4C Steering geometry - Page 33 - Alfa Romeo 4C Forums
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post #321 of 325 (permalink) Old 01-04-2017, 07:46 PM
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Originally Posted by Call me Al View Post
You pose an Interesting trade off question! On a road course does a car spend more time cornering than braking? I would say yes but not a whole lot. And transversely if a car can brake better it doesn't need to corner as well. Hum!

Here's a question for you: which is scarier pushing it in corners or pushing it in braking? I think most people would say braking. But I think I'd rather go off the course going straight than going sideways!!

If a car is spending more time going straight or braking, then I'd say it's not going as fast as it can. The straights merely connect the corners. The fastest cars I know that run my local track at otherworldly lap times (like LMP type GT cars) actually don't brake at all for a couple corners which you'd never catch me dead not stomping on my brake pedal.

As for your other question, I'd say cornering is scarier but that's the most exhilarating part of track driving and why we do it Having a soft brake pedal can be scary too, but you can always write off the corner if push comes to shove and just keep braking most straight until you're under control. Being mid-corner and realizing that that extra few mph of entry speed is the difference between 9/10ths or 11/10ths - now that's scary.
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post #322 of 325 (permalink) Old 01-04-2017, 08:01 PM
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4C Steering geometry

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Originally Posted by heelntoe View Post
Being mid-corner and realizing that that extra few mph of entry speed is the difference between 9/10ths or 11/10ths - now that's scary.

Not braking in turns, I can't do that at the road course either but I just did that a couple weeks ago.... at the go kart track!! The operator said it was impossible to go around the track at full speed ha!! I applied my newly made up term of "drift braking" and went around the track with the gas pedal floored several times.

Regarding real cars at a real track in your scenario, almost magically trail braking at the same speed could turn that 11/10ths back into 9/10ths with it's unnatural massive grip it puts on the front tires by compressing the suspension. It's almost like aerodynamics, something you can't see but it's there.

And going into that turn at that higher than natural speed knowing full well that if you don't properly apply trail braking that you're going too fast for that corner and that you will definitely fly off the corner.....that's what's a bit scary to me. It combines the fears of under braking and over turning in one event.

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Last edited by Call me Al; 01-04-2017 at 08:08 PM.
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post #323 of 325 (permalink) Old 04-17-2017, 05:54 AM
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I spent the time in reading all these posts related to geometry settings. I don't own a 4C yet but I played with geometry settings a lot on my current car and I currently have camber = -3.5 grd
I looked at alfa OEM geometry values and to me the TOE looks too open --> this would determine a tendency to turn with a minimal steering adjustment but I don't think it behaves that well in the bends nor straight lines. Probably the tires would wear on the inside in some cases.

Anyway, below are my findings so far with geometry settings on my current car and some may apply in alfa's case too:
1) Adding camber drastically improves the handling in bends. For an alfa driven only on the roads I would go with a setup with -1.5 to -2 grd of camber. TOE should be adjusted to generate even wear on tires + confidence when turning and high grip when turning. FORGET ABOUT OEM TOE RECOMMENDED VALUE!!!
2) As Jamie said before: I would first adjust the car geometry to make it behave properly before adding a suspension. A proper geometry can make huge improvements in performance and worth any penny invested.
3) I would try to find a proper alignment service. Those with laser adjustments (sometimes called 3d - 4d - ... are designed for fast adjustments (to make more cars in a certain amount of time) and sometimes the level of deviation accepted is not ok.
4) Did anyone here modified the geometry (TOE to be precise) before fitting Jamie's blocks? --> Like making the TOE closer to 0 grd? I am confident that even without Jamies blocks a proper TOE value can improve the car a lot.
5) In any case (see point 4) in the end I would still buy the blocks and tune the car to behave like it should (after all is a 900 Kg CF chassis that should destroy on the bends any car).
6) Tire wear --> Even with high values of camber if you properly adjust the TOE, the tire wear will be uniform. Basically: in the bends you need to keep the entire surface of the tire on the pavement because this will generate grip. The harder you take the turn the bigger the tendency of the wheel to lean --> The negative values for the camber basically cancel the wheel leaning when taking a turn.
7) Did anyone tried some really sticky tires with this car? Like slicks or federal fz 201 ? How does it behave ?

Ultimately, even though I understand that Jamie provides a "new value" for TOE different from OEM and tested by him, I would recommend for those who alter the camber to also make a few visits to an alignment center and modify the TOE value. Start with the recommended one and add / remove ~0.05 grd just to see what happens and maybe improve the handling.

PS: I'm anxious to buy an 4C and do all this tests myself
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post #324 of 325 (permalink) Old 04-17-2017, 03:03 PM
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Originally Posted by cipsony View Post
I spent the time in reading all these posts related to geometry settings. I don't own a 4C yet but I played with geometry settings a lot on my current car and I currently have camber = -3.5 grd
I looked at alfa OEM geometry values and to me the TOE looks too open --> this would determine a tendency to turn with a minimal steering adjustment but I don't think it behaves that well in the bends nor straight lines. Probably the tires would wear on the inside in some cases.

Anyway, below are my findings so far with geometry settings on my current car and some may apply in alfa's case too:
1) Adding camber drastically improves the handling in bends. For an alfa driven only on the roads I would go with a setup with -1.5 to -2 grd of camber. TOE should be adjusted to generate even wear on tires + confidence when turning and high grip when turning. FORGET ABOUT OEM TOE RECOMMENDED VALUE!!!
2) As Jamie said before: I would first adjust the car geometry to make it behave properly before adding a suspension. A proper geometry can make huge improvements in performance and worth any penny invested.
3) I would try to find a proper alignment service. Those with laser adjustments (sometimes called 3d - 4d - ... are designed for fast adjustments (to make more cars in a certain amount of time) and sometimes the level of deviation accepted is not ok.
4) Did anyone here modified the geometry (TOE to be precise) before fitting Jamie's blocks? --> Like making the TOE closer to 0 grd? I am confident that even without Jamies blocks a proper TOE value can improve the car a lot.
5) In any case (see point 4) in the end I would still buy the blocks and tune the car to behave like it should (after all is a 900 Kg CF chassis that should destroy on the bends any car).
6) Tire wear --> Even with high values of camber if you properly adjust the TOE, the tire wear will be uniform. Basically: in the bends you need to keep the entire surface of the tire on the pavement because this will generate grip. The harder you take the turn the bigger the tendency of the wheel to lean --> The negative values for the camber basically cancel the wheel leaning when taking a turn.
7) Did anyone tried some really sticky tires with this car? Like slicks or federal fz 201 ? How does it behave ?

Ultimately, even though I understand that Jamie provides a "new value" for TOE different from OEM and tested by him, I would recommend for those who alter the camber to also make a few visits to an alignment center and modify the TOE value. Start with the recommended one and add / remove ~0.05 grd just to see what happens and maybe improve the handling.

PS: I'm anxious to buy an 4C and do all this tests myself
Good point(s).

What is 'grd'?

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post #325 of 325 (permalink) Old 04-18-2017, 05:15 PM
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grd = degrees
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