Autocross- SCCA EV-X Class vs. SS

[RacerChris]

Interesting thought. Thought I had checked this before, but worth a very close look again.

I'm running some fat yokes right now and was running some fat Falkens and have not experienced that. Have you looked to see if there is even minor fraying, rubbing, exposure on your wheel speed sensor wire? Is the sensor secure in the hub? My car had that behavior when my wheel rubbed through the wheel speed sensor...There was no coming back though (till I replaced the sensor).

 

[dsgerbc]

What's the verdict, do EV-X rules allow only one set of adjustable arms in the rear (camber or toe) but not both camber+toe?

 

[superflyrolla]

You can do both arms. I suggest reading the SCCA solo rulebook.

I don't think the traction control errors are speed sensor related. I've checked mine 100 times and it's back to normal after exiting/re-entry. Happened more on Hoosiers than anything else, if you're running A052s then you're on something super sticky as well. I've had errors occur less with the latest party box software, but I can't verify that's really the reason.

 

[gearchruncher]

I don't think the traction control errors are speed sensor related. I've checked mine 100 times and it's back to normal after exiting/re-entry. Happened more on Hoosiers than anything else, if you're running A052s then you're on something super sticky as well.

Yep, I'll double check everything, but this is where I am too. It's happened 10+ times, never once on the street, always resets when I get out/back in. I really don't see how damage could be so reliably intermittent.

Got an AutoX this weekend, gonna check the wires and then try a different wheel config and see if it changes anything.

 

[dsgerbc]

You can do both arms. I suggest reading the SCCA solo rulebook.

I did.

1. On double/unequal arm (e.g., wishbone, multi-link) suspensions, only the upper arms OR lower arms may be modified or replaced, but not both. Non-integral 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, changed, or modified.

We have a multi-link setup in the rear. Technically the camber linkage is upper, and the toe linkage is lower. Why does this part not prohibit having both?

The same rule is in place for ST and SP classes, so there must be an interpretation out there.

 

[superflyrolla]

Ah I see your point. Sorry, I assumed.

 

[dsgerbc]

I guess technically this part I quoted is under 'camber kits,' but the toe arm is not a camber kit and hence allowed?

 

[gearchruncher]

Glancing around the internet, there seems to be the same question with other platforms. Replacing both a toe and camber arm seems questionable. Some think it's OK as long as the toe arm uses identical geometry except length change. Others not at all. There's also an issue with the arms you pick, as they have integral bushings, and bushing changes are also limited:

If the standard bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts

That said, are you running in a super competitive group and do you expect to be at the top? If not, then basically nobody cares around stuff like this. The other side is that you don't really need toe arms in the back unless you are running really interesting heights/cambers. If you wanted the toe arm for the bushing, well, there's your answer

 

[dsgerbc]

and bushing changes are also limited:

This quote seems to be from the ST rules, and isn't present in SP and EV-X rules, so I assume toe arm/camber arm/FUCA bushings found in MPP/RW/UP products are fine.

The latest Fasttrack appears to feature a proposed rule change just to the ST category somehow, even though the SP language is currently identical. And it still does not clarify the issue, since those are still nested under 'camber kits.'

That said, are you running in a super competitive group and do you expect to be at the top? If not, then basically nobody cares around stuff like this. The other side is that you don't really need toe arms in the back unless you are running really interesting heights/cambers. If you wanted the toe arm for the bushing, well, there's your answer

I'm contemplating making it to some national tour events or the Nats at some point. And if I go that route, I'd attempt to fit 305-wide Falkens, which will require plenty of rear camber and necessitate toe-correction arms. Hence the question.

 

[SK360]

Like most SCCA rules they seem out of touch with reality and most people aren't fully class legal anyway, I ran a short throw shifter for years in SS/AS in my C7. lol.

 

[Zextraterrestrial]

@gearchruncher I had some issues when I was running one of my bigger sets (275 Nexen or 295 Hoosiers) - did have a frayed speed sensor but cut and cleanly spliced it. After that I only had a couple of runs where it had problems still but then nothing after that one day of auto x....was a bit worried as I was heading to an enduro and hill climb season. no problems since April fortunately.
W/no regen auto X is super tricky, the need to brake tap so awkwardly through runs is a PITA. can't float through slaloms with regen & any throttle tap is too much and needs left foot counter. extra 'fun'

 

[gearchruncher]

W/no regen auto X is super tricky, the need to brake tap so awkwardly through runs is a PITA. can't float through slaloms with regen & any throttle tap is too much and needs left foot counter. extra 'fun'

My issue wasn't the lack of regen when whatever is happening to me happens. When it happens to me, the first thing that happens is TC turns off and the car goes totally unstable, spinning one or more wheels. Then after I back off the power, the car highly limits power for the rest of the run. The power limit is clearly tied to steering wheel angle. Acts like a 100HP car with any real angle turned in, and then it has some sort of delay from going wheel straight to delivering maybe 350HP instead of 500. It's this lack of power that really eats into my times.

It does seem like both grip and diameter are possible issues here. Interesting. What is everyone running as their wheel config? (I'm set as zero g)

 

[SK360]

19x10 +35 265/35/19 RT660. Never experienced anything close to that.

 

[superflyrolla]

Yeah I'm not losing power, just losing regen and it's rare. I have had "front motor disabled" errors after autocross runs but that was a different issue. I'm usually using the 18" wheel config. I have also questioned if it's something with tires under 26" diameter, but MPP has told me it is not.

At least two of the three Model 3s in ASP at SCCA solo nationals last year had both rear camber and toe arms, so I'm not saying it's legal but they're doing it. Now none of them finished near the top of the class so like you said maybe no one cared.

 

[dsgerbc]

Point taken, chances are nobody's gonna care what I have
Off too order more stuff before it gets more expensive...

 

[MasterC17]

My issue wasn't the lack of regen when whatever is happening to me happens. When it happens to me, the first thing that happens is TC turns off and the car goes totally unstable, spinning one or more wheels. Then after I back off the power, the car highly limits power for the rest of the run. The power limit is clearly tied to steering wheel angle. Acts like a 100HP car with any real angle turned in, and then it has some sort of delay from going wheel straight to delivering maybe 350HP instead of 500. It's this lack of power that really eats into my times.

It does seem like both grip and diameter are possible issues here. Interesting. What is everyone running as their wheel config? (I'm set as zero g)

Curious what tire and size you are running? I've kind of always preached for staying within 2% of the stock heights (26.3" - 26.8"). So, anything between 25.8" and 27.3" should be OK, though if you can select something closer to stock heights that's obviously preferred.

 

[gearchruncher]

Curious what tire and size you are running?

275/35R19 A052's. Published diameter by Yokohama is 26.6"

 

[MasterC17]

275/35R19 A052's. Published diameter by Yokohama is 26.6"

Interesting, if it were me I might try replacing the wheel speed sensors one at a time and seeing if the concern changes. The tires shouldn't be the root cause.

 

[gearchruncher]

Interesting, if it were me I might try replacing the wheel speed sensors one at a time and seeing if the concern changes. The tires shouldn't be the root cause.

The reason I doubt it's the wheel sensors:

I ran hundreds of runs on 265 RE-71's and 265 PS4S's and never had this error before.
I changed to A052's and on the third run had this issue. It now happens every ~10 runs over multiple venues.
I've run 50+ runs on PS4S's since, 4K street miles on the PS4S's, and 300 street miles on the A052's, with no issues.
It only happens in very high power, turning, possibly slightly sliding conditions
It's happened turning left and right

 

[MasterC17]

The reason I doubt it's the wheel sensors:

I ran hundreds of runs on 265 RE-71's and 265 PS4S's and never had this error before.
I changed to A052's and on the third run had this issue. It now happens every ~10 runs over multiple venues.
I've run 50+ runs on PS4S's since, 4K street miles on the PS4S's, and 300 street miles on the A052's, with no issues.
It only happens in very high power, turning, possibly slightly sliding conditions
It's happened turning left and right

Not to be contrary, but is it possible that the wider tire is making slight contact with a wheel speed sensor? I obliterated both front wheel speed sensors when I moved from a 275 to 295 because I totally forgot to zip tie them back. But, I've killed one before on 275's too. Just seems odd, I didn't have that problem with the A052's.