Mach 1 as a dual purpose street-track car (DE)

[VictorH]

If there's one downside to Apex wheels it's that sometimes the tire does not seal. It may be just a Michelin thing but I've had it with the VS-5 wheel and Michelin PS4S with 3 out of 4 wheels and now only one (thankfully) of my SM-10s with new Michelin Cup2 tires (no road use at all). I'm almost certain it's the knurling on the bead surface of the rim. The fix is to unseat the tire and apply some black sticky goop, to the bead surface, which seals up the leak (It leaks out of the side of the tire by the bead if you put the wheel under water).
The VS-5 had a very coarse, aggressive knurl. The SM-10 is much smoother but evidently, not quite enough for some tires.
(wheel picture is just a demo, no spacer on it)

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[Turbeau]

How bad do they lose air? Are we talking days or hours? I’m mounting mine next week with cup 2’s (SM-10RS). Preemptive goop application recommended?

 

[WItoTX]

Those SM-10RS look so good. That is going to be my next set.

I've never had that leak issue with any tires I've mounted on my VS-5RS. Make sure the tire guy gets all the tire lube out, and sprays hairspray on the knurling. It also looks like the tires are stretched a lot. I didn't dig through your thread, but what size tire and rim?

 

[VictorH]

Air loss is highly variable. Worst wheel was 2 psi per day, slow leakers lose 1 psi per week. Needless to say, pretty annoying.
The SM-10 wheels were mounted on Feb 6th and were pumped up to 40 psi, today (I hadn't checked them since mounting) today is at 14 psi.
Maybe next time maybe we can try the hairspray trick. I trust my tires guys, they are super experienced but for some reason these wheels have given them some fits.
Not sure what the brand of "goop" is but it seems to be a common tire shop supply item, it's s very soft, rubbery substance that's easy to rub off but is effective for sealing the tire. Might not be a bad idea to have them apply preemptively.

Wheels are 19x11 with 305/30/19 tires.

 

[VictorH]

Mounted and torqued. Camber is -3.5 degrees. Really good wheel and tire fit.
Toe set to 0.0, this is my track set-up.

 

[VictorH]

Missed my VIR event in March due to some suspension mechanical issues of my own doing.
Today ran CMP (Carolina Motorsports Park, Kershaw, SC) with BMW club. Only 23 of us which makes for plenty of space on track. Weather was perfect, but the Eclipse was not that impressive where we were.
Ran my PS4S tires as I didn't want to wear down my new Cup2s.
Set up was -3.5 neg camber front, -1.8 rear, front sway far, full-firm last hole in adjustment and Eco-Boost rear bar.
Some of you may remember me complaining I couldn't get the car to rotate with the brakes I'm sure it was probably mulit-factorial including a driver component too. My solution which some forum members didn't like was to stiffen up the rear, now 345 front and 1200 rear.
As it relates to rotating with the brakes, I'm back in business and car does what I want it to do in the corners with trail braking (some people call it turning with the brakes). Rear grip over bumps and corner exit is still excellent.
Also, the overall ride comfort is perfectly good, the rear is not too stiff, it's firm, but not really any different than my BMW was, so still fine. Stock Mach 1 is sooo soft. Still love the car, run all day, then head home, seat coolers on, stereo on and enjoying life.
Next up, Ozarks International Raceway.

 

[shogun32]

My solution which some forum members didn't like was to stiffen up the rear, now 345 front and 1200 rear.

Hey if it works for you then it's right, even if it's wrong.

Source of the 345 front?

 

[M1N]

Heading to Las Vegas speedway, outer track, on Friday with the Shelby Bash. First time running that track. We usually go to Spring Mountain Racetrack which I really like, but they changed it up for this year. Always a great group of people at the event.

 

[shogun32]

Does the event provide the number plates?

 

[Biggsy]

Missed my VIR event in March due to some suspension mechanical issues of my own doing.
Today ran CMP (Carolina Motorsports Park, Kershaw, SC) with BMW club. Only 23 of us which makes for plenty of space on track. Weather was perfect, but the Eclipse was not that impressive where we were.
Ran my PS4S tires as I didn't want to wear down my new Cup2s.
Set up was -3.5 neg camber front, -1.8 rear, front sway far, full-firm last hole in adjustment and Eco-Boost rear bar.
Some of you may remember me complaining I couldn't get the car to rotate with the brakes I'm sure it was probably mulit-factorial including a driver component too. My solution which some forum members didn't like was to stiffen up the rear, now 345 front and 1200 rear.
As it relates to rotating with the brakes, I'm back in business and car does what I want it to do in the corners with trail braking (some people call it turning with the brakes). Rear grip over bumps and corner exit is still excellent.
Also, the overall ride comfort is perfectly good, the rear is not too stiff, it's firm, but not really any different than my BMW was, so still fine. Stock Mach 1 is sooo soft. Still love the car, run all day, then head home, seat coolers on, stereo on and enjoying life.
Next up, Ozarks International Raceway.

Just to confirm you settled on full stiff front bar and full soft rear ?

 

[M1N]

Yes they do. We put them on a magnet sheet so we can use them again.

 

[VictorH]

Front and rear springs are Eibach coil-over springs. They are from AJ Hartman front coil-over kit and Mike Maier rear coil-over kit. Fronts are actually 325.

Yes front bar is full-stiff, rear is non-adjustable "soft" rear bar.

For my style of driving and tracks I run, I think I have a set-up now that fits me really well. My main goal was to still maintain full street driveability as though I run a few events per year, still more than 90% of my miles are street miles.
There was plenty of fancy hardware at this event, the only car that was clearly better in the corners was the Porsche GT4 running some sort of Falken track tire. Most of the other cars were also on street tires, lots of Michelin PS4s and then most of the M4 CSLs were on Cup2 tires (which probably should have been better than me, but their drivers were pretty conservative). I was definitely getting smoked on the straightaways though.

 

[VictorH]

Couple pictures of the wear items.
Front rotor, yes they got hot but still run completely consistent from beginning to end of session.
Left front tire, the one that has the most abuse. Looks pretty good to me, 6, 20 minute sessions.
Cold pressure 31, hot 37, seems to be pretty good happy medium.

 

[TeeLew]

Hey if it works for you then it's right, even if it's wrong.

Source of the 345 front?

Exactly. Just because *I* like something doesn't mean that *you* will. There is no single 'correct' answer to chassis tuning. There are a series of compromises which need to compliment the driver.

 

[VictorH]

For those of you who are track junkies, would like to point out these AJ Hartmann brake deflectors. Firstly, I think they have NO utility for street only cars and you're not going to see the carbon fiber as it's obviously under the car.

This CMP track, which used to be home base for me and has never been my favorite in a heavy car, i.e. M3 or Mustang as it has a reputation for eating up brakes and tires. It's very brake heavy track and if you're not careful you can boil you fluid and turn your brakes to mush.
Lots of the cars coming off track had rotors that had heat waves coming off them like Pizza ovens and lots of them were cracking and popping so several minutes afterwards.
Now, my brake were running pretty hot too, wish I had brought my IR temp gauge but even though I probably had the heaviest (M8 was there and that's heavier) car, my sense is the brakes never really got super hot (definitely never popping and didn't see any heat waves coming out from under the fenders).
I think these deflectors are effective. At VIR or RA it's usually not an issue but at CMP you always have to worry about your brakes. Now in retrospect, the brakes were great with no issues at all. Again, this would be a recommendation for track guys only where having the best cooling possible without dedicated ducting, I think this is the next best thing.

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