Need Help

[Horsebeater]

Hey Im building a "go kart" for my son (4 years old).
It's a little over the top but what the heck.
I got the frame for $150.
Just picked up a raptor 660 front suspension.
I have a cheap Honda clone for power, for now.
I need help figuering out the rear suspension.
I was thinking about going independent, any way for
me to do this semi-inexpensive?

 

[Blazkowiez]

Welcome.

Those are some mighty big tires for this build, did they come with the purchase?

Why must the suspension be independent? Surely a 4 year old will be happy with anything that rolls.

 

[landuse]

Welcome. Maybe this kart is not only for the kid. The old "i am doing it for the kid excuse". We have all done it. Lol

 

[souperman000]

looks to me like the backend has no suspension now, so you would have to remove it, fabricate trailing arms/A-arms, get CV axles, repostion everything.

Or you could put a swingarm on it i guess. still need to remove back end.

 

[Doc Sprocket]

Surely a 4 year old will be happy with anything that rolls.

Anybody who's had a 4-year-old knows how true this is! In fact, he'd be more than happy with a seat to sit in, and a steering wheel to hold!

Engineering a rear suspension on the cheap pretty much boils down to having very good fabrication skills, and the ability to score parts dirt cheap, too.

That said, your best option may not be IRS under the circumstances- perhaps a simple swingarm with the engine either sprung or unsprung? The difference being whether the engine rides with the suspension or the chassis.

Oh- and yeah- "I'm doin' it for the kid." Welcome to the denial stage.

 

[r97]

Unless you're rock crawling, IRS with a 6.5hp clone is completely unnecessary. A rear swing arm would be the most you need. I mean, how fast are you planning for your 4 year old to drive this thing around?

 

[Horsebeater]

Old rear setup has been removed. Im definitly open to a swing arm set up
with the engine not on the swing arm. I was looking at a raptor swing arm.
Has anyone ever done that? Just not sure how the chain would work coming
in at a different angle. Any help is much appreciated!

 

[Horsebeater]

Welcome. Maybe this kart is not only for the kid. The old "i am doing it for the kid excuse". We have all done it. Lol

No it's for him, I dont even fit in it.
I have my toy.

 

[r97]

An ATV swing arm can work. If you choose not to mount the engine to the swing arm, your engine's crank, or a jack-shaft must be inline with the swing arm's pivot. If you do not lineup those two parts to within an inch or so you will likely have massive chain tension issues. Either you can mount your engine:

-On the side of the buggy (engine is less protected, and weight dist is affected).
-In front of the swing arm (longer wheelbase).
-Above the swing arm (limits upward suspension travel, and requires chain to be redirected).
-On the swing arm itself (should use custom built swing arm, harder on engine, very slightly makes suspension less responsive.)

Let us know if you need further clarification.

 

[anderkart]

Welcome to the forum Horsebeater!

I think you should research the proven suspension designs that Trophy racekarts use. I've posted a couple google search/Image links below that should give you some really good Ideas:

Just left-click on these links for that info:
http://www.google.com/search?q=trop...TtygHyqYCQDw&ved=0CAgQ_AUoAA&biw=1024&bih=556
http://www.google.com/search?q=trop...aEI3YyAGk8oGACg&ved=0CDIQsAQ&biw=1024&bih=556

 

[Horsebeater]

An ATV swing arm can work. If you choose not to mount the engine to the swing arm, your engine's crank, or a jack-shaft must be inline with the swing arm's pivot. If you do not lineup those two parts to within an inch or so you will likely have massive chain tension issues. Either you can mount your engine:

-On the side of the buggy (engine is less protected, and weight dist is affected).
-In front of the swing arm (longer wheelbase).
-Above the swing arm (limits upward suspension travel, and requires chain to be redirected).
-On the swing arm itself (should use custom built swing arm, harder on engine, very slightly makes suspension less responsive.)

Let us know if you need further clarification.

I'd like to go in front of the swing arm, just not sure how to make it happen without causing chain tension problems.
Thanks again for the help.

 

[spyder1968]

thats an awesome looking kart ! do you mind my asking where you found that frame?
a rear swing arm is not that difficult to fabricate. unfortunately i don't have any good pics to show you at the moment though.

maybe see if you could find some pics of a Carter trailhunter model 2910 or 2911. that is the basis the frame i am currently using.

 

[r97]

Picture this... When the kart is finished, you should be able to run an imaginary line straight through the center of all the swing arm pivots, and through either the center of the engine crank or the center of a jack-shaft driven by the engine. You should also include a chain spring loaded tensioner. Let me know if I'm still not being clear enough and I will try to get/make a diagram.

 

[Horsebeater]

thats an awesome looking kart ! do you mind my asking where you found that frame?
a rear swing arm is not that difficult to fabricate. unfortunately i don't have any good pics to show you at the moment though.

maybe see if you could find some pics of a Carter trailhunter model 2910 or 2911. that is the basis the frame i am currently using.

Found the frame on Craigslist, very rusted with a 660 cc motorcylcle engine in it.

 

[Horsebeater]

Cut the frame up some.

Bracket for new raptor swing arm. 1/2" plate steel.

Mocking up swingarm.

 

[landuse]

Looking good. Your welds look really good

 

[Horsebeater]

Looking good. Your welds look really good

Thanks!

 

[Horsebeater]

Ok, next problem. How do I go from the comet #40 sprocket to the Yamaha
520 sprocket? Can I just swap one or the other easily?
Also is the raptors 42 tooth sprocket large enough?