All-Wheel-Drive Go-Kart!

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Smurph

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Yeah, that's the very same diff that northern tool sells for $40 less.

As far as the suspension goes, I'm engineering and building it all myself (With the help of my friend who has the CNC machines... But I'm still doing the G-Code). I do have a mock up of my ideal spindle, though. Just drew it up earlier today.

*edit* brain fart. I need to modify it to work. haha.

I think I'm putting my differentials on front and center.

And like I said, I'm not competing with any cars on the street. I just want to transfer my power to all 4 wheels.

The mopar differential is just too big no matter what. This thing is designed to literally tow tons. It would still be overkill on a full size buggy with a 1.x or 2.x liter VW engine. I will probably find a use for the bevel gears, though.

I think I still wanna go drive shaft.
 
Kaptain Krunch

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I really dont think you need the middle diff, that would basically defeat the purpose of 4wd on a kart anyways, unless its an LSD, but good luck finding one that isnt too big.
 
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porsche930dude

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Smurph said:
Yeah, That's what I'm looking for. I doubt It'll happen. We'll see.
Click to expand...

you can pack a regular open diff with really heavy greese to limit its movement. But we are warning you. You dont want a diff in the middle. Think about it. when your going up a hill your front end will tend to slip first right. So you know how a diff works im assuming. all the power will go to the front which is slipping and youll go nowhere. And this will happen in every situation front and rear. you may as well not bother and leave it rear wheel drive
 
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joshpit2003

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hey porsche930dude:

thanks a bunch for that first link you posted... lots of helpful stuff for me. Now lets just hope they actually have everything in stock.

as for the center diff: I just remembered I have a lego set at home somewhere that I believe came w/ 3 diffs. It was a 4wd truck kit, and so just the fact that a tiny lego set may come with 3 diffs is telling me something. Im away from home currently and wont be back for a while, but if I can remember i'll be sure to throw together a crude set-up and see. But as already mentioned, you can always add the diff later (after building it without) if you feel like you really need to.
I'm pretty sure my design will require that third diff. I also need to figure out the best way to have all three diffs lockable. (talk about tricky) haha.

best of luck.
-josh!
 
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With partially complete wishbones. Also. That's just a dummy piece that its connected to to make it work right in the program. I'll, of course, connect it to the frame that won't have a wall that blocks a drive shaft.

Remember, Inventor portrays the "ideal situation" and I mostly use it to prove a concept.What goes on my kart may be different.
 
Doc Sprocket

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The center differential is a requirement for driving on clean, dry pavement. It will alleviate "driveline bind" that can occur on a 4wd when there's no front to rear slippage allowed by full traction. Even slight differences in tire pressure can load up the driveline under these conditions and generally results in broken driveline parts. Off-road, the center diff is not only not required, but a liability. With dirt, mud, sand, bouncing, etc, the driveline bind is a non-issue, as there is ample opportunity for slippage and torque release. With only front and rear differentials, you essentially end up with 2wd under really loose traction conditions. The front tire with the least traction will spin freely, as will the rear. If you add a center diff to the mix, now the AXLE with the least traction will spin freely, and so will the tire with the least traction, on that same axle. In short, if one lousy tire is in mud or hovering above the ground, that tire, and ONLY that tire, will recieve power, and there you shall sit, revving away. You're gonna have to take my word on this, I've been into 4wd systems and offroading for decades.

Additionally- If your cente diff was a selectable locker, all your problems are over. If you have the ability, maybe you could engineer one. If you have and LSD or locker in your front or rear diff, the best you could hope to achieve is a full 2wd (both tires, same axle) under adverse traction conditions, with your open center diff.

To summarize- If your not going to be driving on clean dry pavement, don't bother with the center diff, it's not worth the time, money, and weight. If you will be driving dry pavement, either engineer a way to lock the center diff, or accept the fact that you'll have less traction in loose conditions that any of the rest of us with Rwd live axle.
Cheers- Chris
 
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The problem I'm seeing once I got the driveshaft and u-joints in there is currently with the spindle.

In order to move up and down, as well as left to right (wheel to turn), the spindle's two pivots must be collinear.
 
newrider3

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Instead of the pivot at the end of the arm, and the big two piece spindle thing, just have a heavy duty heim at the end of each a arm. It can act as both suspension pivot and steering joint.
 
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My solution. I redesigned both spindle parts. The inner spindle to be basically two dimensional. The other spindle to be longer to compensate for the difference.

Works pretty good. Shown is its max turn of 34.5 degrees off center. I'm not sure if this is good or not. anyone have any wisdom on that?

Problems that I can see from here include:

I just realized that I'm going to have to mount the shock absorbers on the top wishbone arm. Making my kart at least a little taller.

The length of that inner axle between the u-joints might be a real pain in the a$$.


Here's another sketch. Doubled it up. Put hubs on them, and put a wheel on one. It's the same wheel I drew on my street kart. Didn't bother drawing another wheel. I'll, of course, use bigger tires.

 
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Again, that wheel is just what I already had drawn. It's only like 6 inches tall. I'll put taller wheels/tires on it for off roading.

And that piece that the upper part of the shock and the control arms connect to is still a dummy piece, and the shock absorber will actually connect to another frame rail.

The shock is only scale in length/travel. The lower piece is a half inch outer diameter, with a .375" inner diameter. The length between the centers of the mounting holes of the shock absorber is about 14 inches fully extended..
 
freakboy

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be careful that you dont have it to a point were it will bind when fully up or fully compressed...
 
motor_head

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looks good, instead of the center diff you could use a transfer case from one of those little 4x4 nissan trucks then if your on road just use 2wheel if your offroad use 4wheel and as a plus you would have 4 low for climbing or pulling
 
Doc Sprocket

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Functionally, a part-time transfer case like mentioned would be ideal, you could even get about a 2.6:1 low-range gear reduction. Practically, that'll be a very large, heavy piece of kit regardless of what mini-truck it's coming off...
 
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