Fighting understeer in high speed corners

[honeybadger]

Hi all,

Figured I'd post this separately from my ongoing thread so it's easily found in searches.

Hoping for help with some setup questions. I put on Goodyear 3Rs for the first time this weekend and I was getting some intense understeer in highspeed corners (as seen down below). While I could absolutely lift a bit to get the bite back (and that's what I did when not trying new things), I was really struggling to get the rear to start to come around. No matter what I tried (within limits), the car would understeer. Tried a few different pressures 32 hot, 33-34 hot, and 35-36 hot. Tried lifting and inducing a bit of oversteer with throttle/steering input. Nada. According to my pyrometer, temps across the tires were within a 15 degree window.

I pulled a degree out of the wing and that helped a bit, but not a whole lot. Still terminal. My understanding is this probably a roll bar adjustment given my lack of adjustable coilovers? AS another data point, I am getting a good bit of body roll (from the entire car). What would you recommend, tightening up the rear bar? Would love if I could reduce the understeer without making the car twitchy in the rear.

Thanks for reading!

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[pilotgore]

Hi all,

Figured I'd post this separately from my ongoing thread so it's easily found in searches.

Hoping for help with some setup questions. I put on Goodyear 3Rs for the first time this weekend and I was getting some intense understeer in highspeed corners (as seen down below). While I could absolutely lift a bit to get the bite back (and that's what I did when not trying new things), I was really struggling to get the rear to start to come around. No matter what I tried (within limits), the car would understeer. Tried a few different pressures 32 hot, 33-34 hot, and 35-36 hot. Tried lifting and inducing a bit of oversteer with throttle/steering input. Nada. According to my pyrometer, temps across the tires were within a 15 degree window.

I pulled a degree out of the wing and that helped a bit, but not a whole lot. Still terminal. My understanding is this probably a roll bar adjustment given my lack of adjustable coilovers? AS another data point, I am getting a good bit of body roll (from the entire car). What would you recommend, tightening up the rear bar? Would love if I could reduce the understeer without making the car twitchy in the rear.

Thanks for reading!

Which springs and sway bars do you have and what settings on the sway bars? In general, how did you like the SC3’s compared to Cup2’s?

 

[honeybadger]

Which springs and sway bars do you have and what settings on the sway bars? In general, how did you like the SC3’s compared to Cup2’s?

FP springs and bars, full soft for both. I had tried 1 stiff in the rear in 2019, but I found the rear super twitchy (but I wasn't trying that at COTA)

GY 3Rs are interesting. Feel like a less-grippy slick to me. Incredible turn in, can take stupid amounts of heat, and work incredible until their limit - but then fall off hard without much warning.

Overall, I liked them a lot. Estimating they're 2-3 seconds off a Hoosier R7/Pirelli DH. As long as I get 4-5 days from them, they'll be worth the $$

 

[pilotgore]

FP springs and bars, full soft for both. I had tried 1 stiff in the rear in 2019, but I found the rear super twitchy (but I wasn't trying that at COTA)

GY 3Rs are interesting. Feel like a less-grippy slick to me. Incredible turn in, can take stupid amounts of heat, and work incredible until their limit - but then fall off hard without much warning.

Overall, I liked them a lot. Estimating they're 2-3 seconds off a Hoosier R7/Pirelli DH. As long as I get 4-5 days from them, they'll be worth the $$

Trying one stiff on the rear might help (85 ft/lb torque I believe). You may also try decreasing the rear tire pressure to induce oversteer (maybe start with that.)

Good to hear on the SC3r’s. I have 3 more sets of takeoff cups to go through before trying something else, and the Goodyear’s were top of my list.

 

[Rob-17GT350]

Taking grip away from one end to “create balance” is never a good thing. It may feel faster because your driving effort has increased with a looser car but overall doubtful it will be. Always want to figure out how to increase grip to the end that needs it. How stiff is the sidewall on the 3R? Maybe rolling tire too much. If so I’d actually increase negative camber in front to keep more on contact patch. Unfortunately, with your current setup you’re limited to alignment, sway bar settings and tire pressure.

 

[luc]

Hi all,

Figured I'd post this separately from my ongoing thread so it's easily found in searches.

Hoping for help with some setup questions. I put on Goodyear 3Rs for the first time this weekend and I was getting some intense understeer in highspeed corners (as seen down below). While I could absolutely lift a bit to get the bite back (and that's what I did when not trying new things), I was really struggling to get the rear to start to come around. No matter what I tried (within limits), the car would understeer. Tried a few different pressures 32 hot, 33-34 hot, and 35-36 hot. Tried lifting and inducing a bit of oversteer with throttle/steering input. Nada. According to my pyrometer, temps across the tires were within a 15 degree window.

I pulled a degree out of the wing and that helped a bit, but not a whole lot. Still terminal. My understanding is this probably a roll bar adjustment given my lack of adjustable coilovers? AS another data point, I am getting a good bit of body roll (from the entire car). What would you recommend, tightening up the rear bar? Would love if I could reduce the understeer without making the car twitchy in the rear.

Thanks for reading!

Which size tires, squared or ?
How much camber?

 

[honeybadger]

Taking grip away from one end to “create balance” is never a good thing. It may feel faster because your driving effort has increased with a looser car but overall doubtful it will be. Always want to figure out how to increase grip to the end that needs it. How stiff is the sidewall on the 3R? Maybe rolling tire too much. If so I’d actually increase negative camber in front to keep more on contact patch. Unfortunately, with your current setup you’re limited to alignment, sway bar settings and tire pressure.

The 3Rs are pretty damn stiff - not as stiff as a Hoosier, but closer than not. I can try adding negative camber to see what happens...is it common that the pyrometer measurements would indicate the right camber but the feel would indicate a need for more camber?

Which size tires, squared or ?

Goodyear 3R 305 squared on 19s

 

[Rob-17GT350]

The 3Rs are pretty damn stiff - not as stiff as a Hoosier, but closer than not. I can try adding negative camber to see what happens...is it common that the pyrometer measurements would indicate the right camber but the feel would indicate a need for more camber?

How is the tire wear on the front? How far onto the shoulder?
You know, to maximize grip on street tires and not kill them quick, it’s a fine balance between alignment, roll stiffness, tire pressure, alignment and driving style. Honestly, I‘ve never put too much stock in pyrometer readings with street tire because to go fast more sliding is required than when on slicks, which can give misleading data.
If getting on shoulder to much, try increasing roll stiffness with front bar.

 

[JAJ]

It's hard to tell from the video where your hands are, but it looks like you're more or less holding them in one place in the first long corner. When I was just starting out, I got a lot of instruction from a pro endurance racer, and one of the things I had hammered into me was "keep your hands moving" in a corner. Apparently, if you move your hands to a position and hold it, a strip of the tire tread can overheat, reducing tire life (bad for enduro's) and reducing grip.

To counter this, even in big sweepers, try to smoothly turn the steering in then smoothly back out without stopping along the way. If you can't do that easily, then take a double apex line so you don't hold the steering wheel still until you're going in a straight line.

I've run on 3R's and liked them a lot. Sort of like MPSC2's without the tramlining.

 

[honeybadger]

How is the tire wear on the front? How far onto the shoulder?
You know, to maximize grip on street tires and not kill them quick, it’s a fine balance between alignment, roll stiffness, tire pressure, alignment and driving style. Honestly, I‘ve never put too much stock in pyrometer readings with street tire because to go fast more sliding is required than when on slicks, which can give misleading data.
If getting on shoulder to much, try increasing roll stiffness with front bar.

It's hard to tell from the video where your hands are, but it looks like you're more or less holding them in one place in the first long corner. When I was just starting out, I got a lot of instruction from a pro endurance racer, and one of the things I had hammered into me was "keep your hands moving" in a corner. Apparently, if you move your hands to a position and hold it, a strip of the tire tread can overheat, reducing tire life (bad for enduro's) and reducing grip.

To counter this, even in big sweepers, try to smoothly turn the steering in then smoothly back out without stopping along the way. If you can't do that easily, then take a double apex line so you don't hold the steering wheel still until you're going in a straight line.

I've run on 3R's and liked them a lot. Sort of like MPSC2's without the tramlining.

I'm like 95% it's not user error here (at least in in this particular case). When on my clapped out Cup2s, I was completely unwound before the 3rd apex with the car still rotating because I could get the rear to come around. However, with the 3Rs it didn't matter what I do, couldn't do it unless I started initiate a full on drift.

Here's a run through the esses a couple events back on some clapped out cup2s. You can see I'm struggling for front end grip, but notice how in the last third, I have some slip angle with the rears and it's rotating perfectly.



No matter what I tried, I couldn't do it on the 3Rs. I'm assuming the overall grip is now too high and it's not longer masking my poor car setup

Or I can't drive. that could be it too ha

 

[pilotgore]

I'm like 95% it's not user error here (at least in in this particular case). When on my clapped out Cup2s, I was completely unwound before the 3rd apex with the car still rotating because I could get the rear to come around. However, with the 3Rs it didn't matter what I do, couldn't do it unless I started initiate a full on drift.

Here's a run through the esses a couple events back on some clapped out cup2s. You can see I'm struggling for front end grip, but notice how in the last third, I have some slip angle with the rears and it's rotating perfectly.



No matter what I tried, I couldn't do it on the 3Rs. I'm assuming the overall grip is now too high and it's not longer masking my poor car setup

Or I can't drive. that could be it too ha

Sounds like you need some shitty cups on the back and 3Rs on the front to complete the setup. BOOM, problem solved!!! You’re welcome!

 

[Rob-17GT350]

No matter what I tried, I couldn't do it on the 3Rs. I'm assuming the overall grip is now too high and it's not longer masking my poor car setup

That‘s why I suggested increasing front roll stiffness. The intuitive solution to correct understeer on “street suspension” with sticky tires is to decrease front roll stiffness and/or decrease tire pressure. This usually doesn’t help and most the time makes it understeer more.
We discussed it before, your car is under sprung for weight, amount of aero and size of tires (just look at photos ). Now add NEW, stickier tires and yes, the car setup limitations become more apparent. You and your car are super fast but have long ago reached the limit of the street suspension.
I’ve tried so many spring rates, sway bars, alignment settings on my previous ST/TT3 car and current TT/ST4 car. Different spring rates and setups are needed to optimize grip for all tires (Hoosier R7, A7, Pirelli, Michelin and fast street tires). To optimize your setup and have the ability to adjust for different grip level tires (especially new slicks), it’s time for coil-overs .

 

[JAJ]

I'm like 95% it's not user error here (at least in in this particular case). When on my clapped out Cup2s, I was completely unwound before the 3rd apex with the car still rotating because I could get the rear to come around. However, with the 3Rs it didn't matter what I do, couldn't do it unless I started initiate a full on drift.

Here's a run through the esses a couple events back on some clapped out cup2s. You can see I'm struggling for front end grip, but notice how in the last third, I have some slip angle with the rears and it's rotating perfectly.



No matter what I tried, I couldn't do it on the 3Rs. I'm assuming the overall grip is now too high and it's not longer masking my poor car setup

Or I can't drive. that could be it too ha

I wasn't thinking user error, just adjust the technique a bit to keep the tires cooler. It sounds like the front tires are losing grip in that particular set of corners, and that could be a heat problem that's unique to that tire on your car. I have had my front GY3R's go away in a corner in the middle of a session (four weeks ago). I got them back by switching the suspension magride setting to "Sport" (with the chassis still in "Track") but the next session out they were dead - 19 heat cycles and they were pretty much grip-free.

So, I do have a dumb question - when was the last time you were out on new tires? It sounds like it's been a while... And how were the lap times - faster on the GY's or slower?

 

[ShatterPoints]

Hi all,

Figured I'd post this separately from my ongoing thread so it's easily found in searches.

Hoping for help with some setup questions. I put on Goodyear 3Rs for the first time this weekend and I was getting some intense understeer in highspeed corners (as seen down below). While I could absolutely lift a bit to get the bite back (and that's what I did when not trying new things), I was really struggling to get the rear to start to come around. No matter what I tried (within limits), the car would understeer. Tried a few different pressures 32 hot, 33-34 hot, and 35-36 hot. Tried lifting and inducing a bit of oversteer with throttle/steering input. Nada. According to my pyrometer, temps across the tires were within a 15 degree window.

I pulled a degree out of the wing and that helped a bit, but not a whole lot. Still terminal. My understanding is this probably a roll bar adjustment given my lack of adjustable coilovers? AS another data point, I am getting a good bit of body roll (from the entire car). What would you recommend, tightening up the rear bar? Would love if I could reduce the understeer without making the car twitchy in the rear.

Thanks for reading!

Dampers are the best, and most expensive of all the options to give you the changes you want. You most likely need more low speed damping in the front. Otherwise you have too much front spring relative to the rear. You would want stiffer springs all around if you are still getting un wanted body roll. Too much ARB and you will start causing some cross weight loading issues.

Things you can do;

-Take toe out of the front
-Add more toe out in the rear

-Add rear spring rate + add front ARB to trim the mid corner US/OS balance
-Lessen front spring rate + reduce rear ARB to trim mid corner US/OS balance


Also check your DMs.



*edit* we really should diagnose what phase of the corner you are experiencing or anticipating the understeer.

The turn in your video is notorious for people to wait...wait...wait.. steady maintenance throttle because of the understeer. Part of that is the line you take into it, and the other part is definitely setup.

To further clarify, in the turn in your video that is nearly all spring / ARB balance since the shocks velocities are low (low speed damping). With more low speed damping you can load the front tires and get the initial turn in response and then transitional US/OS balance when you are carrying speed through the mid corner and then power on corner exit.

 

[WCRookie99]

All the above, plus easiest is to flatten the rear wing, if it’s totally flat.

Then to adjustable shocks, then to springs.

Unless your springs are way too stiff then start there.

I like the coil over suggestion.

You’re going to get 50 different opinions out of 49 people.

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