I helped my son build his pinewood derby car for scouts and it bounces around going down the track rather than rail riding. The rear holes are drilled at 2.5 degrees. When moving the car forward one wheel goes out to the head of the axle and the other slides up against the car and when the car is rolled backwards both whens go to the axle heads and stay there so I know the one hole is off alittle. whats the best way to fix this issue. The COG is 7/8 inch in front of the rear axle. Any help is much appreciated.
Best way to fix a slightly crooked rear axle hole
- Thread starter Sambob414
- Start date
Try twisting the axle head 1/4 turn at a time and see if it does what you want it to.
Yes, your axles are most likely slightly bent. All BSA axles are! By twisting the axle, you are trying to get the side that is riding against the body to move outward. Right now, that side has too much toe in.
I would twist it a little at a time then test. I normally turn it about an hour on a clock face at a time.
Thank you! Ill give it a try. Is there somewhere on here I can find if there's a track somewhat local to me that I might be able to use for testing as well as possibly get into the racing more seriously?
Agreed, not all straight axles are straight. I do 1/4 turns until I get somewhere......then like you I'll fine adjust it.
I tried turning the axle it helped a tiny bit but it’s still not right. What would you try next?
I see a few options ....
One: try a reamer using slight pressure toward the rear on the wheel that is toed in.
Two: slightly bend one axle ...maybe 1/2 - 1 *. Install and rotate as needed to correct the alignment. Or find another axle that has greater runout and prep it for that side.
Three: toothpick the hole and re-drill. Choose a toothpick that fits as snug as possible and use wood glue on it. This swells and interlocks the wood fibers for a strong bond.
What exactly is run out? Same thing as the axle being bent causing the wheel to run out to the axle head?
Basically it would have a bend in it. As you rotate the axle it will wobble. In this case, because you had some success by rotating the axle, an axle that has more run out (wobble), would allow you to further correct the issue. Ideally, you are trying to get the toe set to zero ( straight ahead). That way both wheels will migrate to the axle head while rolling forward.
...clear as mud?
These are good options, but before trying one of those three I would try this. Try turning the "good" side to see if you can get the opposite to occur on that side. WARNING- if this works, make sure you're not going to drag your rear wheel on the rail. My fastest time down the league track so far was with a car that had toe-in on one side and toe-out on the opposite(not intentionally).
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