Track Tac

BACK SPACING vs HUB SPACING ll

foreverfaster

foreverfaster

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Again, Rambling,
On a race car, your rotor or drum is a fixed mounting point for the wheel. so to off set the chassis to the left you use back spacing of rims. example 1 inch back space on the rights and 4 inch back spacing on the left side. left being more under the car.

NOW, on karts you have the option of moving the hub farther out from the centerline with shims.. or on the axle. why would you need so many options on rims?

what is the benefit of say having kart track width at 40 inches with the big off set rims VS having the same track width and using shims to get the wheels in the same location and using rims with less back space?

8 inch rim example... if the mounting point of the rim is farther to the back (2in BS) or more central (4in BS) which is better regarding the fact that the wheel will be in the same location both on the track and under the kart.

would it not make more sense to have a wheel that's bolt pattern is more central between the outer most extents of the rim??

is anyone following along or am I way out in left field.. :confused:
 
The difference in rim sizes is to change the circumference of the tire which then changes the stagger measurement without having to shrink or stretch tires.
 
Having the same width rim with different offsets and using the spindle to put it back in the same location is used on asphalt karts mainly to adjust "spring rate" "feel" and generally A handling adjustment. Works in dirt too but not used as commonly. JMO
 
Moving the hub farther from the center line changes flex characteristics of the axle..... Which is what the post above was saying I do believe.

StaggerDog said:
The difference in rim sizes is to change the circumference of the tire which then changes the stagger measurement without having to shrink or stretch tires.
Click to expand...

He's not talking about changing the width if the rim, keeping same width rim, just changing backspace on said given width rim.
 
the flex issue (spring rate of tire and chassis) is the only reason I could imagine why you would want to change the location of the hub mounting point in reference to the wheel backspacing.
for an extreme example:
RF wheel. given any particular track width, if the hub was mounted in as far as possible (close to chassis), and the backspacing of the rim was say 4 inch. you would have very little leverage from that corner. I would consider this a STIFF set up....
now the other way, if you had the hub out as far as possible, (all shims between hub and chassis)and a wheel with a 1 inch backspacing. you would have more leverage over that corner.. More flex, as the moment arm is longer..
Same would apply to the rear of the kart.. if you had the RR hub out to the extreme and the rim with about 5 or 6inch back spacing,, I would think this would make the axle flex more..
IS MORE FLEX MORE BITE??
 
I don't think flex is bite.

I'd consider timing before I'd worry about bite when you start talking flex.
 
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