I have some older cars that need wheels. When I was at Walthers, I noticed they come in different sizes. How do you measure the wheels, and how do you know what size you need? Is it better to have plastic axles or metal?
Doug
As a rule of thumb, most freight cars take 34 inch diameter wheels, heavyweight passenger cars take 36" wheels. To measure a wheel use vernier calipers to take the size across the wheel tread. Multiply the ca;iper reading in inches by 87 to obtain the wheel diameter in HO scale inches. The run of the hobby shop wheel sets come with axles more or less the right length to fit your trucks. Metal wheels look better than plastic, they show a bright shiny metallic tread as opposed to flat black plastic. Metal axles ought to be brass, non magnetic, so they don’t pull forward or backward over magnetic uncoupling ramps. Dunno what to say about plastic axles, don’t remember every having any metal wheel sets that didn’t have metal axles.
The easiest and best way to measure wheel DIAMETER (which is likely what you’re talking about) is with a caliper:
They range in price from dirt cheap to more than you can afford. Happily, the former will do the job nicely. But the latter have more wonderfulocity.
You measure the tread diameter, not the overall diameter. When you multiply that number by 87 (if you’re in HO), you’ll get a number lie 33". Or 36". These are nominal sizes, pretty much.
Ed
Typo, Most freight cars from the transition era take 33" wheels. Modern freight cars may use 36" as well.
33" wheelsets measure approximately .382" +/- .001 in the middle of the tread (there is a slight taper).
Walthers Proto 2000 and Kadee wheelsets have plastic axles, useful if you have metal sideframes. I use Walthers Proto 2000 wheelsets and Intermountain wheelsets mostly.
I do not use plastic wheelsets. They get their axles cut and the wheels get added to scrap loads.
If you think you might be interested in scratch building in brass, get an inexpesive metal one, instead of a plastic one. You get what you pay for with precision instruments. Starrett is a trustworthy brand name. Their low end dial calipers are made in China. The next most inexpensive one is made in USA, in Athol, Massachusetts. Your buget may vary, and an inexpensive hardware store or hobby shop caliper will be more than sufficient if all you are doing is measuring wheelsets.
Before I had a dial caliper, I would assume everything used 33" wheelsets. If the couplers were low, I would swap them for 36". Too high at 36" they get 33" and fiber or brass shims.
Doug back when I started the common understanding (which as it turns out was somewhat flawed) was the 33" wheels were for freight cars and 36" wheels were “passenger car wheels.” But very heavy capacity freight cars have 36" wheels, especially these days. And there were some passenger cars with 33" wheels. And to further complicate matters, some intermodal cars have even smaller wheels for clearance purposes.
But except for modern heavy cars such as 100 ton covered hoppers and such, the run of the mill boxcar or tank car or gondola likely should have 33" wheelsets.
There are more areas of potential confusion as many decades ago prototype wheels had ribbed backs and those are available in HO and other scales but are not appropriate for cars built after about the mid 1950s.
If you have a wheelset of each size and have good eyesight it is pretty evident which is which. Holding them up to a scale ruler is not always helpful because a slight tilt one way or the other can easily involve a 3" error. A dial calipers is a better way to measure.
Actually I have a jig made by Minuteman to paint the outer surfaces of wheelsets, one for 33" and one for 36" and if I found a wheel and did not know the size I’d use my paint masking jig to find out. American Model Builders makes something similar
https://www.walthers.com/wheel-paint-mask-for-kadee-r-similar-rp-25-wheels-33-quot-wheels
Most modelers feel that metal wheels are better than plastic. As far as axles go, I am not sure there are such strong feelings. In theory plastic axles might bend and thus be inaccurate in gauge but this must be pretty rare. Metal axles might be attracted to magnets that are placed between the rails for remote uncoupling of Kadee and similar couplers and I think that
Just a little caution note. Some manufacturers use different length axels. Once you have vernier calipers you can measure the length (axel point to point) so you know which axel length to buy.
And get yourself a “Truck Tuner” from Micromark.
This little gadget cleans out and smooths the axle bearing in the trucks and helps your wheels run better.
FYI, I use Intermountain wheelsets.
And the other source is Reboxx, who I believe invented the tool.
One thing to remember, Kadee wheels are sintered metal wheels. Most others are machined metal wheels. Many like the machined, especially because of the shiny thread and they are a little heavier. Sintered are black thread and more capable of picking up dirt compared to machine metal. They are made of compressed powered metal and still ok. Price is lower also.
Many here have noted the cars roll better with machine metal wheels.
Don’t forget the truck tuner.
For many years I used a cheap plastic dial caliper. I have a digital but it eats batteries.
Rich
Here’s my two cents worth. I prefer Intermountain wheelsets and recommend the truck turner…
Another vote for Intermountain wheels. I use them in models with both plastic and metal trucks. Locos can pull longer trains as the rolling resistance will be decreased.
I’d certainly recommend the truck tuner, too, but wouldn’t waste money changing the wheels unless there’s something wrong with them.
Wayne
Many prefer metal over plastic - even though there may be nothing “wrong” with the plastic wheels. I have noted one thing wrong with plastic wheels is they tend to get a layer of gunk built up on them with running.
Jim,While that is very true I have notice a thin layer of grime on some of the metal wheels on the cars I used at the club while other cars I used at the club did not have any grime… The grime was located the wheel next to the flange. All wheels are IM 33".
The issue may not be that metal wheels don’t get dirty, but a lot of folks have reported that plastic are particularly bad that way. YMMV but just thought I’d point out a common complaint - don’t shoot the messenger!
Jim,I’m not ventilating the messager…I just wanted to share a strange phenomenon I notice on some of my club cars…
Needless to say I will be scratching my head over that phenomenon for the foreseeable future.
Another thing to consider when buying metal wheels is the tread width. .087" and .088" are more prototypical in appearance, but they can be fussier when dealing with less than perfect trackwork. Kadee wheels have wider treads, but they are more forgiving, and they still give that nice “clackety-clack” sound. [swg]
I do agree that some plastic wheels seem to collect dirt, but they’re certainly not creating that dirt, merely picking it up from the track. The solution, for me at least, is to simply vacuum the track occasionally…Once a year seems plenty, although my layout is in a dedicated space which I keep fairly clean.
I do clean track after ballasting or adding scenery near the tracks, operations which are usually performed at the same time. After that, the vacuuming only has sufficed for over 20 years.
While some folks like the look of metal wheels, I find that they draw too much attention to their overly-wide treads (unless they’re Proto-87) and the resultant overly-wide sideframes which accommodate them. I also find the racket they make annoying - not at all like the noise of a real train.
The claim that metal wheels roll better is, I think, specious. The better-rolling attributes are more likely due to a more precise interface between the axle ends and the shape of the plastic “journals” in which they run.
Metal wheels do add some weight, but too much is made of “placing the weight down low”. At prototypical speeds, placing the weight on the underside of a car’s roof works just as well. I often do so with passenger cars, where there’s little room otherwise to hide that weight Of course, there’s seldom need to do so on most freight cars.
All of that being said, I do have metal wheels on about 10% of my rolling stock - most of those came that way. [swg]
It’s certainly up to the individual modeller to make their own choices, so my experiences are offered here only as another possible alternative. [:D]
Wayne
Way back when, I used to run just about any car with the original trucks and wheels, including the very deep flanged AHM cars. And on those plastic wheels the “gunk” - it was more than just a coating of dirt – would build up enough on the tread to nearly eliminate the flange. Then it would eventually peel off leaving an odd circle of gunk on the ROW.
Metal wheels would get a coatint of grime or dirt but never a build-up of the stuff like that. Perhaps static electricity plays a role?
What I always assumed was that at least part of the gunk might in fact have been worn away plastic, that is, that the plastic wheels themselves were slowly but surely wearing due to contact with the (then-brass Code 100) rail and sharp curves and that the plastic “dust” that resulted was part of the wheel gunk.
I have dim (very dim) memories of an article in MR where they actually sent car wheel gunk in for a genuine chemical or spectographic analysis to try to answer the age old question, just what IS this stuff? I no longer recall the results and whether micro bits of plastic made up the gunk. I suspect oil and lubricant and household dust were ingredients however.
Dave Nelson
Thats what I noticed when I used to run trains in my garage layout; basically all of my rolling stock had plastic wheels back then and they would get quite a thick layer of gunk on them. Of course a grage layout is subject by it’s environment to more dust etc. I had no other place at that time.
I do clean track after ballasting or adding scenery near the tracks, operations which are usually performed at the same time. After that, the vacuuming only has sufficed for over 20 years.
It seems most of the manufacturers have decided that metal wheels are better o