cases. As I said before, if the LSD component stops working the diff will still function as normal, but obviously without the limited-slip ability.

[Jay]

I'm with Hawaiin here - do a proper fluid change first, that totally revitalised my LSD.

[cyber-punk]

And I have yet to see a MKII with a stock rearend that is pushing the kind of mileage mine has, not to mention being turned by a 300rwhp 7mgte.

Talk to SUPRAGTE(i think its SUPRAGTE) on toymods.org.au

he is running a 7M-GTE with about 225rwkw(300rwhp) in his mk2
he might be able to shed a bit more light on this

oh and his webpage is http://supragte.freewebspace.com/index.html

[turbo357]

The only extra moving parts you'll find in an LSD are the clutch packs,
HTH


Can you see the clutch packs when you open the cover? I bought a differential & I can't tell if it is a LSD or Open.
HELP !!!!

[SkoonMA67]

Reg Riemers Supra-GTE car is running about 400rwhp on a daily basis, and his LSD handles the power perfectly even when its flogged!:lol:

He changed the gears on his, but the actual diff (side gears, carrier etc...) are all original and he has over 300000km on the car.

Aaron

[Angkistrodon]

ALright heres a real stupid question.

I have a 1985 MKII...140K.......How do I tell if I have a LSD or not?
I have looked at it and changed the oil in the diff. and the clutch.....so at least I have been under there.....but I couldn't tell you what it is(meaning LSD on non).

[Muchbzy]

The two easiest ways are, one, look at the diff and they have a sticker on them that say "LSD"; two, jack the car up and turn one of the wheels, if they turn together then you have LSD if they turn opposite then you don't.

[Norbie]

You can also check the axle code on the build plate (located on the firewall). It will look something like "F293". If it ends with a 3 it's an LSD, if it ends with a 2 it's an open centre. Of course this only applies if the car still has its original diff. :)