This is really a drive line issue but this heading was as close as I was able to find.
I need help with
I have a couple bent 40mm axles (1040mm long) and when I say bent I mean…maybe a 1/16 of an inch (3 to 4mm) on one end.
These were some great axles, a medium and a hard.
Any help here or do I have expensive pry bars.
Mark the high point with a Sharpie by spinning the axle and then give it a couple big wallops with a rubber mallet. We do this all the time.
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Just about every axle can be straightened, unless you have to sawzall it out. You probably have someone local who straightens axles if you ask around.
If not, CKT Racing is my go to. PKT Axles is another option.
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Thank you gentleman you just made my day
I’ve used PKT on several occasions, and they get them in and out within a day usually.
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Yup, Brandon at KartSport did this for me when my (lack of) budget was going to make me miss a race day when I found undiscovered crash damage. FWIW you have to hit the axle HARD to straighten, tapping on it won’t get it done.
It depends on the axle and where the bend is. Usually it’s the last few centimeters of the axle. Hitting too hard simply moves the bend and then you chase it around the axle, weakening it in the process.
Personally, I’ve only straightened an axle as a last resort on a race day, when I didn’t have any other option.
Otherwise, I’d just replace the axle. It’s so core to the rear of the kart and the handling, I’d rather just not mess with it.
It is also very expensive to replace axles. If it’s a very small bend, I would absolutely hit it with a hammer and let it ride.
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I wouldn’t argue with that at all. It definitely depends on the bend. I’ve won races on slightly bent, or restraightened axles. I’ve also seen people just wailing on an axle when they should just replace them.
I spent a good portion of the season on an axle so soft it would bend if I hit a curb wrong. You can definitely take a rubber mallet to an axle and it’ll run fine, just make sure theres a hub on it so you don’t deform the axle into an oval.
As an extended question, if an axle is bent on both ends and in the middle between the frame rails, is that straightenable? Asking for a friend
(Almost) anything is possible right? Not sure if it would be worthwhile though.
Also, your friend is talented.
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A friend of mine made an amazing tool for straightening axles. It’s a solid aluminum bar, approximately 2’ of it is exactly the same diameter of the ID of a 50mm axle then there’s about a foot that’s a bit bigger to hit with the hammer. Basically like an axle removal tool but longer. Works like a charm, most times you don’t even have to pull the axle.
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Pictures of that would be sweet. 
Oh, he didn’t bend it, he’s just in possession of it now. I gave it to him after I got a new one.
As a side note: CRG 2 axles are ridiculously soft. I hadn’t even hit anything all weekend but just running the curbs at Road America did that axle in, I was kinda surprised Sunday morning to see the center of the axle fluttering a little as we were warming up the karts.
I’ve seen on occassion some folks run PKT clamps or stiffening clamps on the middle of the axle, albeit usually more for a handling change than to reinforce the axle. Maybe this could help minimize central bend in the future?
How does that change the handling though? I assume it would stiffen the center of the axle, right?
Yes, it stiffens the center of the axle which tends to free modern karts up in the rear. The opposite would be true for karts pre 2009 or so. It’s a somewhat common idea used on cadet karts and I’ve seen more of it on oval track karts and mini sprints.
They used to do this in super high grip, high horsepower stuff about a decade ago. A bunch of collars on the center of the axle will keep it from deflecting as much.
Not really of use anymore with more modern karts or at lower weight/power. @Aaron_Hachmeister_13 I suggested it to Todd on the grid at Joliet last year. I was half joking but based on what he was saying how the karts were handling, it seemed like a reasonable experiment.
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Make sure the axle is straight like an arrow.
There is a chance that you get cracks in the chassis,when it is not completely straight.