1JZPWRD

iTrader: (59)

Since my 1JZ swap I have noticed the rear end is getting a little squirly. What I mean, is that while in boost, low or high, the rear end is swaying back and forth at ALL speeds. This is now more noticeable since the wheel and tire change from ADR Decadence style rims running run flats (Bridgestone Potenza), to G35 Ray's forged aluminum, which are much, much lighter. I originally started with 245/40/19 in the rear on Michelin Pilot Sports tires. I figured since I was originally running a 275 on the ADR's, this is what the problem is. I then switched the tire size, and put a 265/35/19 in the rear on the G35's, with another set of Michelin Pilot Sport tires. No change. I am also running spacers, size 10mm with extended studs. I also have a bad right rear wheel bearing, which is on the way from Aliga.

I made several phone calls today to confirm nor deny what the possibilities are. Many of other SC owners say its not the rims or tires, its because I need a Soarer LSD or one out of a Supra TT. This is because when the boost and torque comes on, the rear wheels are not spinning together, they are spinning uneven, and trying to play catch up. This does indeed make sense.

Another member said to switch out the rims and tires with another set of rims and then take it for a ride. Then report back. This would eliminate the wheel/tire theory all together. They all stated to try and find the LSD out of a Soarer, but like trying to find a needle in a haystack. I tossed around the option of welding the differential together, it would be the cheapest, but it would chew up the tires more rapidly. Other person said not to do it, since my car is so nice and clean, don't half do nothing, just try to find a LSD rear end.

The point of this thread is to determine which route to go, and what do you think is causing the swaying in the rear end. Again this is done at ALL speeds while in boost.

Another main points is that I have somewhat new struts, strut mounts, sway bar bushings, and all of the rear bushings have been replaced.

I appreciate any comments with help in this matter.

emoFTW

iTrader: (1)

Honestly, to me it sounds like you need new diff/subframe bushings.

JeffTsai

iTrader: (1)

BTW: Finding an LSD for a SC is not hard. It shares the same diff type as a Supra. So buy a Supra diff and bolt it in. It's just that they're not cheap. But they are definitely out there.

1JZPWRD

iTrader: (59)

I will be under the car tomorrow. I will check that out.

1JZPWRD

iTrader: (59)

You are correct. I have been web searching for one for the past two hours. I also have notified my two Japan contacts for one also. I am awaiting their findings.

jwin

iTrader: (16)

what tranny do you have? Get the auto TT diff or if you are happy with the gearing in your rear end just get a TRD LSD and be done. Look to spend about 1k for a rear end. Auto TT diff are 700-900 depending on the deal you get and a TRD LSD for 1000. You don't need a soarer rear end or wait to source one from japan.

1JZPWRD

iTrader: (59)

I have the OEM Soarer R154 tripod tranny. It has also been built.

What are the differene in gearing between the TRD and the Auto TT? I think I am a bit confused.

Everyone is recommending this upgrade, but is this my problem? Has anyone else seen this type of sway in the rear end with 400-600 rwhp?

Wicked SC

iTrader: (3)

The TRD LSD is used mainly for strenghthening and if I'm correct, it's 100% LSD at all times, meaning the two wheels turn simultaneously. There are no gearings involved with it, it's basically beefed up internals.

The TT Auto Diff is also a LSD but it's a Torsen Diff, which means that when one wheel senses that the other is slipping it catches up to spin at the same time. It was explained to me at one point that it's probably spinning together 90% - 95% of the time versus the TRD LSD at 100% of the time. The TT Auto Diff has 3.76 gearing as well.

A TRD LSD can be installed in a TT Auto Diff or a Six Speed Diff...

jwin

iTrader: (16)

TRD LSD is a clutch type and the auto TT is a torsen type. When you buy the TRD lsd its just the LSD no gears and anything and you use the gear that is in your car. Usually when you buy a auto TT LSD its a complete pumpkin so its more of a plug and play type. It is really up to you. The TRD LSD is stronger than the torsen LSD. Torsen is gear based and the TRD is clutched base. Clutch base LSD are a little more aggressive than the Torsen but I have not heard anything bad about the TRD LSD. What rear end do you have in your car right now? if its the stock sc auto rear end you might wanna get the auto TT 3.76 gearing or a GS400 rear end with a TRD LSD. I have a r154 with a auto TT diff. I like it but again I am not turbo charged yet.

I want to say that I am 80% sure that is your problem you just have too much power and with a open diff you have one wheel spinning and the other one isn't spinning as fast causing you to get the sway action in the rear. It probably doesn't help the situation if you have a the stock sc rear end as its geared highed

jwin

iTrader: (16)

The TRD LSD can be install into N/A diff as well

blk&blu*j

iTrader: (1)

You kill me Mark. 10 digits and answers.

1JZPWRD

iTrader: (59)

Thanks man. Makes sense now. I was just on Youtube and saw your awesome video for like the 100 time. LOL

1JZPWRD

iTrader: (59)

I posted the thread to see if others on here had a similar problem and could find there answer on the forum.

blk&blu*j

iTrader: (1)

You need to get some more current pricing ^^^^^^^ cause your $$$$ are off a TRD LSD for a 200 mm Auto diff is about $1150-1200 and a TRD for a 220mm 6spd diff is about $1300

Also a Supra auto 3.76 diff is in the $1200-1400 range and the 6spd 3.26JDM diff is in the $1500-$1700 range both are torsional.

All TRD parts have gone ^^^^ about 30% in the last approx 6-8 months.

1JZPWRD

iTrader: (59)

I have always been told that the stock SC400 rear end is the best gearing combo with the R154 and what I wanted the car to feel like. This was a highway killer, not red light to red light. So you are saying the GS400 has the same rear end as the TT auto, or it has to be specific in a TRD LSD? This is will narrow down my search.

Thanks everyone for their contribution on this thread. I believe also that it is due to the rear end as well. I will get under it tomorrow and double check all the bushings and in the drive train including the rear end bushings. Maybe this is a contributing factor as well.