Question for y’all. What is your go to for setting up the kart in the morning on a low grip track or as the track rubbers in during the day? Or just in general when working on setup?
For example it seems to rain every week here in the Carolina’s plus rental karts running through the week, so the track tends to be a bit green on the start of the race day. Also with cooler weather there is a big change in grip from a warm noon qualy to a sun is starting to go down final.
As grip is coming up during the day do you add castor to aid in jacking or go to a harder axle to free it up on exit? Conversely as the temps drop do you pull castor or go to a softer axle to compensate? Do you purely play with air pressures or track width?
I’m just curious as to whats your “silver bullet / I normally try this first” change through a raceday or weekend? Thanks!
Whatever is fastest/easiest in direction of the problem I’m trying to solve. Green track, I’ll throw scrub radius (front track width) at it first and iterate form there.
Unless I have notes to go to, in which case I’ll throw that setup on.
I rarely deviate from full rear width in the dry, I try to keep max rear width and tune around it, it’s a personal preference that probably hinders me to be honest
Track width and air pressure is easiest for me. Pretty easily to dial in the balance with small front or rear adjustments.
As grip goes down and rubber builds, you should be able to take grip out of the kart and rely more on the rubber on the track. So typically if a track is really gripping up, you’re taking caster out and trying to reduce hop or keep the inside rear from setting down too early.
Well first, not necessarily. And second, I couldn’t possibly give you a set number to change your tire pressure. There’s just too many variables to consider.
I use tire pressure to control when the tire comes in or goes off. If the kart has a balance problem, it’s going to move toward under or oversteer as the run goes on. Tweaking pressures on one end can bring that balance problem back in check and keep the tire in it’s operating window.
Typically, I’m focusing on tire pressure more with regards to track temperature. Hotter track temp requires lower pressure to keep the tire cooler and consistent through the run. Colder track usually requires higher pressure to get the tire to slip and build pressure and heat easier.
You always have to remember that the tire is your suspension and your contact patch so there’s a balance you need to find.
Ok makes sense. Let’s pretend it’s a hot day, like 90 degrees. Let’s say I normally run at 10.5 psi. And, let’s say it’s 15-20 degrees hotter than normal…
Are we talking about .5 psi downwards adjustments or bigger?
As we lower pressure. At what point do we feel having gone too far? Will it be such that you feel lateral folding in the tire?
I adjust in 0.5 psi increments usually. If you take hot tire pressures when you get off the track, you can figure out how much to change pressures, as tire manufacturers usually have an “ideal” operating pressure they recommend. If you go out at 10.5 psi cold, and come in at 15 psi, you can drop your cold pressure whatever you need to to get it back into the window.
Yeah that could be a problem at some point. More than likely you’ll find the tire takes too long to come in first. I’ve run MG Yellows down to 7.5 psi but it does start to feel like the tire begins folding over and you can develop a hopping condition from the tire deforming. Like 10-15 years ago I remember the tires having a much softer sidewall, and this was a bigger problem then. Tires now tend to be fairly stiff and the limit of where the sidewall starts flexing too much is harder to reach.
Testing out a variety of pressures to determine a working range is really the best way to find your “box” you can work in, and then you can adjust accordingly based on temperature.
Pressure rises as tire heats. Are you saying to yourself, "I came in at 15lbs, my best laps were mid practice so the final pressure needs to be lower than 15? Let’s try 1 psi less and see where the laps come in?
Yeah exactly. I almost never check hot pressures because at this point I can just tell when the tires are falling off by feel. You look at your MyChron and see your lap times getting worse toward the end of a run and you feel the kart not rotating and rolling off the corner as well and you can kind of infer that the tires are getting too hot.
All great info. Since we are talking a bit about tires. Do you ever look to change camber? To me with the very round profile of the MGs it really seems to lessen the effects of camber adjustment. I tend to set it a bit negative and forget it. Maybe go one click positive before the final to compensate for wear?
I use camber a little to fine tune the lift rate on the inside rear and tune front tire wear, but I don’t mess with it too much. It’s a fairly small adjustment.
The reality with any adjustment is, I can’t tell you that you should be doing adjustments in a set order throughout the day, in an order that will work every day. What we really need is a guideline of adjustments to look at between each session as the day goes on. Adapting to the track is going to be a moving target each weekend.
I’m not after a single change or when to perform it exactly. Just curious as to what people tend to adjust first. I guess for myself tire pressure depending on temperature is a given, but maybe not to others? Outside of that do people tend towards making changes at the front or rear first, that sort of thing.
I guess for myself outside of pressure a quick easy change to try is tossing in the two bottom bolts on third bearing to slightly free the rear or swapping the caster pills for more or less axle lift. Both can be done quickly on race or practice day.
It totally depends on what the kart is doing. Sometimes customers will ask me things like “what axle should I run at this track?” and I always say “I have no idea. Put it on the track for session one and see where it’s at.” You can’t predict what the track will do from your garage at home.
That’s why it’s important to always set up the kart at a baseline setup, usually very neutral on all adjustments, and just give it a go for practice one to see where it’s headed.
If you’re looking for quick adjustments to try stuff, the third bearing bolts is a good quick test, as well as pressures. Track widths for me are probably the quickest changes that produce noticeable results in the balance of the kart.
I’ll have to give track widths another try on a practice day. Haven’t played with front width much outside of going wider in a rain race a couple weeks ago.
