Crosskart Xtreme best center of gravity height?

[pcnsd]

Tire pressures?
Sometimes just a couple-few psi can make a difference with starts.

My reading of the tire rules is grooving, siping and grinding is prohibited. (Mechanical treatment).
If not... cross sipe those rears.

Assuming day racing, Do you sun soak your wheels with dark covers if possible based on conditions.

[ptuomov]

Minor update from the ski slopes:

https://youtu.be/cr-cAiam6lg?feature=shared

[ptuomov]

No updates on the geometry as I'll be on the other side of the world for the next little while. However, they did ice-track test the car with new tires. Initially, the car had understeered somewhat in the corners. That was cured however by making all settings in the rear shocks much stiffer and the driver now likes the car again. My theory for why stiffer rear shocks were required on the ice track vs. summer gravel/asphalt tracks: There's less traction and less lateral cornering g's on ice track. With the earlier settings, the inside rear wheel wasn't pulled up but instead dragged the car to understeer. Stiffer rear shocks caused the inside rear wheel to come off the ice and the car started turning correctly. This is in addition to the usual effect of a stiffer rear suspension reducing understeer in differential cars. Does this theory make sense?

[allencr267]

Dry clutch allowed?
Can see some might say it's a non-allowed rotating engine or gearbox part.

[Rick!]

I need more info regarding what adjustments were made. Is the video after the adjustments or before?
Does stiffening all the settings mean just turning screws for increased compression and rebound (and maybe low-speed compression) or were the springs twisted a tad tighter? Fundamentally, the rear roll stiffness was changed slightly to accommodate the changed tire traction conditions (amount of screws) if I understand correctly. If four things were changed on each corner, one may not know what really made the car better. Cornering is a low shock speed event unless there is a bump or curb hit during the turn. Bumps are high speed events. That would then tell you that the low speed compression my have been the most influential adjustment.
Going way over the top, one might want to remove the rear shocks and have them dyno'd to understand how the feel and response of the kart changed. Or, on good dampers, there is usually a force-velocity (f-v) and/or displacement-force set of curves plotted to help with guiding adjustments. You'll see that the Low Speed Compression screw has a HUGE effect on damping at shaft speeds slower than 50mm/sec. Maybe contact the damper OEM to get the curves since the cart was bought used.
Was the sharpness of the traction screws checked after each set of hot laps? Slight dulling of the rear traction screws may have been the "loosening" of inside rear wheel traction that made the kart handle better.
Since the ice is fairly flat and a bit smoother than a typical "summer" track, it's best to log the changes that were made and experiment some more.
Maybe change the brake bias and return the shock compression settings to where they were and leave the rebound stiff and record the driver feedback. Also, driver feedback of bumps in the track in his line are very helpful to narrow the scope of adjustments and speed up setup.
Changing only one variable at a time is highly recommended. Were the lap times being recorded to have that data? Is there any data acquisition on the kart? Three IMUs (Inertial Measurement Unit - not a gyro, just a 6DOF sensor) would go a long way to relating driver feedback to kart responses. If channels are at a premium, then one IMU at the kart CG will give the most bang for the buck.

[ptuomov]

Thank you got this post! It’s currently way above my pay grade but a great roadmap of what I need to learn about. Thank you.

I need more info regarding what adjustments were made. Is the video after the adjustments or before?
Does stiffening all the settings mean just turning screws for increased compression and rebound (and maybe low-speed compression) or were the springs twisted a tad tighter? Fundamentally, the rear roll stiffness was changed slightly to accommodate the changed tire traction conditions (amount of screws) if I understand correctly. If four things were changed on each corner, one may not know what really made the car better. Cornering is a low shock speed event unless there is a bump or curb hit during the turn. Bumps are high speed events. That would then tell you that the low speed compression my have been the most influential adjustment.
Going way over the top, one might want to remove the rear shocks and have them dyno'd to understand how the feel and response of the kart changed. Or, on good dampers, there is usually a force-velocity (f-v) and/or displacement-force set of curves plotted to help with guiding adjustments. You'll see that the Low Speed Compression screw has a HUGE effect on damping at shaft speeds slower than 50mm/sec. Maybe contact the damper OEM to get the curves since the cart was bought used.
Was the sharpness of the traction screws checked after each set of hot laps? Slight dulling of the rear traction screws may have been the "loosening" of inside rear wheel traction that made the kart handle better.
Since the ice is fairly flat and a bit smoother than a typical "summer" track, it's best to log the changes that were made and experiment some more.
Maybe change the brake bias and return the shock compression settings to where they were and leave the rebound stiff and record the driver feedback. Also, driver feedback of bumps in the track in his line are very helpful to narrow the scope of adjustments and speed up setup.
Changing only one variable at a time is highly recommended. Were the lap times being recorded to have that data? Is there any data acquisition on the kart? Three IMUs (Inertial Measurement Unit - not a gyro, just a 6DOF sensor) would go a long way to relating driver feedback to kart responses. If channels are at a premium, then one IMU at the kart CG will give the most bang for the buck.