Motorway speeds and steering

[Smokin]

In would like to add that since RFT's have a thicker sidewall, they tend to flex less, leading to the tramlining.

No, not leading TO tramlining, but exacerbating it. My 325Ci with 17" wheels, nonstagger, non-RFTs would tramline just as bad as my Z does. Took me by surprise the first time, but then noticed it almost always happened on one single stretch of road. (still does)

 

[a11y]

Well, I'm certainly blaming the RFTs.

Although this is only based on one 60-mile drive on my newly fitted non-RFTs, it was on roads I drive very frequently - a mix of motorway, A-road, town driving and a B-road blast. Tramlining almost non-existant now, still pulls around a bit in lane 1 on the motorway but that's largely down to the f**ked road surface (heavy trucks leaving Grangemouth refinery).

 

[cj10jeeper]

All very true of tramlining the 'how and why' and it's relative decrease when changing tyres.

This is actually nothing to do with the issue that Chillz and myself have been referring to and the initial post.

Tramlining is in simple terms the tyres picking up roughness in the surface, wheel ruts, etc. and pulling to one side or the other. I get it on the Zed on our rutted dual and motorways.

The issue we both appear to have is at speed on smooth surfaces the steering wheel moving left to right constantly in tiny amounts. That I have yet to bottom out if it is steering geometry or EPS related. Changing tyres, lowering pressures has reduced, but not alleviated it.

 

[ell_p]

i had had my fair share of trammling in my 3.0si, sometimes going down the motorway especially in bad weather seems like a bit of a death trap even at 60mph.

I really dont rate those bridgestones RFT, bmw should of put a better quality tyre on, i have the Michelin PS2's now and I would say it has cured 95% of this.

 

[gannet]

i had had my fair share of trammling in my 3.0si, sometimes going down the motorway especially in bad weather seems like a bit of a death trap even at 60mph.

I really dont rate those bridgestones RFT, bmw should of put a better quality tyre on, i have the Michelin PS2's now and I would say it has cured 95% of this.

+1 I dont get ANY tramlining anymore

 

[Smokin]

Jeeper--I never notice what you two are describing at speed. However, I *do* occasionally experience a twitch back and forth when stopped at a light if the wheels are turned just a tick. Very small movements, but if you have your hand resting on the steering wheel, you'll notice it. I would have to chalk it up to the EPS. Do you notice it more with sport mode on or off?

 

[ChillZ4]

I think I am goin to ditch the runflats for falkens 452s. I have had the steering etc checked and no problems found.

 

[cj10jeeper]

Jeeper--I never notice what you two are describing at speed. However, I *do* occasionally experience a twitch back and forth when stopped at a light if the wheels are turned just a tick. Very small movements, but if you have your hand resting on the steering wheel, you'll notice it. I would have to chalk it up to the EPS. Do you notice it more with sport mode on or off?

Smokin - sorry - I missed your post. Sport does not make much difference probably since it reduces at speed anyway. I need to do some more geometry work and that 's down to when I can get to the specialist to set it up and road test. Last time we had to abort due to ice and snow. :thumbsdown:

 

[oliver.brace]

Mine used to do it all the time with stock ROF tyres i think this is due to the re-enforced side walls on the Tyre, I have since changed to a set of Toyo Proxes r888 and they are simply fantastic highly recommended!!

 

[ChillZ4]

UPDATE - fitted 452s today and the tramlining etc has been significantly reduced. Problem sorted!

 

[cj10jeeper]

UPDATE - fitted 452s today and the tramlining etc has been significantly reduced. Problem sorted!

Mine is booked in for its full geo set up and some road testing by guys who know how to make a Bimmer handle. Scheduled for a couple of weeks time having gone through various experimentations with tyres and wanted to wait until I had finished changing wheels, rotors and various other bits.

Falkens and tyre pressures did a lot to mask but not eliminate a specific problem.

 

[ChillZ4]

Update - went out this morning and the problem seems to be as bad as ever even on the falkens. Going to start experminenting with tyre pressure. Car is booked in for next week to have it all looked at.

 

[Smokin]

If it is the same RFT to non-rft, the alignment is definitely suspect.

Also, are you having the same effect on the same roads? There is one stretch I drive that even made my 325 tramline and it never had rfts.

 

[ChillZ4]

Update again. The ride comfort seems to have detiorated in the last few days, suspecting bushes. Car is booked in tomorrow. I would describe this problem as becoming dangerous!

 

[cj10jeeper]

Update again. The ride comfort seems to have detiorated in the last few days, suspecting bushes. Car is booked in tomorrow. I would describe this problem as becoming dangerous!

I assume you've checked the obvious of tight wheel nuts, etc.? Bushes deteriorating tends to be really gradual, however perhaps after the change of tyres you have heightened awareness.

Mine finally goes in tomorrow for it's full set up. Will report back. Downside is I have to spend half a day in Daventry. Starbucks here I come....

 

[ChillZ4]

Car has just come from the garage and they have said the issue with the steering etc is due to the car not having runflat tyres!!! I have heard it all now!

 

[cj10jeeper]

Well a bit of an update on mine.
It spent several hours in the workshop having the geo set up today.

Firstly the good news is that a top guy on geometry and Bimmers could feel the problem, knew it was wrong, not tramloning, etc. and set about fixing it That's a big step from claims of tyres, pressures, wrong something or other...

In the end increasing the toe out to closer to the limits has vastly improved the performance, but we're not there yet...

One potential problem is that the mounting brackets (part 5) at the back of the wishbone (part 8 ) has more movement than they believe it should have and the next step is going to be to replace them. http://www.realoem.com/bmw/showparts.do?model=BT52&mospid=47797&btnr=31_0642&hg=31&fg=05

Question - has anyone any experience of wear on this part? Is there an uprated or improved OEM or aftermarket item available?

 

[ChillZ4]

Thats a good start and very interesting, have you noticed a significant inprovement and also what is the garage called?

Thanks

 

[sp3ctre]

Sticky steering only happens in the heat, like where Melbs is, not in the UK at the moment

Not technically true... it happens when you have been driving for quite a while and/or you have the heating on... Mine is a potential death trap when it starts doing it... VERY scary!

 

[cj10jeeper]

Thats a good start and very interesting, have you noticed a significant inprovement and also what is the garage called?

Thanks

As noted in my post 'has vastly improved the performance'

The specialist is Steve Guglielmi of http://www.guglielmimotorsport.co.uk.

He came recommended to me from many sources inc. 2 race drivers who are friends of mine, who's cars he sorts out, but also his years of experience working with BMW's, combined with experience on setting cars up, sold me on the 1 hour drive each way. Seems one guy drove from Aberdeen yesterday to hand his car over for work so he must be trusted.