I like that they have the vertical adjustment too. I never knew how much wheelbase changed but height was always a huge change. Are those carriers really only held on by two bolts though? I’m used to seeing at least 4
Looks like three actually with the third on the top left. It’s an arrow I belive.
Here’s a stupid thing I just thought of.
What about adjusting wheelbase for only one side of the kart? Say a track is exclusively left hand turns except for 2 of them. Would shortening the right side wheelbase but not the left allow for better turn in at left hand turns wit out changing how the kart turns right? I must be missing something here.
Aaron,
An interesting thought. Assuming to do that you would move the right rear axle cassette to its forward position and the left to its rear position. Not sure how that would make the kart handle but that would cause a gear alignment problem. Possible other solutions would be to use tires on the right that were a little larger in circumference or have different toe-in/out settings for each side.
That’s going to make an interesting handling kart. If you think about it… (At least with a rear axle based wheelbase change) you can’t change the wheelbase from one side to the other without putting the rear axle out of square with the chassis. Essentially a permanent rear wheel steering.
I’d experiment with F/L weight split first. Or even offsetting your rear hubs. The other thing to consider is that your axle sprocket is going to be out of square with the motor sprocket
Well the first thing would be the axle would be at an angle relative to the direction of the kart, so it wouldn’t drive straight at all, and when you were trying to drive straight, it would scrub like crazy and you’d probably have to have the steering wheel turned 45 degrees.
As James said, it would be permanent rear wheel steering toward one direction.
If you’re trying to offset something, weight or track widths are a good place to start.
Moving just one side fore and aft in the rear is common in dirt karts. Usually only an 1/8" or less. It does create A little miss alignment in the rear sprocket and so on. Moving your RR forward will tighten A chassis on entry and Back will loosen it on entr. Its not A common GO TO adjustment, just another crutch to do at track in A short time. What I find interesting in oval, just like NASCAR And Indycar of pre 98 season, they will offset the fronts also on just one side. Different theories and ways to accomplish it, but still very cool and thought provoking.
Just an example… http://outcastkarts.wixsite.com/race/outcast-chassis?lightbox=dataItem-is669vkb
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I haven’t actually tested the effect of changing wheelbase just one side, but I would assume the negative effect would outweight the positives. I believe a combination of caster, toe and weight adjustment would give you the desired end results.
A lower caster angle allows that corner to rotate easier. So if a track is exclusively left hand turns, run a higher caster on the right side than the left. Then watch the tire wear and adjust toe and camber accordingly.
You can look up the effect of caster adjustments and specifically, CASTER STAGGER. I can break it down a bit more if desired.
disclaimer:*** I have never adjusted my kart’s caster, but I do this on the car all the time.
Well yeah that is completely stupid, unless it works and then it’s pure genius!
I think it works on dirt as bandaid because of the more constant turn mode.
As TJ say offset something else the you can do to one side. Moving one side of the axle is not just wheelbase but toe-in on one side and toe-out on the other. I’d say it would be different if it were independent, but it ain’t and that shows up in the straight even if it were independent. You could do something with the hubs being different lengths as well as different track width distances.
Just as a brief clarification:
Wheelbase is distance between axles - front to back
Track width is distance between wheels - side to side
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This was definitely a last resort type of idea. I’d never do it in a race without trying it out on a practice day first. I just have a bunch of things I think of and this one seemed too straightforward to work but I couldn’t figure out what was wrong until I posted it on here
I tend to think in real basic terms at times. So my basic thinking would be along the lines of justifying when to have an asymmetrical setup vs how to accomplish it requiring more complex thinking. Specifically on a sprint kart when would you want an asymmetrical setup? Even if a direction is predominant, wouldn’t the turn type have to be an exception as well taking into account following straight and possibly track surface? I can come up with a layout that would be 6 right 90’s and 1 left hairpin 180. Street course?? Seems that would be begging for an asymmetrical setup, assuming all 90s were similar and fast relative to the hairpin being tight.
Expanding on what Mike is saying, I think the question should be what exact issue are you trying to solve? Is the Kart failing to rotate quickly enough, is tire wear not where you want it, etc.
In oval racing, Corners can be longer than straights. So if an offset chassis does in fact improve the turning radius through a long corner then, maybe that trade off (as long as the negatives do not hurt the kart) would be worth it
I think adjusting the “skew” of the axle in the kart is something we’ve seen in oval Karting for a long time. Running stagger, or running different size tires with same circumference is another way to accomplish a similar thing.
I have seen on rare occasion people running hubs at different widths on the rear and front. I think it was a common thing for some racers at a track in Las Vegas at one point, for example.
I also spoke with Dustin Courter about this the other day,he mentioned how many road or street races like the Elkhart Grand Prix or Lancaster are predominantly one direction in turning. So at those events, some people chose to run LTO (left turn only) chassis, and apparently were quite competitive.
KP members, “the effects of wheelbase changes” is an unclear topic for me. So, maybe I am bringing up a fundamental question, but let´s go for it.
What are the effects on weight transfer when we reduce the wheelbase? Are we increasing or decreasing it from one side to the other? Are we increasing or decreasing it from the front to the back end?
Thoughts?
How aggressively the weight transfers fore/aft is related to the ratio of CG height and wheelbase. For lateral transfer, it is the ratio of CG height to track width.
In other words, raising CG or reducing wheelbase/track width can give you the same ratio. Picture it as “how much leverage does the CG have over the tires”. The more you increase CG’s leverage (height) or the more you decrease gravity’s leverage (track width and wheelbase), you get more weight transfer.
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Thanks for your reply @dodo
So, checking if I followed correctly your train of thought, you meant that changing the wheelbase affects only or mainly longitudinal weight transfer (fore/aft) and changing the track width affects only or mainly transverse (lateral) weight transfer?
Remember those statements are only related to weight transfer since that was your original question, but other things are also at play. Increasing wheelbase will increase the leverage that lateral tire forces have on the rotational inertia of the kart, so this is a fancy way of saying it is harder to spin (so you get understeer as a consequence or at least less oversteer).
So when you say “wheelbase affects only longitudinal weight transfer”, that is incorrect. My answer only focused on that particular aspect because it is what you asked about, but that does not mean that is the only aspect to look at.
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Perfect. This is what I was also thinking, I mean, changing the wheelbase will somehow affect lateral weight transfer as well. Thanks for your clarification, but it is still not clear to me the reasons.
This statement above is exactly what I felt when I changed the wheelbase. Actually, I reduced the wheelbase to decrease the understeer and it worked with a consequent reduction in time lap. But, when the track became rubbery, it became an issue and the time lap increased. So my thought was: “Maybe we lost traction or the reduced wheelbase made it to become anchored to the rubber”
This collateral effect of reduced wheelbase makes sense to you?
If the only change you make is moving the rear axle fore/aft, then you are also changing the weight distribution. My previous responses were assuming that CG was not a function of wheelbase, but the reality is that it is unless you manually move the seat or lead around to achieve the original balance. I find it very useful to isolate the original question, but this always has be understood as just a leaping-off point.
Look at it this way. Lets say your CG is 15" in front of the rear axle on a 40" wheelbase. That’s 62.5% rear weight. Now, move the axle forward 2" and make no other changes. The new rear weight will be 65.8%, and the only way to isolate the effect of moving the axle is to move your lead forward to get back to the original 62.5%. Picture an extreme example where you move the rear axle farther forward than the CG, and it’ll pop a wheelie.
Corrected math now.
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