Do different stiffness axles do anything?


(Bill Holt) #21

@PFox There are 7 grades of Freeline 50mm KZ axles (50x2x1040) with out counting the other axle diameter sizes or lengths. Did you go from extreme hard to extreme soft? or just move a grade?
I have heard that the “extreme soft” axles are more susceptible to bending than the “harder” axles.
I use a “F” in KZ2 (mediumish) and I asked the Birel/Freeline team guy here in Aus which axles they use to make sure I didn’t have something odd, and they basically only use the “F” and the “T” a hard medium and a soft medium. I would be surprised if axles in the mid range of freeline grades would bend that easily.


(Paul Fox) #22

I went from a hard axle to a soft. As far as what exactly it is I will have to check. It was a slightly used axel from j3 and I would doubt they would give me a bent axle. Also its not like I’m pounding curbs at OVRP and I only had about 3 sessions on this axle. If they are this soft that is insane…


(Morgan Schuler) #23

How bent is bent? Every axle has a little run out in it. Axles don’t bend unless you hit something, even the really soft ones. Just about every axle can also be straightened so don’t think it is junk and throw it out.


(Paul Fox) #24

I can visually see the wheel move up and down while spinning the wheel freely. Other side doesn’t do it. Kart handles much different than the last time I drove it but that may be in my head now.


(Michael Zahorski) #25

Since I have a question regarding axles, I decided to put it here rather than starting a new thread. My question is regarding axle length. I’m going to use cadet lengths in my examples since that is what I am used to.

What difference does the axle length make assuming all other factors are the same. For example, what would be the handling difference between a 1000 mm axle with the hubs at the end of the axle and a 1060 mm axle with the hubs set in 30 mm on each side? So, the rear track would be the same, and assume all other factors are the same.


(TJ Koyen) #26

I think a shorter axle helps the outside rear tire dig better. I have no empirical data or no hard logic behind this… It’s simply based on what (I think) I’ve felt as a driver. It could be completely placebo, but we use the short medium axle as our baseline on most of our team drivers.

My only thought would be that it changes where the flex (if there is any) occurs inside the hub and therefore affects how the tire surface interacts with the track surface. Completely speculative though.


(Noah Koenig) #27

I posted in wrong forum my bad
The more grip the kart has means less lift?(too much grip in kart?)
The Less grip the kart has means more lift?(Not enough grip in kart?)


(TJ Koyen) #28

The answer is, sometimes.

Generally, if the kart feels too grippy in the rear, it’s because both rear tires are on the track, causing the kart to bind. But this can be caused by a bunch of things. You could have so much lift, that the kart wants to over-rotate on turn-in, causing you to set the inside rear wheel down by countersteering. Or you could not have enough lift and the rear inside tire never gets off the ground. Both are opposite issues causing the same end symptom. Determining the cause of that symptom is up to the driver and what he’s feeling.


(James McMahon) #29

Col down under does a good job explaining it


(TJ Koyen) #30

Nice! I watched all of Col’s vids back in the day but couldn’t find them for some time.


(James McMahon) #31

Same. I think they must have gone offline for a while. I like his approach though.


(Noah Koenig) #32

Great video. Is it logical to tune like this?Thanks for the video @KartingIsLife. @tjkoyen, does innovative use rate of lift as a means of tuning? Can it be used?


(TJ Koyen) #33

I mean, the entire goal of kart tuning is to control rate of lift. So yeah, we are tuning rate of lift. Everyone is. Any adjustment you make is tuning rate of lift.


(Noah Koenig) #34

Well now I feel like an idiot. Then why do people say understeer and oversteer?


(TJ Koyen) #35

Because they’re related. Understeer comes from not enough lift, oversteer from too much lift. So if you have understeer, you need to increase your rate of lift to get the inside wheel off the ground quicker and get the kart to rotate. If you have oversteer, your rate of lift is too high, so you need to slow down the rate of lift so the kart doesn’t overload the outside tire and break traction.


(Noah Koenig) #36

Would flat sliding be caused by too much lift or not enough? Sticking to the topic, does a hard axle free up the kart because it cuts through the rubber or because it slides over it?


(TJ Koyen) #37

Flat-sliding is generally too much lift. The kart overloads the outside rear immediately on turn-in and causes it to brake traction and slide.

Regarding the axle, again it totally depends on a whole host of other variables. Sometimes a hard axle frees the kart up, sometimes it binds the kart up. Generally, we’ve found the harder axle in high-grip conditions on an OTK kart will help eliminate hopping and keep the rear from rebounding, so it stabilizes the kart.


(Noah Koenig) #38

In low grip situations would the hard axle bind kart up due to lack of rubber? And you don’t change axles though? I know a cut axle can help with high rubber due to its ability to dig harder.


(TJ Koyen) #39

Again, it depends. Maybe! Are you seeing a pattern here? :joy:

The kart probably won’t lift very well with a hard axle in and no grip to help the kart flex and get side-bite.


(Noah Koenig) #40

Lots of maybes. :joy:I apologize and thank you for your time. So what I am getting out of all of this is that there are many variables that make up what setup that you should be running. Track conditions, rubber to work with, tires and etc.
For this topic though, axles have certain circumstances they need before they can be used. In other words. I think I’m going to stay neutral and avoid the headache of making changes that may or may not work. I need to fell the kart before I make changes.