two seater kart design

[tiremikejr]

so the build will begin before long on a two seater kart project with my two sons ages 5 and 7! I guess you could say that I am still in design stage however I do know a few things that are definite. I actually picked up a cheap kart the other day that only needs an engine which I plan on using as mine to ride with them (one seater). I have the metal stock already for the build of the two seater so heres my idea. I picked up two preditor 6.5 hp motors from hf today one for each cart 20% off black Friday deal so I will use these for power, and I know I want to use cent clutch for both. for the build I want it to be fairly simple with dead axle and probably a band brake I might do a caliper setup but im leaning band setup. for the tire and wheel setup I really want to find a set of lawn mower tires and wheels probably a 15x600x6 in the rear or so and unsure on front if I want the same or a little smaller but I do like the staggered look. or I may just use a little smaller tire and wheel setup. but here is the main question as far as frame design. I cant decide if I want to build just a rectangle frame from front to rear or if I want to inset the front and rear frame where the tires set as to make them "even" with the seating area as far as width. I need pros and cons for dementions on the cart I was thinking 30-36 inches wide for seat area and 50-60 inches in total length.

 

[tiremikejr]

I was thinking something like t-mans two person kart I like that setup minus the swinging rear setup

 

[tiremikejr]

something allong these lines

 

[firemanjim]

That's a slick little kart. Just copy that..... Put your own twist to it.... IIRC the best ratio for width versus length is 3:4....... If its 45" wide, then the axles should be 60" apart...... See how that works? It will keep your turning radius at a usable /steerable configuration.....
(after reading that, that just sounds stupid.... BUT it works..... )
EDIT
Look here..... Site your kids down, side by side..... Put 8" between them.... Now measure from outside hip to outside hip..... Add 6" to that...... What do you get?

 

[OzFab]

3:4 is a good starting point, try not to go much longer; the closer you get to 1:1 (or 4:4) the more stable the kart becomes & the smaller the turning circle will be; making it longer will, obviously, have the opposite effect...

 

[machinist@large]

3:4 is a good starting point, try not to go much longer; the closer you get to 1:1 (or 4:4) the more stable the kart becomes & the smaller the turning circle will be; making it longer will, obviously, have the opposite effect...

I'm sorry Tony, but this post seems to point in opposite directions??!?? Could fully be me, but I'm guessing that I might not be the only one......

 

[firemanjim]

That's a slick little kart. Just copy that..... Put your own twist to it.... IIRC the best ratio for width versus length is 3:4....... If its 45" wide, then the axles should be 60" apart...... See how that works? It will keep your turning radius at a usable /steerable configuration.....
(after reading that, that just sounds stupid.... BUT it works..... )
EDIT
Look here..... Site your kids down, side by side..... Put 8" between them.... Now measure from outside hip to outside hip..... Add 6" to that...... What do you get?

3:4 is a good starting point, try not to go much longer; the closer you get to 1:1 (or 4:4) the more stable the kart becomes & the smaller the turning circle will be; making it longer will, obviously, have the opposite effect...

I'm sorry Tony, but this post seems to point in opposite directions??!?? Could fully be me, but I'm guessing that I might not be the only one......

:toetap05:
Alright! Now IM confused....... LoL

 

[tiremikejr]

the way I had it figured on my scetch was to have 2:3 ratio being 36 inches wide and 54 inches long or somewhere close to that I don't want it to be too wide, and the 36 wide gave them decent room on both sides to grow into or for comfort. not to mention the swap would be easier if I decided to make it a live axle at some point as they become to learn to control it better. I decided to do one wheel drive so they didn't have to fight the forward drive of the axle.
I just don't want it to be too wide and bulky seeing as it will only have the 6.5hf engine for power. but for giggles if I use the ratio of 3:4 the length of the cart would be 48 inches and I think I need the extra 6 inches for motor clearance at the seat and a little leg room to grow on I was thinking.
But he I am just a noob here!

 

[Poboy kartman]

What's confusing? The closer you come to square the more stable.....

Just convert to feet.....a 1' kart is most stable at 1' and a 4' at 4'.... so practicality demands a compromise.....

Keep in mind though...that what determines stability is wheelbase....not frame size....theoretically you could have a 1'×6' frame on a 4' x 4' wheel base...practically....no....

 

[OzFab]

I don't see what's confusing, I was advising the OP to keep the wheelbase short to improve stability & handling...

As it stands, using the current measurements

36 inches wide and 54 inches long

will make the kart more prone to flipping at speed & would have the turning circle of a large bus because the ratio is 3:4.5...

Having said that, as Doug pointed out, just because you build a 7' long frame doesn't mean you have to have a 7' wheelbase...

 

[tiremikejr]

so I am working everything out in this head of mine before I jump in and just start welding. I do not have tires and wheels yet and I wanted to use mower tire wheel setup. but heres my problem I am lost on how to mount the sprocket and brake setup to the wheel on a one wheel drive if I used a live axle I could figure something out but im lost on how to do it if there is no hub studs to bolt the brake/sprocket setup to. should I just scratch the mower wheel setup and go with cart wheels or something maybe a set of golf cart tires and wheels since they have bolt holes and just buy hubs for the rear and adjust sprocket size appropriately. I just didn't want to spend 200 bucks on tires wheels and tubes because I still have to buy the clutch and sprocket and brake setup.

 

[OzFab]

All you need is to use wheels which have a bolt on hub & replace one with a double flange hub