Autocross- SCCA EV-X Class vs. SS

[SK360]

Two SCCA Members Pass Away from Incident at Packwood ProSolo

The Sports Car Club of America® is saddened to announce the passing of two Club members — Amber Dawn Jorgensen and Des Toups — following an inciden...

www.scca.com

Sorry for everyone’s loss that knew them and were there. It was a very bad weekend for amateur motorsports.

 

[dsgerbc]

Oh wow, not the kind of thread updates I was hoping to read.
RIP.

 

[The Other Dan]

Well, on a more pleasant note, found out my car is faster than me. Altho, isn't that usually the case? Dallas ran the Pro in my car and was fastest in PAX of the group by a couple 10ths after the first day. The group included the Tsangs in their STU Subaru. I believe he was something like 5th in pax overall including some of the BMs.

We ran SoloStorm on Sat afternoon to compare data. As I'm sure it was predicted, he was on the accellerator sooner and as a result carried more speed thru some sections. Also watched back to back camera footage and was able to see some areas of improvement I need to work on.
Unfortunately and obviously, Sunday runs didn't happen.

As of today, as I'm writing this, there's 1 Packwood event left before tour. We'll see if that allows me to practice enough to be competitive at Nats.

 

[dsgerbc]

And I'm getting worried about the car making it to the Nats at all. Another high-speed "autocross" (logged getting up to 90mph on day one of two, wtf), and my steering is crooked again after it. After I tightened everything I could think of. Few explanations left other than my steering rack being f'd up somehow. Gonna reach out to MPP and Redwood to see if they have any ideas.

 

[The Other Dan]

Have you tried doing the "recalibrate steering angle" thing thru the service tab. Or you think this really is more of a overall mechanical issue?

 

[Lindenwood]

I have occasionally seen the same issue. A few weeks of running hard and suddenly I’m off-center again.

However, every time I think about re-calibrating steering center, I genuinely can’t think of a reason to do so. Either the steering is mechanically centered or it isn’t. Even on autopilot, the car will happily run the wheel several degrees of center all day to stay in the lines.

 

[dsgerbc]

Have you tried doing the "recalibrate steering angle" thing thru the service tab. Or you think this really is more of a overall mechanical issue?

Definitely mechanical. I marked every bolt and suspension piece/location last time around. From the ones that I can see, everything is in the same place, except the springs have rotated a bit (which would be related to the issue, not sure). Gonna have to pull the frunk/skid plate to look at other marks on suspension/steering rack mounting bolts during the week.

I did reset the learned steering offset after the event to see if the car would track straight with hands off the steering wheel w/o that offset applied. It did.
Front toe also changed this time (it barely changed after the previous event), picked up like 0.4 degrees of toe-out from a slight toe-in before the event.
All cambers are as they set them, and the rear toe is the same too.

 

[dsgerbc]

However, every time I think about re-calibrating steering center, I genuinely can’t think of a reason to do so.

To check if the issue is in the front or in the rear. W/o the offset applied, letting go off the steering wheel will center it due to self-aligning torque from having positive caster. If it tracks straight then (provided that front right/left camber and caster angles are reasonably similar), the rear is fine and the thrust angle is reasonably close to zero. So the issue is likely the front toe .

 

[Lindenwood]

To check if the issue is in the front or in the rear. W/o the offset applied, letting go off the steering wheel will center it due to self-aligning torque from having positive caster. If it tracks straight then (provided that front right/left camber and caster angles are reasonably similar), the rear is fine and the thrust angle is reasonably close to zero. So the issue is likely the front toe .

So, if the steering zero is off, the car will electro-mechanically center to where it thinks the steering wheel is at “zero,” even if there are uneven mechanical forces (from caster)?

 

[Dallas J]

Well, on a more pleasant note, found out my car is faster than me. Altho, isn't that usually the case? Dallas ran the Pro in my car and was fastest in PAX of the group by a couple 10ths after the first day. The group included the Tsangs in their STU Subaru. I believe he was something like 5th in pax overall including some of the BMs.

We ran SoloStorm on Sat afternoon to compare data. As I'm sure it was predicted, he was on the accellerator sooner and as a result carried more speed thru some sections. Also watched back to back camera footage and was able to see some areas of improvement I need to work on.
Unfortunately and obviously, Sunday runs didn't happen.

As of today, as I'm writing this, there's 1 Packwood event left before tour. We'll see if that allows me to practice enough to be competitive at Nats.

Turns out more throttle is faster

Was pretty how well balanced through transitions the tesla is. My only complaint is not getting any power when the wheel is turned too much. Really cuts into ability to dig on tight bits.

 

[dsgerbc]

So, if the steering zero is off, the car will electro-mechanically center to where it thinks the steering wheel is at “zero,” even if there are uneven mechanical forces (from caster)?

I *think* the car learns how much steering is needed for the car to track straight, and then automatically applies that much when there's no force is applied to the steering wheel by the driver.

 

[gearchruncher]

In my experience, the car doesn't learn force to apply- it learns the center of the power assist. In other words, at what angle it should give no assist to in either direction.
Without this, the power steering will actively add to a bad alignment, as it will pull you away from "straight"- with straight defined as the car going straight down a lane, not the steering wheel.

 

[superflyrolla]

Which reminds me: what's the consensus, rear camber+toe arms = potentially protestable in EVX? I'm thinking I could use more rear camber for higher-speed national courses, But I don't want to lower further to get that camber.

I still don't think this is clear.

Legal argument:

1. The control arm rules are listed under "camber kits." The toe arm is not a camber kit.
2. "longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s) of a multi-link suspension) may not be replaced" The toe arm does not control "longitudinal motion" (across the wheel). Looking straight at it, it's moving up and down only, unlike the trailing and traction arms.
3. "only the upper arms OR lower arms may be modified" Camber arm is at the top and toe is in the center. Maybe it's a stretch, but they both could be upper arms?

If you can't tell I hate adjusting toe with that cam bolt ha.

 

[dsgerbc]

I still don't think this is clear.

Legal argument:

1. The control arm rules are listed under "camber kits." The toe arm is not a camber kit.
2. "longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s) of a multi-link suspension) may not be replaced" The toe arm does not control "longitudinal motion" (across the wheel). Looking straight at it, it's moving up and down only, unlike the trailing and traction arms.
3. "only the upper arms OR lower arms may be modified" Camber arm is at the top and toe is in the center. Maybe it's a stretch, but they both could be upper arms?

If you can't tell I hate adjusting toe with that cam bolt ha.

I have no clue how protests work at the Nationals. Do they follow "what's not specifically prohibited is permitted" motto, or make up common sense rules if they have to? A similar ruleset for the ST category specifically says one link per corner in 14.8.H.7, so the issue has already been discussed/settled for other cars. The EVX rules PDF hasn't been updated in a couple of years.

I did try submitting this very issue for clarification to the SEB. Since there was/is no EVX category to select in their submission menu, I tried routing it through the ST class committee, and haven't heard back in like 8 months now.

Technically, both MPP linkages will change camber :/

Personally, I don't anticipate being in position to protest/to be protested, so, it's all theoretical.

 

[Dallas J]

In EVX or any other classes, if it doesn't say you can then you cant. In CAM/XA rules things open up with much more generic statements like drivetrain is unrestricted.

As Im reading through the EVX and ST rules, neither specify that Toe arms can be changed but ST does have this rule

14.7. On multi-link suspensions only one lateral link or arm per corner may be modified or replaced. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s)) may not be replaced, changed, or modified.”

This would allow a toe arm as long as the one allowed lateral link isn't used already used for camber via upper/lower arm. That rules is absent from the EVX rules basically limiting things to ONLY the upper or lower control arm. No rule grants a change to the Toe arm as far as I can tell.

 

[dsgerbc]

Had an event today on 25" diameter tires on pretty grippy concrete. Uneventful as far as traction control/errors go.

 

[Rodney!]

Had an event today on 25" diameter tires on pretty grippy concrete. Uneventful as far as traction control/errors go.

How was acceleration compared to the 26.3'ish OEM diameter setup?

 

[dsgerbc]

My butt dyno isn't sensitive enough.

 

[Lindenwood]

My butt dyno isn't sensitive enough.

I am also curious. Do you happen to have a Dragy?

 

[dsgerbc]

No I do not. I may invest into Solostorm with a GPS module at some point.