Rmlexus

In the spring of ‘22 I replaced rear shocks on my wife’s 2015 RX 350 after oil change shop stated one ( LR ) was leaking…
since replacement,
I hear a metallic rattle similar to metal on metal during low speed travel over small bumps or variations in street..
This noise is consistent and static movement that appears to also occur during steeper inclines or normal twisting of body and suspension in slow turns.
I have replaced the sway bar links in an effort to correct but no improvement…
I removed the rock guards from the coil springs as a test, but noise is still present.
So I took the rx to a Local repair shop that specializes in lexus vehicles..This shop spent two days listening and examining parts including:
replace and swap shocks in an attempt to resolve..Still no success.
Finally the shop gave up and conceded that they did not know where the noise was coming from.
so…This annoying rattle remains in tact..
This “rattle” or bumping sounds as if it is in the LR 1/4 panel OR in the lower suspension when driving.
Last, the RX doesn’t appear to have the same ride in regard to smooth transition over normal bumps …it appears to be choppy and bouncy in rear.
Complete brakes front and rear since they were due at 90,000 miles..

If anyone has had similar problem, please jump in with suggestions or whom to contact for assistance.
Thank You!
RM

Clutchless

Did they check the parking brakes that are inside the rear rotor? Something may have fallen apart.
Did they check the rear trailing arms and other bushings? Known wear areas.
Has it been in an accident?
What brand rear shocks did they install? Usually KYB are the aftermarket choice.
Check the spare tires and tools inside the rear hatch for loose stuff?
The rear seat is also a known rattle area (shove towels in to stop movement), same with rear hatch cover. (remove it )
Remove the interior L/R panel and check if the subwoofer is broken or loose as it is back there.
What air pressure are you running in the tires?

Madcar

If the Lexus shop is unable to identify, it might be because nothing is mechanically wrong -
It could simply be the result of the new shocks being stiffer and something non-mechanical is rattles around (as per @Clutchless post).

Rmlexus

I will explore LR panel and seat posts..No accidents, spare tire tools are secure..Will look also at the remaining suspension bushings etc…thank you for the hints!

Sweeks2020

I believe that the genuine rear shocks are reasonably priced for the RX350
Each side is approximately $60

richelieu

Hey, let me tell you different story but the meaning is the same...

RX450, 2012, air suspension plus shocks. 100K miles. I decided to replace small rear shocks and used parts.lexus.com page to check proper and correct rear shocks. I get the PN for thisbspecific GYL15 model with air suspension and ordered it...

When I removed the original shock the PN was different and the original one was shorter. Neverthless I have installed the ones but the drivig was terrible.

I decided to proceed double check with partsouq.com website and here there was a different PN - in the end the correct one. So I ordered second pair of shocks. Out it to car and now it is perfect...

So my advise is to check what PN you have on car and what PN you have now...

I was crazy about it.
marek

Clutchless

That is not really an issue in the US because almost nobody has the air suspension. With the regular suspension whether F-Sport or Base, all of the struts and shocks are the same length.

cookie4u

Check the bushings on the rear control arms.

Mine were shot as well as the shocks. Rattling went away after I swapped them out.

ft1980

I'm with cookie4u. I'm guessing it's a bushing or something simple or silly. Sorry if this was already suggested and I'm repeating other responses, but did you check all heat shields, panels, car plate, etc.? Check all bushings, even sway bar bushings.

Rmlexus

To: Clutchless, Madcar, richelieu, Coolie4u....
Thank you for your efforts to assist me with the evasive rear suspension noise.
I have found, from a Certified Lexus technician, that the KYB replacement shocks are actually to wide at the upper eyelet that secures the top of the shock to its upper base, a triangular mount just above the rear wheels and outside the inner wheel shirt.
This created a metal to metal wear area that also created the annoying tapping or clicking over slower speed terrain.
It was literally right in front of me ( and several qualified maintenance personnel ) ..the OEM shocks are less wide and immediately silenced the noise.
I question KYB's engineering now after two decades of using their products. Perhaps it is a fluke?..but we used KYB replacement shocks more than once in an attempt to rectify the issue..ALL were defective..
BEWARE KYB replacement shocks for the 3rd Gen RX 350.
Regards,
Rmlexus

RX in NC

Yet another reason to go with Bilstein (assuming you can find them and actually get them within a reasonable timeframe)....

Sweeks2020

And not the genuine lexus shocks?

Clutchless

The OEM Lexus shocks & struts are from (I meant to write Tokico) not Toshiba. Their handling and ride quality is far worse than that provided by Bilstein. Toyota/Lexus should reconsider their oem suppliers but I doubt they will dump a Japanese company for a German company.

Sweeks2020

I thought Tokico and KYB made Toyota's shocks

Any recommended website to purchase Bilsteins for the RX?

MattRX

The genuine Lexus shocks are mediocre at best and are priced accordingly I think. My original ones on my 2014 rode horribly and had poor damping. Tokico made them on my RX. I think KYB might not make an OEM part for this car, although my Highlander had them.

The Bilsteins shocks are monotube and still find a way to be more comfortable than the stock (at least F-Sport) twintube OEMs. You can feel it working throughout its range and it stiffening up when you push it harder, whereas the OEM one felt like a linear pogostick in comparison.

I got mine on Rockauto, but they may be out of stock there.