Go-kart front suspension design

Brief description of our go-kart project's front suspension design. This has been designed and fabricated from scratch with only the rose-joints as a bought component.

Material is mostly 20mm RHS with the kingpin and stub axle turned from a solid steel 25mm round bar. Bushes are Delrin over a steel crush tube. The aluminium wheelhub is a special design which I'll cover in another video.

Geometry is conventional double-wishbone with A-frame upper and straight lower arms. KPI is 14° with 10° castor. Camber is adjustable but will probably run at 0°. Designed for a 12" (300mm) x 2.5" (63mm) alloy scooter wheel.

Category:

Autos & Vehicles

Tags:

• suspension
• steering
• double
• wishbone
• coilover
• ackermann
• rose
• joints
• gokart
• billykart

[vonzace]

that is nice looking. also expensive looking. I built my suspension for 40.00. that looks much nicer but your bill hurts ill bet.

[GRAHAMAUS]

@vonzace Not really - the only parts we bought were the rose joints. I believe they were about $AU6 each, so $24 for the four. The rest we made ourselves from standard RHS and steel tube which is very cheap, about 6 bucks per metre - but we had a lot of that around anyway left over from another job. Since we just did this for fun and a hobby, we're not counting the labour cost of all the cutting, welding, turning and so on.

[shredder2468]

the problem with yours is that your control arms are to short so not going to have much travel.

[GRAHAMAUS]

@shredder2468 They don't need much travel, it's for use on smooth tarmac not off-road.

[vonzace]

@GRAHAMAUS Cool.

[GRAHAMAUS]

@Tactical300 Well, that's cool. It's just the assumption in your original post that the bend in the arm was accidental or indicative of a failure in progress. Seriously, do you think I'd have filmed it if that were the case?

[Tactical300]

@GRAHAMAUS I'm studying mechanical engineering at Virginia Tech, and I designed Control Arms for our Formula SAE Team (Your accent suggests that you may be in Europe, so you might have heard of Formula Student). So I accomplished what I wanted out of commenting on your post; I learned something about your design. And the title does have some key words in it that will attract the 'experts' (self-proclaimed or not).

[shredder2468]

@GRAHAMAUS just sayin!

[GRAHAMAUS]

@Tactical300 It is angled by design to ensure that the joint has maximum angular travel available to it. Everyone's an expert aren't they? To bend this material needs the strength of two people or an extremely long lever when put in a tube bending jig - short arms like this are never going to bend given the normal forces they'll encounter. I did do the sums you know!

[Tactical300]

What are the dimensions of that 'lower control arm?' Looks like its is slightly bent/already yielded/ will fail in fatigue eventually...

[joeslimon]

@GRAHAMAUS yes it is, although it may not be bottomed out, the spring still exerts a shear force on the rod end. This being said, it's a go-cart! It won't see forces large enough to cause damage, and if it does you can buy rod ends designed to take some shear.