Lexs400

90 LS400 w/traction and air suspension,
new air struts, alignment done twice at different dealers, so these two things are taken care of.
problem: even after alignment the car pulls to one side, during lane shifts the rear sways like a ship, and during rain drive the rear simply gives out without any grip at all.
It's got 180K miles, have had it since new and this is the first time this problem has developed.
I'd like to know what to change to cure this.
Also, over small bumps the rear gives sounds as if the whole differential slams on the body itself making a thumping sounds. both side tires going through a bump gives the same effect....

trukn1

Sounds like your Carrier arm bushings are prety much shot to death, which will explain the rear end sway. I had the same symptoms on my 92 when I first got it. When I updated mines, I went with all new bushings in the rear (if it had a bushing,,I pretty much replaced it) as well as new control arms. As far as the 'body slamming" effect, can't really help there since my car didnt have air.

Lexs400

I've changed the control arms. I guess bushings should be next.
On my mercedes , I recall I had once changed rear subframe bushings to correct this issue, on the LS I didn't see much info on the rear sub-frame bushing... has anyone changed them and if so is there another name for them ?

Bali26

Yeah mine too, on mild sharp bumbs there's a thunk sound. I think it might be one of the bushings shot resulting metal to metal contact.

Lexs400

Agreed, but i can't figure out which bushing to check for this issue...

trukn1

www.lexls.com ,,,your first gen LS bible.

Lexs400

I checked www.lexls.com but nothing regarding the rear-sub frame bushing change etc... anyone replaced them and what was the before and after effect ?

Lexs400

I've had it checked at the lexus dealer as well as independent mech. they both checked all the bushings in the rear and they said they look fine. I've also had new control arms put in... not sure that could create the unstable rear end....
any ideas ?

RA40

iTrader: (6)

They may look fine all squished in there. At 180K miles, they are likely well worn and once removed they will show how bad. When I had the front strut bar bushings done, one shop said they were fine. Once removed was a different story.

williamb82

`its not the subframe bushings. its the carrier arm bushings. i did this to my ls maybe a month or so before it got totalled. made a HUGE difference. jack it up and grab the lower arm that goes forward and give it some yanks. if it moves. the bushings are bad. youll need the adus 505 and adus 5056 bushings. if its the lower arms going toward the diff, its the adus 583 bushings. also, id get some poly rear swap bar bushings. tightens up the rear noticably.

Lexs400

Thanks. which bushing will cure the big thumping sound every time the rear goes through a pot hole and the whole differential bangs with the body creating this sound and at the same time it feels like it's riding without any shocks where as the air struts are brand new....

steve2006

I think the differential is mounted on bushes,may be worth also checking these along with the transmission mounts

Lexs400

Do we know which bushes these are so that I can either order them through dealer or check if ADUS has these poly bushes available.
thanks.