Hey guys so this post is going to surround the eccentric pills that adjust the camber/caster on the front end of karts. I’ll be specifically referring to the newer design that’s on the like of birel, compkart and I think tonykart uses the same setup, basically a dial with holes that you rotate and then lock in place with a little screw.
Right, so the C of all chassis are built with a certain amount of fixed camber and caster, the eccentrics then let you add to or remove from that initial amount.
What I want to know, is there a general universally accepted position on the top and bottom eccentric that is referred to as neutral or base setting across all manufacturers that use the system that I’ve described?
For instance if we reference a 4 point compass N,S,E,W and apply it to the eccentric. Would setting both top and bottom to either both on N OR both on S etc etc really be the same exact setting ? And if so, is this what chassis manufacturers call the base or neutral? Would this be the same as using the static built on camber and caster of the C of the chassis?
Hope I didn’t confuse you guys, looking forward to the discussion
Forgetting the pill manufacturers markings for the moment, and looking at the pills in the metal.
Eccentric pills have the king pin hole out of centre to the 22mm? location diameter.
This gives rise to a variation in the wall thickness of the metal between the king pin bore and the 22 mm location diameter.
The point of max. wall thickness can be marked on each pill to be visible when fitted and used as YOUR datum for positioning.
If the pills, top and bottom are fitted with this datum pointing in the same direction, be this forwards, backwards , sideways or in between, then caster and camber will remain at the neutral setting governed by the positioning of the ‘C’ at manufacture. There will be a marginal change in wheelbase, track or both which can be ignored?
You then need to determine how the pill manufacturer has marked the pills. ie.what symbol on the pills corresponds to YOUR marked datum as above. You are then in a position to use the manufacturers markings to adjust caster and camber to your requirements.
Thanks for your input John. Say the datum is pointing inward toward the centre of the kart top and bottom. If you move the one on top only say clockwise one notch and leave the bottom untouched, what would this do? Change camber? Caster? Or both?
I guess what I’m getting at is can you change camber and keep caster constant and vice versa?
No. The shortcoming of these systems is just that ie. you can’t alter caster without altering camber.
The Sniper type systems and others allow independent adjustment.
Bear in mind that camber changes massively when you put on steering lock .
Hello KP members, there is a while since we do not talk about eccentric pills.
I´d like your thoughts, suggestions, tips, and impressions about adjusting the camber. What do you recommend using, top or bottom pills to adjust camber? Which one are you used to adjust when you want to give more/less camber?
Doesn’t matter which pill you use, top or bottom. But using the top pill is just easier and more convenient.
On an OTK (and most karts), they recommend keeping it within a range of + or - 2 holes on the pill. I run neutral usually, unless I want to fine tuning the lift action or if I’m looking to increase front tire temp I’ll add a hole or two of negative camber.
Just want to mention that you can adjust camber without adjusting caster using these pills, but its a bigger jump in camber. Let’s say you start at neutral with both of the arrows pointing forward. You can turn the top one on notch in one direction, and the bottom one one notch in the other direction, and you’ll have adjusted camber without adjusting caster. Problem is you just did two notches of camber.
Same thing with caster. You can turn one of the pills around to achieve a different caster setting without changing camber, but its a pretty drastic adjustment. The sniper pills are much better in this regard.
Thank you @DIG78x . This information is very usefull and cenlightening. I read and think a lot about how to use correct and precisely caster/camber as both are very sensitive, but I’ve never got this insight. Tks
Hey all, I had a wretched weekend where I was sliding around and way off the pace. I knew something must be wrong so had the shop at my track check the alignment I did before the race to make sure I didn’t get it wrong. Turns out I did, badly.
My previous chassis (older intrepid) required the snipers to be placed on the stub axle (where the spacers and hubs sit), but my new (to me - '20 compkart covert 3.0 4r) apparently requires the lasers to sit on the spindle right up against the kingpin as close to the actual chassis as possible.
When I set my front end I put the snipers on the stub axle, meaning my front end was way off.
Is this something that is just specific to different chassis?
In some cases the polished surface of the spindle between the chassis and the machined area for the hub MIGHT be flat or close to flat; however, I would only ever recommend mounting the lasers on the machined surface where the hub sits. In the video you linked to, you can see Justin has the lasers on the machined surface, just slid all the way in. How far in/out you mount the lasers on the spindle surface isn’t terribly important, I just try to be consistent from side to side. For example, if I am running one big spacer on each side, then I’ll keep that same spacer in place when mounting the lasers.
Not removing the hub is just a lazy way of conducting this operation. Front end alignment is a fairly precise job where every millimeter maters, so I would only go about this in the way I described above.
In the event you’re feeling curious, you could take your reading as described above, and then take another reading with the lasers mounted on the polished surface. If they are different (which is likely) then it reinforces my point. Take both readings without loosening the kingpin, so as not to introduce any slop. I’ve found that the CompKart may settle up to 2-3mm/side if you don’t pre-load the kingpins before tightening.
You’ll notice that if you tighten to 80% there may still be vertical play when holding the spindle on the outer end and moving it up and down. If you were to continue to tighten to 100%, check the laser reading, go out on track, and do another reading with the lasers immediately after, the camber reading may have “settled”, resulting in a reading that is 2+mm/side different than what you went out at.
I’ve found that in order to get more consistent readings it helps to tighten the kingpin just to the point where you have eliminated any of the aforementioned vertical play, lift up on the spindle so as to remove any of that play, and tighten the kingpin the remainder of the way.
This may not be necessary with all chassis; however, I always go through this process in order to allow for more apples to apples readings before and after making and alignment change.
I learned this the hardway… Make sure your kart is fairly close to level too. The bubble levels on the Snipers refference the ground, so ideally what you are measureing is on the same plane.
I set my front end up on my kartlift without it fully “up” so the nose was low, and wow my numbers were wonky. Leveled it back up and they made much more sense. Luckily caught it before I ripped my front end apart looking for bent stuff. I blame the setup whiskeys.
I’m still very new to karting, so this come from no authority whatsoever. But how valid is an alignment in the air? Looking at how much a chassis flexes with the driver on board, wouldn’t you prefer to do an alignment on the ground with full load? Or is it like measuring cold tire pressures - it might not match exactly what is on the track but it is worth it to have a steady baseline?