Bang your head

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asatxj
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Bang your head

Post by asatxj »

I have been banging my head on a wall for about 3 years now. So I'm asking for some help. I've been talking to Sporty a bit but in a multitude of counselors....
Here's my situation. I race on a Freedom track 30' race distance. My best time is 2.543 and I'm right there every year. Now the specs.

Awana wheels and axles. (reduced weight wheels did not help much .005)
Wheels true'd as well as possible with a modded DW lathe, Drill press.
Polished bores.
Axles, polished, beveled head. (No grooves at this point)
Prep is polished well, green rouge, Mothers, Simichrome, Techwax, Jig, Krytox
Body Low profile (Poplar) Covered with vinyl (sign maker stuff)
Extended wheelbase
COM between 3/4 and 5/8 Using Tungsten cylinders as low in body as possible.
Axle location raised 1/32 higher than normal in body in rear to lower mass in car.
Rear cant 3*
DFW is 10*
Steer is 1' in 6'

I would welcome some thoughts, I have a couple races to run in April, I'll try some things and run the cars during the race to see how they work.
Thanks in advance.
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Re: Bang your head

Post by ngyoung »

Main thing I see is that your steer is really shallow. Even many of the best racers start around 4" in 4'. Have you test run it on a track? If so, how stable does it ride? I would think with that low of steer it wouldn't hold it to the rail very well. If you have a test run session before your race I would start with around 4 in 4 and only back off the steer until you start to see wiggles then put it back a touch.


Do you have a way to verify the run out of your wheels after you do your home lathe system? You could be making them worse for all you know if you don't have anything to check it. Axles I would recommend going with a series of sand paper or micro mesh starting around 800-1000 grit and go up to at least 12k. Finish with a polish, I use brasso but the fastest guys I know use a vendor's Cheetah Kiss Axle Polish. Not sure what grit equivalent green rouge is.

Wheel bore prep I use the plastic polish with a qtip chucked in a drill method. Then finish with Red Rocket buffed clean. Looks like you have Jig to coat the axles before applying oil and installing the wheels.
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Re: Bang your head

Post by asatxj »

I raced that car last week. I actually had less steer (8" in 6') and it wobbled a bit so increased it to 12" in 6' and it went away, sat on the rail and ran correctly. It may have looked like 1 inch in 6 feet but it was 1 foot in 6 feet.

I did leave out a step or two on the axle, after modding the head I use a 800g ceramic stick, 1k ceramic stick on the head and then 1k-2k paper on everything. Green actually produces mirror finish on stainless and is a final polish for nickel and similar metals. Simichrome is for polishing injection molds to mirror finish (killer on brass, better than brasso imho). At one time I had paper from 1k to 12k but I read elsewhere that the Awana axles didn't require that much treatment. I suppose I can grab some.
I haven't purchased an indicator to check run out, I usually prep 6-8 wheels and run them on prepped axles, if the test car is noisy I swap wheels until I get a smooth and quiet roll. I have a friend with a precision lathe, he will be making me a new set of wheels with zero run out soon. Talk to me about Red Rocket. What makes it superior? Awana wheels are pretty soft I've tried to be very gentle with the bores. Thanks.
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Re: Bang your head

Post by ngyoung »

Red rocket as well as other car finish protectants like Liquid Glass or Legend's cures harder then the plastic. They are applied like any other conventional car wax but don't actually use wax. The first step being plastic scratch remover for qtip polishing takes down the bumps, RR is used as a second step to fill in the valleys and when buffed like a car wax leaves a smooth hard finish. You apply a thin coat, let dry for 10mins,blow off any excess and let dry another 15,then buff off with a pipe cleaner or soft cloth. Let cure for 24hrs before applying oil.

For oil process I think it likes a high polish on axles. I think where you heard that awana axles not needing a high polish is with using graphite. That is common practice for BSA PWD racing with graphite as well only going up to 2-3k.

Sorry I miss read your steer. At 1ft it seems you may have the opposite problem. You may be able to back off some of the steer if you can test run tuning the weight. Biasing more or less weight on the rear wheel behind the DFW can effect the amount of steer needed to maintain stability. If you don't have time available to test on the track that won't really be an option. You could move your COM slightly forward and back off steer slightly but again you won't know if it will be faster or slower without a chance to test it ahead of time.
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Re: Bang your head

Post by Stan Pope »

I don't know those wheels, but I suspect them based on your description.

At our Cub Scout district races last week, on one of the tracks that almost everyone had to race on to reach the finals, the fastest cars were turning 2.480-2.489 sec. The track was a stock 4 section Freedom track w/standard microswitch start gate. The track was well set up on a level gymnasium floor.

These cars ran at most slightly lightened CS wheels, about 2.5 gram, so these CS wheels were relatively stiff. At least one of those cars ran on well polished BSA axles, so aftermarket axles were not a factor.

It would be interesting to see if your car body running with well prepared BSA wheels/axles would show your slower times. I suspect not ... I suspect they would perform comparably to our district's best.

With these facts and suppositions in mind, consider the following possibilities:

(1) The flex of the softer AWANA wheels is largely inelastic which means that any flex experienced by the wheels is largely lost energy. Since you are running with camber, your wheels are rolling on the inner edge of the tread which has much more flex than the outer edge. This is a likely source of the energy loss contributing to your times. Since your rear wheels are carrying (in total) 6 to 8 times the weight carried by the DFW, and the DFW is rolling on the stiffer outer edge, most of the purported loss would come from the rear wheels.

(2) The conclusions of point (1) can be tested, using your same wheels, by reversing your rear wheels so that they roll on the stiffer outer edge. Care is required that the sidewall does not contact the car body, but with the same negative camber and good alignment, that can be assured. Since the outer edge is stiffer, your times should improve, possibly up to the level provided by CS wheels. (Note that those who run extremely lightened BSA wheels with their more flexible inner tread edge use this wheel reversing technique to get best times.)

What do you think?
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sporty
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Re: Bang your head

Post by sporty »

When I have used alot of can't on the rears with Awan wheels.
the hub there tricky. Because it's so flat. Sometimes I had to polish and I have tried angling the plastic there.
due to being softer. It's not as easy as compa red to bsa hub work.

The axle head can be tricky. With the flatter hub area as I just mentioned.

I like the max v wheels. Awana.
they certainly are faster and. When I tried doing some on my own. On a lathe. A good cut on the o.d. was tricky for me. Very light cuts. Deeper cuts seemed to cause uneven cutting or flex of the plastic and run out can be a issue. Depending how you mount and hold the wheels in a lathe.
that's why after I tried a few. I just found it easier buying the max v awana wheels.

If you wanted to send me a few extra sets. I'd be happy to try a few again for you.

The max v. Ones are lighter and compared to stock are better and faster.

I have tried red rocket. I've had trouble getting to perform for me. But others have done well.
I don't know why. Something I'm doing wrong or how it relates to my bore prep or other polishing methods.

The 3 degree cant on the rears might be to much for the awana wheels. Due to bore size and the flat outside hub. Not being coned..
to much axle head friction might be a courting there. ???

I do recommend the tungsten cubes.

I'm looking forward to some car pictures. You are sending me..

Another side comment.

I know just when I would polish the bores on awana. That softer plastic removed easy and scratched easy. Took me some trial and error to get right. And the softer plastic. I found. I could bend and get the wheel out of shapr. If I used to much pressure when holding the wheel. When working on the bore. Or trying to remove them. After I installed them on the car.

Sporty
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Re: Bang your head

Post by asatxj »

Sporty, I sent the pics yesterday. They should be there. Email me your address and I'll send you a handful of wheels.
I have a pro outer hub tool and have tried it on an Awana wheel with less than spectacular results.

Running the wheels inside out has been a thought, I've yet to engineer a way to make it work but may have to tinker with it.
With respect to the amount of cant in the rear, there is enough slop between the axle and bore that any less resulted in the wheel flat on the track, which I was hoping to avoid. I will commit some time to creating a reverse wheel set up with some of the wheels I receive from Sporty.

Stan, I have built cars with Awana axles and BSA wheels, they are faster than my Awana cars by about 1/2 a car length. I believe I could get into the 2.4s easily with them.

With respect to weight biasing, I do set up the car with the weight biased to the DFW. While describing my build it's a challenge to recall every detail. I suppose I should be keeping the data in a file as it would make things much easier.

A thought, our Adult division allows us to modify the wheels, I've considered narrowing the tread width. This would strengthen the wheel. Any thoughts there? I have a little over a month before the two races I have to run so I should have time to make some adjustments and see what comes to pass.
Thank you one and all, I welcome the aid!
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Re: Bang your head

Post by sporty »

I found email in my spam bin. I just replied.
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Re: Bang your head

Post by Stan Pope »

asatxj wrote:... Running the wheels inside out has been a thought, I've yet to engineer a way to make it work but may have to tinker with it.
With respect to the amount of cant in the rear, there is enough slop between the axle and bore that any less resulted in the wheel flat on the track, which I was hoping to avoid. I will commit some time to creating a reverse wheel set up with some of the wheels I receive from Sporty.

Stan, I have built cars with Awana axles and BSA wheels, they are faster than my Awana cars by about 1/2 a car length. I believe I could get into the 2.4s easily with them.
re "cant": With BSA wheels with modest negative camber, the bore will try to rest flat against the underside of the axle, causing the outer edge of the wheel to lift. The "slop" allows you to position the wheels flat on the track, but as soon as it begins to roll (so long as the rear axles are not toed in), the outer edge of the wheel will lift. Even small lift can be detected by sliding a piece of paper under the wheel from the side.

I don't know of the Awana wheels have enough flex to bend the hub/bore so that the wheel rolls flat when there is camber. If so, then that flex will contribute to further energy loss as the hub / bore rotates at the same rate as the wheel turns! I'd appreciate if you take the car as is, position it with the hubs flat against the axle, and test the lift using as multiple sheets of copier paper. Then repeat the measurement after rolling the car a foot or so forward. Finally, repeat the above measurements with the wheel installed inside out. With those data, perhaps we can estimate the amount of hub flex and tread flex you experience.
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Re: Bang your head

Post by asatxj »

I believe I know what you are looking for Stan, I'll work on that shortly.
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Re: Bang your head

Post by Stan Pope »

asatxj wrote:I believe I know what you are looking for Stan, I'll work on that shortly.
There are a couple of other measurements that may help assure the quality of those I suggested above:
Intentionally attempt to pose the car with the wheels as flat as possible (without bending anything) against the track. How many paper thicknesses of lift?
Intentionally attempt to post the car with the wheels as lifted as possible (without bending anything) against the track. How many paper thicknesses of lift?

The purpose it to have as a basis for comparison. It is possible in the "measurement after rolling" tests that axle misalignment will force the wheels away from the desired "bore against the underside of the axle" configuration. The result of that would be equivalent to one of the measurements above.

It is also possible that you can manually stage the car with its wheels in the desired "bore against the underside of the axle" configuration. If so, then you should be able to detect that with the measurements and skip the "after rolling" measurements. Those "after rolling" measurements could give you some useful info on your rear alignment, though.

As an aside: With normal cambers, the "bore against the underside of the axle" configuration is a lowest energy state. Tilting the wheel toward either more or less camber should raise the axle (and, so, the car) slightly. The fact that the energy states are not very different may be a contributor to some car's tendency to a "roll" wobble.
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Re: Bang your head

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I used my wife's glass top range (yes it was cold!) for the paper test. I positioned the wheels with the hub against the axle head. Each allowed me to push one sheet to within ~ 1/16" inch of the inside edge of the wheel. Sheet 2 was ~1/16" less than that. My calipers are broken so I couldn't improve accuracy beyond that. I rolled it 18" and repeated the test with same results. FWIW the wheels remain at the axle head whether rolled forward or backward. Repeated tests 3x and got the same each time. Wheels reversed I could insert 1 sheet ~1/16"and that was all. Note: a machinist told me that Awana wheels come with a 1* taper from inside to out. My truing efforts support this as a cutter parallel to the hub begins shaving at the inside edge. My wheels have a rim of graphite picked up from the track at the inside edge.
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Re: Bang your head

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asatxj wrote:I used my wife's glass top range (yes it was cold!) for the paper test. I positioned the wheels with the hub against the axle head. Each allowed me to push one sheet to within ~ 1/16" inch of the inside edge of the wheel. Sheet 2 was ~1/16" less than that. My calipers are broken so I couldn't improve accuracy beyond that. I rolled it 18" and repeated the test with same results. FWIW the wheels remain at the axle head whether rolled forward or backward. Repeated tests 3x and got the same each time. Wheels reversed I could insert 1 sheet ~1/16"and that was all. Note: a machinist told me that Awana wheels come with a 1* taper from inside to out. My truing efforts support this as a cutter parallel to the hub begins shaving at the inside edge. My wheels have a rim of graphite picked up from the track at the inside edge.
Cool!

We should only be interested in the lift at the outer edge of the tread, as knowing that height and the width of the tread and some trigonometry will tell us angles.

I wonder if sliding the sheets under the wheel edge one at a time might give false reading. Two or three thicknesses of paper pressed together and slid under the edge may give a truer reading.

Assuming that the readings are true ...

With the 1 degree taper built into the wheel's tread (some taper is normal I think for release from the mold), there should be a difference in diameter, inner tread edge vs outer tread edge, of around 0.003 to 0.005" which should be about 1 sheet of common copier paper. (A package of 500 sheets of common (20 lb) copier paper is about 2" thick. So one sheet should be about 0.004".) However, there is probably a similar taper on the bore, which should then total 2 degrees, and, when reversed, should cause a 4 degree reduction in the outside tread lift.

I am not trusting the taper data. Even if there were no tread distortion when resting on the inner (more flexible) edge, with 3 degree neg camber of your rear axle, the wheel should not rest on its near edge when reversed.

So ... what can we do to take the uncertainty of the taper info out of the equation? How about temporarily altering the weight carried by the rear wheel? The rear wheels probably carry about 2 to 2.2 ounces apiece. the wheel behind the DFW probably carrying less and the other carrying more. If tread distortion is present when the wheel is installed normally, then adding weight should increase the distortion. Linear? Maybe, maybe not. But the outer edge lift should reduce if tread distortion is present. How about doubling the weight carried by the wheel behind the DFW ... from about 1.7 oz to about 3.4 oz and taking lift measures before and after.
Stan
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Re: Bang your head

Post by asatxj »

Round two in the morning. Any benefit to using unaltered stock wheels?
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Re: Bang your head

Post by Stan Pope »

asatxj wrote:Round two in the morning. Any benefit to using unaltered stock wheels?
Maybe later. For now, these are the wheels about which we have performance info!
Stan
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