Sudden increase in tramlining...why?

[mancini_mark]

Hi guys,

What would cause a sudden increase in tramlining? I've got 17" wheels with 235/45 Kumho's all around. Tire pressire is 38 psi all around. I've recently rebuilt the entire front end..tie rods, control arms, etc. The subframe bushings and dogbones were done last year. Plus, I've had an alignment last month.

Any ideas?

Mark

[moots]

Hi guys,

What would cause a sudden increase in tramlining? I've got 17" wheels with 235/45 Kumho's all around. Tire pressire is 38 psi all around. I've recently rebuilt the entire front end..tie rods, control arms, etc. The subframe bushings and dogbones were done last year. Plus, I've had an alignment last month.

Any ideas?

Mark

How far have the Kumhos covered?From my experiences,some tyres start to tramline after 50% tread wear.Do they wear evenly?I would try swapping the tyres around and see.I also have the same size tyres on e39 m5 replicas.

[George M]

good question...I would be sure to check the front end alignment (toe) which can have some effect on bump steer/tramlining. Presume you torqued your front suspension bushings with the car set at normal drive height as well.
Aside from the tires as Moots mentioned, a tough call with all the good changes you have made. Tramlining can be influenced also fractionally by worn center tie-rod/idler arm or less than solid connection of pitman arm to the steering box which will compromise control of the front wheels by the steering box hence making the car tend to follow road inconsistencies more. Heavier knock off's with stiffer tire side wall and wider tread width will always tramline more than a stock wheel/tire combo.
Good Luck,
George

[henryw525i]

I recently got absolutely fed up with the tram linning I was getting with my Yokohama AVID 306's I had 17x8 wheels running 235/45 on front and 255/40 on the rear.

I got so sick of it I just had to ditch the rears and put the yokos on the back and went and put some new ContiSport Contact II 235/45 on the front. And the change was HUGE! I still get tram lining but not nearly as much.

Like you I have had all my front end bushed replaced recently and just aligned with 0.01 degree of toe in. I have deduced that bald tyres track more, wide tyres on small width rims create problems, and the quality of the tyre matters aswell

Hope you sort it out, coz it really does get to you!

[mancini_mark]

Hi guys,

I forgot to mention that the tires are almost new. I only drove on them one month last summer before the snows went back on. I did tighten the control arms under load too.

That said, when I did the centre rod/drag link and idler arm, I didn't touch the pitman arm at all. Consensus was that there was nothing really to wear out there? But maybe it can be tightened?

What do you think?

Mark

[George M]

check angular displacement of pitman arm with the drag link/center tie rod static with someone up top slightly rotating the steering wheel side to side on center with you under the car. If there is noticeable steering wheel rotation without the drag link moving then likely you either have a loose steering box out of adjustment or the pitman arm is loose at the steering box. A loose pinch bolt will accelerate wear of the male splined steering box output shaft at the connection to the pitman.
The pinch bolt on the pitman arm can work loose. Some as a further hedge against the pitman working loose...put a bead of weld between the pitman arm female hole and end of the steering box output shaft. The road wheels because of their connection through the tie rods to the center link with proper alignment/dialed in toe are typically self centering by design using the suspension's caster...again by design to be resilient to tramlining independent of how solid the connection is to the steering box....but only to a degree as the steering box adds a further measure of stability to the steering system...so worth a look.
George