Has anyone ran a kart with 17/40 and a 25/50 setup? I am wanting to know what the differences are.
I hear you, there is always a “hot” chassis.
We’ve run on and tested just about every spindle and axle set up around.
5/8 & 1 1/4
5/8-3/4 stepped & 1 1/4
5/8 & 40
17 & 40
17 & 50
25 & 40
25 & 50
Ultimately all can be fast if you put the time in. The question is, how much time do you have and want to put in. What seems to be the draw to OTK is the simplicity. The standard neutral set up seems to be pretty good every where with just a few adjustments in caster/camber and a front spacer.
When you look at the grid for many other brands, the set up is all over the place. Probably take all but the 5/8 spindles I mention above and that’ll cover the big US brands and driver set ups right now. Not to mention a 4-5” difference in track width.
It’s interesting to see what works for certain people vs others. Sometimes it all works though LOL
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It feels different and tunes different, but really doesn’t go any faster. 
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One major concern I have with a 50mm rear is do you swap axles more often? On a 40mm I feel like it was a rare occurrence on most chassis I have run, but on a 50 I feel like guys/gals wind up changing axles more frequently. Can anyone speak to this?
You are on an Eagle, right? Call Comet and talk to Gary. He has tested extensively and in the discussions I have had with him its about feel and hasnt resulted in speed.
Typically on a 50, in lower speed stuff, you get the axle that works and leave it.
There’s always TYCA tho.
How did that experiment go? Worth it or not?
I always go back to the standard 17/40 on the Eagle after I try the other ways. 
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We’ve done more axle changes on the 50 then the 40 but I believe that is more to do with trying to find an axle that had the balance in the kart that Randy liked with the Arrow. Once we got something that he liked l, we set it and left it.
I know the OTK guys typically run an N and then move to the H or HH sometimes up to the HD when grip comes in. Changing an axle is pretty easy. It’s about a 10 minute deal.
Like was mentioned, any of the spindle and axle set ups aren’t really faster. What Randy has said is that it feels much different on entry. We’ve ran back to backs with 17/25 and the 50 and laps were very close but it changed how we tune it.
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Ten minutes. Dang, I must be the slowest axle changer on the planet then. When you say ‘different on entry’ would you be willing/able to elaborate on that?
I know a TB Kart/ LO206 guy who was doing alot of 50mm nd 40mm experiements, also trying hubs of different widths. Being all TB’s are on a 50 I think he was courious to see how the chassis would fair with something different on it.
After 6 months of trying different things, I remember him citing slight handling differences, but I never heard him say anything about one bending more than another. It was funny talking to him because the end result was kinda split, but on his chassis, he felt the 50mm loaded better off the corners; but he said the differences (for him) was ever so slight.
It is interesting you say that. I would have guessed the difference would have been a bit more impactful. I am curious the caliber of the driver. I don’t mean to question or knock the guy, but I read a lot of people say they couldn’t tell a difference in wheels or axles or whatever but any axle change I have made I immediately felt how different the kart handled. Same with wheels. Paul from AMV send me some 3fs to test this past weekend and man it was a whole new kart compared to the stock Birel wheels. Moral of the story is I guess I will have to bite the bullet and eventually test it all myself.
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I remember when we all switched to 50mm in the 2-stroke world and at the time I didn’t feel much difference to the 40mm stuff.
The 25mm front spindles made a more noticeable difference. But I was young then, maybe I wasn’t able to feel those intricacies yet.
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I bet it was George with a J…
No sir, not him. (20 Characters)
In fairness to others, chassis changes are much easier to feel at a place like NCMP or Charlotte or somewhere with big smooth corners. Places with older pavement or less rubber taking ability tend to not have the same drastic reaction to changes.
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5 minutes is possible with deburred brake and sprocket hubs, shaft collars to hold the axle laterally rather than setscrews, and changing between one straight and polished axle and another straight and polished axle.
I have seen many people have built up spares so its just unbolt carriers, seat struts and pull. Slide in new one.
I struggle changing axles mainly because old one never wants to come out after 20 races.
On another note,
I have always ran same thickness and 50mm size in a “Medium” i just change length of axle never mess with hubs or ride height. I am not good enough so between front and rear width and tire pressures is how I do the setup. I generally run with the front pack in every race I have done and have never felt like I was lacking in handling.
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Are you that good or did you get lucky and find the right one on accident? 
Morning fellas! I’ve done a heap of axel testing for briggs. I’m in a 2021 CKR stingray that is also 25/50mm and we are on a very hard tire in CO. We start on the M and move to a stiffer axle as the grip comes. Temperature also plays a big factor as well. The CKR “M” axel is actually soft (because that makes sense) and does well for cooler races like last weekend. I had a tiny hopping as the track came in but nothing I could not handle. If it got any warmer i would have switched to a C4. Before all the testing, I would stay on the M, change hubs, seat struts, etc… Now, I think of it as how can I have the largest tuning window and that generally starts with an axle. Once you get used to changing axles, it does not take long.