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      09-10-2014, 09:55 AM   #1
krx927
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Marbles on the tires and tire performance

Last time when I was on track I was very nice on my cool down laps and was getting away of the racing line for fast cars behind me. What a mistake as I collected so much marbles on the tires it was unbelievable.

The rears clean them selves quite OK and fast but I could not clean the fronts.

Anybody has some nice method? Or you just put the fronts in the back?
I tried with aggressive under-steers but a few of them did not make any difference.

In your experience do marbles degrade the grip a lot when your tires are full of them?

I really cannot say for my self based on the last time I had them. My car was sliding around like crazy the most part of the day. I was really dissapointed with Michelin sport cups. It was only 3rd track day that I used them and there was not grip (on previous 2 days they were just great!).
At first I thought the marbles are the fault, but then I discovered that my engine oil cap was leaking and I had full engine bay + right wheel arch sprayed with oil. Just terrible, really bad spill! For sure my sliding was caused by all the oil dropping from the engine
And I was playing the whole day with tire pressure trying to fix it
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      09-10-2014, 11:11 AM   #2
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I'm confused - did you ask if you should swap the front tires to the rear to clean them? Why wouldn't you wash them off if you have the wheel off the car? Most of them will fall off if you simply run your hand across them... or a hose. You may need a plastic scraper to get some of the stubborn ones off.
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      09-10-2014, 11:31 AM   #3
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      09-10-2014, 02:11 PM   #4
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Yup. When I pull off to dismount the wheels after the last session the tires are usually warm enough where you can brush off the marbles with your hands.
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      09-10-2014, 02:43 PM   #5
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This happened to me my first time on r comps. Here are some suggestions.

You shouldn't be offline unless you have a mechanical or something like that. Point faster cars by and they are supposed to go offline to take the pass.

Secondly, If OP has collected marbles on the surface of the tires, this can't be washed off. If you drive fast enough it should just come off. If not, you may have to scrape them. Hard to tell what you're talking about without pics. You can move them to the rear assuming you are running a square setup ie same size wheels and tires on all 4 corners.
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      09-10-2014, 03:40 PM   #6
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Think he's talking about the tire surface not the barrel. Won't just wash off.
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      09-10-2014, 04:51 PM   #7
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Sorry I was not clear and perhaps I used the wrong word. I was talking about the bits of tires that are lying off the racing line. Not stones and other (hard) debris.

Those glue on my tire surface and some of them are impossible to remove. The only thing that help is some wheel spin...

On my last track day I managed to remove some of them (while the tires were still hot) with the screwdriver. Perhaps really some plastic scraper would be better, but I did not have it. Unfortunately I was not able to remove all. Now when cold = mission impossible.

Like I said the rears cleaned them selves pretty good but fronts are still full of them.

On my previous track days the situation was not so bad and I did not collect so many. But last week I was in Spa Franchorcamps a week after F1 race and the track was full of them. My tires were really bad after I went of racing line
It was unbelievable, I went of line and suddenly I hear/feel something hitting my tires, BANG! After that they started shaking and making terrible noises. I thought I have a puncture. I immediately went to the pits to check. Luckily it was only tire debris...

I hope you can give me some suggestions...

I will also repeat the other question, in your experience how much worse is the traction in you opinion when your tires are full of them?

To throw in one more question about Michelin sport cups: before I bought my track wheels and tires I was reading a lot and deciding which to choose. At the end I went for Apex ARC 8 (18x9.5 square set up) and MSCs as I cannot get Nittos in Europe. I was reading that MSCs should be good until they are bald.
Can any of you confirm this?
The point is that I am not 100% sure only dripping oil was causing bad performance. I am afraid that also tires are giving up. I have half of the tread left, aprox. to that markings that are showing you legal tread limit and they look quite "tired" (some areas near grooves are quite bad and melted).
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      09-10-2014, 04:57 PM   #8
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Quote:
Originally Posted by M3 Esq View Post
You shouldn't be offline unless you have a mechanical or something like that. Point faster cars by and they are supposed to go offline to take the pass.
How true!!! I just did it once. After that I left them overtake on the dirty line - lesson learned.
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      09-10-2014, 05:23 PM   #9
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Your right, if you pick them up you will experience significantly reduced traction due to all the different compounds on the tires.

You can heat them up with a heat gun and scrape off the rubber with a chisel if really bad. The race teams use blow torches.

Next time if you go offline and pick them up you will feel vibrations, that's normal. Do a few good hot laps and it should all come off.
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      09-11-2014, 12:58 AM   #10
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Drive a couple of miles at 70mph or more in the rain and all the rubber pickup on your tires will be gone.
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      09-11-2014, 08:11 AM   #11
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Thanks for the proposal. I will try them out.
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      09-11-2014, 09:33 AM   #12
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I for one find it hard not to be offline at certain points on the track. I run different line than some and it just means I have to deal with a little vibration.
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      09-11-2014, 09:44 AM   #13
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Quote:
Originally Posted by 1MOREMOD
I for one find it hard not to be offline at certain points on the track. I run different line than some and it just means I have to deal with a little vibration.
Plus the pit in at The Ridge is off line........you pick up marbles there.
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