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Post by RichH on Nov 18, 2011 16:53:45 GMT -5
Trying to narrow the rear of my kart. Just discovered that 50mm axles will not go thru the wheel like my old 40mm. Could swap out the entire axle for one of the 40mm off the other karts. (God, I don't want to go to that much work  ) or Could just use one set of the Alum. rims and turn them around large offset to the inside. Assuming that the valve stem clears the hub. Am I missing anything here? Safety issues? Handling issues? |
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Post by ron90 on Nov 18, 2011 17:56:09 GMT -5
You must have forgotten. That is the problem I had all season. The kart had 50mm axle and I couldn't narrow the rear enough. I also couldn't widen the front enough because it was actually a kart that is setup for 40mm axle. I am swapping my 40mm setup to the new kart for next season.
I assume you are talking about road racing. I understand you have to narrow it ALOT. I couldn't imagine that you could narrow it enough by just turning them backwards.
Notwithstanding, an analysis of backspace (the measurement from the mounting pad to the inner edge of the wheel) and offset (the distance from the mounting pad to the centerline of the wheel [offset can be positive with more backspacing or negative with less backspacing) would have to be reviewed.
I am having a hard time remembering that stuff from my days working with tires and rims when I was in my teens. Man I can barely remember being a teen. I will try to remember and let you know.
I vaguely recall that changing the offset from negative to positive can be detrimental to the wheel and bearings because it adds more strain. But in reality we change the strain on the bearings and wheels all the time through longer or shorter hubs, and lengthing and shortening the distance between the wheels.
Just change the axle out.
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Post by Brad Wunder on Nov 18, 2011 18:13:14 GMT -5
I couldn't imagine that you could narrow it enough by just turning them backwards. Notwithstanding, an analysis of backspace (the measurement from the mounting pad to the inner edge of the wheel) and offset (the distance from the mounting pad to the centerline of the wheel [offset can be positive with more backspacing or negative with less backspacing) would have to be reviewed. I vaguely recall that changing the offset from negative to positive can be detrimental to the wheel and bearings because it adds more strain. But in reality we change the strain on the bearings and wheels all the time through longer or shorter hubs, and lengthing and shortening the distance between the wheels. Just change the axle out. Whaaaaat are you talking about Ron? You made my head hurt. The only part I understodd was the last part....yeah, "just change the axle out". Even I can understand that, and better yet, even I can do that....  |
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Post by ron90 on Nov 18, 2011 18:35:03 GMT -5
;D
If you can't dazzle them with brilliance, baffle them with b___s___.
But really it's not b___s___.
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Post by RichH on Nov 19, 2011 18:37:32 GMT -5
OK, the axle is changed out, not as narrow as I like but ran out of key way on the 40mm axle. Cut down the side pods to match rear track. ?s Do I match the front track to the rear or go with what looks good aerodynamically with the nose/pods? front end alignment, toe in a 1/16" per side, what about auckerman? I am assuming less to make it less twitchy Is a full floorpan legal? Am I missing anything? I just realized that I to put all this stuff back!  |
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Post by Brad Wunder on Nov 19, 2011 20:10:02 GMT -5
So, what you are saying is, now we are doomed weatherwise for next weekend because you did all that work on your kart?? I'd leave the front where it is. If it gets too twitchy move it out a half spacer. Front end alignment? Toe? Ackerman? I dated one of the Ackermen twins in high school but no adjustments were necessary. No changes to any of that stuff should be required. Full floorpan is fine. I think you've got things covered. Well, at least till you try and put everything back. Are you planning on welding your nerf bars to get them back to sprint lengths? ;D |
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Post by norcalacr on Nov 19, 2011 22:24:48 GMT -5
Ackerman? You're thinking of caster. Adding caster stabilizes the vehicle at nigh speed. I used to add caster to the Camaro for track days. IIIRC ackerman is the angle offset needed to compensate for the fact the front wheels are traveling along differnt arcs.
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Post by brad42 on Nov 19, 2011 23:56:22 GMT -5
For oval racers and roadracers, Ackerman can be a key to max speed in a slight curve. On a sprint course ackermen can be used to quicken/slow turn-in. For roadracing and big ovals you want to minimize scrub.
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Post by RichH on Nov 20, 2011 13:54:20 GMT -5
So what I'm reading is that a little less of it all( camber & ackerman helps with speed?
Right now my kart is set up with lots of camber & on the last hole for max ack. It is on the razor edge for quick turn in. Once I got used to it I liked it for Sprint racing
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Post by scoots27 on Nov 20, 2011 20:39:02 GMT -5
Keeping the wheels as close to the king pins that you can will reduce scrub and you can also reduce the toe-in lessining scrub. I dont think you can make your karts too narrow for Road racing. If the engine is in the way of the right rear tire, use a longer chain and moving that engine forward. If the clutch hits the seat, you can move the front of the seat to the left alittle.
I hope your moving your side pods in. Punch the smallist hole in the air as you can. You could think about laying your seat back if your moving it for the clutch. Just stuff to think about if you want to go faster than the racer in front of you.
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Post by Brad Wunder on Nov 21, 2011 19:27:44 GMT -5
So what I'm reading is that a little less of it all( camber & ackerman helps with speed? Right now my kart is set up with lots of camber & on the last hole for max ack. It is on the razor edge for quick turn in. Once I got used to it I liked it for Sprint racing Regardless of what your front end geometry looks like, the draft plays a MUCH more important role. When you are tucked into the train you most likely won't be using more than 75-80% throttle. Otherwise you will be bump drafting the hell out of the guy in front of you. Speaking of bump drafting, don't do it in RRing. EXTREMELY frowned upon and will likely get you black flagged. Personally I'd just leave it the way it is at least through the first practice. There are no corners that require quick turn in. Remember, the slowest RR corner is faster than the fastest sprint corner. |
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Post by ron90 on Nov 22, 2011 16:25:02 GMT -5
OK, the axle is changed out, not as narrow as I like but ran out of key way on the 40mm axle. I can measure the 40 mm axle on my old kart that has a axle from 2008. It was made for a older narrower kart and may give you more room to adjust the back end. email me skydivingrlc at yahoo |
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Post by RichH on Nov 22, 2011 20:18:18 GMT -5
Ron, are you trying to kill me? I just got all those parts on the kart. I am only 1" away from the motor with the tire now. I had to cut a key in half to make it that far. I think I will live with it for now. It would be interesting to know if there is a difference  |
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Post by Brad Wunder on Nov 22, 2011 20:20:28 GMT -5
1"? Ohhhhhhh man, someone is in for a WILD ride!
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Post by ron90 on Nov 22, 2011 22:24:18 GMT -5
It is harder to go from a 50mm to a 40mm, because you have to change all the bearings, the sprocket carrier, and the brakes. You've already done that. From a 40mm to a 40mm is easy IF everything slides easily. You take the wheels off, loosen all set screws along the axle, and slide.
Also are you supposed to run an angled mount or a flat mount to get the engine out of the way. If the F200 15 degree mount will work it is sitting on my work bench not being used right now.
I can pull the axle tonight if you want.
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