OPR

[TroyV]

After the event last weekend, as I was packing up the tires, I noticed that the tires that were on the rear had picked up a LOT of other people's rubber. The passenger rear in particular. I'd say there is almost 3/8" of thickness of OPR on that tire, all the way around......and 1/4" or so on the other one. I'd say it was significant enough to change the character of the tire. It would certainly explain why the car was sliding around more on day two than day one. There was some on the fronts, though not as much as the rears. Is this indicative of something I'm doing wrong?

I have had OPR on tires before, but never this much.

Maybe I should go into business, taking corded tires from people and building new tires for them out of OPR.

[breakaway500]

I have pondered the same question...but have no solution. I get a ridge of track snakes all over my front tires on the Atom.You can actually see where the snakes are wearing and the rest of the tire is not,almost like you are riding on a bicycle tire! Going down the front straight at NHMS I could actually see them wrap themselves into a ridge around the center of the tire and would unbalance the tire to the extent of creating a shimmy! However,it did not seem to really make a significant difference on cornering grip,so they must not have a large impact on adhesion.
I'm choosing to ignore opr..unless it hits me in the visor..

[bhoss]

I have the same issue - New Hampshire is the worst, very little pickup at other tracks (The Glen, Mosport,Calabogie). I spend quite a bit of time after every New Hampshire event with a heat gun and scraper cleaning each tire. The only other thing that seems to clean this off of the tires is running them in the cold rain - after a few laps in the rain you can hear the built up rubber starting to unwind off of the tires.

Too much build up and the tire/wheel gets out of balance - also when you start to really lean on the tires for that hot lap you then start to run more & more on this OPR - giving you a very bad feel through the wheel and the seat of your pants.

[breakaway500]

It would be nice to have some sort of rig to scrape the tires clean after an event. Hmm..might have to work on that.Maybe some sort of attachment I could put on my tire machine. I know they shave new tires...why not shave dirty ones?

This is the Rf off my car after time trials..yucko!

Then again,maybe best to keep ignoring it...

[Stynger]

It would be nice to have some sort of rig to scrape the tires clean after an event. Hmm..might have to work on that.Maybe some sort of attachment I could put on my tire machine. I know they shave new tires...why not shave dirty ones?

This is the Rf off my car after time trials..yucko!

Then again,maybe best to keep ignoring it...

Those rocks may have something to do with not shaving

One thing I do is stay on line on your cool down lap, there is a lot less rubber to pick up.
Driving out of the groove, even passing will put you in the junk.

[breakaway500]

Good point about staying on line during the cool down lap.! I will have to remember that.

I guess the rocks would raise hell with a knife edge..

[TroyV]

One day at Devens will clean them pretty well....particularly if I run those tires on the front. The line there changes every event, and the pavement is very rough. I just don't like wasting cycles on the good rubber.

[jlwhorf]

I had some pretty heavy build up on my tires, especially after going out for open track. Now that my line of sight elevation is something like two feet off the track, I see the trouble spots quite well. The entire front straight was covered, so there was little chance of avoiding them.

Jonathan

[breakaway500]

I just tried a sander with 30 grit paper and it actually works quite well.(wear eye protection..) Fills the shop with the sweet aroma of racing rubber too!




I better get back to real work.....

[DanDarcy]

You guys are missing the advantage of "OPR" , its that much more rubber you have to wear off before the cords and more tire life

[breakaway500]

But..it's getting so thick...my final drive gearing changes! I'll be driving around with 30" tall tires in second gear! I gotta say,that stuff is gooey!

[brucesallen]

My experience is that stones and OPR will run off very quickly the next lap on track. But Mark, if that is the right front, you don't have enough negative camber. A tire that is square to the road when cornering will scub off any junk. A perfect camber match and stiff springs are necessary to keep a wide slick square to the track.

[breakaway500]

I have 1.5 degrees of neg camber all around,and measured very even temps across the tire surfaces,with a real tire temp guage on Saturday.I ducked into the pits a few times and checked them. I did have 3 degrees negative all around,and the car felt very twitchy and nervous at speeds over 60mph,and tire wear on the inner shoulders was extreme. I know the formula cars run more camber,but the Atom does not like that much..maybe because of its weight difference?(Atom is 1500lbs) The tires don't seem to pick up junk till the cool down lap.I do tend to go off line during cool down,but won't from now on.

[DanDarcy]

Always drive the "LINE" even on cool down, yellow flag, black flag, what ever --- always drive the "Line"

Although if you get enough stones the tires might wear like rocks hehehehehe
your car does look something like Fred Flintstones just kidding Mark

[breakaway500]

I was pedalling as fast as I could..hehehe! I love the way the Atom looks! I may mount the wings on it for the next outing. Don't know if they really do anything,but they look cool! Maybe they will deflect some of the OPR...