The last issue I have to tackle with the GS450h is a knocking sound coming from what seems the front wheels and mostly the right wheel. This is when driving over a ditch or uneven road like a cobblestone road.

This issue was present before the RSR down sus springs were installed (i.e. in factory setup) but has since gotten more obvious, probably due to the more rigid suspension. Initially I thought it may have been the brake pads, however when braking harder (beyond regenerative braking system) it remains present. So I think the brakes can be ruled out.

The suspension and wheelsetup have been checked by the Lexus dealer three times now and by a suspension specialist. None of them could find a thing wrong with it.

So I am wondering if any of you know what it may be?

Thanks in advance guys!

 

i had something similar - turned out to be a broken tpms sensor knocking around inside.

 

Have you checked to make sure all the wheels lugs are tight? Our lugs have washers that make a considerable amount of noise when not fully tightened. I had the same annoying problem. When I went to go look and was undoing the lugs, I found the security lug VERY loose. When I spun the wheel, I could reproduce the noise. Once I had it tightened, NO MORE noise. Hope yours is as simple! Good luck!

 

Thanks guys,

The wheels have been on and off a few times. It is also not the same sound and feeling (lose lugs happened to me before).

Also the TPM sensors were changed (new wheels). There was no difference in the knocking experience.

The sound is present when driving over a ditch or bump in the highway, but more so on uneven bumpy roads.

This guy seems to b e giving some good advice for suspension sounds:

 

Like many on this forum I have a slight knock on poor roads in my GS (2003 300 sport). Replaced shox, discs, pads etc. My mechanic can find no wear on bushes, ball joints etc. Had a 190 merc some years back similar annoying knock. Replaced everything at great expense no solution. Turns out that it was the engine mounts were a bit worn, so it might be worth checking out engine transmission mounts on the Lexus. By the way I've had a long line (25 odd years) of Mercs, still have a 190e and a classic 350 slc but as a recent convert to the Lexi, I'm hooked.

 

I had this issue in the rear after doing my springs, and I'd bet it's the same issue: sway bar wasn't torqued properly.

I forgot to torque one of the rear links and the clanking gradually went from slight to annoying.

Sway bar end links must be disconnected during spring/strut/etc install, but MUST be torqued "while under load."
This means

• jack up your car
• remove wheel
• using a second jack, jack suspension assembly back up to where the wheel would be while on the ground
• Sway bar end link bolts should slide in and out of their holes easily and initial tightening of the nut can be done by hand.
• If the assembly is not jacked up, the end links will seem torqued (because everything is crooked) but will loosen up once the car is set back down.
• Torque using a 17mm wrench and an allen-head wrench (I forget the size)
• Lower assembly, remove jack, reinstall wheel and set car on ground

Hope this solves your issue!

 

The car is getting the new coilovers (J5) in a few weeks, I'll let the installer look at these specific issues then.

Anyway, thank you both very much for the info, I'll let you know if this solved the issue.