Long Travel Off Road Go-Kart Suspension
Long Travel Off Road Go-Kart Suspension
(OP)
I am starting a project similar the one these guys started. thread800-129475 Just to get my wheels rolling in this field. The only differance is where they went with a on-road suspension, I want to do the same thing with an off road suspension. Push-rod/rocker style. Power will come from a 600cc Street bike engine, and tires will be of ATV sizes. It will probably be a single seat design too. My problem is that the resources I've come across primarily relate to on-road suspensions and I need to know if the same principles will work for off-road as well.
Thanks,
Tyler
Thanks,
Tyler





RE: Long Travel Off Road Go-Kart Suspension
RE: Long Travel Off Road Go-Kart Suspension
You might check out the Honda Odyssey or Pilot buggies. Otherwise you can look up the real thing and perhaps scale it down.
RE: Long Travel Off Road Go-Kart Suspension
Thanks guys,
Tyler
RE: Long Travel Off Road Go-Kart Suspension
The front suspension can be adressed in several ways. Are you running front brakes? Are you starting with a quad spindle or building your own? How much travel are you dreaming of? Keeping the front and rear suspension close to the same travel is a good idea. I wouldn't run any more than 4" more travel in the rear. That means that you may need to figure out the rear end first in order to see how much travel you end up with. Then set up the front with a few inches less. Too many cars have front and rear suspensions that aren't even close (in inches of travel.) If you plan to really tune this thing to work, heed my warning.
As for the rocker link that just drives the shock, as long as the geometry is right on the links there's not much concern. You could set up the links to have a rising rate so that the spring and valve rate would get stiffer as the suspension goes into "bump."
I'm still not exactly sure what info you are looking for. I hope I'm heading in the right direction.
RE: Long Travel Off Road Go-Kart Suspension
A narrow track vehicle will be quite limited. I think a wide track Buggy can get about 23" travel with inboard CVs, and a bit more with outboard CVs.
Regards
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RE: Long Travel Off Road Go-Kart Suspension
RE: Long Travel Off Road Go-Kart Suspension
He was likely referring to up travel as that's approximately where they sit. Otherwise he must have been going awfully slow, wasn't where a TT is designed to go, or having some other problems. The TT's I work around average 24-27" front and 30-36" rear and use every bit of the travel. And BTW, it's possible to get significantly more than 23" of highpower, reliable travel from an IRS system.
RE: Long Travel Off Road Go-Kart Suspension
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Long Travel Off Road Go-Kart Suspension
RE: Long Travel Off Road Go-Kart Suspension
The initial question is about finding design resouces that outline design principles of off-road suspension. And design ideas and problem(opportunities) for building a relatively long-travel buggy style go-kart. I'm not trying to cut anybody off or be rude. I just need some help finding some resouces.
Tyler
RE: Long Travel Off Road Go-Kart Suspension
The cart that I did was a simple rear swing-arm and a-arm front, but as I said, it was too tall to ever really work well. The rear did work decent.
Building a rear independent will certainly cost more, but would be a nicer finished product.
Let me know what you are looking for and I will try to point you in a general direction.
RE: Long Travel Off Road Go-Kart Suspension
Thanks for all your input guys.
Tyler
General overview:
50-60 inches track width
72 inch wheel base
12 inch ground clearance
12 inch bump travel
6 inch droop
16-18 inches total travel wishful thinking all around
at least 600cc sport bike engine possibly 1000cc-1300cc
RE: Long Travel Off Road Go-Kart Suspension
So, you need to make the arms long, and draw it out at teh extremes of travel.
Sorry, i haven't got any particular values in mind.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Long Travel Off Road Go-Kart Suspension
Those numbers just don't add up. A car that size cannot put 16-18" of wheel travel to use. A 60" track with 72" wheelbase could not effectivly use more than perhaps 10-12 inches of wheel travel at most. If you plan to go fast you will need 30-50% droop. But that kind of speed and droop requires that everything else be right, otherwise it will just turn into uncontrolled body roll. This means race type shocks (perhaps even by-pass type), rear sway bar, and exceptional springing. Static ground clearance of around 6" would be more realistic with 1.5-2" at full bump.
Even at 12" travel you will need to, as mentioned above, keep the control arms as long as possible. This cannot be done effectively without a very narrow differential, custom hub units front and rear, moving the CV's out, and a lot of attention to steering.
It can be done but to be effective and/or go fast at all you will literally have to make a minature of the real thing.
You might check out http://www.race-dezert.com or one of the other desert racing sites.
RE: Long Travel Off Road Go-Kart Suspension
I don't see any probs with a little more camber gain (in bump) then usual as well as a little positive camber in droop. Of course that is my opinion, but I have had good luck with it in the dirt. It also would help, a little, with CV bind.
There is a place in Rockfor, IL that can help with CV's and axles, but you're on your own with the center diff.