Strange juddering sensation

[Ala Larj]

Hi all,

When I reverse out of my drive and turn into the road I get a strange juddering sensation through the steering as if the wheels are slipping. Doers anyone else get this or have any idea what is causing it?

Thanks,
Alan

[stevet]

Probably just the angle of the steering geometry on full lock causing the tyres to judder on the road. Normally it does it just when the tyres are cold and hard. Quite normal and nothing to worry about.

[Ala Larj]

Thanks Steve, that's reassuring. It sounds like something is about to break!

[AmbroseJohn]

Mine does it too. I got the geometry checked by Lexus but the say it's OK.

I'd thought about restricting the amount of lock because I wouldn't have thought it would do the suspension components much good.

It's probably done like this, so Lexus can advertise a smaller turning circle, than is actually practical.   

[NemesisUK]

Very common on Mercedes 4Matic models and is due to IIRC the Akerman(?) angle. MB's response is to offer winter tyres.

I've noticed a slight judder/knock on extreme lock but only on cold tyres when turning 'enthusiastically' in my RC. Not really an issue 

[Upex]

Mine didn't do this at all (park in same place, using full lock to swing in and out every day), until i changed the lower ball joints, then was real bad until had tracking alignment done, got a lot better then, but still happens a touch now, although they didn't do great job as my steering wheel not 100% straight, despite a repeat visit and adjustment to tracking shop. It's straight to the stalks, when wipers 1 click down in auto lol, so looks balanced at top, off at bottom lol

[AmbroseJohn]

1 hour ago, NemesisUK said:

Very common on Mercedes 4Matic models and is due to IIRC the Akerman(?) angle. MB's response is to offer winter tyres.

I've noticed a slight judder/knock on extreme lock but only on cold tyres when turning 'enthusiastically' in my RC. Not really an issue 

Mine does it winter and summer.

[Ace8800]

I have recently experienced the exact same on my GS300h.. does it on turning only both forward or reverse. I thought my wheel was loose, or might be a issue with the 19" tyres. But its good to know its nothing to worry about might get it checked out as its still under warranty. 

[Ala Larj]

8 hours ago, Ace8800 said:

 might get it checked out as its still under warranty. 

If you do I'd be interested to see what they say as mine's still under warranty too.

[Guest]

My is and now RC do it as I reverse off my drive as I have to go full lock in reverse and the road is lower than the drive so the front right wheel skids a bit. Bear in mind your rear wheels are pointing straight back and the 2 front wheels are trying to curve 2 different arcs while being pulled sideways at the extremes of the range.  

[AmbroseJohn]

8 minutes ago, Comedian said:

My is and now RC do it as I reverse off my drive as I have to go full lock in reverse and the road is lower than the drive so the front right wheel skids a bit. Bear in mind your rear wheels are pointing straight back and the 2 front wheels are trying to curve 2 different arcs while being pulled sideways at the extremes of the range.  

Which is true for all makes and models but I've never had a car that has done it before.

[Ala Larj]

18 minutes ago, AmbroseJohn said:

Which is true for all makes and models but I've never had a car that has done it before.

Ditto!

[NemesisUK]

As wheels get bigger and tyres get thinner this will be more common.

Does the car on 16" wheels still do it?

[Guest]

1 hour ago, AmbroseJohn said:

Which is true for all makes and models but I've never had a car that has done it before.

Maybe they use different linkage systems and geometry between makes and models...... or do you suppose all makes and models have identical steering systems?

You have a situation where the 4 corners of the car are moving at 4 different velocities, this is true in any turn and the steering has to cope with that but at full lock it's the most extreme variation possible. I haven't done the maths or looked too deeply because, well, it's not an issue. 

If you're worried - go and have the geometry checked at a tyre centre or Lexus. It will still do it though.

 

[AmbroseJohn]

21 minutes ago, Comedian said:

Maybe they use different linkage systems and geometry between makes and models...... or do you suppose all makes and models have identical steering systems?

You have a situation where the 4 corners of the car are moving at 4 different velocities, this is true in any turn and the steering has to cope with that but at full lock it's the most extreme variation possible. I haven't done the maths or looked too deeply because, well, it's not an issue. 

If you're worried - go and have the geometry checked at a tyre centre or Lexus. It will still do it though.

 

Correct, all manufacturers have different designs. What we're realising, from this thread, is the Lexus design seems to be a poor one.

I sometimes think we should put away our rose tinted spectacles and be realistic.

[NemesisUK]

4 minutes ago, AmbroseJohn said:

What we're realising, from this thread, is the Lexus design seems to be a poor one

No, what we are realising from this thread is that with the very low profile tyres and colder weather, we are noticing this 'characteristic' (as Mercedes Benz describe it  ) at extreme lock.

There is no 'poor' design with regard to Lexus or MB come to that.

[Ala Larj]

Thanks for all the comments and really interesting. It seems that it's 'normal'. If so then my concern is if it is doing any damage at all?

[Guest]

50 minutes ago, AmbroseJohn said:

Correct, all manufacturers have different designs. What we're realising, from this thread, is the Lexus design seems to be a poor one.

I sometimes think we should put away our rose tinted spectacles and be realistic.

You say "we're realising" but I suspect what you really mean is "I am realising"  although how you're realising a design flaw based on anecdotal evidence is beyond me.

The only glasses I have are x-ray ones I ordered from the back of Viz. Rose tinted doesn't work on me. I'm a technician. 

 

[NemesisUK]

25 minutes ago, Ala Larj said:

Thanks for all the comments and really interesting. It seems that it's 'normal'. If so then my concern is if it is doing any damage at all?

Most of the movement is in the tyre itself. Flexing then snapping back, which what one tends to hear and feel.

This video of the same thing on a Merc GLC, You can see the tyre deform. Thankfully my experience with the RC is no way as bad,,,

 

 

[AmbroseJohn]

1 hour ago, Comedian said:

You say "we're realising" but I suspect what you really mean is "I am realising"  although how you're realising a design flaw based on anecdotal evidence is beyond me.

The only glasses I have are x-ray ones I ordered from the back of Viz. Rose tinted doesn't work on me. I'm a technician. 

 

The evidence is, it would appear that we're experiencing a problem and because Lexus say it's normal, we should all be happy but I'm not.

My BMW with the same size tyres didn't do it. My Corvette with 285/30/19 tires (Lower and wider) didn't do it.

And if we're bragging about qualifications, I'm an Aeronautical Engineer.

[Big Rat]

All the info one needs to know about this is by simply googling Ackerman Steering geometry and all will be revealed.

Perfectly normal........... I won't go into vehicle related qualifications this page isn't big enough 

Big Rat

[Ala Larj]

I've got an 'O' Level in English!

[NemesisUK]

51 minutes ago, Big Rat said:

I won't go into vehicle related qualifications this page isn't big enough

Write smaller, or use a continuation sheet? 

[Guest]

1 hour ago, AmbroseJohn said:

 

And if we're bragging about qualifications, I'm an Aeronautical Engineer.

I wasn't bragging, I was making a light hearted joke about rose tinted glasses. Technicians are grumpy about everything engineers design don't you know?

I've worked with lots of aeronautical engineers. Where did you do your degree? 

 

[Guest]

17 minutes ago, Ala Larj said:

I've got an 'O' Level in English!

I haven't!