Stock tires on track - chunkalicious.

[SkiRideDrive]

Originally Posted by CSG Mike

Cost effective?

Two camber/crash bolts, maximize that front camber, fix the front toe, and run some "extreme summer performance" tires somewhere in the 140-200 TW range.

The primary cause of your chunking is a lack of camber.

The theory behind a street car and your formula car is identical. Anything you learn here will carry over there, and vice versa. The difference is that you have to do everything yourself with this car, whereas with the formula car all the R&D has already been done for you.

Thanks for the input. Actually it was a Formula SAE project so we designed the car from the ground up and built it ourselves. My specialty was vehicle dynamics, designing the suspension system around the tire data we had available to us, choosing our dampers, springs, bars, and running the data acquisition/testing.

[CSG Mike]

Originally Posted by SkiRideDrive

Thanks for the input. Actually it was a Formula SAE project so we designed the car from the ground up and built it ourselves. My specialty was vehicle dynamics, designing the suspension system around the tire data we had available to us, choosing our dampers, springs, bars, and running the data acquisition/testing.

Lets transition what you learned in college over to the car, and you'll do quite well

[EAGLE5]

Am I weird for not considering formula sae as real formula cars?

[SkiRideDrive]

Originally Posted by jsimon7777

Am I weird for not considering formula sae as real formula cars?

Classify them however you like.

[EAGLE5]

Originally Posted by SkiRideDrive

Classify them however you like.

Wasn't an insult. Just never thought of them as formula cars.

[SkiRideDrive]

Originally Posted by jsimon7777

Wasn't an insult. Just never thought of them as formula cars.

I've interpreted formula as an open wheel car designed to a set of rules and assumed that FSAE fit within that envelope.

[SkiRideDrive]

Alright, solving the camber issue.

From my research. I can take the bottom strut bolt and put it in the top hole, and put the SPC 81260 14mm camber bolt in the lower hole to achieve about 2 degrees of negative camber.

It also seems that each degree of negative camber seems to add about 1/16" of toe in per tire. Can anyone confirm?

Also, does anyone know the ratio of tie rod turns per 1/16" of toe?

This would speed up my alignment considerably.

Thanks!

[Mr.ac]

Yes that the correct way to install crash bolts.
As for the toe setting. You really can't guess it with out having proper measuring tools.
Unless you have a toe setting plate and doing the the whole string and plumb deal, your best and fastest way is to take it to a shop. Sure it may cost a few dollars but it's a lot better than a DIY route. Unless you have alignment tools.

[SkiRideDrive]

Originally Posted by Mr.ac

Yes that the correct way to install crash bolts.
As for the toe setting. You really can't guess it with out having proper measuring tools.
Unless you have a toe setting plate and doing the the whole string and plumb deal, your best and fastest way is to take it to a shop. Sure it may cost a few dollars but it's a lot better than a DIY route. Unless you have alignment tools.

I was going to max out camber and then string it. For toe. Done it maybe 100 times before on an fsae car. Problem with a street car is you have to jack it up, put it down, jack it up, put it down. So I figured doing a little research beforehand would limit the number of iterations.

[dustmann]

Originally Posted by SkiRideDrive

Thanks for the input. There seems to be a lot of "you need to check your tires at the track" responses. Some of them condescending. What pressures do you guys aim for at the track hot?

Not sure if you'll be back on stock tires, but I was most comfortable with about 35 psi front / 34 psi rear "hot" (as soon as I parked after I came off of the track) on a 100* day on stock tires. Set "cold" before my next session (about 2hrs between sessions) here in New Orleans, I was at about 31 in the rear, and 32 in the front. The following day I forgot to put air in the tires after leaving the track and my dummy lights were on for the tires (all <25psi) at about 75* in the morning. I felt like the rear starts to slide a little bit and the front understeers with 2psi more air than that. With 2psi too little air, the car feels more "squishy" like it doesn't want to settle when I was transitioning through "S" curves.


That could just be me though, I'm still pretty new to all of this track day business (only 4 days on the NOLA track). And this was on bone stock suspension/camber/tires.

[SkiRideDrive]

Thanks for the input.

I actually found a deal on a few used stock tires so I am going to swap out the chunked tire for now in the canyons and work on a solution for track days. I also ordered the camber bolts and will install them soon.

[DocWalt]

Thanks for the input on tire pressures for stock tires. I've got my first track day coming up in the BRZ and I don't feel like buying real tires for one track day then leaving them sit all winter. That said, maybe chunking the stock tires will let me justify better rubber sooner