help on steering angles

[sloky slocombe]

Has anyone got the angles for Castor/Camber/KPI im wanting to bild my own grass kart frame

 

[brendonv]

Unless its a race kart i wouldnt worry about all of that. Just give yourself a little toe in to help with steering and a little bit of positive camber (2 degrees or so) to minimise rolling resistance.

 

[theo]

You need castor 5 to 7 deg. Are you using suspension and what are the tire heights.

 

[Doc Sprocket]

I have a book entitled, "Build Your Own Off-Road Buggy", by Ron Champion. It recommends a KPI of 10* inclined (as measured off the vertical). The spindle is built angled 10* down, so that when the wheels are straight, there is 0 camber. As the wheels are steered, the 10* KPI angle loads the inside front wheel. This is in conjunction with a 15* caster angle.
The above angles were designed with the following in mind
*Off road use, sand, gravel, dirt, etc
*Live axle, no differentiation
*The Ackermann angle is employed.
Cheers- Chris

 

[theo]

10 deg. is ok, this also depends on the height of the tires being used. 15 deg. of castor in my opinion is way to much on a buggy or kart. This is ok if you are doing high speed stuff but if you want maneuverability then 5 or 6 deg.

 

[Doc Sprocket]

Beats me. Book says, "...althought the caster angle used is high compared with that used on a car, I found that using less than 15* resulted in the buggy having a tendency to go straight on when trying to steer left or right, and using more than 15* gave very heavy steering."

Obviously, this is one guy's finding, others may think differently. Incidentally, the kart built in the book used larger rear ATV style knobbies (looks like about 20-22 inch) and smaller, but similar tires in the front (maybe 16-18")

 

[sideways]

For king pin inclination, if you were to draw an imaginary line through the pivot point that line should meet with the centre of the tire where it contacts the ground. This makes steering easier and gives you less tire wear.

For camber, just put a few degrees of negative camber on.

No idea about castor, its not really that important, depends on what you want really, it's basically used to make the steering centre by its self.

Thanks

Hayden

 

[theo]

Some builders want the imaginary line to be a 1" or so of the center of the tire for a little scrub to get a steering feel. Castor is the most important, you need some to keep the kart tracking and for stability.

 

[sloky slocombe]

topic title

Thanks for the info guys very helpfull.

I had heard 18 castor * for grass karting so 15 * must be in the ball park as minimum and i have heard as mush as 20 * i was looking for a happy medium that works
I was thinking of making adjustable castor and camber with 2.5* adjustment either way

No suspension and wanting to use 6" rims with 13x500-6 Snow hogs or 4.10x3.50-6 diamond pattern turf tyres or 13x5x6 duro turf tyres still working through maximum size limits for my local club rules.

Engine will be an aircooled yamaha rd 250 2 stroke twin engine ive had sitting round for a bit in the shed.

 

[Stila_R8dr]

RD 250
NICE!!
Had one in my high school days.

 

[Benjo]

hey sloky slocombe what part of NZ do you live in.

 

[sloky slocombe]

title topic

hey there i live in the haka valley inland from oamaru and timaru in the south island.