Huge barstool issues need HELP !

[Joe-405]

It's the one I built for last year's contest.............


Does anybody know what the caster and camber are supposed to be at ? Before it had a wobble above 45 or so mph. Had It fixed supposedly tonight and now its worse. Anything above 20mph will throw you in a ditch.

Before cutting the spindles off again I need to know for sure what it's supposed to be at.

 

[itsid]

looks like you have about 0 caster ATM...
yes.. at speed that doesn't sound like fun to have at all

Now caster is set by wheelsize (well at least at the very very basic levels )
the kingpin should point
A) to the centerline of the tyre where the rubber meets the ground
(that's the ideal kingpin camber)
B) to a Point on said centerline just in front of the contact zone, but at least still fully covered by the wheels shadowlines at noon -if you know what I mean -

Generally 10°-15° are more than enough.
an angle finder is much more precise though

AS I said, very basic guidelines, it depends more than just a tiny bit on the vehicle geometry COG etc as well;
but that should get you at least close IMHO.

'sid

 

[Half-breeder]

The norm is 13* caster from level... as in bubble between the lines 'level'(can vary from 10*-15* as Sid said). The more caster the more laborious a turn becomes due to the 'lifting' of the frame at 1 corner, w/ 1 wheel, plus the offsetness of the pivot of the 'wheel to ground' contact ('trail'). Normally, a shorter wheel base (distance width between the inner sides of a wheel)will result in a slightly lesser need of as much caster angle, due to the geometry and lessened horizontal weight difference... meaning less to lift/drop in a corner, to turn.

Just wondering... how is your alignment, did you leave the tierods set as they were, or was everything readjusted after the 'fix'? And is there ANY play in your tierod ends or steering? 1/4" play in steering alone will scare alotta folk, w/ enough speed... but that alone wouldn't explain how it got 'worse'... so ex that.

 

[Joe-405]

OK. It was zero in the pic. But we went to 6* last night and it made it worse. So we will try 15* this week sometime.

Thanks for the replies. I been pulling my hair trying to figure out why. It just wasn't enough.

 

[KartFab]

That could literally be the death wobble!

 

[Poboy kartman]

What the hey Joe....just drive it....'cause if it doesn't kill you...I might come up there and do it if OU wins!!!! JK....

EDIT : SEE ....you should have used wood....you wouldn't be having all these problems....

 

[itsid]

OK. It was zero in the pic. But we went to 6* last night and it made it worse. So we will try 15* this week sometime.

Thanks for the replies. I been pulling my hair trying to figure out why. It just wasn't enough.

before you do.. flip the spindles and try again
(right to left, left to right.. also upside down)
the control arm should be nearly horizontal
(increase the lever for a better steering and feedback)
check the tierod length as Tihm suggested..

any positive caster should ADD stability and not make it worse.

If it's still worse than before, there must be something wrong we haven't thought of yet..
*shrugs*

'sid

 

[Joe-405]

I called upon a friend today. Its going to his shop tomorrow. I know he can fix it as he has a full machine shop. I didnt think he had time for it but he said bring it on ! Its going on a flat jig and we will get it figured out. Its definately going to 15* for sure. We will cross check all dimensions also while we are there.

---------- Post added at 07:15 PM ---------- Previous post was at 07:14 PM ----------

What the hey Joe....just drive it....'cause if it doesn't kill you...I might come up there and do it if OU wins!!!! JK....

EDIT : SEE ....you should have used wood....you wouldn't be having all these problems....

Lucky for you i hate football ! I wont watch it unless i am at somebody's house for a party. And i'm only there cause i'm bored. haha

 

[Flyinhillbilly]

You might check your steering axis inclination angle also. Draw an imaginary line through the pivot points of your spindle. It should be 5-10 degrees with the camber at zero. This makes the front wheels "lift" the kart a little when you're turning, and due to the center being the lowest spot, they have a tendency to track better.