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Tyres
#11

I have read two comments about silicons, which are "relative truth"
So I feel duty bound to qualify those comments, and clarify what is often repeated as universal truth - but isn't. but is the experience of clubs/members in their environment only.
- A little background, I was a chemical commodities trader, and as part of that time in my life, had to learn both inorganic and organic chemisty, which I applied when I got into the murky, dirty little alleyways of slot car tyres and setup. 
Over time I ran various chemical solvent tests on rubber and urethane tyres, and "cleaned and stripped" silicons in baths of chemicals, in search of the truth among the assumptions, claims and counter claims.
Again, I am qualifying my comments as relating to wood tracks, as we didn't really run non-mag on plastic tracks to gain experience there of traction levels of mixed tyre types.

As more background, my club used silicons a lot at one time, did run urethanes and runs soft rubbers both with an without treatment over 13 years so far.
These days we run a mix of different soft rubbers, seldom urethanes, silicons hardly ever.

First common fallacy, which often drives "you can't mix silicon and rubber tyres"- is that silicons do leave a residue, give off silicon etc. They don't, they are chemically stable, hard as a steel jack boot. 

Where they often do create a problem, is on wood tracks which are "rubbered up" for best grip - as some of that soft rubber deposit ends up stuck to the silicons, reducing the amount of rubber on the track, and tends to leave the tracks rubber surface more polished due to their mechanical action; which in turn reduces grip for rubber tyred cars - at the same time it stuffs the grip of the silicon tyred cars which end up with a film of rubber on them.

Where a wood track is run "clean" and "dry" y- no treatment of rubber tyres, no rubbering up of the track over time, you can happily run rubber and silicon tyres alongside each other. 

Where a wood track allows people to treat their tyres with drying solvents such as "zippo" or other lighter fluids, which are essentially naptha, sometimes with another additive, you MAY get away with it, but the naptha modifies rubber tyre compounds and may cause some depositing which will temporarily increase grip for ubber tyres, which will deposit on silicon tyres reducing their grip.
So I would not recommend using both silicon and rubber tyres alongside each other - but the villan isn't the silicon tyre, if any, it is actually the rubber tyre.

Fallacy number two - zippo is not JUST cleaning rubber or urethane tyres, it is modifying the chemical composition of most types, temporarily and permanently in two different ways. 
Likewise for commonly used "fuelite", 'Shellite" and other evaporating solevnts, "citrus cleaners"  - which contain one of both of orange oil d'lemonene/d'limonene, which is a quite aggressive vegetable turpene, [related to the petroleum solvent mineral turpentine] citrus cleaners give brilliant grip to urethane tyres, but knacker them after a few months.

Where soft rubbers are treated with oils, from sewing machine oil, through NSR tyre oil, to CRC and WD fishoil type products, these soften rubber tyres, but mostly in a safe way, [ some of mine have lasted over 5 years treatment and racing use]  - but those oil residues are typically deposited on a track and reduce grip for silicon tyres, especially on high gloss wood surfaces.
So the use of silicon and soft rubber together there isn't a great idea.

So in all, there are quite a few caveats on surface type, treatment type and tyre type for compatibility.
Silicon tyres aren't quite "of the devil" but you can understand how some folks experience might lead them to walk with a cross held in front of them as they approach a silicon shod car.

But there is also a place for them. The varied sizes available, and durability are pluses. Truing is a pig, I used to take an overnight regime to get close to true.

I still have a couple of pre '65 Ninco classics shod with narrow Indygips, which run happily on clean tracks against urethane shod cars, and neither suffer. 

I hope that helps clarify the big picture a little.  For most folks, only one of the scenarios above will apply.

Feel free to flee silicons as if they had black plague... 

BTW, Slot.it N22 do respond quite well to a good belting with NSR tyre oil, I can get as much grip from them as at least treated supergrips, almost as much as ultragrips - but they remain "re-truable" after oil treatment, whereas ultragrips can be tricky to re-true later, once they have been oil treated.
For that reason alone, I run N22 on a number of cars which I use a lot, as I like to give the tyres a tickle up every few months.
[+] 3 members Like slotloco's post
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#12

Hi slotloco ,a very informative piece , thank you . I don't have any silicon tyres , I used them years ago in the 60,s . What I really wanted to try was sponge tyres as I have no up to date information on how they work with rubber tyres .

Steve
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#13

(5th-Jun-20, 12:16 AM)slotloco Wrote:  Feel free to flee silicons as if they had black plague... 

Thanks!

Interesting read.

My view on silicones was obviously related to direct experience and no knowledge whatsoever. Back in the 60's during a 24 hour race one team put some on their car and everyone else complained immediately about lack of grip. We were all on sponge with wintergreen. Now I know why but I still hate them because last year at Bordo, during my first heat, the car was terrific and I won the heat going away. Then I went onto the lane where the guy who came second had been on. No grip whatsoever and I didn't win that heat or subsequent ones either as I followed him around the lanes. The track there bans any treatment so it was just the silicone versus urethane problem.

They don't normally allow silicones but the rules are relaxed for the December meet and they clean the track afterwards.
[+] 1 member Likes Gordon Steadman's post
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#14

(4th-Jun-20, 10:02 PM)Kevan Wrote:  On a painted wood track:
Urethanes leave a fine white powder which reduces grip for everyone else.

Our club has some classes that allow urethanes, no issue mixing. My home track I run a mix of both, no issues.
There is a fine dust produced while truing, its possible they may deposit a little while running (but they don't wear that fast so I doubt it would be much, if any). 
Either way I haven't seen it or felt a lack of grip with rubber after running urethanes.
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#15

We lay down some masking tape sticky side up on a long straight so the cars get their tires cleaned each lap.

Works fine!
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#16

This is great but can someone give a mention of the sponge tyres .

Steve
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#17

Steve, as you said, you have bought them so I think you are about to learn what you need to know.  

I think the sponge will run OKish but not that great unless you use a traction/grip additive.

This is a point I have made previously about track paint....I use an oil base enamel which gives some degree of protection if a chemical wipe down is carried out after you use said additives.
I do use it from time to time...it works.
Lots use the acrylic/latex house paint on tracks which works and looks OK but I think might be too soft to protect against cleaning chemicals if tire bite/tire glue/tire goop/tire oils have been used.

Please tell us your experience of the sponge tires....one thing, the cars will run smoothly and probably quieter too.
[+] 1 member Likes munter's post
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#18

Hi John ,had a bit of a run round last evening ,as you say the car seems  much smoother .My track is painted with acrylic ,so I don't use anything on the tyres except 3 in 1 oil .The initial run was that the car had a lot more grip but the sponge got dirty very quickly , I've not treated the sponge in any way . As the weather seems like it's turning a bit unsettled I will have longer runs and see what happens .

Steve
[+] 1 member Likes Fluff's post
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#19

Searched the forums and couldn't find a post/thread close enough to match my question besides this one. 

I'm trying to find a way that I verify the tyres being used by other races such as urethanes, rubber, silicone etc as I am banning silicones on my track from Jan 1, 2022 and would like to find a way to verify the tyre type without destroying the tyres.

Thanks
Johnno


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#20

There are producers of urethan tires out there that mark their tires.
That means e.g. you can check the tires with a 4€ UV lamp. 
We have 2 classes using those tires, helps a lot and leaves no doubts!

Nico

Donne e motori, gioie e dolori - Frauen und Autos, Freuden und Leiden
[+] 1 member Likes Nico's post
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