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First of all change tyres to Michelin Pilot Super sports. You’re running the18/19” wheel stagger so no problem there. The Pirellis seem to exacerbate the tramlining effect. I’ve used Rudi Gales’ Street Specs. No idea of the castor specs but have added a bit more negative camber (now -1.7 deg each side) at the front to counter understeer while going to zero toe instead of toe-out. Less tramlining but not eliminated. I’m currently on Hankook R-S4 rubber 215/45x17 front, 235/40x18 rear. My front tyres seem to be wearing more evenly now too.
It’s very important that specs both sides are exactly the same. Some here seem to have accepted alignment specs that differ slightly left and right. Not good. Our cars are very sensitive to spec changes. I’ve also got uniball bushes that tighten up the rear so standard rear toe-in (40’ each side) might be better for stability without these. Specs posted below..
Those values are toe open for track and zero toe for street. Problem solved: none is toe in so tramline is still present.
 

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So far on this forum I so many geometry sheets: most of them were toe open or toe zero. I did't see any toe in (similar to a usual car). I am not bothered by tramlining but some are, yet apparently no one actually tried to go really TOE IN like 15 minutes per side. I bet that such a value would cure the tramlining completely and will remove out of the equation the tires, pressures or whatever element that really can't do much.
If one wants to drive with 250 on the highway then go TOE IN 15 minutes per side (or 30 mins in total).
I would like to see a geometry sheet with such values and the owner's feedback.
 

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Those values are toe open for track and zero toe for street. Problem solved: none is toe in so tramline is still present.
Yes, but I don’t want to deaden the steering. What I have now is great for the roads I frequent. I had slight toe-in set with Pirelli P-Zero ARs. Toe-in I’ve found reduces slightly turn-in precision. Still tramlined and there was an annoying understeer when driving enthusiastically. Now, at the road speeds I drive, it’s pretty damned good.
I went zero toe and added front negative camber and find it a good compromise.
 

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Things like changing the tires or pressures to cure the tramlining... Common! There is no physical explanation for such suppositions. It's just a minor change in feeling and a major placebo effect. These tramlining issues are not present on other cars because they are all TOE IN on the front (10, 15, 20... minutes per side) and not because all other car brands are using michelin tires.
 

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Yes, but I don’t want to deaden the steering. What I have now is great for the roads I frequent. I had slight toe-in set with Pirelli P-Zero ARS. Toe-in I’ve found reduces slightly turn-in precision. Still tramlined and there was an annoying understeer when driving enthusiastically. Now, at the road speeds I drive, it’s pretty damned good.
I went zero toe and added front negative camber and find it a good compromise.
It's not your case. But there are some that just want the look of the 4c and the behavior of a porsche. They should use TOE IN and not change the tires, uniballs, front blocks or the collor of the car :)
 

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You can't isolate toe in. Most other cars have more caster too. My Miata has 7 degrees. The 4C has what? 2 degrees? Caster makes the tires resist turning. When going forward that is. Caster makes the steering wheel feel like it wants to stay on center, and return strongly to center from a turn. Conversely, caster deadens turn in.

Seems pretty clear that some like what others dislike. I'm imagining that if I drove some of these killer cars, I'd say "this is perfect."

If I had a car trying to kill me... to where I wouldn't even drive in the fast lane... that car would be gone in a heartbeat.

These threads have been going on for four years. It just gets silly.
 

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It’s all a compromise. You improve one aspect to the detriment of another. Arriving at the best compromise is a personal thing. I believe I’ve found one I’m satisfied with.
Just don’t aim to completely eliminate the tramlining and steering kick when hitting a bump in the road. It’s part of the character of the thing.
 

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So 1mm toe-in on the front either side + intermediate blocks. Only a half a degree of front negative camber. How does enthusiastic cornering feel? Do you feel you have to turn the wheel a little more for the same line into a corner?( A little more indirect?). How is front tyre wear? Is the inside of the tyre wearing evenly with outside? (Assuming you regularly find twisting roads on which to drive)
Thanks. This data will be helpful for others with same issue as yourself.
 

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FWIW I adjusted my toe to an even 0. It helped significantly although, as philster pointed out, it doesn’t help much on roads with severe tire indentations in the asphalt. But on everyday roads I found it helped dramatically. A simple solution for me. But having said that, in the interest of full disclosure, I’m no track racer and I know less than nothing about technical track driving etc. It just feels more stable in a straight line. So take mine with a grain of salt
 

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Discussion Starter · #31 ·
So 1mm toe-in on the front either side + intermediate blocks. Only a half a degree of front negative camber. How does enthusiastic cornering feel? Do you feel you have to turn the wheel a little more for the same line into a corner?( A little more indirect?). How is front tyre wear? Is the inside of the tyre wearing evenly with outside? (Assuming you regularly find twisting roads on which to drive)
Thanks. This data will be helpful for others with same issue as yourself.
0.5° was horrible on track, it under steered like a pig just thinking about increasing throttle to above "neutral" around 2/3 out of a curve. So fun spoiled.

On enthusiastic driving it was not that horrible, as throttle often is in neutral trough the curve, when you "hit it", curve is usually more or less finished. But if you increased throttle mid curve, it started to under steer.

That said, it was relatively safe for less experienced driver, if it under steered and you "chicken out" and decreased throttle again, it would bite into curve again. If you totally let go of throttle, it would over steer, so not totally fool proof.

When I changed to Michelin, there was plenty left on front tires, so not that easy to spot, but looked quite thoroughly, and it was even over the whole surface. Rear had surprisingly even wear as well.

I have now changed to AW Race spec to increase camber. The two top spacers is decreased:
Upper front: 3mm
Upper rear: 4.3mm
Steering rod adjusted: approx 3mm.
Are not sure what this will translate into. Have not had professional alignment check yet. Regarding 3mm decrease of steering rod, we measured toe as good as we could before and after, and 3mm gave approx same toe, maybe slightly less toe in:
Before: 4mm total(compared to 2mm in the old pro alignment check)
After: 2mm total

Increasing camber made a huge positive difference exiting curve.
 

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Discussion Starter · #32 · (Edited)
If I (try to)convert 1mm toe into degrees[°]:
18" = 457.2mm (18 x 25,4mm)
sin angle = toe/ rim diameter = 1mm/457.2mm = 0.003888
sinh(0.003888) = 0.0022°

Is this the same as 0°20? I originally interpreted it as 0.2°.... Or are my numbers/calculation wrong?

@Gale

Top tip: to get °, use Alt+0176
 

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Discussion Starter · #33 ·
If I (try to)convert 1mm toe into degrees[°]:
18" = 457.2mm (18 x 25,4mm)
sin angle = toe/ rim diameter = 1mm/457.2mm = 0.003888
sinh(0.003888) = 0.0022°

Is this the same as 0°20? I originally interpreted it as 0.2°.... Or are my numbers/calculation wrong?

@Gale

Top tip: to get °, use Alt+0176
OK, I think I found how to do it, numbers seemingly add up:

1. Multiply rim diameter in inches by 25.4 to get rim diameter in mm.
2. Multiply the result by PI to get the circumference.
3. Divide the result by 360 to get mm per degree.
4. Divide the toe mm by the mm/degree result to get toe in decimal degrees
So for me(Front):
1. 18" = 457.2mm (18 x 25,4mm)
2. 457.2 x 3.14159265 = 1436.33612
3. 1436.33612 / 360 = 3.98982
4. 1mm / 3.98982 = 0°251
 

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Discussion Starter · #36 ·
An update.
Race AW blocks increased camber from -0.5 to a bit over -1.6°. Followed @Gale recommendations -ish, adjusted to street +. Toe is parallel in front, and +0.9mm each side rear if memory serves me right. No time to increase rear camber, so thats unchanged at approx. -1.7°. Rear 2x20mm spacer used during alignment, not according to normal procedure, but seems like it did not make big difference(?).

Parallel front toe made steering slightly more agile/direct, as expected, but tramlining is still no problem. Since this is a very subjective thing, I'll try to give an example; Say that I want to put on my phone on charging, using both hands, I can use my knee to hold the wheel for shorter periods, without being afraid(but alert!). Its far from a "flying carpet", but its no problem to cruise with one hand on wheel.

At track, the camber was a revolution. After last alignment, involving rear toe, I had a time of approx 1min46, no ECU tuning, two people in car, and Michelin Pilot Sport 4 original dimension, in other word a street tire. A heavily track modified 4C (Pogea tuning, wide semislics, all unnecessary parts removed, light battery, race seats and steering wheel ++) with a better driver does it in 1min38 if I'm correct. So very respectable time for my car.

And regarding MPS4, yes, they are far better than the OEM Pirellis. More comfort, but can take more at track for those occasions where you did not bother to put your trackday tires on. You can actually have some fun. Quite rare, I was positively surprised.
 

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Discussion Starter · #37 ·
I made a mistake, its
2x15mm NOT 2x20mm!!!!!!!!!

I ordered spacers with 20 screws. For some reason, that translated to 20mm spacer in my head. Sorry for the bad info, first post updated.
 

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Discussion Starter · #38 ·
So far on this forum I so many geometry sheets: most of them were toe open or toe zero. I did't see any toe in (similar to a usual car). I am not bothered by tramlining but some are, yet apparently no one actually tried to go really TOE IN like 15 minutes per side. I bet that such a value would cure the tramlining completely and will remove out of the equation the tires, pressures or whatever element that really can't do much.
If one wants to drive with 250 on the highway then go TOE IN 15 minutes per side (or 30 mins in total).
I would like to see a geometry sheet with such values and the owner's feedback.
I noticed that I did not answer this directly.

I had 1mm+ toe in at both sides(total 2mm) together with AW intermediate blocks, it unfortunately did not cure tramlining. I never tried without AW blocks, so I cannot say how car was bone stock, but if it was a lot worse, I cannot imagine any would like to buy the car.
 

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Not all the same. My stock car does not have a tramlining issue. Drive at 75mph on freeway with my lower thighs when I open a bottle of water. Never checked to see what alignment settings are because it has not been a big issue.

No handling issues at COTA at 130+ either.

Jeff
 

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Discussion Starter · #40 ·
I do not understand "Not all the same"?

But yes, it must be quite a lot difference between the cars, however it seems that you are one of the lucky guys, good for you. If you run 17/18" thats a big difference/advantage as well. Unfortunately, 18/19" combo is how mine was delivered, even my trackday 17/18" semi slicks are more comfortable than OEM 18/19".

So for us not so lucky guys, 2x15mm spacer is worth testing out to resolve tramlining. Honesty, I've been wondering about removing AW blocks(decrease caster) and see how OEM with rear spacer works, might be perfect for me.
 
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