Noticed a bend in the chassis that appears to be centered around the engine mounting plate. The bend has pulled the right rear bearing cassette ~1cm closer to the front right kingpin. While it is not visible when watching the kart on track, it is clearly crab walking down the straights as the rear is no longer square with the front.
The frame rail where the bearing cassette is attached is bent towards the seat. On the underside of the chassis one of the cross rails under the engine mounting plate is bent and has a dent/kink in it (arrow).
Chassis is 25mm. Any hope of fixing this? Doesn’t need to be perfect since as it is a kid kart, but sure would be nice not to rob the kid of speed. Maybe the bends are permanent, but would moving the bearing holder 1cm back be a waste of time?
Seems like this would be a straightforward repair on a chassis table if it wasn’t for that cross member kink/dent under the engine mounting plate.
Where are you located? I live in Indianapolis area. Here, there are quite a few people who could fix this for you. I have seen them drive a sleeve into that tube to remove the kink. It is fairly close to the weld, but should still be fixable.
If we’re being realistic, though, for a KK, its not going to matter. Put it on any chassis table, get the rear end squared up to the front and let it rip.
You’d have to move the cassette back and down or else it’ll still want to turn. Corner heights have to be pretty dead-on. Handling-wise for KK, it really depends how hard they are pushing. Most kids aren’t really activating the chassis, but some certainly are. Rather than moving the cassette, for a first attempt I’d hand it off to someone who can try to straighten it on a jig and then just keep an eye on it. It has certainly softened and may bend again there pretty easily, but it may also be perfectly adequate until the kid goes up to cadet.
I wouldn’t worry about the small dent/kink under the engine mount- it’s not causing the tubes to be out of shape and has so much reinforcement around it that it will not be a “flexy spot” that causes adverse handling if damaged.
I would take the time to correctly straighten the rear of the kart and get the bearing cassette in the correct spot. that’s definitely critical to handling. For as much as it is bent, I wouldn’t worry too much about long term weakening/effects from the repair. those kid karts are light and I’ve fixed many cadets with way worse than that. basically as long as the tubing isn’t bent so much that it kinks, you’ll be ok.
You can likely get it very close at home with hand tools and a straightedge or two. just remove the rear axle and the bearing carrier, then hold the frame down and use a straightedge on the bottom and sides to align it.
If you can’t get a straightedge around the sidepod tubes, then buy a section of angle iron- maybe 2ft long- and then cut a notch about 1.5" wide on it and go around the tube. (that will become yet another single-task tool you can use later on other karts for same issue!)
There are a number of laser alignment kits out there that you can use to square it to the front as well. I have the Kelgate R3 system and have used it mutliple times to square up a chassis.
It’s a big one-time cost for a single repair, but if you plan to continue in karting then it’s a good long-term investment.
My only concern with that dent/kink in the engine mount cross member is that it is clearly contributing to the axle being pulled forward.
If I can get the rear axle square to the front I will be happy. The kart is still fast, but probably doesn’t have best straight line speed from the rear scrubbing.
