goin reverse stagger, maybe...

[ZDan]

Originally Posted by Pat

No, that would not address the root cause. The root cause of your understeer isn't too much grip, although it is a factor. If my theory and personal experience hold true in your case as well, the root cause is ride height and/or spring rate which determine how much you get into the bumpstops.

Yeah, I agree, my thoughts exactly. Higher ride height and/or more roll stiffness (via springs or sways or both) would help if I'm loading up on the outside front bump stop. I don't think that trading 10mm of rear tire width for 10mm of front tire width will make it worse, though. More speed through corners is a plus and any additional understeer by being harder on the outside front bump stop should be offset by additional front tire grip, and having the outside rear closer to the nonlinear portion of its load/grip curve.

See how it goes! If it's still an issue I might get those Tarmac springs. Or get coilovers...

[SCFD]

I also think the fix would be to add ride height and roll stiffness.

If you haven't tried adjusting your line or driving yet, I would try to get the car rotated more on corner entry and go for a point-and-shoot approach. Do you have a video clip of this track?

[ZDan]

OK, I changed my tire order from 255/235 reverse-staggered to 235-square.

Thanks to all who contributed their $0.02! I decided that it would be a better approach to increase roll stiffness than to go with wider fronts. 245/40-17 A052s aren't available, so going with 235/45-17 and using the half-classification-point saved to partly offset the 1-point added with aftermarket sway bars. Might need a few pounds of ballast, but can use that to slightly improve weight distribution...

Thinking about getting Eibach sway bars, if anyone has opinions feel free to share here or in the separate thread I made. Specifically interested about Eibach sways compatibility with Bilstein B8, -1.25" ride height (on stock-diameter springs), and maxed out front camber at -3.9 degrees (via camber plates).

Thanks again, all!

[Cephas]

I don't even track, but this thread was educational. Thanks!

[TommyW]

Originally Posted by ZDan

OK, I changed my tire order from 255/235 reverse-staggered to 235-square.

Thanks to all who contributed their $0.02! I decided that it would be a better approach to increase roll stiffness than to go with wider fronts. 245/40-17 A052s aren't available, so going with 235/45-17 and using the half-classification-point saved to partly offset the 1-point added with aftermarket sway bars. Might need a few pounds of ballast, but can use that to slightly improve weight distribution...

Thinking about getting Eibach sway bars, if anyone has opinions feel free to share here or in the separate thread I made. Specifically interested about Eibach sways compatibility with Bilstein B8, -1.25" ride height (on stock-diameter springs), and maxed out front camber at -3.9 degrees (via camber plates).

Thanks again, all!

Good move. I've run 225,235 and 245 squared with NT01's and I like the 235's the most. I have the Eibach bars and B6 Bilstein's, dropped 1". Great combo. Camber is -3F and -2 R. The bars were at the soft setting and was getting some push so will be stiffening the rear with the adjustment provided.

[NoHaveMSG]

Originally Posted by TommyW

Good move. I've run 225,235 and 245 squared with NT01's and I like the 235's the most. I have the Eibach bars and B6 Bilstein's, dropped 1". Great combo. Camber is -3F and -2 R. The bars were at the soft setting and was getting some push so will be stiffening the rear with the adjustment provided.

I really like 235's square as well. Though I am running 245's in RT660 and 235's in SX2 this year.

[TommyW]

Originally Posted by NoHaveMSG

I really like 235's square as well. Though I am running 245's in RT660 and 235's in SX2 this year.

The 235's just feel right. Great combo of grip and responsiveness IMO. For FI I think the 245 or 255 would be the call

[949 Racing]

So what was the outcome?
Is this NASA or SCCA TT?

[ZDan]

Originally Posted by 949 Racing

So what was the outcome?
Is this NASA or SCCA TT?

Good result at Palmer (CW), where midcorner understeer can be an issue. Much improved with the Eibach sways (front at softer setting, rear stiffer setting)! Better balance through 4, better drive onto the straight between 4 and 2. Won TT by healthy margin, 0.78 sec. Won next event at Thompson as well. Competition bought new Hoosiers for the next event at Palmer (CCW this time), and killed me. But I got him back at Watkins Glen. I'm up by a couple of points going into New Hampshire South Oval this weekend.

This is with COMSCC, regional club here in New England.
https://www.comscc.org/events/results/

[timurrrr]

Originally Posted by ZDan

Good result at Palmer (CW), where midcorner understeer can be an issue.

(For infrequent thread checkers like myself)
The good results are from 235 square, not reverse stagger?

[ZDan]

Originally Posted by timurrrr

(For infrequent thread checkers like myself)
The good results are from 235 square, not reverse stagger?

I ran full tread-depth 245/40-17 A052 rears with 235/45-17 fronts one session at Watkins Glen to check how the gearing would be, but the rear was way less planted vs. the well-worn 235s and I went slower, so I just went back to 235 square for the TT. The plan had been to run sticker 245s all around for the time trial...

I ran New Hampshire Motor Speedway South Oval this past weekend, I ran the newer 245/40s all around for Saturday's sessions. 1st practice Sunday was on 245/40 fronts and 235/45 rears, I didn't change fronts due to front right lug nuts being kinda "stiff" and not freely spinning off, so I just torqued them back down with the 245s up front. I set similar times as Saturday (1:14.3) despite errors and the track being slower (i.e. known references were going ~1/2-sec to 1-sec slower. The gearing was just way better with the tall 235/45s, saved me an upshift before entering the South Oval, before Turn 3, and before Turn 11. I did 2nd practice on 245/40s all around and did a 1:14.77, so I went back to 235/45-17 rears with 245/40-17 fronts for the TT. Made mistakes and didn't go faster but 1:14.79 was good enough to win my class by a lot and barely get the COMSCC T50 lap record

[timurrrr]

Now I'm even more confused

[ZDan]

Originally Posted by timurrrr

Now I'm even more confused

Basically, I ran reverse stagger but not necessarily because I wanted to. I was paranoid about stripping lug nuts out so I left the 245s on front and tried the 235/45s in back, and that was clearly the faster setup at NHMS South Oval due primarily to better gearing, but also the more worn 235s at the back of the car felt more stable in the oval turn. I'm sure I would have done similar times with 235s all around.

[adrianj73]

Originally Posted by ZDan

Basically, I ran reverse stagger but not necessarily because I wanted to. I was paranoid about stripping lug nuts out so I left the 245s on front and tried the 235/45s in back, and that was clearly the faster setup at NHMS South Oval due primarily to better gearing, but also the more worn 235s at the back of the car felt more stable in the oval turn. I'm sure I would have done similar times with 235s all around.

Dan, I don’t think we’ve formally met, but I was the guy on a crutch standing there with Roe as you came up on the scales.

Blistering times you set that day, I’ll take any advice you have setting up my FRS for COM next season. New driver, long time wrench, so I have a lot to learn.

Do you think the larger rear circumference matters to the ABS? I assume you have VSC disabled, but it would seem the opposite scenario of what would trigger traction control.


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