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Old 11-15-2018, 05:42 PM
  #3121  
fatbillybob
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Originally Posted by ProCoach View Post
One of the things that can effect aero balance even more than mechanical grip is ride height, or rather splitter height. Rake also comes into the equation. But I'm not a car engineer. Just someone well schooled in how to make people believe they can do something they themselves don't believe is possible.
LOL! We have never met but exchanged forum posts. Despite that limited input, You have me all figured out. That skill is probably an important attribute to making you a good coach. I was going to post about your exact last post on rideheight but felt maybe I should first get behind the wheel of an aero car and not get ahead of myself technically. I believe you can make me a believer! One day I hope I will have that chance.
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Old 11-15-2018, 07:12 PM
  #3122  
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Originally Posted by fatbillybob View Post
LOL! We have never met but exchanged forum posts. Despite that limited input, You have me all figured out. That skill is probably an important attribute to making you a good coach. I was going to post about your exact last post on rideheight but felt maybe I should first get behind the wheel of an aero car and not get ahead of myself technically. I believe you can make me a believer! One day I hope I will have that chance.


All the way back to the 348 and FChat dayĺs!
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Old 12-05-2018, 04:34 PM
  #3123  
Skibum1963
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Veloce Raptor,
I ocassionally like to peruse this thread (as it is freaking awesome...) and came across this post from 2011. I am in my third year of racing and still feel like I don't fully understand some of the fundamentals. This post makes me feel like I don't understand anything. What I have been working on with my coach is vision, trying to concentrate on when to lift coming into a corner vs. trying to find a braking point (because I have a tendency to coast a bit), and finding the proper way to rotate a car through the turn. We did some exercises at the track where I used throttle to break loose the rear end a bit to rotate the car. Is this what you are saying in the below post? Because the simple explanation is trail braking rotates the car and more throttle induces understeer. Please help me understand...

Originally Posted by kush07
Please clarify what you are saying here. Are you just making the distinction between steering w/ the wheel vs throttle steer (and trail braking) or is there a larger point I'm missing? How do you define "changing the car's direction" vs. "steer"?


Great question. Yes, pretty much that is the distinction. For example, as you start turning, the front tires are doing the work. What you do next predicates how well the car will work in the corner. In other words, do you keep adding steering because the car is pushing (asking even more from overloaded front tires)? Or do you transition to throttle (even a little bit) to move the center of gravity of the car more to the rear & continue the rotation with the rear tires? I assure you, the latter scenario works a lot better! Many folks don't realize how well a bit of throttle helps the car rotate. They are so worried about oversteer that they miss the boat....and kill the car with understeer.
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Old 12-05-2018, 04:57 PM
  #3124  
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Great question! Sorry for any confusion.

My point was that as you turn in (let's say to the left), most of the mass of the car is on the right front tire...more so if you're trail braking. If you're carrying good entry speed, that tire will at some point run out of available grip and understeer will ensue. Doing nothing at this point pretty much assures your trajectory will freeze where it is, until tire scrub slows the car enough for right front grip to return. When it does, suddenly, oversteer car occur.
The other approach, which I was advocating, would be to got to let's say 20% throttle. This moves a bit of weight off the RF tire and onto both rear tires. Doing this stops the RF from being overwhelmed. When this happens, grip returns, and the car can continue rotating into the apex...which then leads to starting to unwind the wheel and exit with more velocity as you roll on power. Going to 100% immediately would cause the understeer you mention. But just a little bit of throttle doesn't. It's you manipulating weight transfer in order to optimize tire grip

Does this make better sense?
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Old 12-05-2018, 06:19 PM
  #3125  
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It would appear that you saw me driving at Laguna Seca recently.. S**t, I came into the corkscrew too fast on more than one occasion and I think that is exactly what happened every time (the part where the trajectory freezes). My car has red lights to indicate lock up of the front wheels (no ABS) but they are so tiny, sometimes I don't see them. Hard for me to feel when the front tire locks up if it doesn't give off the white plume of noxious gas. In the heat of the moment I keep thinking more trail braking is going to put more pressure on the front tire and give it more grip...Wrong!
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Old 12-08-2018, 10:02 AM
  #3126  
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Lol! Well then...I guess my more detailed explanation makes sense and resonates?
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Old 12-10-2018, 06:20 PM
  #3127  
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Maybe I need to go back to the drift pad and get some feel for when that front tire is getting overwhelmed. It seems my natural instinct is to assume my understeer is lack of weight on the front end. I find this sport so difficult because of the long time (usually 3-4 weeks) between events, making it difficult to retain muscle memory. Thanks for the clarification and thanks to all the coaches who chime in here and help us all to understand car control better.
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Old 12-23-2018, 07:31 PM
  #3128  
Kevin Fennell
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I am starting to pick up the inside front tire now through fast sweepers. I passed someone through 16-18 at COTA last weekend and he came up and found me and said my FR barely even touched the ground.

Car is a Exige S with no cage, lowered, good but home made aero, running on 225 front 275 rear A7's Front 600 rear 800 lb springs, Penske DA 7500 shocks. Front roll bar set pretty stiff to tame down turn in oversteer, no rear bar.

What do I do about this? Do I do something about this? The car is almost always understeering, so i assume this isn't helping. It seems that softening the bar and stiffening the front springs might be the starting point? Or am I thinking about this wrong?
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Old 01-01-2019, 02:00 PM
  #3129  
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Originally Posted by Kevin Fennell View Post
What do I do about this? Do I do something about this? The car is almost always understeering, so i assume this isn't helping. It seems that softening the bar and stiffening the front springs might be the starting point? Or am I thinking about this wrong?
This is less of a coaching question unless a driver can induce wheel lift? Otherwise I think of this as set-up issue to be tamed. I was taught springs, bars, the shocks in that order. Your car was never ment to be a trackcar but a safe understeering roadcar. So 1st step is to see if the spring rates support a chassis frequency of a roadcar turned racecar with aero. That means you need the car scaled and weight of unsprung and unsprung and some suspension componants and some lengths of a-arms to calculate suspension leverage etc etc. So lets say the springs in the car have a good chassis frequency toward the racy end of things but standard 10% lower front ride frequency than rear (typical in roadcars) then you tune with bars and finally shocks. Lets say the bars and shocks don't cure the issue. You might encroach on the 10% lower front ride frequecncy and up the front spring rates which will improve corner entry with less pitch sensitivity positively effecting the aero too. Then go back and tune with bars and shocks. Try not to confuse yourself. Caveman basics, stiff front understeers stiff rear oversteers, softening improves grip,
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Old 01-02-2019, 05:11 PM
  #3130  
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In addition to what Billy Bob said, here are a few more things to consider:

You're getting too much front L-R and diagonal front-rear weight transfer. Some of this is related to the front and rear bar settings, as well as possible spring mismatch as he said. But some may also be related to mismatch between the settings of the Penskes and the springs. Also, you may be dealing with differing roll stiffnesses of the front and rear subframes to which your suspension is attached. Consider fully caging your car...not just for your safety at the speeds you run (seems to be a no brainer) but also to help even out chassis rigidity for proper suspension set up. Then, hire someone like myself or another qualified coach/driver who can quickly help dial your car in on a practice or open track day.
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Old 01-03-2019, 10:57 PM
  #3131  
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I can see the dampers affecting momentary roll stiffness but not through an entire sweeper.

If you are lifting the inside front tire in a turn, that tells us that front is more roll stiff than the rear. One way to reduce or eliminate the lift is to match the front and rear roll stiffness. The problem with doing that is it affects the chassis balance. You said the car understeers now. Making the rear more roll stiff or the front less roll stiff will reduce understeer and cause the front to lift less. How much less depends on how much you can stiffen the rear while not removing too much understeer/adding too much oversteer.
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