When i start my car and put it in drive or reverse there's a jerk. also when i have the a/c on and im coming to a stop it jerks twice right before i come to a complete stop but with the a/c off it's fine, and theres also some road noise when driving but the suspension parts seem fine not sure what it might be?

anybody might have an idea?

 

Engine and transmission mounts or the 3 differential bushings. Or all 5

 

i had that problem and it was differential mount

 

I really have to laugh .... Please forgive me!

Ok... Though the previous suggestions may be a resolution, let me prepare you that they may not fix the problem. Why? You ask...

I have had the exact same problem as have many other owners as I have researched for 7+ months for the answere and replaced all possible bushings. Yes, ALL bushings from the rear diff, through the driveline and the into the engine bay. Nope...no fix. No codes are tripped and no reasonable explanation as it is intermittent. I will say that it is considerably less severe after replacing all of those preciously priced bushings, yet still it annoys the dog out of me. Honestly, my feeling is for those that do not resolve with new bushing....and I personally would focus on flex bushings on the drive shaft first....are most likely only going to see resolution Ina new trans.

I do hope that your issue is as simple as a set of bushings, but don't be dismayed if it is not the resolution. There are many that have the same issue with the same trans....this includes the GS and SC crowd as well.

Btw...in case anyone pipes up with more suggestions like..trans drain and fill with ONLY IV Toyota fluid.....check! Three times actually over a period of 6K miles....adjust the trans cable....done exactly within spec per Lexus.....or even the TPS may have worn out a point this not recognizing on/off throttle....replaced and back within Lexus spec and performed by Lexus tech......

These are the most common, if not all major resolutions affecting this noted problem. I hope this saves you some time at the very least. Oh, and sorry may come off a little bitter...this is a supper annoying and unresolved subject for me. However the rest of the car is amazing
Best of luck

 

is there a difference between bushings and transmission mounts? i would assume the tranny mounts would contribute more to the problem than the diff bushings.

 

start with tranny mount - it's one of the first and most common failure points on your LS400

 

I have the same issue with my 00 LS400 when i shift in to reverse. I did my first drain & fill of the fluid but the problem persists.

It's getting too cold out now for me to bother looking at bushing/mounts but I am hoping to resolve this next spring when it starts to warm up so I look forward to see if you find a resolution for your vehicle.

 

trans bushing takes no time at all once the car's in the air. it's 3 bolts to get the metal cover off, prop up the trans with a jack and a 2x4, 4 bolts for the crossmember, and i think 4 nuts on the mount (though it's been a while).

 

whew I am so glad my car has no rust- this is bringing flashbacks of my trans rebuild on my 90 Dodge pickup. Lets just say it was a long year that year.

 

I'd be thinking the solenoids are aging.

 

Tranny mounts are easy to replace. About the shifting deal the tranny mounts will do it, as well as improve the ride.