Twitchy steering 35is - Update now FIXED!

The tire wear can be ok but the tracking can still be out causing the problems you mention so dont discount it just because the tires look evenly worn.

Do you ski at all? I think Its a good analogy. If you go along with your skis dead straight, parallel, every small bump will push a ski off course. You have to concentrate real hard to not fall and stay in a straight line. If you point the tips a little inwards, at the front, you have more direction stability and are more comfortable.

Does sound like it could be the run "work of the devil" flats that could be the problem though.
 
The only time mine got a bit twitchy was after I had 2 new rear tyres fited (18"). Seemed a bit vauge at speed going into corners! After a few hundred miles it all settled down again. Perfect now.
 
Gargybloke said:
Do you ski at all? I think Its a good analogy. If you go along with your skis dead straight, parallel, every small bump will push a ski off course. You have to concentrate real hard to not fall and stay in a straight line. If you point the tips a little inwards, at the front, you have more direction stability and are more comfortable.
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Great analogy - I've not heard it put like that before :)

I used to run toe-out (non-standard settings) on the front of a FWD hot-hatch: turn-in to corners was amazing but it did demand more effort/concentration on the motorway due to less direction stability (to use the terms above). That could be the issue with jelmok's Z4 - simple alignment issue. Like others have said, I'd start there as shouldn't cost more than £80 for a 4-wheel alignment. If not then I'm sure Birds will have a £££ solution - I've heard they can do wonders with the 1-series chassis setup so guess they could transform any Z4 equally.
 
I'd start there as shouldn't cost more than £80 for a 4-wheel alignment. If not then I'm sure Birds will have a £££ solution
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I'm hoping it's the former rather than the latter given I've just forked out for the car!! Curious about Breaker's comment about the two new rear tyres - I know mine had two new rear tyres as part of the AUC - so it could be something as simple as that!
 
I'd be more concerned about you not noticing the wheel firm up in sport settings.

Sounds to me there is a problem with the electric steering as you really do notice the wheel firm up once you select sport.
 
Hey all,

Quick update and things aren't any better. Firstly a better description of the problem - basically when driving on a motorway at constant speed, car is great and tracks straight and true. However if you accelerate, it pulls right, and then when you come off the accelerator, it pulls left! Gets so bad that if you take your hands off the steering when it's running straight and accelerate, you end up in the right hand lane, then if you slow down, you pull into the left lane. Gets very unnerving especially as you are constantly trying to compensate.

Had the car at the dealer and had a KDS performed at their expense. Rear was slightly out, and they have fixed it, but it's no better. I even changed the car from run flats onto new Continentals and double checked pressures, but still not right.

At a loss now, dealer has raised a case with BMW technical, but are telling me it maybe torque steer and a possible characteristic of the car. This doesn't sound right at all to me. Any other thoughts? Could it be the power steering? Dealer reckons everything else seems normal?

Thanks for any help.
 
im no expert, but the symptoms sound like torque steer, but that is usually a problem on FWD cars. Ive not heard of it on RWD cars. i don't know if it is possible to have torque steer on RWD?
 
I'd have the dealer check the suspension again. That is either camber of the road or damage to a suspension bush imho
 
I know - its not like I am really pressing on when it happens either. Just a small amount of acceleration or deceleration is enough???!!!
 
Well what ever the dealer says it does not happen to my Z even at very high speed. In fact it is so steady that I hardly feel a need to hold the steering wheel.
 
jelmok said:
Hey all,

Quick update and things aren't any better. Firstly a better description of the problem - basically when driving on a motorway at constant speed, car is great and tracks straight and true. However if you accelerate, it pulls right, and then when you come off the accelerator, it pulls left! Gets so bad that if you take your hands off the steering when it's running straight and accelerate, you end up in the right hand lane, then if you slow down, you pull into the left lane. Gets very unnerving especially as you are constantly trying to compensate.

Had the car at the dealer and had a KDS performed at their expense. Rear was slightly out, and they have fixed it, but it's no better. I even changed the car from run flats onto new Continentals and double checked pressures, but still not right.

At a loss now, dealer has raised a case with BMW technical, but are telling me it maybe torque steer and a possible characteristic of the car. This doesn't sound right at all to me. Any other thoughts? Could it be the power steering? Dealer reckons everything else seems normal?

Thanks for any help.
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jelmok,

I am watching your post with great interest (and concern) as I have a 35is on order and the last thing I want is a $72K car that will "twitch" as it goes down the highway and then have the dealer tell me that "it's normal."

My question is whether your dealer is familiar with this vehicle? I have an E38 750iL and have to service my vehicle at a dealer in another town because my local dealer has no one with any experience or knowledge of the vehicle. Sure they can "try" to work on my car, but it is such a rare vehicle it isn't worth the risk. I'd rather take it 65 miles down the road to a dealer that has an experienced technician familiar with the V12.
 
dhplachy said:
jelmok said:
Hey all,

Quick update and things aren't any better. Firstly a better description of the problem - basically when driving on a motorway at constant speed, car is great and tracks straight and true. However if you accelerate, it pulls right, and then when you come off the accelerator, it pulls left! Gets so bad that if you take your hands off the steering when it's running straight and accelerate, you end up in the right hand lane, then if you slow down, you pull into the left lane. Gets very unnerving especially as you are constantly trying to compensate.

Had the car at the dealer and had a KDS performed at their expense. Rear was slightly out, and they have fixed it, but it's no better. I even changed the car from run flats onto new Continentals and double checked pressures, but still not right.

At a loss now, dealer has raised a case with BMW technical, but are telling me it maybe torque steer and a possible characteristic of the car. This doesn't sound right at all to me. Any other thoughts? Could it be the power steering? Dealer reckons everything else seems normal?

Thanks for any help.
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jelmok,

I am watching your post with great interest (and concern) as I have a 35is on order and the last thing I want is a $72K car that will "twitch" as it goes down the highway and then have the dealer tell me that "it's normal."

My question is whether your dealer is familiar with this vehicle? I have an E38 750iL and have to service my vehicle at a dealer in another town because my local dealer has no one with any experience or knowledge of the vehicle. Sure they can "try" to work on my car, but it is such a rare vehicle it isn't worth the risk. I'd rather take it 65 miles down the road to a dealer that has an experienced technician familiar with the V12.
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Yes - I know what you mean. I really didn't expect the car to do this at all (who would?), and didn't notice it on the test drive. Although I bought the car from a smaller dealer out of town, it is being looked at by a large main dealer in Central London, who I would have thought would have experience with this model.

I wouldn't worry too much about your order just yet - based on what others on the board are telling me (and my gut instinct) this is not normal behaviour, and there must be a fault somewhere that just hasn't been tracked down yet. At least that's what I am hoping....
 
Jelmok I would definitely have the techs take a look at the steering/suspension linkages as that torque steer effect should not be happening on a rwd car, some slight deviation under acceleration yes but not lane to lane action. I'm too looking to switch to non run flats as I really don't think they suit the Z, just need to find some rims.

Hope it's all sorted out soon for you.
 
I've heard a tyre dealer I know say that once you take the run flats off, the car is all over the place, and very slippery when driven....am sure this may compound the problem if the run flats are off.

You're still welcome to try mine, drop me a PM
 
Nickm said:
I've heard a tyre dealer I know say that once you take the run flats off, the car is all over the place, and very slippery when driven....am sure this may compound the problem if the run flats are off.

You're still welcome to try mine, drop me a PM
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Strange I'd have thought a more advanced compound would help improve handling characteristics. I've also thought of de-sizing and going with 18's to get more rubber under the arches.
 
I think the key here is that the car was designed/setup to use run flats.

Change that and the way the car was set up changes. The question as to whether better would be subjective to the owner.

As per the original topic however, OP I'd have the dealer check all the steering sensors, there are many. Also the actual steering processing unit as this applies steering torque for centring etc and if theres something wrong here the car can exhibit some very odd steering characteristics. There's a defined BMW process for the reset of this system also.
 
OP, my old Z was a 35iS and there wasn't any twitchy steering at all

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Maniac said:
I think the key here is that the car was designed/setup to use run flats.

Change that and the way the car was set up changes. The question as to whether better would be subjective to the owner.

As per the original topic however, OP I'd have the dealer check all the steering sensors, there are many. Also the actual steering processing unit as this applies steering torque for centring etc and if theres something wrong here the car can exhibit some very odd steering characteristics. There's a defined BMW process for the reset of this system also.
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Considering the sheer amount of drivers who have switched to non run flats across the BMW range I'd say there's a lot of proof out there that the handling characteristics are vastly improved. Be interesting to find out the differences in steering geometry BMW apply to cars fitted with run flats and those without. :)
 
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