Can we talk belly pans

I was at a buddies house, and he has about 12+ karts in his garage. 125cc, 175cc shifters, 4 stroke karts- you name it and he seems to have it. As I was looking over his collection I noticed every kart he had- had an aluninum belly pan. The majority of his karts are either Birel or CRG.

Now my carbon fiber pan is pretty shot. Last race two of the bolt holes ripped as appearently I when I first started karting earlier this year, I had an affinity for hitting curbs and no regard for lawn maintenance.

What do you folks use and/or recommend?

Pro’s and con’s from carbon fiber vs. plastic vs. aluminum?

I know you want your chassis to be able to flex. But I’m in a unique situation as I’m a four stroke guy on a two stroke 32mm chassis, so I don’t flex as much as most anyhow.

Not an expert, so I’m curious what others have to say . . .

I know a few people who have experimented with different floor pan materials to adjust chassis flex, but honestly it’s a very in-the-weeds tuning device, if at all. A lot of karts just allow the pan to sit in rubber isolators anyway, so it floats a bit and allows flex. I would just go OEM aluminum to save hassle and keep it durable. Floor pan tuning isn’t really a thing for most, so don’t over-think it.

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Material is less important than rigidity. Nine times out of ten the stock pan is going to be the best option. I tried using a softer carbon floor pan on a previous chassis, and the stock pan was half a second faster. Most times you won’t need to go stiffer than the stock pan, and if you need to go softer you can experiment by loosening some of the fasteners around the middle and/or rear of the pan.

Might be worth trying in your situation, but I would start by installing the OEM floor pan, assuming you’re in need of a replacement.

I always thought the carbon fiber pan was for weight savings. Never thought of it a tuning tool. Like TJ said, most of the time pans are not snugged down enough to effect rigidity.

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Aluminum has a pretty limited fatigue life, but for some reason we use it instead of magnesium that’ll last forever!

Fiberglass and CFRP have a fatigue endurance limit of >80% of peak strength. If you’ve got cracks, you’ve exceeded its critical impact energy instead.

If I were starting from scratch on building a flat floorpan, I’d just use a router and 3-layer plywood underlayment, just because it would be stiffer than any metal or single composite layer for the weight. If I really had to save weight it would be a piece of 1/4" thick foam with a single layer of .003" Kevlar cloth laminated and vacuum-bagged to it!

NEK manufactures five different rigidities of their carbon pan. I’ve only tested one of those five (softer), and it made a pretty big difference.

I’ve noticed the Kart Republic and WPK karts come with paper thin floor pans. All part of that “noodle kart” philosophy those karts use I imagine. So it definitely itself does something.

I would like to dive into it and test it more. I imagine it works the same as a torsion bar for the most part.

But I still would recommend OEM for OP.

Definitely similar to changing torsion bars, depending on the chassis and where it is placed front to rear. It doesn’t have quite the pronounced effect on front end dig, but rather seems to stiffen the middle of the kart (as you’d expect it would).

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I worked with DR and the different NEK floor trays a couple years ago. It’s definitely a tuning opportunity, but if you’re desperate enough to go throwing new floor trays at it you gotta be really far out in left field. The KR/FA/WPK trays are a stupid soft fiberglass tray, but that’s what they wanted the karts to work with.

If you’re looking for a replacement to an old/worn out tray, I would go OEM. Part of the big problem with trying to figure out how tuning with a floor tray works is each one costs between $300-$500 if I recall, making it very difficult to get 5 stiffnesses just to figure out which one works best.

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Do tell…
20 charachters

The one I had was I believe second softest in the range, and for my application I did not like it. It was one that Maximilian Paul used at Supernats in 2018, so a fairly unique application (and it seemed to work for him). As mentioned previously, I switched to the OEM tray and went half a second faster. This was for an M99 Evo3, which seemed quite soft.

Ended up ordering a aluminum pan from VLR. It took some cutting, trimming, and re-drilling to get it to fit my TB Kart. But its in. I cut the bolt holes large and used neoprene washers between the belly pan and the chassis so it can flex and to reduce rattles.

Not bad for $85 bucks +/-

I usually play with 16g for old my old Willys stuff. My first time working with aluminum but it wasn’t too difficult. My old one had the hole under the streering shaft (probably by the karts P/O). Thought it would be a good idea to recreate it so I don’t need to drop the pan to remove the shaft?

Belly pan