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Post by volsfan on Feb 19, 2007 20:33:19 GMT -6
I have read conflicting ideas about angling the axles so the wheels ride away from the car body, some say this makes the car ride straighter and reduces wheel wobble and friction others say it greatly increases the friction against the axles head.
Please help I am very confused now, and my son's district race is this weekend. Thanks for any help.
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Post by RacerX on Feb 22, 2007 11:02:28 GMT -6
It makes for a straight, fast, easy to align car especially with-out a test track.
Drill the body with a Pro Body Tool, straighten your axles with a Pro axle press and polish then. Mark the axle @ .350" from the head and put a dot at 12:00 on head with a sharpie. Instal the axle into the Pro Axle Press at the .350" mark with the dot on the head down and slightly bend the axle with a light hammer tap. I use a digital caliper to measure from the head of the axle to the work bench to verify my bend. On the rears .015" and .010" on the front. Install the rears with the dot up at 12:00 as well as the front (dominant wheel).
The car should roll forward and backwards with the wheels staying on the axle heads. If not. rotate slightly fore and aft untill both are perfect and do not migrate. Use slight rotation of the front axle to steer. There are several good table top formulas on here (someone chime in) but 1" drift towards the dominant front wheel over 6' test roll will get you going well.
Good Luck
Racer X
The trade off is positive vs. axle head to hub face friction.
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Post by backcreekpinecars on Feb 22, 2007 13:54:39 GMT -6
now that's the explanation I've been looking for - thanks racer X
good karma for that one!
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Post by sporty on Dec 29, 2007 13:54:30 GMT -6
my son races soap box derby, we use very precise alignment tools. we go to .000 !!! Some formats of the race our different from Pine Wood Derby. However. crossbinding is still very important to alignment and reducing wheel friction. Unless the car runs completely strait. It is hard to have the wheels stay out on the outside, unless you have cambered them enough to force them to stay there. However, keep in mind this can also increase friction and pressure on the head of the axle. Slowing the car some. I would enjoy seeing a alignment tool like we use for soap box derby for PWD. www.zero-error.com sells a great aligment tool, anyone wanna creat one at a PWD scale ? Sporty
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Post by sporty on Dec 31, 2007 10:55:28 GMT -6
There is one thing that clearly stands out different, when just talking about wheels. the PWD wheels axle whole is not so much a tight fit, versus the Soap box derby wheel.
My thinking is that the camber on a pwd car is simply trying to reduce the wobble on the car.
toe in toe out, in SBD simpley can create drag and to much friction.
Now, we dial the axles to less than the thickness of a human hair, with the weight and racer already in the car. Naturally a PWD car is much lighter and does not bend the axle.
However, the simple process of frilling or trying to place the axle into the wood as strait, level as possible.
but very hard to get to .003 or less accuracy with out a dial indicator and good quality gauge.
food for thought, a car off by .01 (ten thousands) is about a 1/4 car length at the end of the race !!
in SBD cars win or loose by within less than 300 hundredth of a thousands of a second !!
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