14 replies to this topic

[ray b]

If a car oils track it is black flaged.
but tire marbles allso cause unsafe condision and limit
passing off line.
I have never seen marbles on a street from street tires,
is there a way to ban tires that cause marbles in racing
to increase passing and safety. ray

[Bluehair]

I once commented that the FIA should "squeegy" down some rubber (NHRA style) just outside of the traditional racing line to aid traction for cars wishing to pass. I think if the cars were encouraged to take a variety of lines through the corners, marbles wouldn't build up so badly. This is one way of increasing mechanical grip that I never hear any mention of. A more expensive alternative would be to make the outside portion of the corners concrete rather than asphalt. Concrete, while causing faster tire wear, would provide better traction for deep braking and outside passing lines.

[ray b]

I am afiraid concrete would cause more marbles,
but extra grip in unused part of track good idea.
extra wide track good but at a cost of traddisional
lay out of track.
with more than one manafacture in race maybe harder
to limit marbles.lost chance now with 2 in this year.
why do marbles form anyway. do street tires marble if too hot or is it race rubber only.

[Top Fuel F1]

In Top Fuel a car some times does a Burn Out from 1/4 to 1/2 the length of the track. There is a tremendous white cloud formed which can drift over you, even at the top of the stands. As it does tiny black particles show up on your clothing. I've never heard a materials discussion on this; but I think the rubber is vaporizing at the tire and then slowly coming out of that state to a liquid and on to a solid. Of course in F1 they occasionally smoke the tires at the launch but not on the rest of the circuit. So in this case the rubber coming off the tires in the turns may be only partially melted (hot and gummy) and as other cars roll over it it tends to roll up in to a ball before becoming completely solid. I would think a good city street washing truck would be useful if run the night before the race.

Rgds;

[Ray Bell]

Trouble with that is readily seen as you watch a race... the marbles build up virtually as you watch... Ten laps can produce enough in some places to make off-line passing very difficult.
Look, also, at a tyre when a car pits... there is balled-up rubber on the tyre. It balls up on the tyre and then rolls off the side, I thus conclude...

[AyePirate]

TFF1,

wouldn't washing the track remove rubber
laid down over the course of the weekend
make the track slicker due to the lack
of sticky rubber on the racing line?

[Ray Bell]

Sure would, also would remove the rubber that adheres to the surface, making it more abrasive and less adhesive for a few laps... but the point is that the marbles build up during the race, anyway, often in just a few laps, and you can't have the road washing going on during the race (at least not without yellow flag periods!).

[AyePirate]

maybe little fans trackside;)

[ray b]

was this a proplem befor slicks and wings.
or when cars ran the distance without changing tires.

[Manson]

They have liquid compounds that are applied to the track for increased grip, "Track Claw" etc. This could be applied to the outside of the corners but marbles will still remain. Harder compounds reduce the problem somewhat. Whenever there is a tire war, marbles get worse as the manufacturers produce the softest tire they can get away with. Specing a specific hardness of tire is a nightmare, I've seen it tried with karts. A tire durometer (checks the hardness) is somewhat erratic is reading plus the effect the temperature of the tire has on the reading. I've seen guys drive through the grass after a race to try to cool the tires! I don't have a solution

[Top Fuel F1]

Originally posted by Manson
They have liquid compounds that are applied to the track for increased grip, "Track Claw" etc.

In Drag Racing they use something like this and they call it Stickum. When you walk on it it feels like your walking on fly paper. I think they use this mainly in the launch area. On the rest of the track in the center (where most of the cars would have run)is an ideal area called the groove. Especially where Burn Outs had occurred (or any wheel spin on the runs) there would be rubber actually adhered to the track. To have a good run you need to stay in the groove.

I did not realize the F1 cars were producing so many of these rubber balls so fast. I haven't heard about a problem with these in Drag Racing. That's probably because the Burn Out rubber is either blowing off in a white cloud or actually adhering to the surface. Also they have occassion to sweep/vacuum the track between runs. Especially if an Oil Down occurs.

Rgds;

[Ray Bell]

Just before the introduction of slicks the rubber became a problem... say 1969 or so. There was always cleaner track 'on the line' but the off-line buildup rapidly increased from about that point, and I think it progressively worsened over the next decade or so.

[FlagMan]

If you were to walk on the track after any session where the cars are using soft compound tyres, not necessarily just F1 - touring cars can be just as bad or even worse, you find that they do not need anything like 'Stickum'. The track surface feels really tacky already. In fact on hot summer days (we do occasionally have the odd one or two in England ;) ) you can actually see and feel the rubber sticking to the soles of your boots.

This is the main cause of the marbles. As the cars brake/corner/accelerate the tyres get their grip by momentarily welding themselves to the track surface - as the wheel rotates the weld is broken - leaving a thin layer of rubber adhereing to the surface. Following cars weld their tyres to this layer and so on. At some point, when the weld breaks it adds the weld material to the tyre rather than the track surface, leading to rubber build-up on the tyres themselves - this rubber gradually moves across the tyre surface on cornering until it rolls off the edge of the tyre. It either gets thrown off the racing line or picked up by following cars which starts the process all over again.

When drivers refer to the 'groove' they are talking about this area of the track where the welded on rubber is at its optimum as it increases the grip.

Just driving any ordinary road car on the track you can feel the extra grip in the corners on this rubber.

As Ray points out, washing the track removes the marbles but also reduces the grip by removing some of the rubber build up.

Running wide onto the marbles reduces grip as there is less sticky rubber welded to the track and the marbles themsleves tend to reduce the contact patch. In adition it also causes unbalanced tyres resulting from the uneven pick-up of the rubber. As Martin Brundle often points out, it can take a lap or two to clear this build up off the tyres.

I recall one British GP about 5 years ago where the course car picked up so much rubber on/in its tyre treads after a single lap following the final qualifying session that the driver could hardly hold the steering wheel for the vibrations caused by the unbalancing effect on the tyres.

The heavier the car, either physically or aerodynamically, and the softer the tyres, the worse the problem becomes.

To get some idea of the amount of rubber laid down you just have to watch a Sports or GT race - the rubber tends to get thrown off the tyres and builds up under the wheel arches - eventally it gets so big the the lumps fall off. A ball of rubber the size of your fist leaves a fair bruise when it hits you in the middle of the back

[GunStar]

Few notes about street tires. When they heat up, it's not to the high temps that race tires do. When they loose rubber, it's very tiny chunks that aren't very hot. When a F1 looses rubber, it's very hot, and with all the rubber on the track, it just melts it all togather and eventually peels, and forms marbles.

Note about that drag racing compound...If any of you live near Seattle Washington, and go to road races at SIR, you've heard horror stories about that stuff. In the dry, it's some of the best sticking stuff for tracks.....but, in Washington like England, it rains often. In wet conditions, that stuff turns into the best slip'n'slide I've ever seen. I can run down the track, hit that stuff and it's like gliding on ice! I've also responded to many a wreck due to a driver not keeping it straight and even throttle through it. Just think of F1 cars playing Indy Wrecking League.

[regenmeister]

I was at a GT race some years ago.
A big lump of rubber was thrown off one car and smashed the windshield of Andy Wallace´s McLaren, caused a fist sized hole in the glass. [p][Edited by regenmeister on 02-09-2001]