Adding rear suspension questions/ideas?

[jd0401]

Hey guys now that it has warmed up i can get back to this project.

Originally i had went only to go get the TC but was told i could have the whole rig for 250 so of course i got it knowing it needed a little work. the plan is to make this into an offroad kart used in the mountains stump jumping etc.

Engine starts on the 1st pull but electric start buttons need replaced.

The frame itself is very sturdy stable but in my opinion could be improved upon in areas.

I would really like to begin by adding/making this a swing arm supsension for the rear but have a few questions:

1- As far as shock placement goes where is a good place to put them? At what angle is optimum?
2-I believe i can cut the existing back end off and then extend it a little so that i can have plenty of room for the jackshaft and motor. The question again here is where would the best place be to mount the shocks on the swing arm?
3- would it be best to chop the back end off and start from scratch to accomplish this?

 

[jd0401]

 

[firemanjim]

Uhh, I don't see you stump jumpin with that with out extensive modification........

 

[jd0401]

That's the plan I'm not leaving it as is but I want to start with the rear suspension.
the front is going to have dual a arms.
It's running a 14hp greyhound comet 40 converter

 

[firemanjim]

Oh ok..... Ima play nice then......
So, how do you want to do it? Engine sprung or unsprung? You want A arms in the rear? Oh no, you said swing.... That's right. Would you be interested in an IRS design, but simple? (that's the pic)
Me personally, if I was gonna do this, I'd hack off everything from the seat back. Now design a non moving engine mount, so it's weight isn't on the swing axle but rather attached to the chassis. Now fab up the pivot points with bearing tubes. You want like a 3/4" or 5/8" axle to hold it all together. The pivot points need to be far enough away from the chassis and swing arm so you can run a 10 tooth (or what ever is the same as the one on your tc) sprocket. The swing arm pivots on that axle, also allowing you to drive the axle, and maintains the correct chain tension throughout the arc of travel..... Does any of this make sense?
The standard way would be to build a swing arm that the entire drive system mounts too, engine included...... I don't like that version.....
EDIT
If you look at the pic, it drive the irs the same way. Using an axle and small sprockets (same as final drive of tc)
EDIT #2....
Actually, he has it set up as a jack shaft, but you don't have too.....

 

[jd0401]

Thank you I have been looking for other opinions as I'm not sure how exactly I want to accomplish this...
I am for sure chopping the rear off from the seat back.

I will have to do some more drawing on a stationary drive system but I definitely belive it would be better in more ways than mounting to the swing arm.

 

[firemanjim]

Do you want me to draw up the simplest design I can for ya? With stationary engine mount? Or engine on swing arm? I don't mind, but I would not draw it up till after everyone goes to bed. I can post it up later tonight or early morning.....

 

[jd0401]

I wouldn't mind that at all I'll also post what I have come up with in a bit I work overnights so I'll be up. Thanks it's a lot easier to grasp concepts and have ideas come to life being able to converse about them

 

[firemanjim]

I'm up late every night.....
I haven't been on much lately, been under the weather to speak. But I'm feeling much better today, and already hit the ground running..... been on here off and on all day....
So you want the engine mounted to the chassis or swing arm?

 

[jd0401]

I've thought about both what are your pros and cons for the 2? Glad your feeling better! Nasty bug has been getting around Colorado as well

 

[firemanjim]

Thanks....
I prefer engine mounted to chassis. The thought of the engine getting all shook up all the time just doesn't sit well with me. When you "come down" from, say a small jump. All that force is absorbed by the engine as well, if it's in a swing arm. Mounted to the chassis, the force is exerted over the whole chassis, and a negligible amount to the engine. Well, that's my belief any way.... You never see a sand rail or serious mini buggy with the engine flopping around with the rear end...... There has to be a reason.....
What kind of budget will you have? That plays a key role in the design. A chassis mounted engine will cost a little more, but it would be worth it, IMHO....

 

[jd0401]

Ultimately I want to get into dundes/sandrails....budget wise not sure I'm more than willing to put 1000+ into this to get it where I want it to be. (Ideally I'd like to stay under that if possible but know that it may not happen lol) let's go with a chassis mounted engine. It will be a good learning experience as well

 

[firemanjim]

With that kind of budget, I'd suggest starting completely from scratch, maybe using that kart for parts like spindles and what not..... Or just get that kart running, and set aside time and $$ to build you a custom buggy. I'm gonna post a link in a second, to a buggy build that it pretty nice, and could be done close to your budget.....
http://www.minibuggy.net/forum/proj...xxer-600-powered-micro-2-seater-build-23.html

 

[jd0401]

Definitely food for thought. Perhaps I'll go about that build for myself as for this one I would still like to make an off road kart out of it for my siblings

 

[firemanjim]

If the youngins are gonna be the typical drivers, I'd say a simple engine/swing arm type. You can get good travel out of 3" travel shocks.
Yeah, I'm gonna draw that up..... Learn from this, so yours turns out bad asterisk......