Caster/Camber with concentric pills only

Chassis Setup, Tires & Handling Forum
1

Hi,

I have an OTK Cadet kart and just trying to get my head around the Caster/Camber can of worms!

We only have concentric pills so the only option for the arrows is either forward or backward. I’ve read the OTK official wiki guide but that also mentions eccentric pills when describing position and so that has me confused.

I was looking for a dummy’s guide for someone who only has concentric pills and what the positions mean in caster/camber terms and expected handling.

top arrow forward/bottom arrow forward - Neutral camber and caster
top arrow forward/bottom arrow backward - camber/caster??
top arrow backward/bottom arrow backward - camber/caster??
top arrow backward/bottom arrow forward - Maximum caster?

Any help appreciated!

Thanks.

2

If you only have concentric or ‘neutral’ pills, then turning them has no effect. You aren’t moving the kingpin at all when rotating them.

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3

Oh wow! That I didn’t know! So it’s a bit pointless having the arrows on them as they can be pointed to any direction but have no effect…

4

Perhaps you have eccentric pills. Which is what come stock with the kart.

5

Yeah the kart does come with eccentrics and the eccentrics do have arrows on them. Pic maybe?

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6

Thanks for the responses. Pics attached. Perhaps my terminology is incorrect. What I meant to say was that the pills I have can only be set in the forward or backward position.

bottom_pill
bottom_pill2100×1576 86.2 KB

top_pill
top_pill1920×2560 205 KB

7

Okay so those are eccentrics and they are therefore adjustable.

Both arrows forward = neutral
Both arrows backward = neutral

…because you aren’t changing the kingpin angle at all.

Top arrow forward, bottom arrow backward = full positive caster

… because you are tilting the top of the kingpin back as aggressively as you can

Top arrow back, bottom arrow forward = full negative caster

… because you are tilting the top of the kingpin fore as aggressively as you can

Any deviation from the arrow straight forward or back will change camber.

Arrow pointed out = more negative camber
Arrow pointed in = more positive camber

8

That’s awesome! Thank you so much - that’s exactly what I was looking for!

I didn’t realise that I also had the option of pointing the arrows in or out!

9

When you move into full size OTK karts you have pills that offer increments between the 4 90 degree positions you currently have.

image

10

This does change wheelbase slightly.

11

Ok. What effect does that have by changing the wheelbase?

12

It’s a very small change, but a shorter wheelbase will make the kart twitchier and help it rotate quicker. Longer wheelbase will make the kart a bit more stable and less reactive.

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13

Ok. So is the wheelbase made shorter or longer depending on whether I have both arrows forward or backward?

14

Yes. But it’s so small a difference as to be insignificant for almost all drivers. Some will feel that change, most will not.

Short will rotate easier, but can feel less stable. Both upper and lower in the back position would be neutral caster and short wheelbase.
Longer will feel a bit more stable but not rotate as easily. Both upper and lower in the forward position would also be neutral caster and long wheelbase.

Also note that moving the kingpins around will change your toe in / toe out and require resetting anytime you adjust them.

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15

Wow! Thanks for the comprehensive answer. I didn’t realise I had to reset toe in/out when I adjusted the kingpins, Is this where I need to get a laser?

16

I would very much recommend a sniper if you plan to race with any regularity. You will use it.

All of the below are areas where you will appreciate having a laser on the front end.

  • Adjusting initial turn-in. Toe-out can be used to provide a bit more initial turn-in. Excessive toe out scrubs the front tires increasing wear and slowing top speed. I sometimes add a half box if I narrow the front or take out caster to try to recover some initial entry.
  • Adjusting toe for circuit needs. Short tight track = more toe-out. Fast flowy track = less toe-out.
  • Checking toe after adjusting kingpins. This would apply for caster or camber adjustments on karts with separate adjusters as well as for karts with pills like the OTK.
  • Checking toe and sweep after minor on track contact. Can make sure your tie-rods, kingpins, and steering shaft are all straight with these checks.
  • Checking toe and sweep after replacing bent tie-rods, kingpins, or steering shafts. If you race this will happen!
17

Thanks for that. Are there any viable alternatives for measuring this (like toe plates) or is there no real alternative but to get a sniper?

18

Toe plates are viable. If your kart uses front hubs then Comet has them for about $50. If you do not use hubs then you would need some hubs also, which makes cost savings less. Also if have fabricating skills to plates are pretty easy to make. For a real budget you can use marks on tires, or plates/bars strapped to front wheels

19

You could also just mount the bare wheels (no tires), and measure from each edge, front/back/top/bottom.

20

Yes there are other viable options. There are even other viable laser options. Snipers are perhaps easiest and best option out there.