Go-kart front suspension design
October 23rd, 2011 | 
Author: “Go Kart”
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.
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@shredder2468 Yadda-yadda-yadda. So many armchair engineers out there. I built it, it works, works well, does everything it was designed and intended to do. Not perfect? Perhaps, but then I’m just some guy in a garage, not bloody Audi.
the problem with yours is that your control arms are to short so not going to have much travel.
@Moopcan It’s not – the arm is articulated so those forces cause the arm to move (unless it hits its end stops but in normal use that will not occur). Also, the rose joints used are much larger than that needed for the weight and force carried – i.e. they are very over-specified.
Rod ends are not meant to be loaded in shear + bending
@teddyandsalemrules The other video shows how the steering works.
@sccopez ??? This is a very common design, used on loads of classic race cars. Ariel Atom, for instance.
how did you put the steering into that?.ive been wondering fo ways to have suspension and steering at the ame time..couldnt think of anything? so far!
Not sure that using rose joints in bending is the greatest idea.
I’d have moved the pick up points rather then use that odd lookin spindle to get it lower. I’d also make the shock inclination adjustable to change it’s effectiveness and spring rate, it looks like there’s room enough. With the spindle located like it is just looks weird to me, and it’ll stress the upper arm more, which is why I don’t like drop spindle mods on “normal” cars. Cross torsions like sprint cars use is an intresting set up too. How does it work anyway, any unexpected quirks?
@GRAHAMAUS You should see the **** suspensions guys build for outlaw figure eights, you can check the cars out by youtubeing Indy 3 hrs race, or world championships, they’re real serious cars not junkers. Talk about scrub, you’d need a yard stick to measure it. I raced in a class where they limited camber for some stupid reason, how come morons always run race tracks? Anyway I just cranked in the caster to the tune of about 13 degrees and had all the camber gain I needed. I like a lot caster
@505197 The geometry gives it a) a low ground clearance, and b) a zero scrub radius. There is an additional lower strut which we added later that isn’t shown here. Originally we thought it wouldn’t need one, with longitudinal control provided only by the upper arm, but that turned out not to be strong enough. You can see it in our later video.
It looks designed upside down to me, why have the spindle so close to the upper control arm? No sturt or such on the bottom at all?? Time to go back to the drawing board and do this one over again. You call it a double wishbone but it’s missing a link on the bottom, or I’m not seeing it.
I have over 8 1/2 inch of travel on mine. Might be a little over kill but it is cool.
@pyroman675 The kingpin inclination is 14° (more out at the bottom than the top, viewed from the front). The castor angle is 5° (more forward at the bottom than the top, viewed from the side). Hope that clears it up. These are fairly common sorts of values, nothing unusual here.
so it the king pin at an angle at 14 degrees out ward or in
@vwaudi914 a mailorder company called ‘small parts and bearings’ supplies this kind of thing, though the rose joints were off the shelf from a local hardware store. The bushings were made by us from Delrin rod.
where did you buy the components like balljointa, and the end of the A-arms where the bushings go and the bushings for that matter, regards, Zach