Michealprater
Member
Precisely where I am headed.
Adding 50lbs of lead to a kart... Help
- Thread starter Michealprater
- Start date
Ted Hamilton
Helmet Painter / Racer
If enough people gravitate to the lighter classes, the money will follow. The money's where it is because the entries are there.
KartRacingLA
Member
A driver with 30lbs to make 375 and a driver with 0 lbs added weighing 375. The added weight driver will have an advantage. Or so Ive been told....
1fasttiller
Member
The driver adding weight can always put it exactly where he needs it to get the numbers perfect,... so yes of course its a mild advantage.
Ted Hamilton
Helmet Painter / Racer
If one is not smart or motivated enough to move one's seat to get the numbers wanted, then those adding weight will enjoy a small advantage over the lazy. Regardless of total weight, I'd have my seat "ideally" positioned for the Cg first....then all the weights can be added mid-seat where they'll affect rotational momentum less...
KartRacingLA
Member
I never move a seat to get numbers. The seat gets mounted a certain place and then weight added if needed.
Ted Hamilton
Helmet Painter / Racer
The driver is the single largest element of the kart, by mass. So if you're unwilling to move him/her, then yes, you MUST add and position weights. I don't know where people get these ideas that some element of a kart MUST be positioned somewhere static...every driver, every driving style is different. If you're unwilling to try different ideas and test to see what's faster for you, the more committed drivers will continue to beat you. It becomes more critical with lighter drivers, who may require a HIGHER seat mounting to get same Cg effects, etc. If your program is working for you, great. If not, consider trying something out of your box.
KartRacingLA
Member
Seat strut positions matter greatly. Especially the right rear and front
Ted Hamilton
Helmet Painter / Racer
If you analyze the load paths, you can achieve the same results with different geometry sometimes.
KartRacingLA
Member
Most of the time a large seat or larger already has the rr strut at near vertical (with the left rear strut maxxed out at the nerf bar pin) so any more vertical would result in side loading the strut rather than transfering along the strut. This would be amplified more on a flat track vs a banked track
Ted Hamilton
Helmet Painter / Racer
All struts get side-loaded dynamically anyway...not an issue for me. And with creativity, most issues can be resolved. Think: wiggy bar concept.
flattop1
Dawg 89
The wiggy bar concept.
Seat struts transfer dri ver weight . Longer bars get side loaded more as do the ones straight up and down .
Thus absorbing the weight transfer.
Wiggy bar has shorter struts less load absorption so better load transfer .
Is that the correct concept ?
Ted Hamilton
Helmet Painter / Racer
As I understood it, heim-type joints prevent binding and a lateral rod allows fixing seat wherever it needs to be. The seat crossrail is a beam and its' deflection is negligible (compared to the waist, etc.) so the down loads are all that matter. All seat struts transfer is a down load in terms of weight. Since there's 2 of them, the whole seat acts like a lever for the Cg. The only thing that matters in the end from a physics standpoint is where that Cg is. The front seat rail takes its' proportion of the down loads, and the rear seat struts take down load as well as act like levers for the Cg on the rear of the chassis. The front right noserail and side rail resist that load based on their geometry and cross section. I'm not convinced that location of the rear seat struts plays a major factor in the handling -- it's where that rear crossrail connects and positions the loads. So a kart can basically be simulated by 2 T's.... All the bars of the chassis are doing is determining how these T's interact.
KartRacingLA
Member
So you are telling me weight removal and transfer on the rear tires are the same with the two different (red and blue) strut positions Ted?
Ted Hamilton
Helmet Painter / Racer
No, I'm saying that a heavier driver moving the seat left is the same effect as a lighter driver staying put and adding weights on the left of it, assuming your seat struts still have the same BOTTOM pickup points. It's left to your imagination how to achieve this.
Feel free to PM me if you'd like to continue....
Feel free to PM me if you'd like to continue....
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KartRacingLA
Member
The thing is Ted, most large+ drivers are already maxxed out on the left strut position. So if you move your seat over it and lets just say you cut the strut down to allow for proper seat height to remain, what you do is you will "sit" on the left rear too much. Even if you keep your right side strut mounting point the same
Ted Hamilton
Helmet Painter / Racer
Cg is Cg and while rotation cares where the mass is, the Cg will act the same working downward whether it's a big guy sitting over to the left, or a bunch of weight hanging there. I'd rather suspect big guys have a problem with not being able to move their seat RIGHT to allow their Cg to compare with a light driver with a ton of weights about 12" in... Unique motor mount situations may help.
Michealprater
Member
You guys lost me when you brought physics into this. 
KartRacingLA
Member
Seats (and all associated parts) need to be in a certain position for a chassis to work as designed with particular drivers' weights and heights. I dont know of any heavy drivers that are needing to move their seat right. Most have to add weight on the left side to get percentages right. (even though min. weight for the class has been met). This is again because the seat cannot be mounted further left and be mounted correct.
Drivers with added weights can run lower left percentages than larger drivers due to the center of gravity location (should be double stacked, left side thigh to waist area).