Intermittent shake at speed

[Daveyboy20]

I had a thread about a vibration/shake but I thought I'd start a new one, as it seems to be intermittent which must surely be specific to something in particular being worn? I've now had the tracking done properly, and I'm making sure the tyre pressures are OK.  Granted- they're probably due a swap but I'd they were causing the issue, surely it wouldn't be intermittent? It seems the steering is now less precise, too. It starts at around 55mph and continues up to 80ish. Sometimes it's so pronounced that you can see my trouser legs shaking! Other times, it's barely noticeable.  This is on the same 12 mile stretch of motorway i use every day.  I'll be honest, it's spoiling my Lexus experience. Having just spent 800 quid on a water pump and cambelt I'm loathe to give up and sell it, yet I don't want to chuck money at maybes! Could it be a worn rack? It's a generally well looked after 126k 98 LS400. 

[NemesisUK]

Wheel balancing, possible buckled wheel(s)? Vibrations felt through the chassis usually to do with rear wheels or suspension.

[Daveyboy20]

It's intermittent though! Comes and goes.

[NemesisUK]

Points to  harmonics two or more vibrations reinforcing and negating one another.

Get the rims inspected check tyres don't have any bulges. Check the suspension bushes. Check the propshaft bearings as well.

[royoftherovers]

8 minutes ago, NemesisUK said:

Points to  harmonics two or more vibrations reinforcing and negating one another.

Get the rims inspected check tyres don't have any bulges. Check the suspension bushes. Check the propshaft bearings as well.

Why showing 39.7 when that figure is not showing on the Fuelly tag Peter ?

[NemesisUK]

28 minutes ago, royoftherovers said:

Why showing 39.7 when that figure is not showing on the Fuelly tag Peter ?

Not sure what tag you're looking at but when I login to fuelly my ave shows as 39.7?

 

[royoftherovers]

53 minutes ago, NemesisUK said:

Not sure what tag you're looking at but when I login to fuelly my ave shows as 39.7?

 

If I click on 39.7 it gives a another set of figures.

[ambermarine]

5 hours ago, Daveyboy20 said:

I had a thread about a vibration/shake but I thought I'd start a new one, as it seems to be intermittent which must surely be specific to something in particular being worn? I've now had the tracking done properly, and I'm making sure the tyre pressures are OK.  Granted- they're probably due a swap but I'd they were causing the issue, surely it wouldn't be intermittent? It seems the steering is now less precise, too. It starts at around 55mph and continues up to 80ish. Sometimes it's so pronounced that you can see my trouser legs shaking! Other times, it's barely noticeable.  This is on the same 12 mile stretch of motorway i use every day.  I'll be honest, it's spoiling my Lexus experience. Having just spent 800 quid on a water pump and cambelt I'm loathe to give up and sell it, yet I don't want to chuck money at maybes! Could it be a worn rack? It's a generally well looked after 126k 98 LS400. 

Points to worn suspension bushes if it comes on at speeds between 50/80 mph

I had this problem around 130k on my Mark 1 ,turned out to be trailing arm, rear bushes but it can occur on front suspension bushes also.

[Malc]

9 hours ago, Daveyboy20 said:

It's a generally well looked after 126k 98 LS400. 

at this mileage you would expect to have already replaced the rear trailing arms if they haven't been done .  check your service history maybe !

might have had a warning / Advisory on the last MOT ( or before ) about this but not necessarily so ..........  it's worth your mechanic checking them out before ordering

Amayama at about £200 each plus a pitta of a job to fit

Lexus UK price about £300 each + fitting

it could be summat else of course 😐

Malc

[NemesisUK]

6 hours ago, royoftherovers said:

If I click on 39.7 it gives a another set of figures.

Ha!, I think it defaults to US units. I clicked on the link and, yes it's 33.1mpg ave. on the website but look top left the units are US, change to UK and you get the 39.7 in my sig link.

[plexus914]

@Daveyboy20

Quote:

"

Posted October 30

I think the thread is a little confusing as there are 2 cars being spoken about..

 

To clarify:

Mine is a '98 LS400

It has had wheels balanced recently, but the tyres are quite old and worn.

It only happens at speed (55-75ish)

High speed braking had a brake pedal judder.

Round town it's fine. 

"

 

 

How old are the tires?

[Cotswold Pete]

On 12/16/2018 at 7:41 AM, Daveyboy20 said:

 it's barely noticeable. 

From my experience the changes like this are caused by tempature changes affecting the stiffness of bushes.

I would have punted on UCA bushes gone or going.  I have same issue, I know it is off-side UCA and some days at 20mph it vibrates, other days it is 50mph, other days it is okay (mainly when it is about 12centigrade and a little damp.  This UCA has been slowly going for about last 20K miles, but now got to point where it needs doing, and I get some weird tramling, which is probably UCA as well.

Brake judder - had issue on my Mk3, that was drop links.

One other thing might be checking tranmission mounts, but I would assume if you get teh vibration and then go into coasting mode, and it is still there, less likely to be transmission mount.

I would get a good indie to have a prod, and not just with a crowbar.   I had a read UCA picked up as MOT failure, but with that one noticed no vibration or impact (as a far as I could tell) on the handling of the car.

As you know it can get expensive repalcing running gear on these motors.

 

[Farqui]

My wife's car recently had speed related noise and vibration that we thought was due to a bad wheel bearing. 

The noise/slight vibes came and went at different speeds.

I couldn't find anything wrong with any bearings/bushes/etc so dropped it into our trusted indi.

He found that it was due to a bad tyre that had gone slightly out of shape.

As you mention the tyres are getting ready for replacement, it might be worth renewing them sooner rather than later.