12 replies to this topic

[Rich Joslin]

I have searched the Slotblog archives and read several threads on tires. Thanks to those threads I am pretty comfortable with the different rubber compounds used. In those threads hub sizes are often discussed in relation to how they may affect the cars performance, rolling resistance, straight line speed, etc. There has been a little mention of the materials hubs are made of. I have seen plastic, magnesium and carbon fiber mentioned. There may be others I am not aware of. 

 

I have one car. JK 21 4" chassis with a Pro Slot 2002 16D motor. The car weighs 110 grams, the minimum weight for the class.

I race on one track only at this time. It is a 145' Ogilvie Euro Hillclimb. The track does use spray glue.

 

Wonder rubber seems to be the compound of choice. In my first three races I used JK small hub Wonder rubber tires. Size at the time of the races was between .700" and .730". The car barely makes the 50 thousandths clearance tech at .700". 

 

To my limited experience the car handled OK so this is not a case of trying to correct a particular handling issue but more of "is there anything even better" or is there something I should be ready for when the track is just cleaned or slows down because it is dirty. Because tires play such an important role in handling I would like to experiment with other options a bit.

 

To begin the experimentation I bought a pair of Alpha big hub magnesium medium Wonder rubber tires. They were .765"s turned down to .740" for practice. I started with these because they were the only option available big enough for me to get a decent amount of practice time out of. I have run probably 100 laps with them so far. My impression is, they "sound" harder on the track. When the car deslotted it appeared to tip out and run straight to the nearest wall. Too much grip? My lap times were about .2 seconds worse than with the JKs. I don't automatically attribute all of this difference to the tires as I think the change in roll-out ratio and higher clearance may be a factor as well. I will be able to make a better comparison when I run them down to the .720" range.

 

I would like to continue experimenting but want to spend my money as wisely as possible which leads to several questions. 

What difference does the hub material make to tire performance? What handling characteristics might thus be imparted to the car? Are carbon fiber hubs lighter than others? Appreciably so? If you could only experiment with a couple other pairs of tires at this time what would they be given the information provided on the car, track and current tires?

 

Thank you!!

[Pablo]

1. Hub materials, yes carbon fibers are slightly lighter. Magnesium is light also. The JK plastics are always a good quality hub. I've had success with all of them. I think the hub sizes and tire compounds are more important than hub material.

 

2. Wonder Rubber wears very slowly, so I think you do yourself a disservice by making them much larger than needed to clear tech in an attempt to get more life out of them.

 

3. Tilting out, when running small OD wheels and the car handles fine, then put bigger tires on and all of a sudden you are deslotting. Ya know what? I don't think that's a tire comparison - it's a function of your guide tilt on the car being good with small tires, then you slap big tires on and the tilt is down. This is a death sentence for handling. You hit the wall, it bends the tongue down, handling gets worse, you hit the wall again, and eventually you will deslot in every turn. I recommend going and re-reading Cheater's tome on TFlex chassis blueprinting with regards to tongue tilt.

 

4. When in doubt, use a medium sized hub with Wonder Rubber. If you need more grip go to treated rubber. If you still need more grip go to untreaded. Always try and use the hardest compound you can get by with - less rolling resistance = higher speeds.

 

5. If you use magnesiums, have a hub straightener handy 

 

6. It's all a very complicated science combined with black art. Danny Zona put it best: "Lap times are the only truth. Everything else is just theory". It took me many years to figure out slot car tires and I'm still learning.....knowledge is a moving target.

[Rich Joslin]

1. Hub materials, yes carbon fibers are slightly lighter. Magnesium is light also. The JK plastics are always a good quality hub. I've had success with all of them. I think the hub sizes and tire compounds are more important than hub material.

 

2. Wonder Rubber wears very slowly, so I think you do yourself a disservice by making them much larger than needed to clear tech in an attempt to get more life out of them.

 

3. Tilting out, when running small OD wheels and the car handles fine, then put bigger tires on and all of a sudden you are deslotting. Ya know what? I don't think that's a tire comparison - it's a function of your guide tilt on the car being good with small tires, then you slap big tires on and the tilt is down. This is a death sentence for handling. You hit the wall, it bends the tongue down, handling gets worse, you hit the wall again, and eventually you will deslot in every turn. I recommend going and re-reading Cheater's tome on TFlex chassis blueprinting with regards to tongue tilt.

 

4. When in doubt, use a medium sized hub with Wonder Rubber. If you need more grip go to treated rubber. If you still need more grip go to untreaded. Always try and use the hardest compound you can get by with - less rolling resistance = higher speeds.

 

5. If you use magnesiums, have a hub straightener handy 

 

6. It's all a very complicated science combined with black art. Danny Zona put it best: "Lap times are the only truth. Everything else is just theory". It took me many years to figure out slot car tires and I'm still learning.....knowledge is a moving target.

 

Thank you for the comprehensive response Pablo.

 

Each point is good information for me, especially #2 and #3. I realized the taller tire had to change the geometry some but didn't think about it in relation to the angle of the guide flag. I will go ahead and grind them down some to make it a better comparison.

 

I guess magnesium hubs won't be in the short term plans because the picture below represents the entirety of the Joslin Racing Team's gear. 

 

[Bill from NH]

Rich, if you ever use Alpha tires, all/most all of them are mounted on mag hubs. Which controller did you end up purchasing? Is it a Koford?

[Rich Joslin]

Rich, if you ever use Alpha tires, all/most all of them are mounted on mag hubs. Which controller did you end up purchasing? Is it a Koford?

 

Hello Bill,

I purchased the Difalco DD 201. I am really liking it so far. Very solid construction. I am still tinkering with where to set the brake and sensitivity for my driving style such as it is a style at this point but it is great having those options.

[Bucky]

I've mounted the same donuts to metal and plastic hubs of the same size expecting the plastic hub to provide a little more traction, but in testing on a flexi car on a hillclimb the results were negligible based on the lap times and "feel." I have noted some differences using the same rubber on different size hubs, but the results weren't as dramatic as I thought they would be. I can't come up with a hard and fast rule on what changing hub size does to a car. My expectation had always been that a smaller hub would tighten a car up slightly, but this hasn't always been the case when I've tested.  Getting the right rubber makes a much larger impact than hub size or material.

 

JK wonder typically runs well on my home track, so our testing might slightly overlap (but of course there's way too many variables driver/car/track/weather/slot car black magic/etc.). If JK wonder tires are too loose I will typically try Alpha soft wonder and Kelly Retros. The Kelly's are expensive so they are race day only for me. I will do most of my testing on Alpha soft wonder as they're close in handling to the Kellys, but usually a hair slower and last longer. If the track is well rubbered (lots of traction) I usually test the JK wonders and Thunder Rubber mediums. So for me, I typically test the following tires in order from what I perceive to be higher traction to lower traction: Kelly Retros, Alpha soft wonder, JK wonder, Thunder Rubber mediums. Like all racers I keep a lot of tires on hand, but 95% of the time those are the tires I find work for flexi racing on any of the hillclimbs in Florida (we have 3). 

 

Unfortunately my experience is that there are no black and white rules, and sometimes a tire I think will provide more grip simply doesn't when I test it before a race. I've seen others recommend picking a brand of tires, such as JK or Alpha, and keeping a pair of each compound on hand (ex. Alpha: Piranhas, treated Piranhas, Soft wonder, Medium wonder) and supplementing with other brands' tires as you get a feel for what's in your box, and this seems like a solid strategy. Slot car tires can be a pretty pricey rabbit hole to fall into.  

[Rich Joslin]

I've mounted the same donuts to metal and plastic hubs of the same size expecting the plastic hub to provide a little more traction, but in testing on a flexi car on a hillclimb the results were negligible based on the lap times and "feel." I have noted some differences using the same rubber on different size hubs, but the results weren't as dramatic as I thought they would be. I can't come up with a hard and fast rule on what changing hub size does to a car. My expectation had always been that a smaller hub would tighten a car up slightly, but this hasn't always been the case when I've tested.  Getting the right rubber makes a much larger impact than hub size or material.
 
JK wonder typically runs well on my home track, so our testing might slightly overlap (but of course there's way too many variables driver/car/track/weather/slot car black magic/etc.). If JK wonder tires are too loose I will typically try Alpha soft wonder and Kelly Retros. The Kelly's are expensive so they are race day only for me. I will do most of my testing on Alpha soft wonder as they're close in handling to the Kellys, but usually a hair slower and last longer. If the track is well rubbered (lots of traction) I usually test the JK wonders and Thunder Rubber mediums. So for me, I typically test the following tires in order from what I perceive to be higher traction to lower traction: Kelly Retros, Alpha soft wonder, JK wonder, Thunder Rubber mediums. Like all racers I keep a lot of tires on hand, but 95% of the time those are the tires I find work for flexi racing on any of the hillclimbs in Florida (we have 3). 
 
Unfortunately my experience is that there are no black and white rules, and sometimes a tire I think will provide more grip simply doesn't when I test it before a race. I've seen others recommend picking a brand of tires, such as JK or Alpha, and keeping a pair of each compound on hand (ex. Alpha: Piranhas, treated Piranhas, Soft wonder, Medium wonder) and supplementing with other brands' tires as you get a feel for what's in your box, and this seems like a solid strategy. Slot car tires can be a pretty pricey rabbit hole to fall into.

Thank you for sharing your thoughts Aaron.
I like how you lay out the order that you test in.
It is easy to see how this could get expensive. I guess I am "lucky" to only be racing on one track in one Class at this time.

[Eddie Fleming]

Alpha has some interesting information on tuning in the tech tips section at the bottom of the home page. I can't get a link to work at the moment but it is easy to find at www.alphaslotracing.com

 

Try this  https://alphaslotrac.../alphatech.html

[Rich Joslin]

Thanks to those who have offered advice.

 

My take so far is in order of importance from least to most it would be:

Hub material

Hub size

Rubber compound

 

I think I will start with JK medium hub Wonder to compare with the small hub Wonders I have been using and Alpha small hub Soft Wonder to compare the compound to the JK Wonder.

[Pablo]

The only time I'd use small hubs is when I need lots of grip, like on a short flat track. I think you will always get your best handling with a medium or large hub and the hardest rubber you can use to still get the grip you need. Where did I learn that? Terry Kelly.

 

Another tip is, temperature, just like 1/1 race cars. The warmer the temp, the more grip the track will have. When it's cold in the morning you may find the track is slippery - smaller hub, grippier rubber. As the day progresses and warms (especially if the doors are being opened and closed and people come and go) the track gives more grip, and unless you adjust to it by going to bigger hubs and harder rubber, you will start tilting out.

 

Not trying to encourage you to buy more tires, just trying to get you to understand it better so you don't keep buying what you don't need 

[Rotorranch]

It's easy... Buy what the fast guys are buying!    

 

Rotor

[Rich Joslin]

The only time I'd use small hubs is when I need lots of grip, like on a short flat track. I think you will always get your best handling with a medium or large hub and the hardest rubber you can use to still get the grip you need. Where did I learn that? Terry Kelly.

 

Another tip is, temperature, just like 1/1 race cars. The warmer the temp, the more grip the track will have. When it's cold in the morning you may find the track is slippery - smaller hub, grippier rubber. As the day progresses and warms (especially if the doors are being opened and closed and people come and go) the track gives more grip, and unless you adjust to it by going to bigger hubs and harder rubber, you will start tilting out.

 

Not trying to encourage you to buy more tires, just trying to get you to understand it better so you don't keep buying what you don't need 

 

Thanks Pablo,

I have the Big Hub Alpha Medium Wonders so if I true them down to the 720 range that will give me something to try and if I get the medium hub JK's I will at least have three hub sizes to evaluate of similar compound. 

Glad I didn't make any purchases yet!

[James Wendel]

While I have not purchased any Alpha wonder donuts for quite some time, (I mount my own tires).  They seem pretty much interchangeable with JK wonder of the same size.