axle polishing, loss of diameter=wheel wobble

[igpoobah]

We have polished the axles and I noticed that the wheels now wobble quite a bit more than on a stock axle. Did I remove too much material or is this normal? Really frustrated.

[ngyoung]

For BSA axles, yes you can over polish. They all have bad wheel wobble regardless. I suggest for the low grits to keep the sanding time short, 10-15sec. For higher grits you can extend the time a little. Also depend on the rpms of your drill. Drill press is usually a lot slower compared to a Dremel.

Also getting the Revell axles you won't have burs so you don't have to worry about filing and causing deeper scratches.

[Vitamin K]

Do you have calipers that you can use to take a reading before and after?

When grinding off the crimp marks, don't use too much pressure. You just want to take off the raised surfaces, not dig into the axle shaft.

I'll have to experiment with using the Dremel to spin the axles for polishing. I used the drill press last year, but I'm all for speeding up the process! Any tips for getting the nails chucked up into the Dremel?

[davet]

We have polished the axles and I noticed that the wheels now wobble quite a bit more than on a stock axle. Did I remove too much material or is this normal? Really frustrated.

They won't wobble went the weight is on them with the car on the track. We use stock BSA axles and set the axle in the drillpress. We lay a 1/8" thick file flat onto the drillpress table. Raise the table up until the 3 crimp marks on the axle line up with the side of the file. Spin the axle and pull the side of the file into the axle to take out all three crimp marks at the same time. With the side of file contacting the axle, turn the file from the side of the axle to the back while leaving it lay flat on the table. Take the 3 crimp marks down and we gfroove it slightly also. Moving the file front to back ensures the groove is evenly cut. Make sure the table is perfectly square both ways with the chuck otherwise you will get wheels that vibrate on the axle.

Stock BSA axles are actually around .082" where the wheel rides before you even touch them. Our rules say they have to be a minimum of .084" but it's impossible.

Also, the stock BSA axles are oblong(egg shaped) where the wheel rides. They are around .082 on the narrow and .091 on the thick. If you bend them and when you install them, set them so the wide measurement is front to back meaning if it were an egg it would be on it's side. This keeps the wheels from having as much slop side to side and will equal less toe in or out when it goes down the track.

[igpoobah]

I actually do my best to get the egg out of the axle. They are pretty round when I get done with them. Just small. Maybe I shouldn't worry about getting the egg out so much.

[LightninBoy]

Do you have calipers that you can use to take a reading before and after?

When grinding off the crimp marks, don't use too much pressure. You just want to take off the raised surfaces, not dig into the axle shaft.

I'll have to experiment with using the Dremel to spin the axles for polishing. I used the drill press last year, but I'm all for speeding up the process! Any tips for getting the nails chucked up into the Dremel?

A dremel is all I've ever used. I recommend getting the dremel workstation and a dremel chuck adapter. You'll find many uses for it.

[davet]

I actually do my best to get the egg out of the axle. They are pretty round when I get done with them. Just small. Maybe I shouldn't worry about getting the egg out so much.

The easiest and fastest way I found to get the egg shape out is to first just take down the 3 crimp marks. Then press the egg shape out using an axle press in the vise. Then start your polishing. I was able to get it on the thin side to around .085 but never really true all the way around.

I decided (based on nothing but my own idea) that the egg shape could help me if it was layed on its side. This way I was getting the advantage of the larger, .090" for and aft to prevent the toe in or out slop. This is one advantage that the larger aftermarket axles give.

[Stan Pope]

I decided (based on nothing but my own idea) that the egg shape could help me if it was layed on its side. This way I was getting the advantage of the larger, .090" for and aft to prevent the toe in or out slop. This is one advantage that the larger aftermarket axles give.

I concur, Dave, but like you, it is based on intuition. My intuition says that the "attack angle" where the axle meets the bore needs to be as small as possible, which equates to the effective diameters being close to the same.

[whodathunkit]

Can the axle actually be flat on top
as long as the bottom is curved to the proper radius & polished.

[Stan Pope]

Can the axle actually be flat on top
as long as the bottom is curved to the proper radius & polished.

In theory, "Yes, but..."
Watch out for anything happening along the path to the finish line that jiggles the wheel from its neatly nested position on the axle.
Watch out for "edges" where the axle cross section changes from rounded (to fit the bore) to flat, because such an edge could scrape lubricant off the bore.
Watch out for camber that causes the wheel to "bind" on the axle, i.e. outer end of the bore against the under side of the axle and inner end of the bore against the upper side of the axle. (That is a lot more camber than 2 to 3 degrees, but can occur if the rear of the car "wiggles" as it runs.)

There is a theory that a BSA axle cross section can be modified by flattening for and aft which causes expansion top and bottom. If the expansion is "just right" then the axle mimics an oversized aftermarket axle.