newdude

Well Ive been searching but cant find the answer I really looking for. How much can the stock SC300 rear end hold? Im looking at have between 400 and 500 at most hp. Will the stock rear end hold up with that?
Im planning on getting a 2jzgte with an R154 trans, and just leaving the stock twins on with fmic, dp, exhaust and bov.

dumdumgreg

iTrader: (5)

yeah the rear end will hold up, but your gearing is gonna be a bit high

5sp_jzz30

iTrader: (2)

uhm... i blew up the stock rear end in my 93 sc300 5sp.....with stock power. when i called Sound Performance about diff costs the guy thought i was joking because he never seen it happen. im pretty good.

i think my rear end was just cursed. most people say its good for about 400hp. i say get a rear end from a supra or sc400 and weld the diff

Ali SC3

iTrader: (10)

the rear end is the last thing i would worry about.
it will hold just fine unless its a lemon, or if it breaks then replace with vlsd
or with another one.

i would feel shaky about a welded diff with 400-500 hp,
but thats just me

Gunnar

While it'll hold, you probably won't have much fun peg-legging with the factory open diff. Look out for a TT auto pumpkin for better gearing or even just the differential itself to retain the stock gearing. Is your car a 5-speed or an auto right now?

newdude

Well Im picking it up in two weeks and its a 5 speed. And Im not welding the diff lol. Where would I find a TT auto pumpkin? And what is it? :P

Blizzy

iTrader: (-1)

The TT Auto rear end is what you are looking for. Search this forum's classifieds and the Supraforums classifieds. They run ~$1000+shipping, and they are normally snatched up within a week. Run a classifieds search for "supra differential" and see if there are any available.

As was mentioned, the gearing will be much more ideal for your application. Just as importantly, the Torsen LSD will be a welcome addition to having all that power. 400-500hp with an open rear end would turn your car in to a three ring circus.

newdude

If you mean by the revs being high I dont mind that.

newdude

https://www.clublexus.com/forums/sho...a+differential

Is that what I would need?

Blizzy

iTrader: (-1)

There is more to the story than just revs being high (and, yes, they will be higher with the stock gearing):

The 3.76 gearing from the TT Auto Supra puts more strain on the motor when not in boost as compared to the stock 4.08 gearing. Getting the motor huffing and puffing is a good thing, because that increase in exhaust flow will spool the turbocharger more quickly than it would otherwise, increasing boost response.

While the revs will be lower with the 3.76 rear end, the major motivation is to get the turbo spooling quicker from the increased engine load when out of boost.

As for the rear end you have found on the classifieds, I would steer away from that. That unit is a clutch-type unit from an n/a Supra that is weaker than the Torsen LSD rear end from the TT Supra. In addition, the TT gearing at 3.76 is more preferred for your application to the 4.08 gearing of the unit for sale.

If you keep your eyes peeled, you should be able to find a 3.76 Torsen unit every month or so for ~$1000.

Gunnar

You don't even have to have a boosted car to rue the open diff. When my car was just a lightly modded NA car with some weight taken out, it'd just blitz one tire mercilessly, even from a low roll.

2jzlex

iTrader: (3)

Blizzy:

Im not clear as to why you would want an AUTO diff instead of a 6 speed. You probably clarified in your later post, but I am still confused. Do you want the auto because of the gearing? Or because you are under the assumption that he has an auto SC and would mate up to the driveshaft? I already have the 2jz, and am working on the R154 swap as of now. So are you trying to say that the auto is ideal for gearing purposes behind the R154 gearing and 2jzgte? If so, does the pumpkin on the AUTO matter? Are the different, or are the U-Joints the same for the manual and auto?

Thanks much
Jon

Blizzy

iTrader: (-1)

Jon-

The 6MT differential is larger in diameter than the other Supra differentials (and the Lexus differentials). The different dimension of the 6MT rear end requires that the driver's side axle be sourced from a 6MT Supra for the swap. In addition, yes, the 3.13:1 ratio of the 6MT Supra is a bit too tall for the W58 or R154. That ratio is perfect for the V160.

The Auto TT rear end will not mate to the SC driveshaft without swapping the companion flange from your own differential. However, the Auto TT rear end is preferred: not only for the 3.76 gearing that is perfect for a 5MT turbo car but also for the Torsen unit inside. The Torsen unit from the Auto TT is more well built than the clutch-type units in the n/a MKIV rear ends that came with LSD.

If you can source the LSD unit by itself from the Auto TT, you could have a professional swap the unit into your stock rear end, but the 4.08 gearing of the 5MT SC300 is more well suited for an n/a application since it leaves first gear short and quick. The 3.76 ratio would lengthen out 1st gear (and every grear for that matter) to allow boost to be built more early into the power band, effectively widening out the peaky power band of a turbo 2JZ.

If I had an R154 on a turbo 2JZ, I would seek out a 3.76 Torsen rear end from the Auto TT Supra. I would avoid the 6MT rear end for the hassle and the improper gearing, and I would avoid the n/a LSD rear ends since they are geared to short and not built as stoutly.

2jzlex

iTrader: (3)

blizzy:

Thanks. That makes alot more sense, lol. I think it was just the way it was worded the first time. Now I see what you are saying. When I decide to swap the rear end out, looks like I found my baby.

Jon