katg

I just bought a 1992 LS400 with unknown mileage. I am not noticing any handeling problems but I have a noise coming from the drivers side rear of the car. It sounds like something hitting something else and it is in time with the rotation of the wheel. Any idea what it could be? I jacked it up and with the weight of the car couldn't track the source. I have dealt with front end issues before but not rear end problems.

waseem3000

It could possibly be broken differential mounts as they will make a noise and mine was doing a weird noise when wheels moving like something hitting something but only on bumps and bad roads.

Also make sure your exhaust is not hitting and making the noise as mine was doing the same too. Hope this helps!

denverdog

i just had a situation where, after driving about a mile, i got a bad rythmic thumping that seemd to come from the rear end. it would not be there while accelerating, or braking. but it was loud, and you could feel it when cruising. my mechanic diagnosed there is a thing like a shock absorber, or a hood lift, that pushes the parking brake away when you disengage the p-brake, that had broken. unbelievably, the part is only $77 from lexus. none of the regular parts stores have it.

katg

Thanks waseem. Another friend listened to it and suggested the differential and when I mentioned the mounts based on your reply, he said that made even more sense.

Denver, mine seems to be primarily when accelerating or when going up a parking ramp. Anything that puts a little more force on the back end.

waseem3000

Thanks for appreciating the reply, I am quoting myself from another thread of how to change the mountings and believe me its not easy to do so.

"Changing the differential mounts is a pain as they do not cost much and I bought them here in UAE for $15 each and 2 are required and I assume they are the same for all years and mine is a 99 but takes a lot of time for changing!

My differential had to come down to be able to remove the mounts and then new mounts inserted with a device which helps to do so, since my stupid mechanic did not have he used light taps from a hammer which is wrong but more than an year they are still great. And yes I had the thump before and if your differential mounts are broken, then your car will make a loud noise from your rear when going over potholes as if something is broken in the back and is very noticeable noise.

For removing the differential the whole rear lower suspension had to be opened and driveshaft needed to be disconnected which easily took about 1 hour or so as a group of people were working on it with me complaining but they were just arrogant and annoyed me and I objected the hammer thing too, but if one person is working then it will take longer. And plus they had power tools and my car was a high height. Plus the differential is very heavy as I think more than 50 kg and near the vicinity of 80 kg or so as they were moaning when they had to hold it.... it was just priceless to what they did!

Well there are 2 differential mount cushions and two upper mount stopper which are also in the same price range so I would recommend changing them all while you are there just to be safe. I just replaced the mount cushions the two big black in the rear in the pic and not the others and should have done it but have purchased them but since they are still ok at 150k but slightly loose, I just didnt do the job again and pay more money for it.

With the cushions changed the differential became tighter as my car was slipping too much when broken and it brought it back under control

Best of luck and hope your problem is resolved."