Who knows about ride height?

(Davin Roberts Sturdivant) #1

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?

(James McMahon) #2

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.

(TJ Koyen) #3

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.

(Eric Gunderson) #4

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.

(Aaron Hachmeister) #5

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.

(TJ Koyen) #6

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.

(Aaron Hachmeister) #7

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.

(Andy Kutscher) #8

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.

(TJ Koyen) #9

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.

(James McMahon) #10

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.