Low-Tech Front Suspension

[DCProductions]

The following suspension style comes stock on a lot of yard karts and does not provide much cushion. However, I have had decent success and plenty of fun with rigid frame karts, and because it was free, this modification will be well worth it.

Potential problems foreseen:
-The through bolt could bend. Solution: grade 8 bolt?
-What spring rate? Solution: light duty die springs?

Thoughts? Comments? More problems?

We're not looking to make this kart jump worthy, just bump worthy. The springs right now are cut 300lb porch springs. Needless to say, it is a little stiff.

 

[Bluethunder3320]

run the bolt throught both holes. keep the bolt going through the bottom just for support. use springs as light as you need... the worst thing that can happen is the springs are always compressed while your on it.

 

[compguy101101]

Is that a bolt on spring for the front end of a rigid frame kart? I have been trying to figure out how to design one and if that is readily available I'd rather just buy it than design it. If you made it can you post your schematics on how you did it?

 

[DCProductions]

Is that a bolt on spring for the front end of a rigid frame kart? I have been trying to figure out how to design one and if that is readily available I'd rather just buy it than design it. If you made it can you post your schematics on how you did it?

My friend's dad cut a piece of 8" c channel 1/4" thick- HEAVY DUTY- and drilled 2 holes in the short parts of the C. The
springs are cut porch swing springs at 300lbs each, which is too stiff. The spindles were stock on the kart.

I drew up an exploded view (pardon the mistakes, I only had a pen) which should help a little.

If you don't want to make the bracket bmikarts.com has a set of spindle brackets with springs in their steering section I think. They are smaller though but will still provide some cushion.

 

[T-man]

yep , that looks alot like this.

 

[bighead]

Manco Dingos have this set up??

 

[Doc Sprocket]

I can't see it greatly benefiting performance (or comfort), but it won't hurt anything either. Might help a bit. Let us know what you think when do get some seat time.

 

[compguy101101]

That's an awesome Idea. i'm going to try it. I just need a spare set of spindles so I can revert back if I screw it up. Any suggestion of spring tension? I don't have as much space as your Digo. I'm going to attempt to put it on a Kenbar D-856.

 

[DCProductions]

Looking at the Manco I guess it doesn't really have to be very complicated. We are gonna run some bracing to the top of the bracket though like the Dingo.
Thanks guys. I'll give some feed back when he gets this thing running.

Another note, I was planning on putting a "uni-link" suspension on my kart like Doug the Welder; gonna go read his thread. I am also going to try an independent front suspension (a-arms most likely). Are the arachnid threads the best for that or is there another
Thanks again

 

[DCProductions]

Any suggestion of spring tension?

That's actually a question I still have.
Anybody know the spring tensions on these things?

Probably just gonna go with something pretty light based on Blue Thunder's advise.

 

[compguy101101]

I'm thinking that the spring will need to be strong enough to not compress when there is a rider so that it absorbs only when you hit a bump. Should probably put a rubber grommet or something at the bottom so the metal spindle doesn't slam down on the steering bracket.

 

[The Mechtician]

This suspension design is known as a sliding pillar suspension. Cars built by Morgan on the planet England still use a variation on this design.

-The through bolt could bend. Solution: grade 8 bolt?

A Grade 5 bolt would probably be strong enough, but using a Grade 8 (or Metric 12.8) will mean you never have to worry about it. What is the grade & diameter of the bolt you've got in there right now?

-What spring rate? Solution: light duty die springs?

Get 4 bathroom scales and put one under each wheel. Get someone to sit in the kart while you weigh it. Record the reading on each scale and note which corner of the vehicle it came from. This will give you a ballpark for spring weights and weight distribution at the same time. Industrial springs can be purchased from places like McMaster Carr or MSC Direct, sized by coil diameter and spring rate in Inch Pounds (ie; it takes X pounds to compress the spring 1 inch). The amount of suspension travel you'll end up with depends on the total height of your pillar - the compressed height of your spring.

 

[DCProductions]

The current bolt is a 1/2" grade 5 bolt.

Using bath scales is an excellent idea. I will see if I can round a couple up. I will also check out Morgan cars, and spring distributors you mentioned

 

[Doc Sprocket]

I've heard of guys doing this with valve springs. You have a selection of various spring rates, you can combine spring rates for a "progressive" rate, and if you have access to the scrap bin of an engine shop, wrecking yard, or similar- then cheap or free, and plentiful.

 

[Blazkowiez]

Every kart produced at the shop, both Hotshots and Magnum models had springs in the front clips. It was a nice addition and easy to install.

 

[lewikenzie1]

Manco Dingos have this set up??

Ive got a Manco Dingo and it doesnt have any suspension atall
How would i mod the front to get front suspension?

 

[The Mechtician]

I've heard of guys doing this with valve springs. You have a selection of various spring rates, you can combine spring rates for a "progressive" rate, and if you have access to the scrap bin of an engine shop, wrecking yard, or similar- then cheap or free, and plentiful.

That's an awesome idea!

 

[Lynx_Genisys]

Ive got a Manco Dingo and it doesnt have any suspension atall
How would i mod the front to get front suspension?

all three of mine do.. hehe..
(Well ones actualya carter, but its all teh same thing..)

the one kart i got fixed up, it had the wheel laying over onto the frame practicaly..

the spindle part of it was worn out from bouncing and rubbing, ovaling out the tube.

I think there was a nylon busing or some such in thier at one point in time...

what i did to fix it, was pull teh wheel off, grab some washers that wernt slopy around the boltand welded em to the top n bottom of the spindle tube. made it all nice and proper again..

i know eventualy those will wear out as well, but its like a 10-20 min fix every few years.. lol

 

[Doc Sprocket]

Should probably put a rubber grommet or something at the bottom so the metal spindle doesn't slam down on the steering bracket.

I'd try putting a smaller spring on the bottom side of the spindle...

 

[DCProductions]

Compguy and Toystory- I think we'll try putting a spring on the bottom. We may just cut some of the current spring and move it. Also great idea about the valve springs. We need to go to pull a part soon anyway for seat belts and maybe a rack and pinion.

Lynx- The spindle is heavily greased right now, and I hope that keeps it from wearing out too fast. Good to know that it's not a hard fix. Also, no nylon in these spindles all metal.

Mechtician- I looked through mcmaster and msc direct and boy do they have some STUFF! They have so much stuff I need to get rid of my stuff to find room for new stuff. I love the search engines they have on their sites- very easy to navigate and very specific.
I found some springs with about 75lbs/in which I think will be good. Even with someone sitting in the kart I don't think the front will weigh more than 150lbs. There should be 2 1/2 inches of movement AT LEAST over those springs so 75/in should be plenty.

Oh almost forgot to ask! This is kind of a question from Compguy. Any of ya'll who have a kart with this setup, does it compress when you sit in the kart?