18" Tramline? (17" Better?)

Dean-Z4 · Post by **Dean-Z4** » Wed Jan 18, 2012 7:34 pm

Hi, I know it may have been covered the "tramline" issues. I recently went through issues after fitting some 18" Alloys from the standard 17" Oem BMW wheels.

I stated getting steering issues, pulling and completley lossing it`s Mojo! I replaced both front- lower bushes. New wishbone arm, as n/s balljoint needed replacing.
"Great" I thought, getting there. She will be back to a superb drive.
I was wrong; still tramlining (not as bad mind) but still not like the car I knew.
So I spent a further fortune on having a four wheel alignment done. Garage advised it is perfectly aligned and balanced. The mechaninc could feel no movements in the steering/suspension parts, everything solid at the front!
However he did comment on the fact that 18"s with wide tyres fitted on a Z4 will tramline. I would be better going back to 17"s the car will behave in a better manner?

After alignment; car felt different in some ways. Still tramlining (offcourse) Feels a bit wobbly now at high speeds (lawful), less sturdy...
I`m lost...is it really down to 18"s?

Ps, I have Continental Contact 3 on the rear 255/35/18 and 225/40/18 fronts- non runflats...natrually!
Can somebody agree with this?

Should I try going back to 17" with non-stagared setup.

Adamski · Post by **Adamski** » Wed Jan 18, 2012 7:48 pm

18s will tramline to an extent. If you are using run flats the problem is usually made worse.

Swapping to a narrower tyre or wheel will help. If it really bothers you this may be the only option. Personally I think it adds character to the car, and I'm happy to live with it. Each to their own though....

andysat · Post by **andysat** » Wed Jan 18, 2012 8:31 pm

Adamski wrote:18s will tramline to an extent. If you are using run flats the problem is usually made worse.

Swapping to a narrower tyre or wheel will help. If it really bothers you this may be the only option. Personally I think it adds character to the car, and I'm happy to live with it. Each to their own though....

+1

Dean-Z4 · Post by **Dean-Z4** » Wed Jan 18, 2012 8:42 pm

fairplay to both your comments.
I know what you mean. I think I will live with it, especially after just fitting a new set of £300+ Contis on the rear!

Might consider a strutbar? One worked great on my old MINI R53 S

I changed to 17"s from 16"s in my recent car- BMW 120d didn`t find any tramlining. The Z is just a different beast I guess! Love it "daily"

Cool Z4 · Post by **Cool Z4** » Wed Jan 18, 2012 8:52 pm

I got a similiar problem, but with 17"s. Was all fine till i replaced the rears with same style of tire I already had on. Now the fronts tramline like crazy. I just deal with it.

RCT_Z4Coupe · Post by **RCT_Z4Coupe** » Wed Jan 18, 2012 9:17 pm

Dropping the tyre pressures made a significant difference to the way my car tramlined and the overall ride. Now run 32/35 psi (as opposed to the 33/39 BMW recommend on the door sticker). Still going to ditch the runflats as soon as I can though

billygilly · Post by **billygilly** » Wed Jan 18, 2012 9:28 pm

Mercedes benz were pretty interested by the z4 tramline issue and had their engineers look into it and apparently they said it was design for the track and that the rear tyres are toed in for better cornering but unfortunately on normal roads it also causes tramlining

Adamski · Post by **Adamski** » Wed Jan 18, 2012 9:31 pm

billygilly wrote:Mercedes benz were pretty interested by the z4 tramline issue and had their engineers look into it and apparently they said it was design for the track and that the rear tyres are toed in for better cornering but unfortunately on normal roads it also causes tramlining

Was this not on M sport suspension models only?

Normal suspension will tramline on 18s with RFTs. But M sport suspension will make it more apparent IIRC

Sent from my iPhone using Tapatalk

Dean-Z4 · Post by **Dean-Z4** » Wed Jan 18, 2012 10:01 pm

It just seems weird. I dont think I noticed it with 17" Wheels, or maybe just not as much.
Has anybody fitted a strutbar?... Do you notice any difference?

Alot of people seem to eradicate 90% of tramlining with an official 4-wheel alignment...maybe my ocd is catching me up

Bing · Post by **Bing** » Wed Jan 18, 2012 11:05 pm

I found the 'ghost in the steering column' quite unnerving when I got mine too - Sport suspension and 18" run flats. My last car was FWD with 18" non-RFTs and it always felt planted. Reading a few threads on here reassured me, and I gradually got used to it by feeling my way past it - hard to describe, but kind of like when you learn to drive you're worried about everything right in front of you, even at high speed, then gradually you just learn to look further and further ahead without actually doing too much. I think the natural reaction to unfamiliar movement is to try and correct it, which makes it worse as you overcompensate, then overcompensate again... And so on until it gets uncomfortable because of the effort. I just consciously relaxed my grip and my shoulders a little (something I picked up on a track day) and allowed it to happen, eventually it bothered me much less.

Of course now I have 17" non-staggered, non-run-flat tyres on for winter and te change is dramatic - not going to ditch 18s, but I will definitely ditch the RFTs when I put them back on, and get an alignment done too.

JonZ4G · Post by **JonZ4G** » Wed Jan 18, 2012 11:46 pm

I also have 18" and M Sport suspension. Even on motorways, especially the truck grooved inside lane I get tramlining.

I compare this to mountain biking in an odd sort of way...going slowly (and this is not an advert for going fast) but if you just ride through it, you're fine.
If you think about it too much (and if you slow down on a Mountain bike), it makes you more nervous.

Trust the car and keep both hands on the wheel - You're driving a high performance sports car!

Jembo · Post by **Jembo** » Thu Jan 19, 2012 1:06 am

Had similar issue - power flexing the frond AND rear left it 99% tramlines proof

If ur in Kent r welcome to try difference

a11y · Post by **a11y** » Thu Jan 19, 2012 8:43 am

billygilly wrote:Mercedes benz were pretty interested by the z4 tramline issue and had their engineers look into it and apparently they said it was design for the track and that the rear tyres are toed in for better cornering but unfortunately on normal roads it also causes tramlining

Yep, that's what I heard too - not necessarily designed purely for track but certainly a suspension set up that suits track/smooth surfaces better. See here: http://www.z4-forum.com/forum/viewtopic ... ry#p176365

a11y wrote:I was reading back over an old evo magazine report on their long-term 3.0i Z4 that they ran on their long-term fleet for almost a year, and came across this:

"the Z4 seemed to wander from bump-to-bump, sending confusing messages to the driver as to what was really going on. It felt like an advanced form of tramlining and became christened the 'Thrill of Writhing' in the office. At first I thought it had to be the fault of the standard run-flat tyres, so after the Z4's disappointing performance at last year's eCOTY (063), we swapped the Bridgestones (having covered 11,000 miles, they were around 60 per cent worn) for a set of Vredestein Ultracs. The initial ride coarseness certainly improved on the Ultracs, while wet grip was transformed. But even so, the Z4 never felt really relaxed unless the road was glassy smooth.

The real culprit was finally revealed on the Mercedes SLK launch last month. Mercedes brought in a Z4 for evaluation during the SLK's development and had noticed the same strange chassis behaviour that we'd experienced. After putting the car on a chassis rig, the explanation seemed to be a noticeable change in rear toe angle when the Z4's rear suspension moved up and down, meaning it would start to 'steer' from the rear on undulations. Now, increased toe-in on compression is great on track as it tucks the car into the apex, killing understeer in the process, but pretty useless on our lumpy roads as the change in toe angle can cause the constant wandering we'd experienced as the rear wheels steered their own independent course to the fronts."

I've highlighted the intersting bit (to me!) in bold. It sounds like it's the geometry setup of the Z4's suspension/chassis that causes the Z4 to be sensitive to bumps. I'd describe it as "lively" handling if you're tanking along lumpy A/B-roads, and find it somewhat limits your speed even at lower-than-the-speed-limit speeds.

Now, I'm wondering if there's any parts of the suspension that could be changed to give a change in the suspension behaviour, and remove or reduce this change in rear toe angle under load? Possibly a question for folks of the likes of Curtis perhaps but does anyone know about this?

Cheers
Ally

Adamski · Post by **Adamski** » Thu Jan 19, 2012 1:40 pm

a11y - you have winter pram wheels. Do you notice any improvement or reduction in tramlining with the 16s fitted?

Mr Whippy · Post by **Mr Whippy** » Thu Jan 19, 2012 2:45 pm

My Z4 doesn't tramline at all, it generally goes where you point it and resists cambers quite well. It does get in a bit of a fit in lorry grooves in L1 on the motorway though, but again, the cambers there will catch any car out I think.

It did 'move' around a lot on the RFT though... but that is something else I guess?!

Dave

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