So does anyone know some of the general principles about setting the ride height of a kart? From what I’ve been told, setting the kart high is good for the wet condition due to weight transfer, and setting the kart low in the heat is good to reduce weight transfer.
But that’s really all I know about ride height. Are there any other tips that people should keep in mind?
Typically the starting point has been middle in the front and axle down (Chassis up) in the rear. Now where exactly those two end up relative to each other in those given positions I suspect would vary from kart to kart.
Think about it like this…
Higher ride height = More lateral load transfer + (small) change in F/R weight balance if only one end is changed.
When you think about what the lateral load transfer can do on a given end of the kart, you get a sense of what to expect.
James is right. Rear ride height has been something we’ve been playing with a lot lately, as it can have a dramatic effect on the kart’s handling.
Higher rear ride height yields a lot more transfer, making the kart dig and lift easier in the rear. Drivers asking for sidebite have liked it as a change.
We jokingly call it the silver bullet change. At last year’s Pro Tour race at New Castle we were really struggling, far more than we had before at that track. We qualified 36th on Saturday and ran solidly around 25th all day. That was with high rear ride height, which we had changed on Friday during practice when the track had significantly less rubber and it was way faster. Sunday we qualified P15 and finished the final P2 after lowering the ride height back to stock. So our joke is that any time you change the ride height you go faster.
Obviously that’s not true, but it’s been a really good way of swapping the kart balance around.
I’ve always shied away from ride height changes before, as it has always seemed like some sort of strange voodoo thing that never really worked for us, or that it would go way, way past where we needed to go in terms of magnitude of change. However, recently, particularly with some Tonykart cadets I have worked with, it makes a huge, huge difference.
Even just one ‘click’ (or slot) in ride height makes a huge difference. So now, instead of throwing an axle at a kart, or changing track width, if I see a kart hopping in the middle or exit of the corner, I throw ride height at it as well as possibly caster change, and it almost always helps.
Generally the ride height change is a big difference. So, if you’re looking for a small adjustment, ride height may not be the best option. Important to keep in mind, however that it could make sense to make the ride height change and then have the luxury of having to add grip to the kart or vis-versa with smaller tuning adjustments.
We had our kart set with the axle all the way up for most of the year. We found when coming out of a turn, a lower ride height (axle up) helped reduce binding on a sticky track. We stuck with that until this past weekend. The track had very little grip in it and I could not get rid of a slide at all until we moved the ride height back to the middle. Things got a lot better from there, but I’d be tempted to try playing with ride height more now after doing that.
We figured changing ride height one slot is equivalent to about an axle and a half of change, assuming axles actually do anything. We’re covering that in the other discussion thread, though.
Last weekend was a tough beast to wrangle. The track had so much grip in T1 that karts were bicycling, but the concrete portions in T2, T3, and T6 never really built grip, so the karts were sliding there.
I hate that track.
One thing I noticed when I watched you a bit Aaron, was how quick your hands were in T2. I know you’ve been struggling with understeer on your “Kart of 1 Million Welds” so maybe that was it, but it looked like you were really chucking it in there.
I felt like I had to throw it in there in order to work with the transition over bank to flat. It seemed like whenever I would go over that transition, the kart would slide on me.
We were also working on trying to carry more speed through 1 into 2, as I always leave a bunch of time at new tracks by not driving in as hard as I could, and struggling to convince myself I can charge in harder and still make the turn. That might have had something to do with that as well
Surprisingly, actually, I had issues being loose all weekend up until the final on Saturday night when the kart suddenly started pushing/hopping through the double rights, but that was the only issue. That weekend in general was rough for us but still helped a lot.
Bumping this back up for further discussion.
From threads like this and from the CRG tuning guide I thought the basic principal was that by raising one end of a kart you’ll add grip to that end of the kart. Need more rear grip, raise the rear of the kart.
But the 2 most recent videos from Power Republic on ride height seem to indicate differently. they talk more about rake and moving weight around via chassis rake than the conventional wisdom shared here.
One example they stated was if the kart has too much rear grip and doesn’t release off the corner that you’d want to lower the front (effectively raising the rear) to put more weight over the front of the kart. He mentioned that the side effect was less stable on the brakes again because of weight movement.
To further the argument they stated that to add rear grip you’d lower the rear to decrease rake or create negative rake to put more weight over the rear to add traction.
So just when I thought I had this height stuff figured out they throw another wrench into the equation.
Thoughts on focusing on it just from a rake perspective?
Also found it odd that they said they rarely adjust the rear of the kart and mainly do their adjustments with the front only.
Would be interesting to see how much of a weight % change it actually makes when changing the rake. I had never really considered that.
I think they’re actually reinforcing the “what” of how it changes handling, but they differ on the “why” it changes the handling.
It gets a bit confusing when we talk in terms of more “grip” or less “grip”, because we are actually referring to the inside rear lift the kart has, not the grip it has.
A kart that isn’t lifting enough will feel tight in the rear, because the inside rear is scrubbing. Raising rear ride height fixes this, because you are putting more force onto the outside rear tire and helping the kart “tip” easier. So to fix the “tight” condition, you’re actually adding what most would conventionally call “grip” by adding side-bite.
One of these stems from grip getting mixed up with “lateral load transfer” in karting and is one of the things that makes tuning interesting.
Anything that raises the center of gravity or roll center will increase lateral (and other) load transfer. On the rear especially, this increases the likelyhood of lifting the inside wheel, thus giving the impression that the kart has “more grip”… when in fact it does not.
Raise the front and you assist diagonal load transfer, which should help take weight off the inside rear.
Of course, the height of your seat is crucial here too.
Andy I’ve seen the same video and you’re spot on, it basically goes against whats traditionally done. Anyone have specific experience on what lowering the rear ride height (chassis lower to ground) does on a tag/rotax/x30 senior application ?
In our experience almost universally takes rear grip away from the kart. Lowering rear ride height is a great tuning tool to fix a kart that is stuck overall in the rear if another axle (usually harder) isn’t available.
One downside is that for some drivers it can make the kart bottom out or flat slide in high speed corners.
TaG or KA adjusting ride height is a great tool. In a higher horsepower kart I’ve used it as a confirmatory test with drivers before making an axle change.
Rear Ride Height
TonyKart-Rotax past experience running Mojo tires, a relatively hard tire. Cold winter practice day so no rubber. There was a slight drift in all the fast corners, throttle still flat but the kart had a tiny 4-wheel drift. I raised the rear of the kart and it was 3/4 second faster on a 55 second track and no drift angle.
Front ride height
Much more difficult to understand what this does.
I dinked around with front ride height this weekend and found almost no difference in feel between the three settings.
I’ve always found the following:
Rear: Predominantly affects rear grip from center off in high speed corners.
I generally don’t make this change too often because it can be a pain in the ass vs. making a track width/hub/axle change. I’ve found that most manufacturers have a baseline setting that works 90% of the time, and if needed, you can go lower when the track reaches high grip levels.
Front: A smaller change that will affect front end weight transfer, as well as overall balance thought the entirety of the corner.
We have used this predominately in higher horsepower classes. Lowering the front can be great if the front end is slightly over-reactive, and if you also need a tick more rear grip/stability. That said, I’ve only really found this change especially helpful with CRG brands (including DR). I never found any benefit to this change with Sodi/TB/Birel/OTK.
I agree. If anything, when I lowered the front it felt like the steering got lighter.
The rear ride height is one of my number one favorite tools to play with on the OTK. As a smaller driver, it can help a lot to get that weight transfer that some taller drivers get.
lol
@Andy_Kutscher I felt exactly the same this week. As I am studying effects of different ride heights, I got confused because there are two different theories going in the opposite way when talking about rear height.
Some says that, if you increase rear height you transfer center of mass forward and has less grip in the rear.
Others says that, when you increase rear height you increase the down-force to the outer rear tire against the surface giving more grip at that tire. Besides that, increasing rear height makes the lateral inclination of the kart (jacking effect) greater when you are rounding a corner and it makes the inner rear tire to have less contact with the surface, reducing grip of this specific tire. It is considered good when you are having trouble with understeering, I mean, if the inner rear tire is touching the surface, there is a tendency of going straight instead of turning.
In summary, we have a lot of reactions coming up when you increase rear height, but what it is still unclear to me is the winner of the battle, I mean, forwarding center of mass with higher rear-end brings greater effect to the front-end grip than the increase of the grip in the outer rear tire? Or we should consider the opposite?
Any thoughts @tjkoyen @Aaron_Hachmeister_13?
The amount that the center of mass moves forward from raising the rear ride height is negligible. It’s such a small movement it doesn’t mean anything. Put your kart on the scale with the rear ride height low and with it high and I think you’ll see the weight bias numbers don’t change much, if at all.
The adjustment for ride height is to alter the center of gravity of the rear of the kart. Higher rear ride height has a similar effect to raising the seat. It will help the rear of the kart lift and dig the outside tire in more effectively. The debate comes from what kind of “grip” you’re looking for.
In most cases, in normal conditions, you will want to raise the rear ride height to increase the jacking effect and get the kart to dig harder in the corner. However, in very rare cases, there are possibilities where you are better off lowering rear ride height to get the kart flatter to generate grip. We used to tune by this theory when we ran extremely hard tires at local club events. The goal was to get the rear wide and flat, because the tires were hard enough that you were never going to generate proper grip to effectively lift the inside rear wheel and drive the kart properly.
I adjust rear ride height at almost every race weekend at some point. I’ve tried it on all varieties of track surfaces, grip levels, tires, and classes. It makes a very noticeable change in the reaction of the rear of the kart on turn-in.
TJ, what kind of kart. It was my general understanding that, for example, the Zanardi karts liked to be up in front and down in back while the Tony karts like a “rake”, down in front and up in the rear.
I run OTK karts, but the adjustment should perform the same way on any kart. I can’t vouch for what one brand uses as a baseline over another, but raising the ride height raises the center of gravity on all karts. Maybe one brand’s construction or material dictates that it needs a different baseline ride height configuration.
We don’t run the front down as baseline on the OTK. I’ve tried it up and down but I think it’s a much finer adjustment than rear ride height.