Axles and wheels.

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jolly roger racing
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Axles and wheels.

Post by jolly roger racing »

Currently we are machining our axles on a drill press. We remove all burrs and then straighten the axles. Then we use micro files to perform the following-

-taper the axle heads.
-groove the axles with a round profile using a round file.

We usually machine 8-10 axles to pick the best for a car. Axles are checked with a dial caliper for max and min diameter. Also we throw out ones whose groove is not consistent ( the cub cannot stay awake for these steps).

I dont remember the exact #, but obviously the axle dia. gets smaller.

Now when we prep our wheels including coning the hubs and bore polishing we note a good bit of slop in the wheels. Sideways play.

Our question is this a problem?

Jolly Roger Racing
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FRANKLIN WHALEY
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Re: Axles and wheels.

Post by FRANKLIN WHALEY »

Sideways movement of any kind is not good. It's causing extra friction and costing speed. Question is, are the wheels wobbling ,or are they running smooth on the axle and just moving in and out from the car body to the axle head? Also are they doing the same thing before you are coning and polishing the bore?
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Stan Pope
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Re: Axles and wheels.

Post by Stan Pope »

Franklin's got it right.

A further question, tho, since you seem to be increasing the gap between bore and axle:
Is the axle getting smaller or the bore getting larger?

If the axle is getting smaller from your treatment, it creates just a small problem, and so long as the wheel does not actually twist sideways on the axle, you are losing a bit, but not a lot. I really don't like to reduce the axle diameter if it can be avoided, but the performance cost is slight. I think that it may shorten the lifespan of your graphite because of the increased angle between the axle and bore where they rub. (I can't prove that but I think it is true.)

If the bore is getting bigger, then this is a problem, and you should review your process to find out why. Larger bore increases losses in proportion to the ratio between bore diameter and tread diameter.
Stan
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Re: Axles and wheels.

Post by Mike Doyle »

Along this same topic, I've been reluctant to use the Pro Tool to ream the wheel bore since my goal has always been to keep that diameter as close as reasonable to the axle.

I'm in agreement with your observation about internal bore angles / axle relationships. Larger bores with reduced axle diameter seem to produce a quicker degradation of the graphite.
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Stan Pope
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Re: Axles and wheels.

Post by Stan Pope »

Mike Doyle wrote:Along this same topic, I've been reluctant to use the Pro Tool to ream the wheel bore since my goal has always been to keep that diameter as close as reasonable to the axle.
There is some advantage to having all the bores the same size. It goes along with having the Cf's in all the wheels the same, etc. ... makes the car more stable.
Now, if you have 3 wheels with bores smaller than standard, then how about setting them to a smaller common size? That gets what you want without unbalancing the drags moments on both sides. :)
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Re: Axles and wheels.

Post by Mike Doyle »

Exactly! I'm all for it.

I wonder which mold numbers will yield the *best* wheels for the 2006 season :roll:
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Re: Axles and wheels.

Post by Alex »

jolly roger racing wrote:Currently we are machining our axles on a drill press. We remove all burrs and then straighten the axles. Then we use micro files to perform the following-

-taper the axle heads.
-groove the axles with a round profile using a round file.

We usually machine 8-10 axles to pick the best for a car. Axles are checked with a dial caliper for max and min diameter. Also we throw out ones whose groove is not consistent ( the cub cannot stay awake for these steps).

I dont remember the exact #, but obviously the axle dia. gets smaller.

Now when we prep our wheels including coning the hubs and bore polishing we note a good bit of slop in the wheels. Sideways play.

Our question is this a problem?

Jolly Roger Racing
Slop in the wheels is a big problem. Try ordering a quantity of axles in bulk, they are cheap if bought from the right supplier. Use a caliper to measure the diamater. Often many are larger than the rest. Use the larger ones of course, matching them so the 3 that touch are all the same. Be sure your axles are straight or use Max V's nail straightner. The same principle applies to the wheels. When you polish your axles don't over do it. Lightly with #600 grit paper. Move up to #1500 grit. Finish off with #2500. You've got the right idea about preparing more axles than you need. Do the same with the wheels. Measure all the specs and examine with an eyeloupe. Select the best to run, be sure they all have the same specs as close as possible.
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Re: Axles and wheels.

Post by Pinewood Daddy »

jolly roger racing wrote:-groove the axles with a round profile using a round file.
It's been discussed in other threads that grooving the axels reduces the the surface contact between the axel and wheel, but it increases the contact pressure, accelerating wheel bore wear. The uneven wear won't allow the wheel to freely float on the axel, theoretically increasing friction.

Stan talked me out of using grooved axels for the pack race. Unfortunately, in testing 2 days before the race, I noticed the car was getting slower each race, so I replaced the wheels (bore wear after 20 runs!) and ungrooved axels (not knowing what the problem was) with my backups (grooved axels). The car was the fastest in the Pack by .02 seconds. I've made new axels (tapered head, not grooved, and polished with Mothers), burnished the wheel bores, and am working on alignment for the District race next Saurday.

It's nearly impossible to compare apples to apples with so many variables.

My $0.02.
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Stan Pope
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Re: Axles and wheels.

Post by Stan Pope »

Pinewood Daddy wrote:The car was the fastest in the Pack by .02 seconds. I've made new axels (tapered head, not grooved, and polished with Mothers), burnished the wheel bores, and am working on alignment for the District race next Saurday.

It's nearly impossible to compare apples to apples with so many variables.

My $0.02.
Good luck next Saturday! But, it sounds like you are making a lot of your own luck! :)

Truly, too many unmeasured variables!
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Stan Pope
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Re: Axles and wheels.

Post by Stan Pope »

Pinewood Daddy wrote:Stan talked me out of using grooved axels for the pack race. Unfortunately, in testing 2 days before the race, I noticed the car was getting slower each race, so I replaced the wheels (bore wear after 20 runs!) ...
Since you have identified a problem, it would be useful if you can set those wheels and axles aside for careful analysis at leisure, i.e. after the racing season. Look at the patterns of bore wear, look at the roughness/smoothness of the axles. If you come up with some explanations, I would welcome them!
Stan
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Re: Axles and wheels.

Post by Pinewood Daddy »

Stan Pope wrote:
Pinewood Daddy wrote:Stan talked me out of using grooved axels for the pack race. Unfortunately, in testing 2 days before the race, I noticed the car was getting slower each race, so I replaced the wheels (bore wear after 20 runs!) ...
Since you have identified a problem, it would be useful if you can set those wheels and axles aside for careful analysis at leisure, i.e. after the racing season. Look at the patterns of bore wear, look at the roughness/smoothness of the axles. If you come up with some explanations, I would welcome them!
I set aside the axels, but the wheels ended up back on the car, after additional testing, because they were my best wheels (run-out). I just reburnished the bores.

OT -
Alignment (wax paper shim) is driving me nuts! After 3 hours I had 3 wheels (nearly) perfect and the car rolling straight for the 5 feet of my test ramp. After adjusting the one remaining wheel, the car no longer rolls straight (6 inches right over 4ft), but the wheels don't float in or out!! I can't get it back! I put it away for the night. I think I'll add more graphite to make sure the CF is consistant between all the wheels, and start over tonight.
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Re: Axles and wheels.

Post by Stan Pope »

Pinewood Daddy wrote:Alignment (wax paper shim) is driving me nuts! After 3 hours I had 3 wheels (nearly) perfect and the car rolling straight for the 5 feet of my test ramp. After adjusting the one remaining wheel, the car no longer rolls straight (6 inches right over 4ft), but the wheels don't float in or out!! I can't get it back!
Ouch!
Recheck wheel treads and alignment surface by rolling wheels individually.

To speed up the process, I do following:
1. install axles, sans wheels, to planned depth in correct orientation
2. using one side of car as reference for a try-square, check fore-aft alignment of axles
3. using one (clean) part of underside as reference for a try-square, check for up-down alignment of axles.
4. still without wheels, shim to true by try-square.
5. now install wheels and proceed with roll tests and alignment decisions.

Every time you reinstall an axle, be sure to maintain orientation and depth.

The try-square pre-alignment "gets you real close." The roll testing "zero's it in."
Stan
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Pinewood Daddy
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Re: Axles and wheels.

Post by Pinewood Daddy »

Stan Pope wrote:The try-square pre-alignment "gets you real close." The roll testing "zero's it in."
Unfortunately, the try-square method doesn't always work on a sanded & painted car (no flat & square surfaces). I was pretty close before I started shimming, but I lost it somehow. I'll get it back tonight.

I have a mark on the head of each axel to maintain orientation. Depth could be an issue, I've been eyeballing it. I didn't make the depth insert block, as you suggest.

The biggest problem I had was shimming the axel up. Instead of drilling holes in the body to fold the shim into (as you suggested), I laid the shim in the bottom of the slot and held it in place while I inserted the axel. It took two layers of plain paper to get the adjustment right.

I haven't roll tested the wheels, but they were lathe turned on the Pinecar arbor. I need to get MaxV's Pro-Wheel Mandrel. I'll use better wheels next year.

I'll use the Pro-Body tool this summer to make a few cars for fun (and practice shimming). I need more good wheels (#2's).

I asked Randy (at Maximum Velocity) to update his wheel table. I told him about the #8 wheels with .010 run-out, not 2.4 as his table shows. He said he would do it this summer. As it has been mentioned in this thread, there must be variations in the manufacturing process. Only #2 seems to be consistant.
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Re: Axles and wheels.

Post by Stan Pope »

Pinewood Daddy wrote:The biggest problem I had was shimming the axel up. Instead of drilling holes in the body to fold the shim into (as you suggested), I laid the shim in the bottom of the slot and held it in place while I inserted the axel. It took two layers of plain paper to get the adjustment right.

I haven't roll tested the wheels, but they were lathe turned on the Pinecar arbor. I need to get MaxV's Pro-Wheel Mandrel. I'll use better wheels next year.
The insertion guide block is essential for me ... without it, I've got another uncontrolled variable. :(

Shimming up: A 1/8" hole vertically through the slot, centered halfway between the shoulder of the nail point and the edge of the car and extending 1/16" beyond the top of the slot gives you an "anchor point" for the shim!

Re individual roll test ... it is only important if one of the wheels is out of shape! I do it because it tells me about the wheel and about the test surface!
Stan
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Re: Axles and wheels.

Post by Pinewood Daddy »

Stan Pope wrote:The insertion guide block is essential for me ... without it, I've got another uncontrolled variable. :(
I've got to make one.
Stan Pope wrote:Shimming up: A 1/8" hole vertically through the slot, centered halfway between the shoulder of the nail point and the edge of the car and extending 1/16" beyond the top of the slot gives you an "anchor point" for the shim!
The problem I'm having is the axel pushes the shim in, tucking it into a hole won't hold it. I use a dental pick to hold it.

WAIT!! DUH!! The shim tucks into the hole towards the outside! The axel will pinch it and hold it in place!
Stan Pope wrote:Re individual roll test ... it is only important if one of the wheels is out of shape! I do it because it tells me about the wheel and about the test surface!
I made a gage to check O.D. & side tread run-out (hardened steel w/drop indicator). I don't think they run-out more than .005 :( My test surface is a 3/4" thick melamine board, 15" X 72", stiffened with two pieces of 1/8" X 3/4" angle iron, leveled side to side.

I'll have to leave some room for improvement next year. :mrgreen:

I'm going to have my son do most of the woodworking next year, but I'll still do the alignment.
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