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Well the test drive was great. Wasn't sure what to expect. I can definitely feel the difference much more confidence inspiring. Tramlining would be 80% less in the twisties. Can still feel it at times in the freeway. So not sure if it was the zero toe or the wheel spacers.
You won’t completely eliminate it but it will be reduced to the point that it’s a non-event. I ride motorcycles and the odd twitch of the handlebars is nothing to worry about just like the odd twitch of the 4Cs’ steering wheel, once the zero toe alignment is made. Relax and ride it out.
What you’ve done is tuned in a little more understeer so the steering will seem a little less direct or, as you say, is feeling softer. Add a little more neg camber to reduce this….but you’ll get a little more tramlining….It’s all a compromise. The trick is to find what the best compromise is for you on the tyres you are using. There’s no other way to do this than by trial and error.
 

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Discussion Starter · #63 ·
Well the test drive was great. Wasn't sure what to expect. I can definitely feel the difference much more confidence inspiring. Tramlining would be 80% less in the twisties. Can still feel it at times in the freeway. So not sure if it was the zero toe or the wheel spacers.
Congratulations! I have not tried with spacers and OEM front geometry, so cannot say how much each part does.
 

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Discussion Starter · #64 · (Edited)
What you’ve done is tuned in a little more understeer
Not quite right, initial response is reduced, but when weigh is shifted and car is settled in curve, you get less understeer. No, I did not figure that out myself, but easy to understand when I got it explained. Can give less stability during curve, so as you say, trial and error what you like.
 

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I was reading another post on here regarding the tramlining. The guy had quoted he put spacers in and it cured it. I dont think that was the cure looking back as the spacer were fitted before he bought the car it was more likely steering geometry was set up correctly.
The spacers if anything have created more understeer and i will explain.
When the car is under brakes i do not experience understeer it is very natural. When the car is accelerating though a corner or there is a transition from brake to throttle it understeers.
My thoery is the front is too stiff (valving related). Putting the spacers on the rear will effectively make the rear softer for obvious reasons and in turn increasing understeer. So in summary yes there could be more understeer. At this stage im note sure but if i had to make a call i would say it does under more in certain conditions.
 

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Discussion Starter · #66 · (Edited)
I was reading another post on here regarding the tramlining. The guy had quoted he put spacers in and it cured it. I dont think that was the cure looking back as the spacer were fitted before he bought the car it was more likely steering geometry was set up correctly.
The spacers if anything have created more understeer and i will explain.
When the car is under brakes i do not experience understeer it is very natural. When the car is accelerating though a corner or there is a transition from brake to throttle it understeers.
My thoery is the front is too stiff (valving related). Putting the spacers on the rear will effectively make the rear softer for obvious reasons and in turn increasing understeer. So in summary yes there could be more understeer. At this stage im note sure but if i had to make a call i would say it does under more in certain conditions.
This is (well explained) exactly what I experienced, without and with spacers. Cure to that was to increase front camber from -0.5° to -1.6°(Max I could get, race blocks). But I’ve never tried without spacer and -1.6°. That said, my track wheels, custom made for racing 4C, is basically same ET as OEM wheels with spacers.
 

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Discussion Starter · #69 ·
Was it max 1.6° because of bolt length or you didnt have enough shims?
Bolt length. Edit, I see you have plenty, hopefully reliable numbers, but there can be more than one thing giving the same experience I guess.
Gas Bumper Automotive exterior Rim Fixture
 

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Discussion Starter · #71 ·
Yes, I was shooting for -2°, but it depends on so much more, so for all I know, -1.6° is the sweetspot for me and my car, I don’t know. But I assume -2 to -3° is better for track use, maybe more.
 

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Yes, I was shooting for -2°, but it depends on so much more, so for all I know, -1.6° is the sweetspot for me and my car, I don’t know. But I assume -2 to -3° is better for track use, maybe more.
Not sure what effect the more negative camber will have on the car. From my research its more about tyre wear
 

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When the car is under brakes i do not experience understeer it is very natural. When the car is accelerating though a corner or there is a transition from brake to throttle it understeers.
That is, by definition, just about any rear or mid-rear engine mounted car. When you accelerate, the front gets light and the weight shifts rearward. When the engine is behind you, it makes that issue worse. Some more expensive mid-rear engine cars have anti-squat designs in place to reduce that effect. You might be able to minimize it but the solution for the 4C is really going with a more race focused suspension / coilover setup.
 

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Discussion Starter · #74 ·
Not sure what effect the more negative camber will have on the car. From my research its more about tyre wear
If I got it right, there is two main reasons OEM camber is lower than what a spirited driver like:
1. Safety, slight understeer when close to the limit is considered more safe, therefore slightly less camber at front than rear
2. As you say, tire wear. Compromise towards handling.
 

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Not sure what effect the more negative camber will have on the car. From my research its more about tyre wear
More negative will increase tramlinining as it rides more on the tyre edge the more negative you go. Braking stability will also be reduced for the same reason. It’s all a compromise. I’ve got -1.7 deg front with zero toe and tyre wear is pretty even.
 

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