Lexus is300h vibrations when at 40 and 70 mph

maxj0 · August 5

Hi,

I’ve a 2020 is300h which vibrates when at 40 and 70+ mph. I’ve had all 4 wheels balanced twice. I’ve had the alignment checked twice. I’ve had the tyres and alloys check to make sure that they are actually round (not just balanced). I’ve had the car in at a main Lexus dealership for a full service where they’ve checked the car over and replaced the diff oil. Apparently the Lexus software update (referenced on old posts to this forum) is not available to apply to this year of manufacture.

But the car still vibrates. It’s not unsafe, just really annoying on the motorway. And I guess I’m looking out for it more too.

What do you advise? Feels like a power train ‘resonance’ to me.

The rest of the car is super but this is so annoying.

Pauly C · August 5

27 minutes ago, maxj0 said:

Hi,

I’ve a 2020 is300h which vibrates when at 40 and 70+ mph. I’ve had all 4 wheels balanced twice. I’ve had the alignment checked twice. I’ve had the tyres and alloys check to make sure that they are actually round (not just balanced). I’ve had the car in at a main Lexus dealership for a full service where they’ve checked the car over and replaced the diff oil. Apparently the Lexus software update (referenced on old posts to this forum) is not available to apply to this year of manufacture.

But the car still vibrates. It’s not unsafe, just really annoying on the motorway. And I guess I’m looking out for it more too.

What do you advise? Feels like a power train ‘resonance’ to me.

The rest of the car is super but this is so annoying.

Interesting....although I'm not going to suggest any kind of a 'fix' 'cos I just picked my 250h up today from the 'local' Lexus dealer. What I was going to say is, whilst I'm not sure how pronounced your vibration is, I thought I detected something similar on mine, just below 70, on the test drive. It seemed to kick in whilst I was gently accelerating. The drive home was pretty perfect and it's probably me, and mine being an F Sport - it may well have been the lumpy road I was feeling through the slightly firmer set up. I will shut up now and let the experts on this forum chime in with some proper sage advice😄

IS300FSPORT · August 5

If I had to guess it's either a bad wheel bearing in which case you will hear a rumbling sound & it gets louder as you drive.

Or potentially a failing sticking brake caliper or slider pins causing the pads to stick to the disc as you build up speed it is applying a brake on the impacted side potentially causing a vibration through your steering.

An obvious check is ensure your wheel nuts are torqued correctly I really hope they are not loose. & check there isn't a small stone or rock stuck in your tyre treads (unlikely).

cdmaskell · August 5

Prop shaft balance, worn U/J’s or centre bearing?

Notamech · August 5

This one can be hard to diagnose if you've already done balancing and have ruled out the tyre being out of round. Out of curiosity how did they make sure your tyres are not out of round? If the vibration is at certain speeds only it does infact sound like a balancing issue. I had this on a previous car and no one was able to diagnose it too in the end i took a punt and just got new branded tyres to replace the cheap ones the dealer put on it. Fixed the issue for me. If your tyres are cheap chinese ones they're most likely out of round.

Chris111 · August 5

I had a similar issue with my previous GS 450H and the problem was traced to the fact that both the prop shaft centre bearing and offside rear wheel bearing had failed.

Bounce75 · August 5

As Colin has already mentioned, I would check the prop shaft as I had this on an old rear wheel drive Escort.

ColinBarber · August 6

17 hours ago, maxj0 said:

Apparently the Lexus software update (referenced on old posts to this forum) is not available to apply to this year of manufacture.

It would already be incorporated into the software that is loaded at the factory, and the damper that was retrofitted should have been introduced/design out in the facelift model so I feel you have a different issue - the old vibration issue occurred around 1,300 rpm so as soon as you changed your cruising speed by 2 mph the issue went away.

I'd try and borrow a set of wheels just to test. You wouldn't be the first person to have had wheel balance and roundness checked but there was still a problem.

What's the mileage on your vehicle. Seems too young for an issue with the prop bearings.

maxj0 · August 8

Really helpful, thanks everyone. I’ll try a different set of tyres first. Fingers crossed.

Jon Dee · August 9

Have some time on my hands, so had a read of this thread and then looked up a few other similar threads, as resonance in rotating systems is a bit of an interest of mine 🙂 There are several recurring themes in the threads... vibration at specific engine speeds or road speeds, vibration at low engine speeds (ca 1300 rpm), changing tyres usually has no effect, dealership reluctance to acknowledge that there is a "fixable" problem etc.

The IS300h uses the 2AR-FSE 2.5 lire 4-cylinder inline engine that has two counter-rotating balance shafts to smooth the inherent out of balance forces of a 4-cylinder IL engine. The 2AR-FSE engine design and management prioritises emission and fuel economy over performance. Thus the engine is required to operate very efficiently at low rpm resulting in a low power stroke count versus 6 or 8-cylinder engines at similar rpm.

A flexible rubber disc coupling (guibo) is provided in the propeller shaft to smooth out the engine pulsations, and in a manual transmission car this would be the first place I would look when trouble shooting vibrations at specific engine/road speeds. However, with an auto trans the torque converter should de-couple the drive train unless it is locked up. Lockup is controlled by the ECU, and given the design objectives for this engine, it would not surprise me if the trans was locking up at low speed/low load operation.

If a slight nudge of the throttle results in an increase in engine speed and a reduction in vibration, with no appreciable change in road speed, that would indicate that the engine had been lugging (trans locked up) at low rpm. Vibration at higher speeds is likely to be torsional resonance in the drive train when two rotating components start fighting each other via the flexibility of the guibo (sorry, can't think of the correct terminology just now... something to do with harmonics).

Adding mass to a structural member was/is an interesting way of addressing this problem, but if the differential is bolted to the chassis, and the vibration is being transferred into the body of the car by this route, then someone a lot smarter than me had a think about it 😄

Cheers...

Notamech · August 9

8 hours ago, Jon Dee said:

Have some time on my hands, so had a read of this thread and then looked up a few other similar threads, as resonance in rotating systems is a bit of an interest of mine 🙂 There are several recurring themes in the threads... vibration at specific engine speeds or road speeds, vibration at low engine speeds (ca 1300 rpm), changing tyres usually has no effect, dealership reluctance to acknowledge that there is a "fixable" problem etc.

The IS300h uses the 2AR-FSE 2.5 lire 4-cylinder inline engine that has two counter-rotating balance shafts to smooth the inherent out of balance forces of a 4-cylinder IL engine. The 2AR-FSE engine design and management prioritises emission and fuel economy over performance. Thus the engine is required to operate very efficiently at low rpm resulting in a low power stroke count versus 6 or 8-cylinder engines at similar rpm.

A flexible rubber disc coupling (guibo) is provided in the propeller shaft to smooth out the engine pulsations, and in a manual transmission car this would be the first place I would look when trouble shooting vibrations at specific engine/road speeds. However, with an auto trans the torque converter should de-couple the drive train unless it is locked up. Lockup is controlled by the ECU, and given the design objectives for this engine, it would not surprise me if the trans was locking up at low speed/low load operation.

If a slight nudge of the throttle results in an increase in engine speed and a reduction in vibration, with no appreciable change in road speed, that would indicate that the engine had been lugging (trans locked up) at low rpm. Vibration at higher speeds is likely to be torsional resonance in the drive train when two rotating components start fighting each other via the flexibility of the guibo (sorry, can't think of the correct terminology just now... something to do with harmonics).

Adding mass to a structural member was/is an interesting way of addressing this problem, but if the differential is bolted to the chassis, and the vibration is being transferred into the body of the car by this route, then someone a lot smarter than me had a think about it 😄

Cheers...

Just FYI the IS 300h does not have a traditional auto gearbox but an e-cvt and hence does not have a torque converter. It has a clutch that looks visually similar to a manual transmission clutch except it is bolted to the flywheel and is permanently "locked" as far as i know. Its function is to only work as a damper rather than a clutch. Especially because whenever the engine is running the transmission is also always spinning. Even if its not outputting power to the wheels its charging the Battery. Heres a full video on how it works.

https://youtu.be/vHc-_E8xWnM?si=mbnjE8pj0xCu2FL1

Jon Dee · August 9

Good point and my bad... was thinking old school trans not eCVT.

And having a look at how the eCVT system works I can see that the optimum engine speed is higher rather than lower so "lugging" is not a factor. The eCVT control computer essentially adjusts the "gear ratio" according to a range of different sensor inputs, and it seems that a software update was implemented (without much success) at one time to try and address the vibration problem.

I'm still of the opinion that the drive train is generating some kind of torsional vibration. If that vibration happens to coincide with the resonant frequency of a connected structural component, then the connected component could amplify the vibration. Adding mass would lower the resonant frequency of the structural component, moving it away from the excitation frequency.

This modification appears to have been effective in multiple cases.

Cheers...

maxj0 · August 20

So… an update… I’ve replaced all four tyres with a new set of Bridgestone Turanza and the 40 mph resonance has all but disappeared. A major win. I’ll keep the car.

However, the 65 to 75 vibration is still there.

wharfhouse · August 20

4 hours ago, maxj0 said:

So… an update… I’ve replaced all four tyres with a new set of Bridgestone Turanza and the 40 mph resonance has all but disappeared. A major win. I’ll keep the car.

However, the 65 to 75 vibration is still there.

Approx 40mph and approx 65mph are generally associated with tyre wheel problems such as imbalance, out of round and bent rims. I had a car with a slightly bent rim and it had a slight shimmy at 65 - 70mph. It's a hard one to pin point though as to which rim. I never changed the wheel and sometimes the MoT mentioned it and sometimes not. I was advised to put the slightly bent rim on the rear as it wouldn't be as noticeable but that was a fwd car so not sure of that holds true for rwd (and of course can't be done if they are staggeree wheels).

Notamech · August 20

6 hours ago, maxj0 said:

So… an update… I’ve replaced all four tyres with a new set of Bridgestone Turanza and the 40 mph resonance has all but disappeared. A major win. I’ll keep the car.

However, the 65 to 75 vibration is still there.

As mentioned above. Could be a problem with the rims themselves. My reco would be to go to a proper professional place that does wheel refurbishment so that they can check and assess if there is a problem. If so you might want to consider repairing your wheels.

Boeryeoes · August 20

Are we sure this is not the vibration for which a mass damper modification was introduced since years ago?

wharfhouse · August 20

23 minutes ago, Boeryeoes said:

Are we sure this is not the vibration for which a mass damper modification was introduced since years ago?

I believe that only affected older models - OP had a facelift 2020 so this should not be the issue.

maxj0 · August 23

OK. Off to a wheel specialist next then…

and the Lexus garage confirmed that the damper and software patch were not appplicable to my 2020 MY car.

Jon Dee · August 23

A recent development in wheel balancing is Road Force Balancing....

This is claimed to correct some "difficult to correct" wheel induced vibrations.

There is also "on the car" balancing that operates in a somewhat similar manner, but has the benefit of balancing the whole rotating assembly. I have stood beside a car while the wheel was run up to a decent speed with the car was supported on a floor jack and the wheel left hanging just off the floor. The front wing started to vibrate very noticeably at two different speeds when the wheel out of balance vibration matched the one of the resonant frequencies of the wing.

Variations of on the car balancers have been around for many years, and if all else fails you might be able to find a garage with one to spin your wheels up and check for vibration. Note that the guy in this video puts his hand on the vehicle... he has obviously been doing this for a while.

Cheers...

Inazone · August 23

On 8/20/2024 at 3:18 PM, Boeryeoes said:

Are we sure this is not the vibration for which a mass damper modification was introduced since years ago?

Hi there, when was this introduced as I have a low down vibration? Is there a recall?

ColinBarber · August 23

7 minutes ago, Inazone said:

Is there a recall?

No, there was a TSB if an owner complained which would be investigated under warranty. I doubt you could get it retrofitted now, even if you paid, and it didn't completely resolve the issue.

There are a number of reasons for the cause of a vibration though - it would be worth getting your vehicle checked out to make sure you don't have any other issue such as a mounting or bearing with wear.

Inazone · August 23

The low down vibration only appears when the engine RPM is around 1500, above or below this and it's fine. Ok so no recall but I should be able to retro fit the damper myself.

Paul29 · August 27

I don’t have an answer for you, but just wanted to share that I had 4 alignments done in 4 separate places recently. Only in the 4th place did they solve the fact that my car was driving like a shopping trolley drifting all over the road. The majority of these alignment places either haven’t a clue what they’re doing or else are using Commodore 64 software.

maxj0 · September 17

I'm pleased to say that I've sorted my problems eventually. I had all 4 wheels balanced on a road force balancer. Two of the wheels needed the tyres rotating on the wheel and much less weights added in the end. The car is now so smooth at all speeds. I'll never balance another way again. Thanks for the advice everyone.