Hacc

When ever I put my car from P to D Or D to R my cars rear differential pushes the body downwards I am attaching the video ...also my car vibrates at 120 and 140 km ph. ..Please help me diagnose this issue my car is GS 400
sorry for my bad English 😁

regards

Behemoth7

I have this same problem, and I asked the same questions. Just for some background though, I will tell you what is wrong with my car so you can have yours checked out. I know for sure that my differential is worn out, because of a whining sound coming from the rear when i'm at about 40mph and I take my foot off the accelerator, plus a delay in power delivery to driver inputs. I know for sure that the flex couplings on my driveshaft are bad, mostly because of vibrations and I was told they are starting to tear. I also know that my rear upper control arm bushings are looking pretty decrepit, and from what another CL member told me, that is the reason for the clunking from the rear when putting the car into drive or reverse from park or going between them both because of the transfer of torque.

But frankly, it could be all 3 problems I mentioned contributing to my problem(the same problem you have). So I would have your car checked out for those things. Good luck!

Kyle Harty

iTrader: (17)

I had a hard time telling from the video exactly what's going on but if you're differential is moving like it appears to be its possible the bushings are worn out. There are poly bushings available that would keep the differential firmly in place. There's a member selling a set right now, he also has the link here to the original thread with more info on them. https://www.clublexus.com/forums/2ge...-bushings.html

marshun

bushings. those diff ones are a real pain.

angus

iTrader: (4)

They are designed to move a lot to cushion noise and harshness.

Yours may be worn more - but if you install any urethane bushings it's known to add gear noise.

Both my GS4's will "sit" down when you drop it in gear.

If your car vibrates from the rear, it could be your rear knuckle bushings, I just did mine and it made a world of difference.

Hacc

Let me add one more thing here....My car is some times smooth @120 and 140 and at time vibrates...
can really figure out what is the problem...is there any problem with my rims or tires?

angus

iTrader: (4)

Read what I posed above - the rear knuckle bushings cured mine - and I replaced EVERYTHING else trying to find the problem.

ALSO - adjust you're steering rack if you have not.

DMPesso

I second that! I changed the entire spindle/knuckle in both rear wheels and it did make it drive much better. BUT just FYI these are what you should check if your experiencing vibration.
NUMBER ONE is your tire pressure and alignment, you would be surpised what low or too much air will do, and ESPECIALLY the alignment I shouldnt even have to digress. In my opinion with the 16 inch wheels the car drives the best at 33-34 PSI. 32 is a little too low and thats what most mechanics use. After you made sure the PSI and alignment are perfect then the 3rd and equally most important thing is the tires. If your tires are unevenly worn or older then 20k miles or a couple years or have any bubbles or arent balaced these will also cause TONS of vibration. When I bought the car it came with "new" tires so the guy said. They look new but when I changed the tires it took away like 70% of all vibrations. Regarding tires what also made a huge difference was keeping the OEM tire size as well which is displayed on your drivers door sticker. Besides those 3 things make sure you check your struts and all the bushings from your control arms especially in the front of the car as well as the ball joints. The biggest culprits are the ball joints, upper control arms, lower control arms, sway bar bushings/links, wheel bearings. Also, dont forget the motor mounts! Sounds like alot but check everything and replace them little by little and the car will drive like its brand new for a long time. I spent over $5,000 replacing parts and now the car drives so good even when I drive my friends 2014 BMW 750 I still get into my car and enjoy driving it and even he says my car drives amazing, thats saying alot!

marshun

you really got gear noise? i have battle version aluminums on the diff and i got no noise.

angus

iTrader: (4)

Yeah, my 3.76 dif had a TINY noise. When I went urethane it went crazy!

I might switch back.

marshun

ahh. gotcha.