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Track Alignment Setting

azshelby350

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It might be worth checking the toe. It could have changed. If it turns in well but starts under steering mid corner, I’d say you may have picked up some toe-in. Or maybe the tires are starting to heat cycle out.
Tires only have one other track day on them and maybe 1000 road miles, so I don’t think it’s heat cycling. My last set of Cup 2’s went thru about 5k miles of road driving and 6-7 track days.
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Egparson202

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Tires only have one other track day on them and maybe 1000 road miles, so I don’t think it’s heat cycling. My last set of Cup 2’s went thru about 5k miles of road driving and 6-7 track days.
Agree. How are the front tires wearing? Specifically how much is the outside shoulder wearing? I ask because I like more camber than you listed. Even better, can you get tire temps? That can help unlock the mystery.

Also, at what point in the corner does the under steer begin?
 

svttim

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Today at the track my car was experiencing understeer like I’ve never felt before, especially in one corner. It was a long 180 right hand decreasing radius turn with a late late apex, and my car kept wanting to push. My settings haven’t changed at all from the last couple tracks (-2.5F/-2R, neutral toe, SC2’s at 28 cold, 30-33 hot) so it must’ve been the crappy asphalt surface.

I want to start experimenting with toe more. Some tracks (again I think it’s the surface) almost make my car feel “slow”at responding to steering inputs where I think a tiny amount of toe out could help quicken it up.
Have you thought about a tire pressure changes?
 

azshelby350

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Agree. How are the front tires wearing? Specifically how much is the outside shoulder wearing? I ask because I like more camber than you listed. Even better, can you get tire temps? That can help unlock the mystery.

Also, at what point in the corner does the under steer begin?
I don’t have a tire temp gauge but I may have to invest in one. Tires are wearing well with most of the scrub to the center and inner 1/3. The understeer would begin at mid-corner as I lined up for the apex. Unfortunately with the track configuration and minimal runoff I did not feel confident enough to add throttle to try to counter the understeer.
 

azshelby350

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Have you thought about a tire pressure changes?
Yessir, I’ve experimented in the 28-37 range, but at least for the tracks I run in AZ and CA optimal pressure is 31-33 for Cup 2’s. At 35 they start to feel greasy, 36-37 they just give up, haha.
 

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I don’t have a tire temp gauge but I may have to invest in one. Tires are wearing well with most of the scrub to the center and inner 1/3. The understeer would begin at mid-corner as I lined up for the apex. Unfortunately with the track configuration and minimal runoff I did not feel confident enough to add throttle to try to counter the understeer.
Given the tire wear and mid-corner understeer you’re experiencing I think you may have a little too much toe-in. Moving to neutral toe or a pinch of toe-out should help.
 

ShatterPoints

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Given the tire wear and mid-corner understeer you’re experiencing I think you may have a little too much toe-in. Moving to neutral toe or a pinch of toe-out should help.
I thought too much toe out would cause understeer mid corner. I'm not sure that his understeer is toe related.
 

svttim

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Yessir, I’ve experimented in the 28-37 range, but at least for the tracks I run in AZ and CA optimal pressure is 31-33 for Cup 2’s. At 35 they start to feel greasy, 36-37 they just give up, haha.
Last event in Purump NV I saw pressures in the mid 40's and I started at 28. My car only got a little squirrely at the upper end. Now, those were the R cup 2's.
 

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What are your toe settings in the rear?
 

azshelby350

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Last event in Purump NV I saw pressures in the mid 40's and I started at 28. My car only got a little squirrely at the upper end. Now, those were the R cup 2's.
I think the part of the problem is that on this car I’m still running the 35-series tires, rather than the 30-series R spec.

Toe was set to dead 0 F/R when I had all of the suspension installed.
 

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Egparson202

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I thought too much toe out would cause understeer mid corner. I'm not sure that his understeer is toe related.
I’m not sure either. Could be (as he’s said several times) something to do with the track surface. Or cornering speed. His comments have mostly eliminated insufficient camber, Hest cycles, early throttle induced understeer.

Now he’s saying his toe is 0. I’m stumped.

I did read an excellent post at one point by @BillyRacing that described how toe in and toe out affect cornering. Unless I’m mistaken his description indicated that toe in would respond quicker at initial turn in but could induce mid-corner understeer since the outside (loaded) tire has to overcome the inside (unloaded) tire. Whereas toe out would be the opposite: slightly slower to respond to turn in but more resistant to mid corner understeer.
 

ShatterPoints

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I’m not sure either. Could be (as he’s said several times) something to do with the track surface. Or cornering speed. His comments have mostly eliminated insufficient camber, Hest cycles, early throttle induced understeer.

Now he’s saying his toe is 0. I’m stumped.

I did read an excellent post at one point by @BillyRacing that described how toe in and toe out affect cornering. Unless I’m mistaken his description indicated that toe in would respond quicker at initial turn in but could induce mid-corner understeer since the outside (loaded) tire has to overcome the inside (unloaded) tire. Whereas toe out would be the opposite: slightly slower to respond to turn in but more resistant to mid corner understeer.
To much toe in on the rear will cause understeer. If what you're saying about his toe being 0 then the understeer is definitely not toe related and more than likely user induced.
 

VictorH

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Last event in Purump NV I saw pressures in the mid 40's and I started at 28. My car only got a little squirrely at the upper end. Now, those were the R cup 2's.
Don’t take this wrong, but it’s not always the car’s fault. I was at a track event, guy next to me says how his tires are crap with no grip from mid-session on and I say, ‘let’s check your tire pressures.”. Pre-session pressure was good start, just off track his front tires were 52 PSI. Told him, you might be over-driving your car, maybe slow your corner entry a bit and see how that works.
Whenever I see really big temp changes in the tires, I think it’s partly set up, but then driver contributing to the car not wanting to do what the driver wants and pushing harder. Might not be your situation but something to think about.
 

Egparson202

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To much toe in on the rear will cause understeer. If what you're saying about his toe being 0 then the understeer is definitely not toe related and more than likely user induced.
Good point. My comments so far have been limited to the front wheels. I do like a pinch of rear toe in for stability under braking. But I can see how too much toe in on the Rear could contribute to understeer. IIRC OP indicated 0 toe front and rear. Maybe he could share more about his inputs…
 

Egparson202

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Don’t take this wrong, but it’s not always the car’s fault. I was at a track event, guy next to me says how his tires are crap with no grip from mid-session on and I say, ‘let’s check your tire pressures.”. Pre-session pressure was good start, just off track his front tires were 52 PSI. Told him, you might be over-driving your car, maybe slow your corner entry a bit and see how that works.
Whenever I see really big temp changes in the tires, I think it’s partly set up, but then driver contributing to the car not wanting to do what the driver wants and pushing harder. Might not be your situation but something to think about.
That’s certainly worth considering. In my track exploits many of my car’s shortcomings were fixed by adjusting the loose nut behind the wheel😉.

For big swings in tire temp another variable is how much moisture is in the inflation air. If it’s not dry enough it can really push pressures up and be hard to diagnose.
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