Hi,

if the bearing is loose/damaged, could that cause a sharp knock sound. I have always tough that if bearing is damaged, the sound is more like humming sound, not sharp knock. Every time I put the Ls400 to D or Reverse, or when leaving from standstill to speed I get this knock from left front suspension. Also garage told me that bearing is damaged in the front left, so do you think these are same or different problem?

[quote name='itarumaa' timestamp='1317311298' post='764226']
Hi,

if the bearing is loose/damaged, could that cause a sharp knock sound. I have always tough that if bearing is damaged, the sound is more like humming sound, not sharp knock. Every time I put the Ls400 to D or Reverse, or when leaving from standstill to speed I get this knock from left front suspension. Also garage told me that bearing is damaged in the front left, so do you think these are same or different problem?
[/quote]

My GS300 brakes had a really annoying, loud rattling sound as well as the droning/humming noise. I knew the bearing on the right was shot, but focusing on the rattling I changed everything - sway bar bushings, droplinks, brake pads etc & the noise continued. My nephew convinced me that both bearings were very bad as he could reproduce the noise with the wheels off the ground by basically thumping the tyre to recreate it hitting a bump. I had them changed (bought bearings for £100 from auto factors, and fitted both sides for £120) and the rattling is gone now.

There is a barely-perceptible 'clunk' remaining when you put the car in gear or reverse or put in a full lock, but I'm going to install a brake fitting kit & hope that really sorts me out.

[quote name='itarumaa' timestamp='1317311298' post='764226']
Hi,

if the bearing is loose/damaged, could that cause a sharp knock sound. I have always tough that if bearing is damaged, the sound is more like humming sound, not sharp knock. Every time I put the Ls400 to D or Reverse, or when leaving from standstill to speed I get this knock from left front suspension. Also garage told me that bearing is damaged in the front left, so do you think these are same or different problem?
[/quote]
Hi
The sound you are getting is consistent with the condition that points to upper control arm wear .If you jack up that wheel just off the ground place a bar at the bottom centre of the tyre and lift inwards ,if the bushings are worn the wheel will have excessive play .
Bearing wear usually as two symptoms One is a clicking sound that increases with the speed of the wheel and a steadily increasing screeching sound as the bearing heads for its eventual failure.
Also there will be play in the wheel but usually more prominent in a side to side movement.

Hi, both upper control arms were changed about 3 moths ago. Also in the front there are new brake pads, discs, both inner tie rods and left tie rod end. Also stabilizer links has been changed.

Also, when the old upper control arms were in awful state (before they were changed), there was not a sound like there is now.

I have asked two garages opinion and both said they do not know what is the cause. But I was adviced that the bearing in the left is damaged, and in this forum I was offered second hand hub (with bearing) for small money, so it is tempting to try this, but I also think that faulty bearing should not cause sound like this.

Thanks for the advice so far:)

[quote name='itarumaa' timestamp='1317472887' post='764303']
Hi, both upper control arms were changed about 3 moths ago. Also in the front there are new brake pads, discs, both inner tie rods and left tie rod end. Also stabilizer links has been changed.

Also, when the old upper control arms were in awful state (before they were changed), there was not a sound like there is now.

I have asked two garages opinion and both said they do not know what is the cause. But I was adviced that the bearing in the left is damaged, and in this forum I was offered second hand hub (with bearing) for small money, so it is tempting to try this, but I also think that faulty bearing should not cause sound like this.

Thanks for the advice so far:)
[/quote]
Hi
By a process of illimination you are finding out what is not the cause of your problem If you had severe wear on the upper control arms this could have caused a knock on effect to other parts of the suspension , check out all moving parts and bushes in the lower arm and its associated parts also check the upper and lower connections of the spring and shock absorber.
If you do go down the road of putting in a new bearing I would advise only lexus genuine parts there is a lot of crap after market bearings out there.

[quote name='itarumaa' timestamp='1317311298' post='764226']
Hi,

if the bearing is loose/damaged, could that cause a sharp knock sound. I have always tough that if bearing is damaged, the sound is more like humming sound, not sharp knock. Every time I put the Ls400 to D or Reverse, or when leaving from standstill to speed I get this knock from left front suspension. Also garage told me that bearing is damaged in the front left, so do you think these are same or different problem?
[/quote]


Try replacing these first.
From PRI Racing.
Toyota - Rear - Differential Pinion Mount Bushes
4 bushes, 2 washers. Upper is replacement bushes, lower is insert to original rubber bushes
Part No. SPF2769K


Baz.

The reason for noise was that upper control arm connection was loose, so now the noise is gone.

There was no need to change bearing after all.