When is it time to Replace or Upgrade Your Kart Chassis

I did that after the second time it was super lazy in the corners so I’ve been 2 full seconds off pace basically the kart is fighting me in every section of the track un like when i first got it im having to manipulate the cart as much as possible in the corners, body weight breaking you name it I’ve tried it to get this kart to rotate it’s been getting worse after every race Ironically, I was faster in it when it was bent then after it got straightened

2 seconds off the pace is not going to be solved by a new chassis unless yours is physically broken or cracked somewhere. Check the welds for cracks. If it isn’t cracked, there is more to find in driving.


Has it been scaled too?

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For sure would scale it and make sure the seat is in the right spot. I’m assuming @Wach_racing has had Franklin work on it, so Jamie probably set the seat in the right spot but after a few straightenings it would be worth scaling again.

I measured 1.5s from it being bent once. The reason for the large loss was that I had to turn the wheel a minuscule amount to track straight, even though it aligned straight. This made it scrub, and my top end suffered a lot. I could tell from the G circle and sector times that I should’ve been 1.5s faster and sure enough I instantly gained that much back after it was straightened

I would say that’s an unusual case though. No doubt if the kart is twisted or scrubbing like that, it could be a big loss. More often though when a frame bends, it’s one of the front yokes getting bumped up or down several mm. It’s not as common to see it twisted or bent in the way yours sounds like it was.

Knowing the guys at FMS (who I assumed straightened OP’s kart), they would’ve measured for that sort of bend while they were straightening it.

No has not been scaled out

I think it depends entirely on what type of material the chassis is built on. OTK and VLR are both known for being very quick karts when new and falling off a good bit after 2 seasons. Then there are other karts like our SWIFT chassis that is built using Docol and its is actually faster after the first 5-6 races and stays fast for as long as we have been on the current frame design.

I would say on average 4-6 seasons is a lifetime on a kart chassis.

I will say that if you want to get a new chassis, go for it. It kinda sounds like you’ve saved up the money and that’s what youre itching to do, and there’s nothing wrong with that.

With that said, I also agree with what has been said by others.

  1. Make sure the seat is in the right place.
  2. Make sure the seat condition is also good.
  3. Check the frame for cracks. They can be hard to find - check the seat struts and bearing hangers first, as these are the likely candidates.
  4. Make sure your axle isnt bent.
  5. If your frame is flat-spotted, that could change the handling too since you’re taking material away from the tubing. Check under the frame for this. If its just paint scraped away or a very small flat spot I wouldn’t worry, but if it’s noticable then that’s not great. Nobody should expect not-round tubing to bend the same way that round tubing does.
  6. Make sure your spindle kingpins arent bent. It’s something that can be easily overlooked.
  7. Check the more straightforward “wearable” items like the steering shaft and tie rods to ensure they arent bent.
  8. Getting it scaled would be good, but honestly if the seat is in the right spot and you’re not putting an insane amount of lead, it should be darn close.
  9. Finally, if all of that is good, I’d make sure it’s straightened. Like TJ said, unless its really bent I’m not seeing that making a 2 second difference.

Or, buy a new chassis and forget all that (except for #1) :smiley:

Thank you for the feedback this goes for everyone who commented :pray:

Sorry if I used “bent” too generally, but I didn’t mean to imply any particular type of bend. For my case of losing 1.5s, it was the front C by 4mm according to the guy. Sitting on the ground, you couldn’t tell. Even going down the straights, you couldn’t see that I was turning the wheel, it was just a slight upward force from my hand to get it to track straight. This was with Briggs though, so maybe that’s why y’all don’t seem to think this can happen, but it doesn’t take much scrub at all to sap the power from that lump. It was also cold for both before and after sessions, so cornering speeds were a bit down. I have the weather in my notes, so I can check that though.

It felt like it was way down on power on the straights, but it had normally low power on sweepers. That (and requiring correction to go straight) were my clues it was the bent chassis robbing nearly 2 seconds. Looking at the delta times between similar sessions, I could see that my straight acceleration just sucked, and the delta added up to 1.5 on three main sections alone.

I can post the breakdown of the data in a little bit if this still sounds unbelievable. I won’t take it personal, but I am very confident in the statements I am making here.

The one spindle was up 4mm but it still lasered out normal? I assumed the kart was twisted in the middle, that’s why it still aligned properly.

No, it didn’t laser normally at first. I tried chasing the issue by tweaking toe and camber (CCS system, so caster was constant). By adjusting the tie rods, I could get it to toe and camber fine, but the toe and camber settings were asymmetric to make up for the asymmetric spindle heights. This was in the air, too. Under my weight, I’m sure toe was off again, but that wasn’t worth chasing. I just played with alignment enough to prove to myself it was a problem that couldn’t be fixed with the alignment (or it wasn’t a problem created by a bad alignment).

Bottom line is that a realistically damaged kart can cost a ton of time. I’ve also set a PR in a race with a damaged kart, so emphasis on “can”. So to wrap around to OP’s question, I fear that my kart has gotten to the point that it is easily damaged to the point of losing time that will affect a race outcome. Maybe if it was fresher, I could expect less frequent race-affecting damage. But I also have a dog that just got knee surgery, so he blew my kart budget for a little while, haha

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…run frame protectors…

Are these also referred to as skid plates? Three or four per frame?

I had a quick look online after reading your post. Common complaints about plastic being too thick, but steel is thinner and works just as well?

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Yes. Plastic ones will hit the ground so frequently that they’ll ruin the handling. The right material to use is stainless steel, which ground contact hardens to about Rockwell C70, and will then have very little friction.

Both work but as Charles said, thinner is better to avoid bottoming out. As such, the stainless ones tend to hold up better and be thinner.