SCCA Solo D Street discussion

[MacSpeed]

Originally Posted by Desertnate

Thinking back over the event I just ran this weekend and reviewing the more recent posts I noticed this.



You were able to get 245's on a 7.5" wheel? I'm going to gradually upgrade my car to stay in DS and the first step for next season is wheels/tires. However I was looking to a 17x7.5 wheel with 225 RT660's. Didn't think anything wider would be a good idea on a wheel of that width in addition to any potential rubbing issues.

On a side note, the OEM pilot sports seem to get really greasy after 2~3 runs in 95F-ish heat.

Yup, bunch of people are running that setup. I did a 6MM spacer in the front to clear the strut. Smaller might have worked but thats all I had.

[cmiovino]

My car's generally been terrible all season. This past weekend I ended up 68th out of about 100 in PAX. Last year I was typically in the upper 1/3.

Last year I ran Yoks in 225/45/17, stock front swaybar. The car generally worked well. The car had good balance, some roll, but once it caught, it stuck. You could trust it throwing it into any corner.

I changed to RT660's at just about everyone's recommendation locally that "they're the tire for the car" with low camber and all. Also added a 19mm Perrin front swaybar on stiff (+72% increase, about that of the Strano bar)... because well, that's usually a non-brainer from everywhere I read. I opted not to get with the Whiteline 20mm or anything larger thinking it would lead to understeer.

The car's pretty much terrible now. Understeers and you basically have to baby it through sweepers. I haven't even once almost lost the rear or even come close now. With transitions and slaloms, it doesn't just stick anymore and you can't trust it.

.... so, do you think it's the tires or FSB? Tires now have 170 runs on them, but they weren't much better even in their prime. It's been the whole season like that. I'd be very curious to try the Yoks and 19mm bar together.

I'm at a loss. Only think I can think of it setting the bar on soft and seeing if that helps, even with the well worn tires.

[DocWalt]

170 runs is probably like 80 runs too many for Falkens, IME. The cost per run for Falkens is way higher than with Yoks because they cycle out and yoks just don't.



I would not run the 19mm Perrin front bar that stiff without being paired with appropriate rear bump stops. RE Suspensions COT Blues in 58mm length are your friend, and then trim the stock front stops.





Welcome to autocross where people prefer to turn their cars into gigantic dump trucks and then use shocks to make the car loose instead of getting the balance right and using shocks to tune transitional behavior...

[andys_garage]

Originally Posted by DocWalt

Welcome to autocross where people prefer to turn their cars into gigantic dump trucks and then use shocks to make the car loose instead of getting the balance right and using shocks to tune transitional behavior...

roflmao


I put a massive rear bar on my WRX when it was in DS. Autocrossed alright, killed the handling on my favorite on-ramp.

[strat61caster]

@cmiovino alignment specs?

Agree with others, typical autox setups in street class rely on you having at least adjustable dampers to compensate for only one bar and subpar alignment.

[DocWalt]

Originally Posted by andys_garage

roflmao


I put a massive rear bar on my WRX when it was in DS. Autocrossed alright, killed the handling on my favorite on-ramp.

Yeah, street class autocross setups are... stupid.

Literally the only reason I went to STR with my BRZ was to avoid this nonsense. I had my CS car working well in 2019 but to get it there was not a very enjoyable process. It was much more fun in 2020-2021 in STR lol

[cmiovino]

Originally Posted by DocWalt

170 runs is probably like 80 runs too many for Falkens, IME. The cost per run for Falkens is way higher than with Yoks because they cycle out and yoks just don't.

I agree on the tire life. I was closer to where I should have been earlier in the year, but since hitting about 125 runs, my placement has decreased to where I'm at now.

Lesson learned - I really did like the Yoks. Suckers didn't heat cycle out and the 660's seem to be just like my last two sets of RE-71R's. If people start saying the 71RS starts heat cycling out, then IMO, the Yoks are the way to go.

I caved because price went up a good bit over last year too. Lesson learned.

Originally Posted by DocWalt

I would not run the 19mm Perrin front bar that stiff without being paired with appropriate rear bump stops. RE Suspensions COT Blues in 58mm length are your friend, and then trim the stock front stops.

Also a good comment here. I might give a last ditch effort on these 170 run tires and set it to soft (only a 25% increase) for some testing the final few events of the year. I didn't think a ~70% bump up would make that much of a difference. Maybe it's driving style, but I'm not a fan. Although, it did completely fix the clunking I had with the stock bar's endlinks after they wore out. If anyone's running even a 20mm Whiteline, you'd have to be nuts IMO.

[cmiovino]

Originally Posted by DocWalt

Yeah, street class autocross setups are... stupid.

Literally the only reason I went to STR with my BRZ was to avoid this nonsense. I had my CS car working well in 2019 but to get it there was not a very enjoyable process. It was much more fun in 2020-2021 in STR lol

I'm very much thinking of moving to STX.

I have the performance pack Brembos and finding a street class acceptable wheel in 5x100, 7.5".... PLUS clearing the Brembos is a chore. There's like 2 wheels that I've seen fit that allow a 245 and I hate the design.

I've had my heart set on RCE Tarmac 2's to start my STX experience, but I've stumbled upon the Super Street-1.... which puts the price with tophats at ~$1800 vs $2800 for the Tarmac 2's when you factor in front camber plates. $1800 there, proper wheels to fit 245's, the added camber and stiffening, etc... eh, probably worth ~0.5 seconds vs the 225's and virtually no camber I have now.

[cmiovino]

Originally Posted by strat61caster

@cmiovino alignment specs?

Agree with others, typical autox setups in street class rely on you having at least adjustable dampers to compensate for only one bar and subpar alignment.

~1.1 was all I was able to get in front on one side with the OEM acceptable replacement bolts. 1.3 on the other, but with me sitting in the car on the rack, it was reading at 1.3 each side. Rear is at 1.4 even each side. Zero toe around because when I got the alignment done 2 years ago with the Yoks and stock bar, it generally did everything I asked of it without needing any toe adjustment out back.

[DocWalt]

When/if you do rear bumpstops and trim the stock fronts, you'll be surprised how much more swaybar you can get away with. The Whiteline 20mm is a good option then, as is the Perrin 22mm.


None of them have the range of the Karcepts though.

Originally Posted by cmiovino

I'm very much thinking of moving to STX.

I have the performance pack Brembos and finding a street class acceptable wheel in 5x100, 7.5".... PLUS clearing the Brembos is a chore. There's like 2 wheels that I've seen fit that allow a 245 and I hate the design.

I've had my heart set on RCE Tarmac 2's to start my STX experience, but I've stumbled upon the Super Street-1.... which puts the price with tophats at ~$1800 vs $2800 for the Tarmac 2's when you factor in front camber plates. $1800 there, proper wheels to fit 245's, the added camber and stiffening, etc... eh, probably worth ~0.5 seconds vs the 225's and virtually no camber I have now.

or do Shaftworks for ~$2300 or so and have them custom valved for your use...

I do like the Racecomp stuff though.

[andys_garage]

Originally Posted by DocWalt

Yeah, street class autocross setups are... stupid.

Literally the only reason I went to STR with my BRZ was to avoid this nonsense. I had my CS car working well in 2019 but to get it there was not a very enjoyable process. It was much more fun in 2020-2021 in STR lol

In the wrx, I too went to ST to fix the handling. Now I just do track days in the 86 so I don't have to worry about silly things like "rules" or "being fast" and can worry more about things like "having fun" and "getting better"

[justinco]

Originally Posted by cmiovino

....

.... so, do you think it's the tires or FSB? Tires now have 170 runs on them, but they weren't much better even in their prime. It's been the whole season like that. I'd be very curious to try the Yoks and 19mm bar together.

I'm at a loss. Only think I can think of it setting the bar on soft and seeing if that helps, even with the well worn tires.

I would put the front bar on soft, or try the stock bar again. Quick and easy, and doesn't cost you a new set of tires to test it. The balance will (*should) not change much going to new tires, just overall grip will improve obviously.

[cmiovino]

Soooo, I figured out the issue I've been fighting all season that we discussed above.

The the Yoks, I always ran them high at around ~37PSI, so I figured with the 660's having a crazy stiff sidewall in comparison, lower was the answer. They're basically an RE, right? I did my typical testing to get the wear down to the triangles and settled at 31PSI in front. My co-driver and I tailored the rear down to 26PSI to get it to cooperate. Any higher, even at 28PSI, and the rear was too unstable. Ran 180+ runs of the season like that at various venues. Understeer on corner entry and I felt like you couldn't trust it through slaloms or transitions, so you backed off on both.

Turns out 660's like higher pressures. Ran them at 35F/33R and magically the understeering issue went away and the car was much more stable through slaloms and transitions. Left the swaybar on stiff. Came back from one run and literally said "That's the best the car's felt all year, by a longshot."... even on 185 run 660's.

I must live under a rock or something because it seems a ton of people knew this. One guy runs his at 40PSI on a Tesla, although that's a heavier car. Other twin drivers run at at least 35PSI, if not more. I hear some SSC folks run at 32 and lower. Likely camber related.

Bummer it totally botched my season. It never crossed my mind to go higher because why would you raise pressures if yours understeering up front and they're right on the triangles?

Video of our last local SCCA event. Still a few non-SCCA locals to do some testing/fun in.

[strat61caster]

Triangles are irrelevant to finding the best pressure, glad you figured it out.