Autocross- SCCA EV-X Class vs. SS

[SK360]

Everyone is so pessimistic! We can theorize all we want, but at the end of the day, it's not always pen to paper on how a car performs on course. When I started in ES when street category first came about, I was told the Miata would never compete against the likes of the MR2 Spyder. The Miata was camber limited, couldn't power out as well as the Spyder, terrible at Pro's, etc. Years into the class, I trophied/won multiple national events. Then finally won ES in 17' at Nats and won the Pro champ for the season. Now, I know we're talking apples and oranges here, but I'm hopeful! And, I can talk Bartek(if you know, you know) to drive with me

Now, the talk is there's going to be a big reorder of SS and AS, if that happens, all this talk is moot! But hey, I'm optimistic. Either way, nothings better than just being out there racing.

Looks like 4 of the top 5 at nationals in ES in 2017 were Miata’s. I wish you the best in your quest for sure but there are lots of us that have been working with this car for 4+ years at this point, it’s not like it’s unfounded pessimism

 

[mron]

I definitely believe the car needs to be in BS for it's best possible outcome. AS is an uphill battle, while SS, like it's been, dead in the water. I'm optimistic, but I also am realistic about the scenarios. Either way, it's nice to see the SEB is thinking about the Model 3 and not just leaving it dead.

Yes, ES in 2017 was a good year for the Miata, 3rd place was my co-driver, and 2nd (Matt) although identified as Nebraska region primarily competed in my local Chicago region. Matt co-drove with Chuck Matthews (T10). So a very good year for my region alone.

 

[gearchruncher]

A 4,200 lb sedan, on 9" wheels and super low camber against an M2 CS, Cayman, C7?
More than an uphill battle.... I feel like I do pretty good when I can raw time AS in EV-X trim, much less street trim.

 

[dsgerbc]

Either way, it's nice to see the SEB is thinking about the Model 3 and not just leaving it dead.

So far I'm largely seeing neglect. I've requested a separate line in the SEB comment submission menu for EVX like a year ago. All my EVX-related comments that I tried to submit via SP or ST routes have gone unanswered. Heck, they haven't even bothered updating the EVX-legal list of car to cover 2022 and 2023 model years.

 

[The Other Dan]

I was told today, and haven't confirmed, that the Cayman/Boxster GTS with the 4.0 will be in AS next year.

Aside from that, I didn't sleep at a Holiday Inn, but I finally got a decent alignment. We'll see how it does this weekend on a Tour type course. What is the collectives thoughts on the rear camber? Fine? More?

 

[dsgerbc]

I'm no expert, but to me it looks like a track alignment. For autox, I would (and do) have less rear camber.

 

[The Other Dan]

Last event I was running only about -1.2 and would get a fair amount of oversteer during braking, and a bit on power coming out of corners. Wouldn't have been too bad if it wasn't so unpredictable when it happened. It was also noticeable the difference in tire wear between front and rear.
I since added rear camber arms and the alignment.

 

[Lindenwood]

Last event I was running only about -1.2 and would get a fair amount of oversteer during braking, and a bit on power coming out of corners. Wouldn't have been too bad if it wasn't so unpredictable when it happened. It was also noticeable the difference in tire wear between front and rear.
I since added rear camber arms and the alignment.

I found my car has become pretty neutral with ~2.3ish degrees rear camber and full front camber.

Further, I run 1mm toe out in the rear, plus a heavier rear anti-sway bar at the stiffest setting, to get even more rotation relative to the front. Still, it is pretty neutral and only oversteers on abrupt heavy lift-off or heavy throttle on corner exit.

A bit of rear toe-in, 2.8 degrees of camber, plus the factory rear bar sounds like a tendency for under-steer to me!

 

[The Other Dan]

Thats good to know.
My full set up currently is RW Ohlins with their 11k/13k HPDE Track springs, RW sways at full stiff F/R. MPP FUCA, RUCA, and almost all the MPP bushing they offer. I didn't do the caster adjustable bushing cause I thought it would move the wheel too much and cause rubbing.

On the alignment rack, we did play with rear camber and see just how much toe difference it made with various camber adjustments. Unfortunately that was all based on where I am now and increasing camber. Decreasing would just give me significantly more toe in at your camber amounts.

This weekend will be my final outing before tour in 2 weeks. Considering Bruce will be there, it should give me an idea where the car and I sit, and what needs to change assuming I go to Nats. Which BTW, I've been hearing it's expected to cap out on Tuesday, shortly after reg opens.

 

[dsgerbc]

Decreasing would just give me significantly more toe in at your camber amounts.

I'm at 2-ish degrees of camber in the rear just from lowering, and OEM toe adjustments are enough to zero out the toe +- a bit.

 

[Lindenwood]

Hrmm.

I installed Sport Coilovers and lateral grip has significantly reduced (genuinely 15-20% less lateral grip). It is adjusted a bit lower than before and I only re-zeroed the toe so I could drive it; I am wondering if the increased camber is just a hair too much for the street now.

I really like the way it feels now and I still have a few experiments to run with various camber & damper settings before panicking. But, hopefully I didn’t make a mistake!

 

[gearchruncher]

A 20% grip change is like the difference between all seasons and race slicks. Ate you actually measuring that somehow, or is it a butt Dyno?

 

[Lindenwood]

A 20% grip change is like the difference between all seasons and race slicks. Ate you actually measuring that somehow, or is it a butt Dyno?

I used to be able to comfortably maintain about 57-58mph on the 270-degree off-ramp heading to my job, before the tires started squealing. Now, the Nannie’s start kicking in around 49-50mph.

That is about a 20% difference in centripetal force.

Note 1: the road isn’t perfectly smooth. I still have a lot of experiments to run before I conclude anything, but that fact does make me worry the stiffer coils aren’t compliant enough for imperfect surfaces.

Note 2: with Stock dampers and Eibachs I could do about 53mph before Nannie’s would have to start helping. Going to MPP Comfort Adjustables immediately pushed that to 58mph.

Note 3: these numbers are on my daily all-seasons. With my race tires I run out of courage around 62mph .

 

[dsgerbc]

A 20% grip change is like the difference between all seasons and race slicks. Ate you actually measuring that somehow, or is it a butt Dyno?

I'd guess Hoosiers would give 1.6-1.7g laterally, while top tier all-seasons would probably top out at 1.1g, so, more like 60%.

Losing 20% is still too much, I doubt you're losing that much.

I'm experimenting with 4 degrees of camber up front. It seems a bit much for asphalt lots, since my inner tread gets warmer than outer/center parts. But on a high-speed concrete track tire tread temps are even-ish.

If one lowers too much, it's possible to make the car slower, but making it ride the bumpstops up front, but even then 20% seems like too much.

 

[dsgerbc]

Note: the road isn’t perfectly smooth. I still have a lot of experiments to run before I conclude anything, but that fact does make me worry the stiffer coils aren’t compliant enough for imperfect surfaces.

Ah, just buy 4-way adjustable shocks then

 

[gearchruncher]

I'd guess Hoosiers would give 1.6-1.7g laterally, while top tier all-seasons would probably top out at 1.1g, so, more like 60%.

I realize not a whole AutoX course is traction limited, but you don't see even 50% changes between the fastest car and slowest car at an AutoX, much less that much just due to a tire. There's a reason real tire or handling tests don't just involve a skid pad.

I used to be able to comfortably maintain about 57-58mph on the 270-degree off-ramp heading to my job, before the tires started squealing. Now, the Nannie’s start kicking in around 49-50mph.

It's interesting that you mention squealing before but stability control now. That seems to indicate the car is significantly understeering or oversteering now requiring the active systems to kick in. That could easily be alignment, or it could be you hitting bump stops and basically going infinite spring rate.

 

[Rodney!]

I wouldn't waste time with a street class build on a Tesla JMO. It's pretty dreadful without camber and better springs/bearings.

I wouldn't say it is dreadful, but it does require quite a different mindset and driving style to get the most out of it.

 

[Lindenwood]

I realize not a whole AutoX course is traction limited, but you don't see even 50% changes between the fastest car and slowest car at an AutoX, much less that much just due to a tire. There's a reason real tire or handling tests don't just involve a skid pad.


It's interesting that you mention squealing before but stability control now. That seems to indicate the car is significantly understeering or oversteering now requiring the active systems to kick in. That could easily be alignment, or it could be you hitting bump stops and basically going infinite spring rate.

To be clear, it was about 1” lower than stock on the Comfort coils, and is now about 1.3” lower. I will triple-check but I set all toe to zero.

I mentioned the squealing because with the Eibach coils, the suspension couldn’t keep the tires evenly on the ground, resulting in intermittent traction loss with minor road undulations. Going to the Comfort Adjustables, with no other alignment changes, the tires stayed planted so I could consistently and comfortably maintain my line up to the tires complaining. Now, with the Sports, I am back to the tires not seemingly being controlled evenly on the ground, so I can’t help but wonder if it is too stiff for my imperfect conditions.

Really, I am looking for some specific recommendations as a starting point (I.e. reduce camber if lowering it increased camber significantly, damper settings that have worked well on imperfect roads, etc).

 

[dsgerbc]

When did you add a stiff rear bar? Was that before the Sport coilovers?
I think I do get those weird TC notices on the street during bumps while cornering, and I think those started when I added stiffer rear bar, not when I went with hpde springs.

 

[Lindenwood]

When did you add a stiff rear bar? Was that before the Sport coilovers?
I think I do get those weird TC notices on the street during bumps while cornering, and I think those started when I added stiffer rear bar, not when I went with hpde springs.

The bar has been on for months, since before my last road course track day. At that’s event, I let two instructors drive my car and both remarked specifically at its balance, predictability, and overall lateral grip. I even asked if they had any recommendations to suspension changes that would help reduce the instability under high-speed braking, and the only think they recommended was maybe stiffer bushings / bearings, or aero if I wanted to get real hardcore (hence my wing ).

The only change I have made in 8 months was the FLCABs about 6 months ago (and I could feel the positive benefits), and now last weekend’s swap to the sport set. Perhaps it is a bit over-sprung in the rear with both the sport coils and stiffer rear bar, but I am reticent to blame the bar entirely.

Just verified Toe is 0/0, but camber did go up a bit in the rear.
Front: 3.2 & 3.4
Rear: 2.3 & 2.6