bmanson

Based on the readings I have seen here and at lextasy.com the supra rear diff. and the GS diff is interchangeable. However this swap is not without comprimise. To the acceleration junkies switching to the 3.76 final drive of the supra would add some welcomed acceleration, but to those who endure regular highway mileage it would seem that it is more of a detriment. So my question is; is it possible to just use the LSD from the Supra utilizing our GS400 final drive??

I think in mechanical terms that would entail using the ring and pinion gear from the GS diff bolted to the Supra LSD.

Sorry to make my first post non introductory. My name is Brian, I recently purchased my GS400 and have since performed mods I felt it should have had from the factory, Pio D1Navigation, MB Quart QSD components, 12" IDQ sub in a custom enclosure, PPI PC650 with DEQ 30 band EQ, integrated CD changer in the factory location, 6000k Philips Ultinon bulbs, 35%TINT, 17" OEM wheels, TRD swaybars front and rear, and a fresh coating of the silver hue... I will post some pictures tomorrow after I wash her.

morris

iTrader: (2)

you dont have to go with a supra LSD. I have a TRD LSD with the stock gears installed in it.

There are also several other LSD's avialable for our cars Kazz is one that also comes to mind. The point is that you can install the stock 3.23 gears in any of them.

Now whether you should or not is up to you.

bmanson

The TRD LSD is not the same style LSD as the Supra unit, the clutch type LSDs used in the TRD unit tend to be more durable under higher hp applications but less smooth then the Gleasen Torsen style diff. during periods of engagement, which is why I want the Supra unit. However I did not realize that Quaife had an application for the Supra/GS so thank you for bringing that to my attention.

After a quick trip over to Quaife's website, and looking under the Toyota section there is not listing for the Supra or the Lex for an ATB LSD.

Any other suggestions or comments?

Also Morris,
What are you impressions of the TRD LSD, driveavbility, noise, functionality etc. a quick review with pros and cons would be much appreciated! Thanks.

3dog

iTrader: (1)

I'm not sure if I understand what you are asking.

I have a 3.76 LSD on my GS400 and find that it runs a little higher RPMI
I get great acceleration when I go to pass someone out on the freeway.
I don't think it is any detriment as far as driving on the highway

The only downside I know of is it will only top out at about 130MPH.
Of course I don't drive that fast very often so it really does not bother me too much

I have to admit that when I did hit 130 a couple of times on my trip to So California last year I would of liked to have be able to get it up to 145 MPH.
That was on brand new road in a lonely part of NE Calif, no one else anywhere in sight..
Very fun!


Ivan
3dog

morris

iTrader: (2)

Well I'm happy with it, there is no additional noise at all, even when cornering I dont hear any noise. I think initially there was some on cornering but that quickly subsided.

In terms of normal driving it does not act any differently and you wouldnt know iti was there.

Now the down side and I dont know if this is truly a down side and I think it is a function of all LSD not just TRD. But the car with the stock diff understeers, which makes it pretty easy to slide through corners when driving hard like mountain driving. Now the car oversteers when cornering hard and can make for some uncomfortable surprises if you are not used too it or dont know how to deal with it.. I'm probably not being clear with this but the car does corner better it doesnt seem to loose traction as early as it originally did but when it does break loose in a corner the tail definitely wants to come around.

The car also walks sideways pretty easily especially off the line under hard acceleration, I dont think it used to do that before but then again I'm not sure. I should mention that I am boosted.

bmanson

"I have a 3.76 LSD on my GS400 and find that it runs a little higher RPMI "

Running at a higher RPM translates into a decrease in gas mileage and a decrease in civility (to me anyways), which is what I am trying to avoid. I am quite content with the acceleration of the vehicle, I just want to address the handling side.

Morris,

As for your review thank you, my experience with clutch type LSDs is their engagement is more abrubt and less linear than the Torsen Gleason style LSD, When cold and making sharp turns the rear does not emit any unusual sounds or give off any strange sensations in terms of feel? Also what kind of enginemanagement are you running with your suspercharged setup? Do you have any dyno graphs or your setup with a/f ratios?

morris

iTrader: (2)

Nope nothing to really speek of even on sharp turns if you have the wheel turned to the stop you may feel a little something but it is barely noticeable.

I'm no longer supercharged now I am turbo charged and used the SAFC for both of them. The dyno graphs should come in a couple weeks, we are still tuning it.

FutureGS400

Bmanson-first of all-welcome to CL! Sounds like you have a good start on your car mods already!
I have had the 3.76 LSD for quite a while now and I also do a lot of fwy. driving (about 20k per year). Depending on speed, you are only turning about 250-350 rpm higher than stock. At 80 mph it is around 300 rpm higher. To me, the car feels more responsive to throttle input without having to kick out of lockup or down to 4th gear and our engines are so smooth and quiet that I don't notice the extra rpm at all. True, mileage will suffer a bit, but I'm not pushing for ultimate mileage anyway and I'm willing to deal with the trade-off.
I like the Torsen type LSD a lot and have no regrets at all. One advantage is that it is a direct bolt in replacement rather than having to tear down the rear end and install the new carrier and set up the ring and pinion, side gears etc.
Most people who are staying with stock gears are FI as far as I know. For NA cars, the 3.76 LSD is an excellent mod. It works especially well with the high stall torque converter too!

3dog

iTrader: (1)

I'm out a total loss here.
What on earth do you mean when you say that it results in a decrease in civility?

How can an extra 300 RPM's at 80MPH make athe car less civil?
I'm starting to wonder why you did this mod and even why you got the V-8

Ivan
3dog

bmanson

Okay to clarify, the first sentence was a quote from another user, and to sum up my reaction to that quote goes something like this. I am against the added 300rpms while cruising that the 3.76 gear ratio of the Supra diff would add, because with that extra 300rpms would be an increase in vibration, noice, and a decrease in gas mileage. No matter how miniscule that may be, I am trying to avoid it. I have a 550whp obnoxious Acura Integra that when I need to, satisfies my craving for acceleration and uncivilness, so to try to squeeze out an extra tenth of acceleration at the cost of luxury and economy from the Lexus just does not do it for me... However, having the added benefit of a Gleason Torsen style LSD in the rear while cornering is just what I am looking for. Which is why I would like to know whether or not just the LSD from the Supra diff will fit into ours. Since no one seems to know I guess I will be the test dummy, further more, the supercharged guys out there that claim to hit revlimiter as a result of the shorter gearing could benefit from this as well because they could retain the 3.26 gearing with the added traction benefit of the LSD.

FutureGS, thanks for the input, did you notice a noticable improvement with all the chassis bracing you did? Which was most noticable and beneficial?

DaveGS4

iTrader: (2)

BM,

I think you will be the test dummy - don't know of anyone that has put the stock GS gears in with the Supra Torsen LSD. May also want to check Supraforums to see if any Supra owners may have changed gearing on their stock rear end.

FutureGS400

First, let me just reiterate that you will not feel or hear any increased noise or vibration with the GS due to the higher rpm. Not trying to talk you into doing something that you're set against, just want you to know that it isn't an issue. Even with the intake and exhaust, my car is very quiet while cruising(excluding the tire noise which is inevitable).
Slightly off topic (but it IS your thread after all ) but yes, the chassis bracing transforms the car's handling capabilities! Of course, this all works together with the coilovers, sways, tire/wheel combo etc. But most of us feel that the GS really needs the chassis stiffening to enhance the performance of the car. Hard to say which brace does the most good. They really all work together to triangulate and reinforce the platform for higher cornering loads made possible by the sways, coilovers, tires etc. The only one left for me is the rear suspension Tom's 6 link. Everyone has a different opinion on which is most beneficial, and at some point you begin to get into "diminishing returns" but they all help IMO.
I'm sure that any local CL member would be happy to let you ride in or drive their modified GS so you can see the difference for yourself!

bmanson

Future thanks for the insight on the bracing... That is definately next on my list of things to do.

That being said is there a GS owner in the Philadephia area that has a GS with suspension mods I could use as a basis for comparison purposes??

As for the differential, I am in the process of aquiring the Supra LSD so when it comes in I will tear it apart along with mine to see if I can get some blending going on. If not I may just suffice to have the Supra unit on the GS. Thanks again to all that are providing info that has no doubt been covered to a newb too lazy to search...

FutureGS400

Good luck with your diff project. I have upgraded domestic diffs (Dana 44) with different ring and pinions, added limited slip (clutch type) etc. but have virtually no first hand knowledge of this application as to the "inner parts". One person who would know for sure is Todd Matsubara of TM Engineering-a CL sponsor and all around great guy! He has done work on my car and many others here and if you shoot him an email or PM him I'm sure he can help. His username is Doublewhoosh or you can go to his site by linking from CL forum.

bmanson

How ironic I just ordered Daizen control arm bushings from him today, I will have to call to bother him tomorrow...