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Discussion Starter #1 (Edited)
We just did a 0-60 mph comparison test of the Bolt with 16" X 6.5" Cruze OEM mags, with the Bridgestone Potenza RE71 205/45 series tires mounted, versus the oem stock wheels and tires. These rims weigh about 19-20 pounds, so may be several pounds lighter than OEM ones.

The results, after several runs averaged, was that we cut the time by better than 0.25 seconds. which is excellent. I figure the difference in times is more important than the actual time obtained, as conditions and cars always differ. Times were taken with an Accusplit timer, which only those who raced in the '60s would be familiar with. Look it up on Google.

We turned off traction control for both sets of runs, to be consistent, but left stability control on. Interestingly, even the OEM tires only chirped a small amount, due to the clean dry concrete highway we tested on, (from a stop light, so no laws were broken, or even stretched) And even with the lower gearing, the Potenzas had more grip than needed, as there was absolutely no trace of wheel chirp.

So, Mr. Tavel, thanks for doing a superb job on the Bolt suspension and handling. We are quite pleased.

On the handling issue, we added a prototype 3/4" hollow tube sway bar to the back suspension, and will be evaluating that at an autocross Sunday. I will try to add a comment here by afternoon. (California time) Preliminary skid pad tests indicate a larger one would probably be better, and the materials are ordered to make the next version.
 

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My math says those smaller wheels/tires lowered the car 1.1" and lowered the gearing 8.6%.
 

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Discussion Starter #3
That is what I was expecting from the size ratings on the tires, but my tape measure on the diameter, etc. only read about 1-7/8" difference, or about .95" ride height.
 

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...

So, Mr. Tavel, thanks for doing a superb job on the Bolt suspension and handling. We are quite pleased.

On the handling issue, we added a prototype 3/4" hollow tube sway bar to the back suspension, and will be evaluating that at an autocross Sunday. I will try to add a comment here by afternoon. (California time) Preliminary skid pad tests indicate a larger one would probably be better, and the materials are ordered to make the next version.
I think you're on the right track tackling the Bolt's AutoX capabilities. Stickier rubber, and rear sway bar. Within the limits of the tires (not great) the stability control does a good job of helping turn-in, but when you throw the car around you can tell that it's set up to push (safer than oversteer) and would greatly benefit from more rear sway bar. Especially noticeable when trying to apply power out of a corner (hint, you can't). At some point I could see adding a bar to the rear as you're doing, so I'm very keen to see how your experiment turns out. I used to have fun turning quicker times in my Focus ZX3 (with SVT bits) than a lot of faster cars in my years of AutoX, I'd love to go back and represent for EV nation.
 

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Is there a tire size that is the same? Your speedometer is probably inaccurate now.
 

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Looking forward to hearing about the rear sway. Usually on an FF car it does wonders.

I am thinking about trying some 16's also.
 

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Took the Bolt out to a local SCCA "winter" AX event here in Colorado last weekend.

About mid-way through the event, some of the organizers came out to measure my car. The Bolt is taller than it is wide; so their insurance apparently won't cover it at AX events (rollover risk). Therefore, it's not eligible to compete. Of course I explained how the battery is mounted in the floor, etc. They let me finish the day, but told me I'm barred from future events.

They said that if the SCCA classifies the Bolt in its national rules, it'll automatically be covered by their insurance as an acceptable car to use for SCCA AX events. Apparently that takes technical analysis of height, weight, center-of-gravity, blah blah.

Until that happens, I'm no longer allowed to run it. Already wrote a letter to SCCA asking them to classify the car...we'll see what happens and where it ends up.
 

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Took the Bolt out to a local SCCA "winter" AX event here in Colorado last weekend.

About mid-way through the event, some of the organizers came out to measure my car. The Bolt is taller than it is wide; so their insurance apparently won't cover it at AX events (rollover risk). Therefore, it's not eligible to compete. Of course I explained how the battery is mounted in the floor, etc. They let me finish the day, but told me I'm barred from future events.

They said that if the SCCA classifies the Bolt in its national rules, it'll automatically be covered by their insurance as an acceptable car to use for SCCA AX events. Apparently that takes technical analysis of height, weight, center-of-graveity, blah blah.

Until that happens, I'm no longer allowed to run it. Already wrote a letter to SCCA asking them to classify the car...we'll see what happens and where it ends up.
Bummer. The Bolt's chief engineer is an avid SCCA racer, so you'd think that would have been in the back of his mind!

Oh, and how'd you do??
 

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Bummer. The Bolt's chief engineer is an avid SCCA racer, so you'd think that would have been in the back of his mind!

Oh, and how'd you do??
Hopefully SCCA makes it right! They already responded saying that they received my letter, and have approved it for processing at their next meeting.

As far as how things went, it was a really fun time -- but man those low rolling resistance tires are like driving on gravel, haha. I was not very competitive. If SCCA classes the car, I'll likely invest in some stickier tires and run it for real next season. Looking forward to seeing a lot of puzzled faces from fellow autocrossers and having a ton of laughs. :D
 

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Want to talk about TALLER than wide.. Remember the "Tango" electric car? That thing used to wreck other car's times at AX. How the heck did they allow that thing?
 

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Bummer. The Bolt's chief engineer is an avid SCCA racer, so you'd think that would have been in the back of his mind!

Oh, and how'd you do??
Hopefully SCCA makes it right! They already responded saying that they received my letter, and have approved it for processing at their next meeting.

As far as how things went, it was a really fun time -- but man those low rolling resistance tires are like driving on gravel, haha. I was not very competitive. If SCCA classes the car, I'll likely invest in some stickier tires and run it for real next season. Looking forward to seeing a lot of puzzled faces from fellow autocrossers and having a ton of laughs.
Yep, I know all about that horrible tire squeal of the OEM tires. =P
 

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Did you try any left foot braking? Does it help promote rotation.. or does the ECU put a stop to those shenanigans..
 

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Did you try any left foot braking? Does it help promote rotation.. or does the ECU put a stop to those shenanigans..
I think I just used my right foot for both. I was a total n00b, so stuck with what I was comfortable with. Ran with TCO off, but stabilitrak on.
Ran in L, but I would put it in D in the future. Slowed down too much in the cicanes.
Here's a writeup of my experience. At least I wasn't last. ;)
https://bro05.blogspot.com/2017/07/autocrossing-bolt.html?m=1
 

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Gotcha, I haven't tried it yet either. I think the car would not allow any throttle under braking anyway. I'll try it tonight if I can remember.

How was the balance? I'm guessing understeery mess like most cars are these days..
 

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Gotcha, I haven't tried it yet either. I think the car would not allow any throttle under braking anyway.
Makes sense since your breaking is regen first before friction. How can I initiate regen if I've asking for acceleration? Unless the brakes switch to friction-only when you're applying the accelerator. Now that I think about it, I think you could still get friction brakes while applying throttle. Seems the friction brakes should always work with regen braking a "nice to have". Friction brakes are a safety feature so regardless if you're mashing the accelerator or if it got stuck "ON" somehow, your friction brakes can be used to stop the car.
 
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Gotcha, I haven't tried it yet either. I think the car would not allow any throttle under braking anyway. I'll try it tonight if I can remember.

How was the balance? I'm guessing understeery mess like most cars are these days..
It was a-plowing!
 
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