Prepping for districts

General discussions for car and semi-truck racers.
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DCDAD
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Prepping for districts

Post by DCDAD » Mon Feb 11, 2019 8:31 am

Hi all-

Brand new to the forum, but really appreciate all the info folks share here and it paid off - my sons (tiger and bear) went 1&2 in their pack, so are on to districts in May. This will be the first time they've raced more than 1 day in the season. Any tips or tricks for prepping for the next race? In the pack race, each car ran 8 times on a 42'' best track, with times in the 3.11-3.12 range. Have to run graphite. Different body styles, but each car is set up as a 3 wheel rail runner, with straight rear axles drilled on a 2.5 degree cant and the front axle bent around 1.5 degrees. On our "tuning board" - a 6 ft long folding table - the cars each drift about 4 inches in 6''. Does this amount of drift seem about right for the Best track?

Rules allow polishing bores and removing mold marks, but specifically forbid using a lathe to modify the wheels. So, in a quest for better wheels, I have a run-out gage and am considering buying a few dozen BSA wheels, and having the boys sit down with the gage, find the roundest wheels, then use calipers to size match the roundest wheels into batches of 3. Worth it? I would love to see the cars run 2.9xx, but not sure it is possible without more aggressive wheel work (not allowed) or running oil (not allowed).



ironband
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Re: Prepping for districts

Post by ironband » Mon Feb 11, 2019 9:42 am

Hi DCDAD,

Awesome - I wish we had a district race to go to here...I might have to see about putting one on.

It is absolutely worth it to sort through wheels and find the ones with the least runout. I did the same with my son this last race, and had him sort our wheel collection into good (less than 0.003" runout), OK (0.003-0.005"), and Bad (>0.005"). We then sorted the good ones to find the ones that were less than 0.002" and used those. In my experience, the ones that have low runout are almost always close in diameter already.

In our case all the good wheels came from mold 11, but your mileage may vary. we noted that there were some light scratches on the wheels so we used some 1500 grit sandpaper to just smooth the outside of the wheel.

Definitely make sure you polish (at least Novus 2 and possibly some synthetic wax) and burnish the bores with graphite, outside hub (where the axle head rides), and the inner part of the FDW which may make contact with the car.

It is also worth noting that if the rules permit, it can be helpful to increase the bend of the front axle to get that wheel at an angle that makes the friction against the center rail less like sliding and more like rolling. It is more difficult to tune, and also more fragile (as we discovered at our last race where the stop section wrecked our alignment), but performs better due to rolling being better than sliding.

Additionally, assuming that you are limited to BSA axles, we found this year that filing the crimp marks is not necessary - removing the burrs under the head and then polishing from 1000-3000 grit on the head and from 2000 to 3000 on the shaft right over the crimps, followed by brasso keeps the axles "thick" and gives better stability in the bore.

There is anecdotal evidence that pledge on the axles (sprayed, then wiped off with a clean cloth) can provide a small boost as well.

A good starting point for drift is 4" over 4 feet. 4" in 6 feet seems a little light, but I think it really depends on your wheel base an your COG. More aggressive COG requires more drift to keep the car stable.

Good luck!



DCDAD
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Re: Prepping for districts

Post by DCDAD » Mon Feb 11, 2019 10:34 am

Thanks Ironband. I'll definitely follow the plan with the runout gauge and wheel prep. I've also heard the Pledge rumor, but our pack and district rules specifically ban the use of silicone spray.



Loud2ns
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Re: Prepping for districts

Post by Loud2ns » Mon Feb 11, 2019 10:42 am

So if lathed wheels are illegal....do them on a drill press. Unless that's outlawed as well.

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DCDAD
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Re: Prepping for districts

Post by DCDAD » Mon Feb 11, 2019 3:23 pm

Loud2ns wrote:
Mon Feb 11, 2019 10:42 am
So if lathed wheels are illegal....do them on a drill press. Unless that's outlawed as well.

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Is it possible to set up the drill press to actually end up with rounder wheels than you start out with? I was afraid those efforts might just make things worse.



Loud2ns
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Re: Prepping for districts

Post by Loud2ns » Mon Feb 11, 2019 5:01 pm

It would be a learning curve as to what works and doesn't. I had good luck with my Awana wheels on the drill press. There is nothing wrong with sorting through a pile of wheels to find some good ones. I just wanted to throw that option out to you.

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Speedster
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Re: Prepping for districts

Post by Speedster » Mon Feb 11, 2019 5:30 pm

Gentlemen, I have 100 tubes of BSA wheels that were destined for a workshop for 100 Girl Scouts. The workshop never happened and I am still storing the wheels. Since I am retired I decided to check them on knots concentricity gauge. None of them are any good. The way to get a set of decent wheels is to buy the Preferred numbers from one of the Vendors. I use Maximum Velocity because of his fast shipping, The numbers are 2, 8, and 15. I like to buy one of each set and that gives me 4 sets. I take the Best 3 wheels and sell the rest. The runout is almost always .003 or less. I'm beginning to think the vendors make sure the wheels are .003 or less so folks keep buying them.

I doubt a wheel can be improved by spinning it around in a drill or drill press. You might even suggest to your inspector that they are lathed wheels by sanding them.

I set the drift at 2" in 4'. After tuning on my Best track the drift ends up at 2" in 3'. All 3 of the wheels are set with 1 1/2 degree camber. Rears with Negative camber and Dfw with positive camber. They are set with that degree because of the rules. The rears ride on the inside edge at 1 1/2 degree camber. That's what has worked best for me the past few years. Without a track and timer it just a guess.
Best wishes for everyone this racing season.



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