JimsGX

Hi Everyone,

I bought a 91 LS400 a couple of weeks ago with 76,300 miles on it. It's a one owner vehicle and I know the previous owner. She is 76 years old and only drove it on the weekends. Every service was performed by the local Lexus Dealer (I have a copy of every single service record) and its had all the standard major service performed including the timing belt, water pump, steering rack, PS pump, all new brakes and rotors just 2k miles ago and only 3k miles on the tires. I've put about 500 miles on it over the last couple weeks and started to notice a vibration about 100 miles ago. I've searched and read all the threads on this subject but haven't really found a condition just like the one I'm experiencing. The car has a vibration only when decelerating at 29 down to 25mph. Then it has it again when cruising at 47 to 56mph and decelerating at the same speed. When accelerating, either the drivetrain is masking the vibration or it doesn't exist. Also, under any of these conditions, I can put my hand on the shifter, and there's absolutely no transfer of the vibration coming through the shifter. At either of these speeds, if I put the vehicle in neutral, the vibration is exactly the same. Once I coast down out of those speed ranges, the vibration goes away. I had the tires rebalanced this past weekend and it made no difference at all in the vibration. I can put the vehicle in park and rev it up to 4000rpm and its smooth as silk with no vibration at all. Also, under the conditions above when its vibrating. there's no vibration being transferred through the steering wheel. I can cruise at 75mph with just one finger on the wheel. Itdrives straight and true...

Any idea's? I know one of the more common recommendations is to replace the motor and transmission mounts but in this case I don't know if that would do any good...

Thanks,
Jim

trukn1

could also be the driveshaft bushing that needs to be replaced. and driveshaft re-balanced.

pfantom68

Check the driveshaft bushings and trans mount to start with. Also, check the pivoting joint on your driveshaft.

JimsGX

Thanks for your replies...

Do the drive shaft u-joints and pivot joint have grease fittings on them or are they permanently sealed?

Smoothie22

JimsGX.... I know this is a little late, but I just noticed your post while searching for vibration issues. First off I have to say that is a great description. I have the exact same thing happening and I am trying to diagnose the problem. Did you ever get any resolution to the problem? I really thought mine was a tire issue, but I just put new tires on the car and to my disappointment the vibration is still there. Mine is about the same speed from around 43-50 and is a little loud. It has gotten worse over time. I am going to check out the tranny/motor mounts and see what they look like.