51 replies to this topic

[KTM300]

How many of you racers do your tire mounting?

The only donuts I've seen for sale in bulk are the Parma tires. They are about .97 cents a pair if you buy 104 of them for about fifty bucks. I've mounted several hundred pairs of R/C foam tires so I imagine they would mount the same way.

I've also had good luck with the mounted Parma tires so if the donuts are the same rubber they should work fine for me at a great savings.

[Cheater]

Jay Guard mounts tires sometimes and he gets his donuts from Lee Gilbert of Speedshop Raceway in WA.

Ron Hershman also sell donuts, or at least he so did fairly recently.

[team burrito]

Well, there's the Alpha donuts for $2.40 a pair: (Alpha Products) or Lee Gilbert's rubber at $4.00 a pair: (Speedshop).

One question, do you have your own tire grinder?

[KTM300]

One question, do you have your own tire grinder?

Yes.

[team burrito]

Excellent. At .98 cents a pair, that's cheap racing. But is that regular foam or Tuna rubber? The price may be too good to be true.

[idare2bdul]

I'm curious what the wing car guys are doing to mount tires. I've seen a couple of problems with tires coming loose.

R/C tires are commonly mounted with CA glue. Slot tires are often mounted with various types of contact cement. The method I'm most familiar with involves putting the cement on the donut and on the rim. After they both dry, the donut is dipped quicly in a solvent and mounted in position quickly on the rim.

Hershman's donuts I bought are vintage orange rubber, not modern race rubber. I bought some and they were fine for what they were intended.

Modern tires are better in virtually every way, but they ain't vintage cool!

[Ron Hershman]

Those are SBR foam rubber and not the stinky natural rubber donuts. SBR does not have the traction the natural rubber has.

[Ron Hershman]

Well, there's the Alpha donuts for $2.40 a pair: (Alpha Products) or Lee Gilbert's rubber at $4.00 a pair: (Speedshop). :

Same rubber... same source for both.

[Ron Hershman]

Mounting tires 101... ring the bell... class is now in session.

DO NOT USE CA GLUE to hold donuts on wheels. They will come apart.

1) Clean old wheels of old glue. Soaking them in laquer thinner will do the trick.

2) Clean wheels, both new and used in acetone... this gets rid of any oils from thinner, old glue, or newly-machined hubs.

3) Use 3M Weatherstrip Adhesive... the yellow snot stuff. The best trick is to squeeze some into a class jar then add 25 to 35% Laquer thinner and mix. This stops the "stringing" of the glue when putting on wheels or donuts. This also thins so the donut will absorb the glue into the pores. Better adhesion.

4) Get some pipe cleaners... fuzzy stuff on a piece of piano wire... you know what I am talking about. Craft stores sell them and they are longer and thicker. Bend the fuzzy stick in half and in half again. Now you have a real nice thick swab. Dip this into the glue and then slide in and out of the hole in the donut getting the glue to fully coat the inside of the donut hole.

5) BIG STEP HERE... put donuts on a sheet of WAX PAPER and let the glue dry. The donuts and glue will not stick to the wax paper. They will stick to your workbench if not using wax paper.

6) Coat the out side of the rim/wheel with glue mix. Stand on end with the set screw up in the air. Again set onto wax paper and let dry.

7) After a hour or two of the donuts and wheels drying, you are ready to insert wheel into donut. Get a small container and fill with some laquer thinner. The quickest way is to dip the donut into the thinner and let it sit for about five seconds or so then quickly slide wheel into donut. Leave set on wax paper and dry.

8. Another Big Step... let assembled tires set for at least 24 hours before grinding/truing to size.

You have lots of fun and possibly get quite a buzz making tires.

[Jairus]

Excellent class, teacher!
Only change is I would suggest is to dip the rim instead of the donut in the lacquer thinner on Step 7.

The Reason: Any traction treatment the donut received (JK rubber for instance...) might be removed in the lacquer thinner. The point is to soften the glue to make the rim easier to slip onto the donut so softening either glue surface should work equally well.

Right? Of course right...!!!

[Hworth08]

I'd follow Ron's method. He's mounted a few thousand more tires than the average person.

[Ron Hershman]

The thinner won't remove any "treatment" on treated tires. I won't reveal the treatment at this time.

It is preferred to dip the wheel, but for first timers, soak the donut. If you don't get the wheel "wet" enough and it locks up while trying to slide it together, you will have to soak the wheel and donut to get them apart. What a mess.

[KTM300]

R/C tires are commonly mounted with CA glue. Slot tires are often mounted with various types of contact cement. The method I'm most familiar with involves putting the cement on the donut and on the rim. After they both dry, the donut is dipped quicly in a solvent and mounted in position quickly on the rim.

The off-road R/C tires are mounted with CA glue but the foam on-road tires are mounted the way you and Ron just described using contact cement. Should be pretty quick and easy doing it with slot tires.

The more I race the bigger the price tag gets so maybe I can trim some fat or in this case rubber. It's possible I can get the Alpha donuts from Chris at BP.

[Jairus]

I'd follow Ron's method. He's mounted a few thousand more tires than the average person.

Gee, I have sure been put in MY place...

I BOW to Ron's greater experience and back away slowly...

[Hworth08]

Full big hubs are usually faster when the grip allows. For me, it's pretty hard to get the doughnut to a nice "relaxed" fit without the extra time the thinner held by the tire allows.

[MG Brown]

IIRC TWP in Brazil also sells doughnuts.

[Cheater]

Ron,

Your method is essentially how Jay does it. Can I add some points?

1) If you have a bunch of old axles laying around, it really helps to mount a cleaned rim on each end, i.e. to use the axles as handles. This makes things a LOT easier, both for gluing and inserting, and also gives a use for axles too bent to race.

2) Once the hubs are cleaned of old tire and glue, a dial indicator and stand is used to check for bent hubs. About a thou and a half run-out is the limit he uses.

3) He's made a piece of tooling out of a steel bar, a pin, and an axle bushing to use with a drill press to trim newly glued-donuts down in diameter so they'll fit on a Hudy truer.

[Johnny]

3) He's made a piece of tooling out of a steel bar, a pin, and an axle bushing to use with a drill press to trim newly glued-donuts down in diameter so they'll fit on a Hudy truer.

Hi Cheater,
Any chance of a picture of this?

I have few ideas of my own, but like to see how others solve this problem!

[idare2bdul]

The thinner won't remove any "treatment" on treated tires. I won't reveal the treatment at this time.

It is preferred to dip the wheel, but for first timers, soak the donut. If you don't get the wheel "wet" enough and it locks up while trying to slide it together, you will have to soak the wheel and donut to get them apart. What a mess.

To get it to line up right does take some practice. I like the extra time I get to fix a mistake that soaking the tire gives me because I don't do it that often these days.

[Ron Hershman]

The off-road R/C tires are mounted with CA glue but the foam on-road tires are mounted the way you and Ron just described using contact cement. Should be pretty quick and easy doing it with slot tires.

While there may some similarities between the R/C and slot tire mounting process... DO NOT and I repeat DO NOT use CA glue for mounting slot tires.

CA glue when it cures becomes very brittle, cracks very easy, hardens and cracks the rubber, etc. R/C tires (very large diameter) have a lot lower rotation speed when compared to the smaller slot car tires. As the rotational speed increases, so does the problems of using CA glue and donuts leaving wheels.

If you don't want to believe this, ask any slot car drag racers about the Pro-Track drag tire problem years ago when P-T was using CA to bond their tires to their wheels. It didn't work then and they switched to contact cement and solved their problems.

And let me make another point here... if CA glue was the "hot ticket" for bonding donuts to slot wheels... then all the slot tire manufacturers would be using that process today as it is quicker to use CA versus contact cement. ALL slot tire manufacturers use contact cement today and have for many years because it's the only way to keep the donuts on the wheels.

[Ron Hershman]

1) If you have a bunch of old axles laying around, it really helps to mount a cleaned rim on each end, i.e. to use the axles as handles. This makes things a LOT easier, both for gluing and inserting, and also gives a use for axles too bent to race.

We used an allen driver handle for this. We took extra aluminum JK, Parma, etc., aluminum handles, removed the set screws, and drilled out the hole where the .050" tip goes to either 3/32" or 1/8" dia. Then we cut a old axle to the desired length and put a flat on the axle where the allen screw sets to keep it from coming out over time. The best part of this type of tool is that the round part of the allen handle where it meets the hex shaped handle part, makes a great "stop" for the wheel and helps to center everything before sliding into the donut. When they get messy with glue all over them, throw them in a container of thinner for quick and easy clean up.

A tool like this will give you extra leverage when trying to put a .500" or larger dia. wheel into a donut with a small 3/8" hole.

[Bill from NH]

The 3M Super Weatherstrip Adhesive is also available in black for those of you mounting black rubber who tend to be messy.

[Ron Hershman]

Bill, things tend to get messy when one "snorts" too much thinner.

[Jon Laster]

Ron, that's a good class in mounting rubber!

It reminds me of the peril in following R/C tech when doing slots. About 1985 1/8 scale guys were using epoxy to mount their rubber. Shoot, if it was good enough for them... in spite of the fact that Camen's standard technique; essentially identical to what's been talked about; was working perfectly fine, I THOUGHT, well... and at the Nats my epoxied rubber slid off the rim in the middle of my race!

On the other hand, 1/8 natural rubber turned out to be very, very succesful in slots. It's to my chagrin that although I told Limpach and others about it, I figured it was too hard to true for production, so Camen didn't have the first naturals. It's amazing Joel never killed me, sometimes...

Jon

[KTM300]

While there may some similarities between the R/C and slot tire mounting process... DO NOT and I repeat DO NOT use CA glue for mounting slot tires.

I'm pretty sure I said "off-road R/C tires" require CA glue. Off-road R/C tires are made of rubber, not foam rubber, which is why CA glue is used almost exclusively. Off-road R/C tires are glued after they are put on the wheel and only on the edge of the tire where it meets the wheel. There are rubber on-road R/C tires but they have all but been replaced by foam tires for competition. On-road R/C cars, electric or gas, 1/10 and 1/8 scale, run average speeds of 50 mph and often reach 80 mph so your comment about a large slow rotating tire is not accurate.