CUP2 Wear on 2020 GT350

[Jamesmcga]

Just finished a track day on a new set of Cup2's and after I put on CC plates and the wear is still horrible on the outside. I have FP lowering springs and Steeda CC plates. The shop said they set camber to -2.9, but I would have thought the wear would have been more even. Tire pressures at the end of the runs is between 34/35.

Is this consistent to what others are seeing or is the camber still jacked?
Tire pressure too high?

 

[JAJ]

Just finished a track day on a new set of Cup2's and after I put on CC plates and the wear is still horrible on the outside. I have FP lowering springs and Steeda CC plates. The shop said they set camber to -2.9, but I would have thought the wear would have been more even. Tire pressures at the end of the runs is between 34/35.

Is this consistent to what others are seeing or is the camber still jacked?
Tire pressure too high?

View attachment 79671

Something very strange is going on. The wear on the outside of the tire looks "normal" in a sense, but there's virtually no wear on the inside edge, and that's not right.

It'd be worth getting the camber checked again - I'm running -2.4 with OEM rims and springs and my wear is a lot more even (on R-spec front tires) than that. What rims are you running? OEM or a lightweight set?

 

[byronj]

Something is off there. I would run 1.5 camber of cup 2s (too lazy to change camber at the track) and have more even wear than that. I found that 36 hot seems to be a sweet spot for me on Cup 2s. Your tires are definitely not over inflated.

 

[blacksheep-1]

Check caster, you can gain a lot of camber in the corners by adding caster, if you run only minimum caster the tire will still roll over in the corner.
This is known as " camber gain" .

 

[Egparson202]

Check caster, you can gain a lot of camber in the corners by adding caster, if you run only minimum caster the tire will still roll over in the corner.
This is known as " camber gain" .

This is interesting. In a new/not new kinda way. I’ve long heard the GT350 has “more than enough” caster right out of the box. The published specs are 6.81/6.92 (350/350R). What I’m asking myself now is whether the car would benefit from even more caster. @blacksheep-1 , what do you think? It wouldn’t be that hard to try it and see.

 

[Jamesmcga]

Something very strange is going on. The wear on the outside of the tire looks "normal" in a sense, but there's virtually no wear on the inside edge, and that's not right.

It'd be worth getting the camber checked again - I'm running -2.4 with OEM rims and springs and my wear is a lot more even (on R-spec front tires) than that. What rims are you running? OEM or a lightweight set?

Running the stock wheels...

Check caster, you can gain a lot of camber in the corners by adding caster, if you run only minimum caster the tire will still roll over in the corner.
This is known as " camber gain" .

what caster/camber/toe do you run?

 

[blacksheep-1]

Running the stock wheels...

what caster/camber/toe do you run?

All the caster I can get

 

[Egparson202]

All the caster I can get

Thanks for that. Am I right in thinking that with more caster (and if tire temps, pressures and wear back it up) I might be able to run a bit less static camber? Could help in braking performance if possible.

 

[blacksheep-1]

Thanks for that. Am I right in thinking that with more caster (and if tire temps, pressures and wear back it up) I might be able to run a bit less static camber? Could help in braking performance if possible.

Probably, but you're going to have to experiment with that.

 

[Egparson202]

Probably, but you're going to have to experiment with that.

Then there’s the obvious one… lap times!

 

[blacksheep-1]

People visualize camber and caster in their respective planes, but in real life they actually arc around the upper pivot point.

 

[Vettel-ish]

Damn! I got a whole year out of my CUP2 on track with my GT350.

Is the car suffering from mad understeer? Are you pushing through the corner?

 

[Egparson202]

Damn! I got a whole year out of my CUP2 on track with my GT350.

Is the car suffering from mad understeer? Are you pushing through the corner?

This is a good question for OP. And for any of us who are really hard on front tires. I know there have been times when I had driver-induced understeer I was trying to fix in the shop. The fix is sometimes (OK, often) in the driver’s seat.

An example from my past: Overslowing for a corner and then applying the throttle too much and/or too early. That can cause power on understeer and excessive front tire wear.

Or, it could be the car. Thoughts?

 

[Jamesmcga]

Damn! I got a whole year out of my CUP2 on track with my GT350.

Is the car suffering from mad understeer? Are you pushing through the corner?

Yes bad pushing.

Damn! I got a whole year out of my CUP2 on track with my GT350.

Is the car suffering from mad understeer? Are you pushing through the corner?

Yes bad understeer (push) on a tight road course like Atlanta motor sports park. I don’t feel as bad on high speed courses like Road Atlanta.

 

[Jamesmcga]

This is a good question for OP. And for any of us who are really hard on front tires. I know there have been times when I had driver-induced understeer I was trying to fix in the shop. The fix is sometimes (OK, often) in the driver’s seat.

An example from my past: Overslowing for a corner and then applying the throttle too much and/or too early. That can cause power on understeer and excessive front tire wear.

Or, it could be the car. Thoughts?

Yes… I just wanna go faster in a I hav corner and it just keeps pushing

 

[JDee]

Push can be managed. It's my experience that drivers often aggressively charge the corner and that's never going to work out well, ultimately lap times suffer. I'm going to suggest you back up your corner entry a lot and not be as aggressive going in. Sometimes you go faster by going slower and this is one of them, if your entry is ruining the corner then you need to slow down more on entry. Once you are getting a good, tires hooked up entry then slowly move your entry speed up to find the limit.
Get the car turned in and settled and then start working the throttle as grip allows. If you do that you'll get better exit speeds and that's critical to getting higher speed on the straights.
I look for hot pressures of 32 psi with 305s on 11 inch rims.

 

[Stan Whitney]

Is this a square tire setup - 305's of staggered 305/315? The FP springs and stock swaybar combo may be too understeer balanced at mid corner. And that just gets worse if you come in too hot in the corner - my own common problem.
Look at adjustable swaybars to start with, to fine tune your mid corner balance to be more neutral, they can also help with corner entry. All of the aftermarket bar sets - FP, Steeda, BMR have a broad range of adjustment.

 

[Vettel-ish]

Are you going to track soon? Maybe try a tap of the brakes before corner entry, this will bring the front end down and help plant the car into the corner. Mid apex you can move the rear around with throttle then to bring the car around and help you steer a bit.

 

[Jamesmcga]

Is this a square tire setup - 305's of staggered 305/315? The FP springs and stock swaybar combo may be too understeer balanced at mid corner. And that just gets worse if you come in too hot in the corner - my own common problem.
Look at adjustable swaybars to start with, to fine tune your mid corner balance to be more neutral, they can also help with corner entry. All of the aftermarket bar sets - FP, Steeda, BMR have a broad range of adjustment.

Standard staggered. I was thinking about moving to the Steeda springs

 

[Stan Whitney]

Standard staggered. I was thinking about moving to the Steeda springs

If you are thinking of switching springs, I would recommend the bmr linear rate ones. I ran them for 2 seasons on my '18 gt350, worked perfectly with the mag ride and bmr adj. bars. Very good balance at 250f/980r and a square setup. And street ride was perfectly fine, sporty, but nor super harsh.