Need help with design

ok so I’m trying to build my own kart chassis. I had a new idea about how to mount the rear axle to the frame of the kart by using little tie-rod with hiem joints. as shown on the picture they are mounted vertically from the chassis to the bearing cassette. The only problem is that since the are mounted vertically they will have horizontal play in them which i do not want since that will in turn change the wheel base of the kart on the track. I was trying to avoid welding anything to the frame itself for the rear asince that is how the chassis makers do it now…http://wardkarting.com/Ward023v.jpg
so im trying to avoid doing that but I’m not sure if it is possible to do it another way. I wanted to do it something like this…http://picsorban.com/upload/kart%20axle.gif

i dont know if i understand it but the design with the heim looks unsteady or am i wrong?

it looks like it would have alot of horizontal play within the bearing and bearing cassette…do you want it to have that play?

the only way that would be decrease is if you weld a piece of metal in between the two helms and make it like a box design and not weld it to the frame…you know what i mean by that?

but as soon as you start to make hold in your tube frame doesnt it weaken the frame? im asumming there will be a bolt that goes at the end of each tie rod…

like this

so with your new design you get a power burst because when you hit the gas the engine/axle flies forward into the back of the seat?

i wouldn’t try and do anything groundbreaking if i were you because you’re clearly an idiot.

Either I don’t completely get what you are trying to accomplish, or I have to agree with Newman it’s just a plain bad idea.

the whole point of the tread is how to stablize it and not call me a idiot since I ALREADY KNOW WHAT IS GOING TO HAPPEN WITH THAT DESIGN. I have a few idea’s but I don’t feel like drawing them up on ms paint now but it should work to keep it from moving.

no the whole problem with that is the horizontal play in the design.

yes there will be.

why do they not weld anything to the kart frame? is there a good reason or are you just copying for the sake of it?

i think you’re in over your head.

hey roush when u mean horizontal is it from front to back or side to side?

i think with the metal welded in between the tie rod it will stiffen it up. from any kind of movement front to back or side to side.

is the reason you are doing this because you want to change out the rear axle with a whole different setup, changin it with ease? etc…

they currently weld to the frame right now, I am trying to help avoid it if I can. I am trying to come up with something new besides copying what has already been done. Yes I know I am a little over my head on this one but I will have people helping me out if I really want to do this. I’m just not going to spend all the time and money to try it out and see if it doesn’t work. If I have something that looks good on paper I’ll do it.

The main reason I would like to go with this setup is you could adjust frame height quickly, change out axles in a couple of minutes, and I also think it would be more cost effective but that is all yet to remain unseen.

Also when I mean I’m trying to stop the horizontal movement i mean front to back, like how Newman pointed out I don’t want to axle to come crashing into the back seat.

I will come to Roush’s defense, sort of. Per his sketch that design is useless. If it were a axle in a tube (as in a RWD car) his design would work 2 more bars. A torque arm going front to rear and a panhard bar going sideways would make it work well with an axle in a housing.

The problem lies with the bearing cassettes. In a rear end in a car the housing holds the bearings concentric to and in line with the axles. Thus you need to only constrain the movement of the entire housing. This allows 4 bars (two trailing arms, a torque arm, and a panhard bar) to do the job. Three bars if you using a ladder bar setup. In this [go kart]case you need to locate the bearing cassettes relative to the axle as well as the position of the axle/bearings assembly to the frame. Thus to use this bar setup you’d need at least four bars on each cassette to keep things located and in-line.

If you want to adjust ride height put a jack screw up through the bottom of the frame. Reinforce the frame around where the hole goes through it. Put a cotter pin through the top of the jack bolt so it can’t come out on the track.

Now with your kart up on the stand you loosen the screws that hold the cassette and turn your jack screw up or down. Gravity will hold the axle assy’s against the screw. Adjust height on each side and retighten your lock screws.

The reason his design doesn’t make sense and they’ve been doing it with a welded bracket is, THERE IS NO SUSPENSION ON THE CART!!! The frame is hard fastened to the axle and bearings. The panhard bar would really be a support bar with no dynamic functionality, as with the other arms. There is no reason to use a hiem style linkage for anything on this kart. Separating forces into single directions for mounting like this will result in multiple, unnecessary supports. A stronger mount will come from welded brackets, and adjustment accomplished with with slotted, or seperate holes.

Yea, I’m thinking along the same as a lot of these guys, the added weight and increased points of possible mechanical failure FAR outweigh any gains.

If you’re trying to make it adjustable up/down, then just cut holes instead of slots into the welded brackets instead; little less adjustable, but should keep the alignment… to a point… If you make the holes at a slight angle it will address your concern of the wheelbase changing.

I wasn’t really clear I meant to do this with the design as in the photo.

thanks for the help guys. Ive come up with a different design kinda of. I’ll going to use a bracket and clamp it on the chassis farther back, similar to the ones we use for are seats and then connect that to the bear cassette to stabilize forward movement.

you’re reinventing the wheel… why?

Since when is welding such a bad thing?

beat me to it

i can’t believe i approved this thread.

ugh

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