New Tires For Old Engines



General

American Flyer engines have driver wheels made of "potmetal"; a mixture of zinc, aluminum, and what ever was available to fill the pot. When these wheels slip on a metal track a metal oxide is deposited on the track and picked up by the metal wheels on the engine tender. In a short time the oxide reduces conductivity from the track to the tender and the engine runs poorly or stops. My older model 350 Royal Blue 4-6-2 engine had the problem from first use. I first thought that American Flyer added rubber tires to the model 307 Reading Atlantic 4-4-2, and that the tires on my engine had not survived 60 years of use. After measuring the wheel diameters, I have concluded that the rear wheels never had tires on them just the front wheels. At any rate it is time for a retread.

There is a difference in wheel dimensions between the model 307 and the model 350. The wheel flange on the 307 is 80-mils, the 350 is only 40-mils. The tire for the 350 must be much thinner if the engine is to stay on the track. There has to be two procedures.

Plan

The plan was to make tires out of rubber and glue them on the wheels.

First would be the model 307, because it was slipping badly, and it had a larger wheel flange.

More trials would be needed for the model 350.

Material For the Model 307

Rubber tubing was not found that was thin enough to use without disabling the wheel flange. I did not want a seam in the tire so tubing was of the essence. I found a polyolefin heat-shrinkable tubing in my junk box that I think I got about 6-years ago. I do not know the source. It is marked WOER RSFR TUBE 125 C VW-1 (1"). It is 1-29/32 inch wide in its flattened as-shipped condition.

The glue I used was Harbor Freight Super Glue, item 42367.

Polyolefin has been described as un-glueable, but I tested several glues by gluing samples to a sheet of aluminum and then attempting to peel the samples off. The sample using Welwood Contact Cement peeled off easily leaving no cement on the sample. E6000 stuck a little bit. It peeled off with a light pull and left all the glue on the metal, but I thought it might work.

Although I had read that super glue would not stick to polyolefin, and I have not had good luck in the past using super glue, I decided it was pretty easy to test it with my samples already set up.

I spread a thin layer of super glue on the aluminum and placed the sample on top of it. There was no immediate bond. Was this tube of glue to old? Was the layer too thick? I worked the sample by pressing it into the aluminum from one end to try and squeeze out any excess glue. After about five minutes the sample seemed to be sticking. I thought at the time that if the glue worked, the long working time would be helpful, allowing me time to get the tire placed on the wheel.

Wow! What a surprise. The sample bonded very tightly to the metal. Part of the test sample was left on the metal after it was peeled from the metal.

Assembly For the Model 307


Remove connecting rods saving screws and rods on cardboard

Sand inside of tires and wheels

Clean with IPA

Use a thin round steel pick to apply glue sparingly around wheel

Put on tire and position quickly against wheel flange.

Does it work on the Model 307?


Boy does it work.


Material For the Model 350

The 350 metal wheels were coated with a rubbery coating that rubbed off.

I would prefer to put a polyolefin tire on the 350 wheels, but the 350 wheels have a small flange, and the .020 inch thick tire would make the flange much less able to hold the engine on the track. So for the 350, another traction method is needed.

What to use? Vinyl electrical tape, silicone rubber, molding compound, black acrylic-latex paint, liquid electrical tape.

Vinly tape slips off the angled flat of the Ah! Liquid electrical tape. Vinyl dissolved in a solvent. Run the engine,  paint on a thin even coat. Thin ,tough, stays put. Testing required five coats and even going very slow it was a messy procedure. Then after a 72-hour cure the vinyl was too soft and hade a tendency to roll and peel.

Regular vinyl electrical tape slipped off the wheel after a short time. It also would come off faster if there was a butt joint instead of an overlap, and the overlap made the engine wobble even more than it normally does. The flat of the wheel, which is really not flat but angled from wheel flange to the outer edge instead of flat, meant that the tape had to be stretched or cut in a slight arc. No to regular vinyl tape.

Vinyl electrical tape with adhesive removed and attached to the wheel with super glue is a difficult process but seems to be best at this time. The vinyl is fairly firm. The adhesive is easily removeable with a paper towel dampened with xylene. It is only 6-mils thick and I would like 10-mils, but so far it is the best choice.

You must attach one end of the tape to the wheel with a tiny dot of super glue, then glue and attach more, and cut the end to be flush with the starting end so as to attach the last part with no seam. Like a said, "difficult".

Assembly For the Model 350


Clean adhesive off of a strip of electrical tape using a paper towel soaked in xylene.

Tape down the cleaned vinyl at the ends of the strip. Cut the vinyl into 0.140 wide strips.

Remove connecting rods saving screws and rods on cardboard

Sand the wheels and the bonding side of the cut pieces of vinyl.

Clean with IPA

Put a tiny dot of super glue on the wheel where the tire strip will begin and hold the strip on the wheel and against the flange until the strip is attached.

Use a thin round steel pick to apply glue sparingly half way around the wheel. Position the strip quickly against wheel flange aroung the wheel and use the pick to squeeze excess glue from under the strip. Repeat the process for the second half of the wheel, but don't glue the last 1/8 inch of strip.

The last 1/8 inch can be laid over the starting edge of the strip and cut using an Xacto knife so as to get a nearly seamless tire. After the strip is cut, attach the remainder of the strip to the wheel.

Does it work on the Model 350?


Works for the 350 as well.



Copyright Dale Thompson,
12 December 2020 through
last revision on 5 May 2022

Refer to Copyright notice at www.thompdale.com.