Weight setup advice.

J

jacobsdad

Member
With a lot of help from a couple of people on here I got my sons kart set up so it handles great for him. Now my daughter is getting into karts. I found an old kart that she can run for this season. I am not certain what it is, the guy we got it from said it is an old Ultramax. My sons kart is a '97 Ultramax centerforce, the one my daughter has looks similar but different. The steering wheel braces are 2 pipes, and the nerf bars look different.
Anyway, set her on the scale today to see how close it was.
She will be running adult clone class. Minimum weight 360 pounds. She is running an un restricted BSP clone engine, with Maxxis tires. There is an open tire rule with prep allowed.
On the scale tonight we got
right front 66,
right rear 90
left rear 115
left front 90.
Cross 50%, left 57%, front 43%.
For this kart where should we start for setup? The track is 1/8 mile with pretty long corners with decent banking. Any help on a starting point would be great! Thanks!
 
Sounds like maybe an old shadow, put a balanced set-up in it, 56 % left, 56 % cross, 45 % nose, 2.5 RF neg camber, .5 LF pos camber, 1 3/8 " front stagger, 1 1/4 " rear stagger.

Good Luck !!
 
Thanks RP. I thought about messaging you to ask what you thought, but I have bugged you enough for help with Jacobs kart. I wasn't sure with the unrestricted heavier weight if the percentages would be close to his lighter restricted kart or just where to start.
 
I'll leave it to others to tell you what you need to change, if anything.
Total 361
Front 43.21 %
Left 56.79 %
Cross 50.14 %

Left Front % 24.93%
Left Front lbs 90

Right Front % 18.28%
Right Front lbs 66

Left Rear % 31.86%
Left Rear lbs 115.01

Right Rear % 24.93%
Right Rear lbs 90

Front Cross lbs (24.00) Difference Right to Left
Front Cross % 36.36%

Rear Cross lbs (25.01) Difference Left To Right
Rear Cross % -27.79%
 
I got the stagger set at 1 and 3/8 and 1 and 1/4. Got the left at 56 percent and nose at 45 percent but can not get the cross high enough. I have all of the washers on the left side on top of the spindle and all of the washers on the right side on the bottom of the spindle, but the higest I can get the cross is 50.8 percent. Ot does have a weight jack on the left rear, I screwed it so it is all of the way down but still cant get cross higher than 50 percent.
I set the tires at 5 pounds left and 8 pounds right. I had the right at 7 pounds and went up to 8 but it didn't change the percentages.
 
jacobsdad said:
I got the stagger set at 1 and 3/8 and 1 and 1/4. Got the left at 56 percent and nose at 45 percent but can not get the cross high enough. I have all of the washers on the left side on top of the spindle and all of the washers on the right side on the bottom of the spindle, but the higest I can get the cross is 50.8 percent. Ot does have a weight jack on the left rear, I screwed it so it is all of the way down but still cant get cross higher than 50 percent.
Click to expand...
If your corners are what you said, then your percentages are what I said. If you notice, in my printout, the corners are exactly what you said your corners are. With your corners, my printout has the correct percentages.

I find the cross percentages interesting. Most setups that I've seen have a rear cross percentage difference of around 100%. Some a little higher, some a little lower, but very seldom even close to as low as yours.

I've compared my numbers with four other programs and three of them had the exact same numbers as mine, just in case you might wonder about the accuracy of my numbers.
 
I dont doubt your numbers at all Al, one thing I have found is you know your math. My problem is getting things adjusted to where we should be, AND figuring out what my target numbers are.
 
One Fast Kat said:
You are backwards on your washers. put more on the top of the right side and more on the bottom on the left side.
Click to expand...

With all of the washers on the right spindle on the bottom and all of the washers on the left side on top, I had 50.82% cross, 56.52% left amnd 45.38% nose.
When I switched and put all of the right washers on the top and all of the left washers on the bottom my numbers went to cross 42.51%, leftt 55.88% and nose 45.45%.
So, when I switched the washers and put more on the top of the right side and more on the bottom on the left side, cross went down.
I cant get the cross up over the 50%. Is it possible this kart has a bent frame?
 
Might want to check your rear track width to make sure it's not too wide. Moving left rear wheel in will increase your cross. Also check your ride height front and rear.
 
jacobsdad said:
With all of the washers on the right spindle on the bottom and all of the washers on the left side on top, I had 50.82% cross, 56.52% left amnd 45.38% nose.
When I switched and put all of the right washers on the top and all of the left washers on the bottom my numbers went to cross 42.51%, leftt 55.88% and nose 45.45%.
So, when I switched the washers and put more on the top of the right side and more on the bottom on the left side, cross went down.
I cant get the cross up over the 50%. Is it possible this kart has a bent frame?
Click to expand...
even with a bent frame ; that scenario is totally backwards from what the effect should have been.
your cables must be switched.
 
If the kart looks similar to a ’97 Ultramax Centerforce, it probably also has similar spindles and is not an L-block or heim front end. If that is the case, then moving spindle washers has the opposite affect to today’s karts. i.e. adding washers on top of RF would move the spindle up relative to the frame and reduce cross. On newer karts, adding washers on top of RF would lower the spindle relative to the frame and add cross.
jacobsdad said:
With all of the washers on the right spindle on the bottom and all of the washers on the left side on top, I had 50.82% cross, 56.52% left amnd 45.38% nose.
When I switched and put all of the right washers on the top and all of the left washers on the bottom my numbers went to cross 42.51%, leftt 55.88% and nose 45.45%.
So, when I switched the washers and put more on the top of the right side and more on the bottom on the left side, cross went down.
I cant get the cross up over the 50%. Is it possible this kart has a bent frame?
Click to expand...
This tells me I am correct about the spindles being the old style and not the newer heims or L-block.
 
#65 said:
If the kart looks similar to a ’97 Ultramax Centerforce, it probably also has similar spindles and is not an L-block or heim front end. If that is the case, then moving spindle washers has the opposite affect to today’s karts. i.e. adding washers on top of RF would move the spindle up relative to the frame and reduce cross. On newer karts, adding washers on top of RF would lower the spindle relative to the frame and add cross.

This tells me I am correct about the spindles being the old style and not the newer heims or L-block.
Click to expand...

I'm pretty sure you are correct Sir, exactly what I was gonna have hm look for.
 
Right rear is 1/4 inch off the frame, left rear is 3/4 inch off the frame.
RP, I will try to give you a call this evening before I go to work.
Also, I am using 4 bathroom scales leveled on the shop floor. The weights may or may not be exact, but they are all within a couple of pounds of each other. I have found the $7 wal mart scales I am using are not consistent. Every time I zero them with a known 10 pound weight they are off one direction or another, but I know they are within 3 to 5 pounds of being right.
 
Also, getting a 14 year old girl to sit still while scaling is harder than I thought. I thought my son was hard to get to sit still.
 
Racing promoter, I was going to call you last night, but I got called in to work. I am going to try either Wednesday or Thursday evening.
 
Move your right rear hub in so the right rear tire is as close to the frame as you can get it without the tire rubbing the frame. Then move your left rear hub wherever you need it to get 39" rear track width. Rear track width is measured from the outside edge of the left rear contact patch of the tire to the outside edge of the right rear contact patch of the tire. Then check your cross and see where you are at
 
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