How to measure rear track

My 2019 slack wants 39 in rear track says right rear should be 1/8 to 3\16 off of frame rail do you measure this from wheel to frame? Also to you measure from the contact patch on the slick to get to 39 in. Thanks
 

CarlsonMotorsports

Premium User
Measure distance from wheel to frame rail.
Measure track from outside to outside of the contact patch.
Keep in mind that this is difficult to measure with some very round cut tires, Burris, etc.
Some chalk dust on the floor of your garage (or tires) and rolling the kart 6" with the driver in the kart, is a simple way to check this.


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Yes inside edge of wheel to frame RR 1/8"
Just set the LR at 5/8" inside edge of wheel to frame, you'll have it close enough to the 39" they refer and it will perform well.
 
Measure distance from wheel to frame rail.
Measure track from outside to outside of the contact patch.
Keep in mind that this is difficult to measure with some very round cut tires, Burris, etc.
Some chalk dust on the floor of your garage (or tires) and rolling the kart 6" with the driver in the kart, is a simple way to check this.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
Thank you what I did.
 

sundog

Member
Rule book measures track width from outside of left wheel to outside of right wheel. That's a big difference from the contact patch method but, if you're a beginner, it won't hurt you to make it a little wider.
 

alvin l nunley

Premium User
Let me submit this as a standard for determining rear tread width. The width of each tire is measured to the side wall, or the rim, whichever is wider. Let's have one standard way of measuring it. This is one way, others may have another way, but we all need a standard way of doing it.
tread width illistration.jpg
 
We are running 8.00 or 9.00 tires on 10" wheels for the rights, and 1 6.00 tire on 8.25"-8.75" wheels. Why should we make it standard way of measuring to the wheel when theres quite a bit of the tire thats not even close to edge of the wheel?
Its more of a standard to space wheel hubs where needed and your tread width is factored into that measurement, IMO.
All this is relatable to dirt LTO.
 

Kj26

Member
Go-kart-tire_LI.jpg

Pardon my phone drawing skills, but contact patch is between the white lines.
Sundog I don't know what rule book you follow, but we measure tread width, not track width.
Al, this is simple, your standard won't work.
 

CarlsonMotorsports

Premium User
I am guessing that Sundog is referring to sprint / road course tracks measuring rear track width on pavement karts.
It's a rule that is closely enforced (or should be) on sprint chassis.
On dirt ovals, they may check the width of the body (or nose), but generally the rear track width on an oval kart is pretty narrow. We are more concerned with the outside of the contact patch to the outside of the contact patch.
As Earl properly explained, we're stretching tires on 2" - 2 1/2" wider wheels or more. Kind of pointless to measure outside of the wheel to outside of the wheel for any sort of chassis set-up.
 

XXX#40

TRUMP 2020
Rule book measures track width from outside of left wheel to outside of right wheel. That's a big difference from the contact patch method but, if you're a beginner, it won't hurt you to make it a little wider.
on a straight rail kart probably, on a dirt oval kart not so
 

Pete_Muller

Moderator
Al,

I have personally *always* measured outer contact edge to outer contact edge (in sprint and road racing). For me, that has always been the key measurement for tuning the rear.
 
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