Independent Rear Suspension

[fowler]

i could make a cv joint for $40 aus
they are just some rod with keyway and two uni jionts at 15 bucks each from an agricultral supplier

 

[r97]

well it sounds like you should just go with the chain setup redsox, me personaly for 40bucks a peice would go for the cv axle, but choose whatever you want and good luck

 

[newrider3]

i could make a cv joint for $40 aus
they are just some rod with keyway and two uni jionts at 15 bucks each from an agricultral supplier

A CV joint and a u-joint are two completely different things. U-joints are also weaker, and have less travel potential before they break.

 

[r97]

hmm.... unless someone has a complete machene shop i dont think there makeing that any time soon lol

 

[redsox985]

Uum ya, I don't have a complete machine shop available until I get back to school. Our shop is pretty decent. 5 lathes, 3 drill presses, 1 vertical mill, 4 stick welders, 3 small migs, 1 monsterous mig (1/2" steel in one pass), a blasting cabinet, a band saw, 2 horizontal band saws, chop saw, hand tools out to wazoo, a forge, an aluminum foundry, a 20 ton press for 90 deg angles, all kinds of sheet metal stuff, and I prob forgot some. I could do it but for the time it would take, and IDK if I'd trust my stuff as much as something that a company makes.

 

[r97]

omg..... im so jelous the high scholl im gonna go to in a few years doesnt even have a machene shop, soooo for now im stuck with 1/8" max mig & hf angle grinder and chop saw, lol. unless you can find some cheap cv axle from a car in a junk yard or somthing go with the chain/jackshaft setup

 

[fowler]

we onlg have 4 small migs 3 lathes a cold saw and a grinder
all the resouces go into wood work (they get a computer auto miller thingy and a laser engraver

uni joints may not be ideal but theyed still work surly

 

[The_Machine]

Universal Joints work fine, and weigh less. I'm using them on my build now as well as ones in the past. depending on the travel you have it may not be ideal. My kart now will sit 4 inches off the ground, so that's not a big deal

 

[Benjo]

I've got a pair of them lying around, i got them off the front of a farm quad.

 

[redsox985]

We have a decked out wood working shop too. I've only taken metal and don't know about the wood shop but it was overhauled about 4 years ago. I believe about $300,000 into it I was told by my shop teacher. We also have robotics with a brand new $15,000 CNC mill.

 

[r97]

what highschool do you go to??

 

[redsox985]

Shaler. It's just outside of Pittsburgh. That's in Pennsylvania (for the international karters).

 

[Raywelder]

i agree with you on the first two paragraphs. in the last one im not showing the prices for all the compnents needed in the system, just the "specialized" if you will, componetns that are needed to setup one way or another. and yes isuppose the cv axles would need to be connected, jack shaft. and i was just guessing prices basedd on memory so there not exact.

Understood My prices are from memory too anyways.

Cv joints, or U-joints can be had cheap on ebay if you are persistant and maybe a bit lucky.

I found a set of porsche U-joint Axles on ebay for 20+ 25.00 shipping. No one bid on them (I forgot to...) They would have worked nicely.

I also found a free set on craigslist, Guy was willing to give them to me but didnt catch him at the right time when I was in town.

camber change during travel is a good thing! during body roll you want the wheel to camber out so that the wheel patch stays level with the road. Can you visualize it? It's difficult to figure what is best without putting it on the road, but that's what's so great about heim joints, you can adjust the length of the arms to get it just right. The reason why they build double a arms with unequal length arms is so that the arc of the travel does not shorten then widen the wheel track arc, and the reason for unparralell upper and lowers is so that they camber during body roll.

I don't worry so much about the costs of building so much, unless it's excessively priced. You can make your own bearing plates for the ends of the arms for the price of metal and all you need then is

Keyed Axle 40$
CV $? (junk yard?)or 4 universal joints 200$
4 flange bearings 30$
2 pillow blocks 15$
Sprocket 15$

Good prices if you ask me. The time you spend working on your project is time spent not wasting your money on less entertaining things.

Double A-arm system would be better and perform better. But I think when building a go cart, you should decided whether the extra complicity is worth the performance, or if you could use a simpler system and sacrifice the extra performance for something that will probably work fine for just a go cart.

On my go cart project, I started it when I was 12 or 13. I built the first version of it in a few weeks, Then I kept cutting it up and adding on to it and rebuilding things and Dreaming bigger. I eventually let the project exceed my resources and Funding. It never got finished. I could have had it done and enjoyed it a lot more had I chosen simpler designs. This was before I had access to a full metal shop and knew where to get supplies, how to buy things cheap.

 

[The_Machine]

Most of the time and work that goes into building any independant suspension system from scratch is the bearing plates. The time spent making the arms is minutes. Make the first one on some plywood then screw in some wood blocks for a jig and you can make an arm every 10 minutes.

This is how I will make mine.

I had an epiphany moment when I realized I could build them with such simplicity.

2 rods, only 1 beveled to fit against the other. weld some bungs in for the heim joints to screw in and you're done.

You can also use this design for the rear, just use rear toe adjustment rods, which is just a piece of tubing with heim joints on either end. Like This: (but not bent)

Double a arms are not any more difficult to make than single a arms or trailing arms. Trailing arms are heavier because they have to be made stronger to fight the torsion forces when cornering hard whereas the natural triangle shape in the a arms makes this of little concern

 

[r97]

just found this pic randomly on the internet

hope it helps

 

[redsox985]

That looks like SketchUp. I wish I could get the whole file and look at it closer with dimensions. That looks pretty legitimate.

 

[devino246]

On my go cart project, I started it when I was 12 or 13. I built the first version of it in a few weeks, Then I kept cutting it up and adding on to it and rebuilding things and Dreaming bigger. I eventually let the project exceed my resources and Funding. It never got finished. I could have had it done and enjoyed it a lot more had I chosen simpler designs. This was before I had access to a full metal shop and knew where to get supplies, how to buy things cheap.

This sounds exactly like me

redsox, if that is sketchup, who ever drew that must be magic. Sketchup is anoying. Thats why I like Inventor, its easier IMO.

 

[wingnut]

The dual chain rear drive is excellent option for a budget IRS setup. It's a proven design. Check out the shredder2 from ubuilditplans.com

I'm working on a Bandit build and I plan on using this setup. My main complaint with the u-joint based rear end in the plans is that the axle needs to be horizontal in the neutral position. With that setup, the drive sprocket eats up allot of ground clearance. The intended use for this buggy is trail riding. The trails around here can get rough and rutted out from all the ATV traffic so I wanted lots of ground clearance.

Another requirement for my buggy is that the track needs to be on the narrow side. The managed trails around here have a limit of 50inches. With that kind of width, I wouldn't have gotten much travel from CV or U-Joints.

The real clincher for me was cost. I just put in the order from surpluscenter.com for all the sprockets and sprocket hubs and the total price was $75 (delivered). A pair of farm U-Joints costs $100 and you still need two or three sprockets (depending on how many jack shafts you use). CV joins are generally much more expensive and I'd still have issues with travel and width.


Here's a shot of my completed right trailing arm. I'm still working out the mounting.

 

[theo]

Wingnut - how are going to set up the hinge line of the swing arms to the center line of the forward jack shaft? And how are you going to mount the forward sprocket? Have you thought of mounting the swing arms off the forward jackshaft?

By the way I like the swing arms, good job.

Like this.

 

[wingnut]

My plan is to mount the swing arm behind the jack shaft. I realize that the chain tension will change through the travel of the swing arm but my hope is that I can get the two pivot points close enough that the tension doesn't change too much. This is how motorcycles are set up so I don't see why it wouldn't work for a buggy. Worst case, I'll add a spring loaded chain tensioner.