Broken seat stays

You would think that as many seat stays that fail or crack the manufactures would redesign them. I see so many late model karts for sale and the owners mentioning the broken, repaired seat stays. Its almost like its expected to fail in some of the conversations out there.

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Karts flex and vibrate a lot. The seat struts are responsible for supporting a lot of the kart’s weight but still need to flex to help the chassis work. Weak points end up cracking.

Thanks TJ. I understand the stress on it and how important flex is the to kart and I’ve learned it from knowledgeable people like yourself…just wondering why they don’t design that all in and mfg. it where it doesn’t fail. I know folks aren’t losing sleep over this just more curious than anything else.

Sell less karts that way.

There are certainly karts that have lower failure rates then others.

From my experience most the failures are just above the weld in the heat affected zone. Manufacturers could take better care on minimizing heat input when welding.

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What kart manufacturers don’t know about machine design and metallurgy would fill two books, specifically “Introduction to Metallurgy” and “Introduction to Mechanical Design”

Karters don’t help them by plastically deforming the seat stays to get seats into them. They’re really only designed for a size 2 seat or smaller.

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Yep, just recently had mine welded back together for the second time. Same spot. Engine side Stay where the tubing flattens out to contact the seat side. OTK 401R. Its just a weak spot I guess. It doesn’t help I weigh more than the kart does.

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100% weak spot on otk when you’re hanging weight on the seat it seems. I’ve seen a ton of them brokwn there, mine included.

Looking for advice… I needed to open the seat stays to get my seat to fit and while I should have cut and rewelded the left stay since I needed to move it significantly, I didn’t and it has cracked above the weld as others noted above. So my question is now that it is cracked do I:

Just weld the cracks

Weld the cracks and fashion a gusset brace too

Cut the stay off and reweld the whole thing

or other suggestions

My question is where exactly did it crack. Engine side? At the base of the Stay where it meets the main chassis tubes?

I haven’t paid close enough attention to know if other chassis makers do this or not, but OTK has their engine side stay attached to the rear cross member and the non-engine side stay attached to the main longitudinal chassis rail. This makes the base of the forked stays attach perpendicular to each other. I don’t think the engine side stay is meant to be moved as it is welded in the same plane as you would want to move it to widen the area for the seat.

The engine side is already a tight fit for engine, so if it is that side I would clean the metal around it and lay a fresh bead down to secure it.

Just weld her up and let her rip.