left side percentages and cross relations

I'll make this very easy. Scale at home/shop. When your at track change cross as needed off the spindles and go race, nothing else needs to be reset. If it was fast take it back home, place on scales and write the new numbers down.
I'll add this 90% of the time, I'll change RF camber at the track and nothing else, hardly ever change cross.
All our rights are 34", LF 32.25, LRs 32.5 or 32.375, that takes the guess work outta what different tire sizes will do at the track. Also because they run different classes, we'll usually run the same set of tires on both karts though out the heats, then see what we need for the features.
 
Kj26 said:
I'll make this very easy. Scale at home/shop. When your at track change cross as needed off the spindles and go race, nothing else needs to be reset. If it was fast take it back home, place on scales and write the new numbers down.
I'll add this 90% of the time, I'll change RF camber at the track and nothing else, hardly ever change cross.
All our rights are 34", LF 32.25, LRs 32.5 or 32.375, that takes the guess work outta what different tire sizes will do at the track. Also because they run different classes, we'll usually run the same set of tires on both karts though out the heats, then see what we need for the features.
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That's your answer to part of his question, What's your thought's on the rest ?
 
Bingo .
We just always threw the kitchen sink at it .
To qoute the Great Mr. KISH .
It's all about on track problems and fixing those.
 
Kj26 said:
I'll make this very easy. Scale at home/shop. When your at track change cross as needed off the spindles and go race, nothing else needs to be reset. If it was fast take it back home, place on scales and write the new numbers down.
I'll add this 90% of the time, I'll change RF camber at the track and nothing else, hardly ever change cross.
All our rights are 34", LF 32.25, LRs 32.5 or 32.375, that takes the guess work outta what different tire sizes will do at the track. Also because they run different classes, we'll usually run the same set of tires on both karts though out the heats, then see what we need for the features.
Click to expand...
Thank you for responding but I didn't say changing cross was the best adjustment ...and I know camber adjustment would work for push ...question was dependent upon the fact that I decided to make a cross change
 
racing promotor said:
Correct BUT keep in mind the more drive the LR has and the RF can handle the FASTER you'll be in the end, So if you get the RF to handle it by more Internal, more bite, camber or caster adjustment ( and there all maybes) you'll love that higher cross.
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I REALLY LIKE this comment. Puts several things in better “visual” perspective. 👍
 
JWD said:
My personal belief is the left and cross relationship is meaningless and Mike made a leap to explain something he did not understand. He's guilty of that several times.

Cross always Always ALWAYS tightens the chassis. Did I say always enough times ALWAYS? ALWAYS!!

Now you say "well I know that's not true, whenever I...." to which I say ALWAYS TIGHTENS

Then you say "But...." and I say ALWAYS!!!!

Then you get smart and say "Well how come when I...." Then finally before I set you on fire for not understanding the meaning of ALWAYS I teach you how cross works and you go "oh, well now that makes perfect sense! cross always tightens" and you live.

What you are managing with cross is the relationship between the RF and RR tires (bet you didn't realize that). In extreme low cross situations the RR is king. Lowering cross will take the LR out of the kart reducing drag and freeing the rear (pay attention this is important) of the kart up. The more cross you add the more drag you get and the tighter the rear (still paying attention yes?) becomes.

Now each time we add cross the RF gets a little stronger and the RR gets a little weaker. Eventually you get to the supposed dead zone where neither tire is strong enough to dominate the kart and cross adjustments really don't accomplish anything. But finally we reach a point where the RR just plain becomes too weak. Depending on design this is somewhere between 58 and 64%.

When we get to this point the RF takes control of the kart and the front (still paying attention) begins to overpower the rear. When this happens the kart begins to break free and "feel" loose. It's actually very VERY tight.

Now simplifying for those that were too lazy to follow:
Low cross = free rear = loose rear
high cross = tight front = loose rear
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I raced stock cars for years. Then have played with karts for quite a few years now. Have discussed with my son this notion of left side/cross percent and the statement or theory that get them close enough kart can become tight. IN ALL OUR CROSS ADJUSTMENTS WE HAVE ALMOST ALWAYS MENTIONED OR REFLECTED ON THIS “statement or theory that get left and cross same or close enough to same kart COULD be tight per a prior READING on Bob’s”.

OUR EXPERIENCE HOWEVER: More cross has ALWAYS been tighter, assuming no other EFFECTS or ADJUSTMENTS, JUST LIKE SAID HERE I BELIEVE.

AND DESPITE: many comments about adjustments are not like stock cars (coil springs, leaf springs, transfer weight differently etc), I say hogwash, raising cross STILL tightens, again assuming all else the same.

In short: I AGREE!! 👊
 
I think sometimes racers and kart adjusters would be better served, learn more, and adjust kart better IF they left the scales in the trailer, made various attempts to adjust kart in ways that NORMALLY improve handling over what kart is doing or not doing on track, and THEN, put kart on scales and go hmmmmmm..... INTERESTING. Sometimes it may be very close to manufacturer recommendations, or MAYBE NOT!! Every track is different, every race weather day is different, and every driver drives differently. GIVE IT A SHOT SOMETIME?!! :).
 
1fasttiller said:
Glad I found this post! Good info for sure!

Kinda helps explain my sons Prowler over this first full racing season on low bite, sandy Florida tracks.... Every time I tried upping the cross to what Prowler or any others told us to it would immediately push. Granted this is a Jr2 kid that weighs 60lbs soaking wet. As long as I keep the cross down around 55-58% this kart works and is fast but as soon as we go up to 60-62% as always suggested we slow down.
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I just happened to run across this post from December.
I'm no expert on dirt racing, but a couple of thoughts occurred to me. Perhaps you're depending too much on cross adjustment and you're forgetting about stagger, caster/camber, weight distribution (front to rear) and tire pressures. Among others.
A complete listing of your weight distribution might help. Include the tracks turn radius, any banking and your stagger settings.
 
I found this thread via Google. Had no idea Ken bumped it 5 days ago.

I'm curious about several things LEFT SIDE%. But as I read this I got different questions than what I came here looking for. From the stands it looks like to me that we need more LEFT SIDE %.

For discussion sake here are our numbers on our Evolve.

Stock Medium 350 lbs
Nose 46.5%
Left 58%
Cross 63%

LF 73 lbs RF 90 lbs
LR 132 lbs RR 58 lbs

I know, tires are everything. But, I'm wondering about going from Dry Slick track A to Bit up track B. The above numbers are basically what we've ran for the last year. On tracks that have zero bite, dusty hard dry slick it seems that we need to be able to rotate in the center of the corners better. Would this be a condition that our left should be 61% vs 58%? Conversely on a track that bites up really well, would that be scenario where we need to be 56~58%?

As dad that has never been in the seat, What is the best way to know your left side is being under or over worked? Measuring tire temps as you leave the track? looking at the graining on the tires?

(.....Yes, I know and recall tires, tires, tires did I say tires??)

Lastly, (Al would have a field day with this next question but I'm going to send it anyway)

Recently we exceeded -2.0 G's at the Apex of a corner. This was the largest G-Force we've ever seen.
In theory, at the apex of a corner with a maximum G-force, what should the weights be on each REAR? I'm talking about a snapshot of the dynamic weight when transferred left to right?

What rear weight distribution (left to Right) would maximize grip? Even? 95 lbs on each wheel? maybe 90 LR and 100 RR?

As for tires, I know tires are king but it seems to me that he better our setup is, the larger our tire window becomes. Therefore, I want to focus on both.

R.I.P. Al Nunley
 
TritonJrBluePlate said:
I found this thread via Google. Had no idea Ken bumped it 5 days ago.

I'm curious about several things LEFT SIDE%. But as I read this I got different questions than what I came here looking for. From the stands it looks like to me that we need more LEFT SIDE %.

For discussion sake here are our numbers on our Evolve.

Stock Medium 350 lbs
Nose 46.5%
Left 58%
Cross 63%

LF 73 lbs RF 90 lbs
LR 132 lbs RR 58 lbs

I know, tires are everything. But, I'm wondering about going from Dry Slick track A to Bit up track B. The above numbers are basically what we've ran for the last year. On tracks that have zero bite, dusty hard dry slick it seems that we need to be able to rotate in the center of the corners better. Would this be a condition that our left should be 61% vs 58%? Conversely on a track that bites up really well, would that be scenario where we need to be 56~58%?

As dad that has never been in the seat, What is the best way to know your left side is being under or over worked? Measuring tire temps as you leave the track? looking at the graining on the tires?

(.....Yes, I know and recall tires, tires, tires did I say tires??)

Lastly, (Al would have a field day with this next question but I'm going to send it anyway)

Recently we exceeded -2.0 G's at the Apex of a corner. This was the largest G-Force we've ever seen.
In theory, at the apex of a corner with a maximum G-force, what should the weights be on each REAR? I'm talking about a snapshot of the dynamic weight when transferred left to right?

What rear weight distribution (left to Right) would maximize grip? Even? 95 lbs on each wheel? maybe 90 LR and 100 RR?

As for tires, I know tires are king but it seems to me that he better our setup is, the larger our tire window becomes. Therefore, I want to focus on both.

R.I.P. Al Nunley
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That left and Cross looks pretty low to me for a new EVOLVE. Aren't they more of a higher cross kart? i.e. 66-68% therefore left should also be higher ~60%

We keep our Slacks around 60% left for 350 Medium and 375 Heavy. It seems to work on both low bite Friday night tracks and the more bit up day time tracks, of course as long as you get those tires right :)
 
1fasttiller said:
That left and Cross looks pretty low to me for a new EVOLVE. Aren't they more of a higher cross kart? i.e. 66-68% therefore left should also be higher ~60%

We keep our Slacks around 60% left for 350 Medium and 375 Heavy. It seems to work on both low bite Friday night tracks and the more bit up day time tracks, of course as long as you get those tires right :)
Click to expand...
We've had our Evolve since early 2023 and I have yet to see Ultramax put their suggested numbers up. I haven't looked in a while. for whatever reason we always LOOK tight to me. Possibly the left if too low, which is one reason I've been looking at the LS%. We were always at 60% with our Pursuits and the driver was 30 pounds lighter and 15 years old. We're normally around 65% cross but I have left it lower since indoors and hoping I can get a reading on the tires that tell me we need more. (Hasn't happened yet) We've also not been on a track with any kind of grip. The tires look too good for my liking.
 
TritonJrBluePlate said:
We've had our Evolve since early 2023 and I have yet to see Ultramax put their suggested numbers up. I haven't looked in a while. for whatever reason we always LOOK tight to me. Possibly the left if too low, which is one reason I've been looking at the LS%. We were always at 60% with our Pursuits and the driver was 30 pounds lighter and 15 years old. We're normally around 65% cross but I have left it lower since indoors and hoping I can get a reading on the tires that tell me we need more. (Hasn't happened yet) We've also not been on a track with any kind of grip. The tires look too good for my liking.
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left has a lot to do with driver height and weight. if you are short with a lot of lead low on the seat left won't be as high as a taller/ super heavy driver will need.
 
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