AX Video, CVR PCA 05/22, I got beat, my car got beat up Options

[mskala]

First AX of the year for PCA's in the northeast. This one was new to me,
Plainfield, CT dog track parking lot. WAY too bumpy for me, I thought for
sure I was going to break something.

Finished second (of 2) 914's. I'm not used to the lower-speed really
tight course like they had. Small turnout since weather was iffy.

CVR 05/22 In-car + Wheel cam

Anyhoo, here's the video of my best run (basically where I didn't make a
huge mistake on either of the slow corners).

Looking at how much the tire moved on the rim scared the crap out of me!
I guess this is why I had small rubbing on the inside fender well even
though it looks like I've got good clearance.

[Jeroen]

very cool vid!
amazing to see those tires working

[ChrisFoley]

Very cool!
I would love to have a second camera in my race car.

[mskala]

Chris,
I'm sure we could find a time where you could borrow my equip
for a race. Roll-bar mounts make it easy. You could see the
people behind you for a change!

[Aaron Cox]

awesomne to watch the tire movement about the rim. very cool!

[jhadler]

Great footage! Randy's camera package has become a big seller... :-)

One thing this does highlight is that wider tires on narrower wheels will get this kind of flexing. I'm going to take a wild guess and say 225/50-15's on 7" wide wheels? You'll be amazed at the difference even an extra inch of wheel width makes with the same tires. The wider the wheel, for a given tire size, the less sidewall flex you'll get under transition and load.

Excellent video, way cool!

-Josh2

[mskala]

QUOTE (jhadler @ May 23 2005, 04:16 PM)

One thing this does highlight is that wider tires on narrower wheels will get this kind of flexing. I'm going to take a wild guess and say 225/50-15's on 7" wide wheels? You'll be amazed at the difference even an extra inch of wheel width makes with the same tires. The wider the wheel, for a given tire size, the less sidewall flex you'll get under transition and load. Excellent video, way cool! -Josh2

Thanks for reminding me, I should have said, these are
Victoracer 205/50 on 6" cookies. I was running about
29psi in them. They feel so much stiffer than my street
tires did.

I remember seeing a couple other wheel videos that
didn't show that amount of flex, but I think they might
have been street rubber at very high pressure.

I know this size is pushing the limit of the 6" width, but
I wasn't about to try 7's because all the extra width is
on the outside and 6's were close before I put in some
serious camber.

[Thorshammer]

Nice video,

One observation is the tire sidewall flexing, but also a relative observation of side slip. It is very normal to see the amount of deformation you see in this video. Even with slicks. Something for thought would be a relative vertical line in which to judge body roll. And also a graduation that will be viewable in the forward part of the fender to see travel. I would love to have this in my car for a weekend. Mounted vertically you could look at camber change and trailing arm flex, that would be cool. I would be a lab rat if you wanted to come to Lime Rock.

Erik Madsen

[crash914]

Wow Mark, cool video....

that was a very dirty lot....sounds like a lot of rocks everywhere....

I think that I would add a few # of air....perhaps try 32? I think that grassroots or tirerack has some specs about slip angle...perhaps you can determine if yours is excessive or not...

re-thinking that....I did not see any slidding around or understeer..you just got to push harder!!!

[davep]

Wow, that is interesting. Looks like, for that course, you need a higher ratio steering rack.
About 1/2 turn lock to lock might do! (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)

[mskala]

Erik, PM or email me.

During the first couple runs it looked like it was snowing there was
so much gravel coming up. I did plenty of understeer, just not as
much on this run, so better time. I'm going to upload another run
where I did quite a bit of oversteer, which is still not easy at these
speeds with my lack of power.

This course was a last-minute kind of affair. The first setup had
the slalom cones like 20 feet apart. The test boxster couldn't
physically make it through (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[mskala]

Okay, here's one with oversteer. Second camera goes out
for about 3 seconds, though.

run 4 CVR 05/22

(IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[blabla914]

Mark,

That is awesome video. Don't be worried about the tire deformation. I run 205-50-15's on sevens and I have still pictures of my car with a lot more tire deformation than that. I would imagine you see a lot more deformation when you run at devens as that surface actually has a little traction. The condition of that lot really disappointed me. It gets a lot of sand run off from the road during the winter. I thought we were going to address that. The course layout was entirely my fault. Our courses are not usually that tight. Since our usual course people were trying desperately to get the timer working I got to setup the course, which I have never done before. I wanted to be as fair as possible and not "test drive" the course myself. I was also trying to avoid the areas with LOTS of sand and rocks and keep it safe. Let's just say, that course was not exactly what I had in mind. I now have the timing equipment and I'm trying to make it work. So far it's not going well. I hope you'll come out and run with us again once the lot gets cleaned up and the timer is working. I'm looking forward to coming up and running with you at Devens this summer now that my car seems reliable.

Kelly