UK LC500 - Clunking noise

mattarazi · January 20

Had a clunking noise from what sounds like the rear for a while (months), it definitely seems to be getting worse. Seems difficult to isolate - mainly when starting/stopping, but also on turns and when going over kerbs etc.

Had one dealer say it's loose brakes and normal. Another says it's body flex and they need to strip down to locate.

I would love to know if other LC500 owners have any knowledge of this - is it normal/not normal?

Brian R · January 21

I'm pretty sure I can help you with this. I can tell you straight away, this is almost certainly to do with the body brace that runs across the car and situated under the rear seats. Essentially, it might need tightening or just possibly, shall we say, a little more intervention. Take it back to the dealer and advise that Lexus HQ are aware of this problem and assuming you have the benefit of the "Relax" warranty, they will fix this foc. Do not be fobbed off by your dealer because this is known about and will be covered by Lexus.

The following photographs hopefully gives some insight as to where this brace is situated and as mentioned it runs across the car. If you can sense the noise is coming from the rear passenger seat on the offside, then it is that side that needs investigating. Obviously if the nearside then that's where the problem is. Conceivably it could be both sides but it is usually offside.

More than happy to provide further details if you pm me.

mattarazi · January 21

Thankyou so much for this, very helpful and have PM'd you!

shapiro · January 21

Out of curiosity, what’s the assumed root cause?

Brian R · January 22

9 hours ago, shapiro said:

Out of curiosity, what’s the assumed root cause?

The brace runs across the car from B pillar to B pillar. The connection to the B pillar(s) is by a "floating" attachment that tightens the two elements as the brace bolts are nipped up. However, sometimes (albeit it very rarely) no amount of tightening is sufficient and there is very slight movement in the attachment technique which in turn allows flex in the body resulting in a click or knock noise under certain loading circumstances.

Flytvr · February 3

On 1/20/2024 at 3:30 PM, mattarazi said:

Had a clunking noise from what sounds like the rear for a while (months), it definitely seems to be getting worse. Seems difficult to isolate - mainly when starting/stopping, but also on turns and when going over kerbs etc.

Had one dealer say it's loose brakes and normal. Another says it's body flex and they need to strip down to locate.

I would love to know if other LC500 owners have any knowledge of this - is it normal/not normal?

I've encountered this with several LCs.

Just be warned that Lexus tend to fix it and the noise returns.

Hopefully the attached will help.

mattarazi · February 3

10 minutes ago, Flytvr said:

I've encountered this with several LCs.

Just be warned that Lexus tend to fix it and the noise returns.

Hopefully the attached will help.

Thankyou! Car is with dealers now, I will post an update when a solution to my specific issue is found, so others can check this out.

Flytvr · February 3

6 minutes ago, mattarazi said:

Thankyou! Car is with dealers now, I will post an update when a solution to my specific issue is found, so others can check this out.

Let's hope they fix it for you - it's the sort of thing that can drive you POTTY!

Brian R · February 3

26 minutes ago, Flytvr said:

Let's hope they fix it for you - it's the sort of thing that can drive you POTTY!

You're right, it can and does drive you potty! The noise can appear to originate from the offside but can also manifest itself from the nearside, albeit the former tends to be more usual.

BTW, well done for getting hold of the "TSB" which I believe was created by Lexus Australia!

shapiro · February 3

Can you describe the noise? Is it a metallic “clunk”. A single one off sound when it flexes?

Flytvr · February 3

8 hours ago, shapiro said:

Can you describe the noise? Is it a metallic “clunk”. A single one off sound when it flexes?

Generally when you pull off and come to stop. A single clunk. Once it happens it won't happen again until you do the opposite motion i.e stop or start.

shapiro · February 3

Okay I’ve had this too. But it’s completely gone now. I thought it may have been the transmission acting up as you say it was when you pull off or coming to a stop. Lexus looked at it and could not replicate it.

It’s not happened in over 6 months now.

It didn’t manifest during any other scenario.

mattarazi · February 27

Update on this; it's taken nearly 5 weeks to resolve but seems to be fixed now.

Diagnosed as driveshafts - replaced (took 3 weeks to arrive from Japan, fair enough). Noise better but still audible.

Replaced axle bushes. Noise better, again, but still audible.

Finally, whilst recording for submission to Lexus UK for advice, the source of the remaining noise was found to be - the strut brace, as originally posted. Tightened and - for now - no noises.

shapiro · February 27

Fantastic and thank you for the update. Was your car still in warranty? Or part of the Lexus relax warranty?

Sorry if you’ve shared this already.

mattarazi · February 27

It was under warranty (used approved), as well as Relax being in place.

Flytvr · March 3

More and more cars seem to be suffering with this - here and over in the US.

The tightening fix only seems to fix it for a while.......

eightk · March 9

On 3/3/2024 at 10:15 PM, Flytvr said:

More and more cars seem to be suffering with this - here and over in the US.

The tightening fix only seems to fix it for a while.......

If they’ve forked out for a pair of driveshafts and some axle bushes and paid the dealer to fit them before realising it was a known problem anyway I’d hope they’ll see sense and come up with a better solution than greasing and nipping some bolts up. Who knows, they could even fix the canbus vulnerability while they’re in there…

Flytvr · July 12

Several dealers and lots and lot and lots of hours, it looks like Lexus UK have come up with a solution. Using this solution, my dealer believes they have fixed the problem - once and for all.

I’ll give the car a thorough testing over the weekend and report back!