Micro-Trains 403 Wheelsets undersized axles?

[bigdawgks]

Hi all, I am very confused about the metal wheelsets offered by Micro-Trains. On their website they specify the axle legnth of the 403 wheelsets as 0.53", yet every plastic wheelset and MTL compatible replacement metal wheeslet from other manufacturers has always had axle lengths specified as 0.54". Now it might not seem like a huge difference but I recently became aware that a huge amount of rolling stock at my club is equiped with these wheelsets and sure enough while they do mostly stay in the trucks they fit much more loosely than a 0.54" axle. So my question is why? It seems deliberate by MTL and having measured a sample of about 35 of these axles they are all in very close tolerance to the 0.53" mark.

I will add that before inspecting the cars at my club I had never encountered these wheelsets before. Personally I use ESM or BLMA metal wheels on most of my own stock and have never had any issues with them, but I was shocked to discover that these wheelsets from MTL are designed to be shorter. In fact I was shocked by a lot of things about these wheelsets - particularly the price per wheelset being even higher than 3rd party alternatives despite not being of all metal construction and using cast wheels - design decisions that personally I think are less desirable.

The most confusing thing however is still the axle length. While I said they mostly stay in the trucks, our club holds ops sessions every month and with 100s of cars equipped with these wheelsets there have been quite a few times where one of these axles has simply fallen out of a truck when being run or handled. I've searched online for any explanation for the length but I have not come across any mention of it. Could our club just be in the minority users who have really put a lot of scale miles on these wheelsets? Are there any other users of these wheelsets out there who have a different experience? I just can't understand what benefit making the axle 10 thou shorter could have.

I suppose this is also partly a rant because now I am in the situation of trying to potentially source 100s of replacement wheelsets for our club's rolling stock, but since I have only been active in the hobby for a few years I would hope to get the opinions and feedback from more experienced members on these forums before I conclude what I am currently thinking: that these wheelsets are overall just not good.

[peteski]

I will add that before inspecting the cars at my club I had never encountered these wheelsets before. Personally I use ESM or BLMA metal wheels on most of my own stock and have never had any issues with them, but I was shocked to discover that these wheelsets from MTL are designed to be shorter. In fact I was shocked by a lot of things about these wheelsets - particularly the price per wheelset being even higher than 3rd party alternatives despite not being of all metal construction and using cast wheels - design decisions that personally I think are less desirable.

The MTL blackened diecast metal wheels with plastic axles have been superseded.  I believe they were not well received (I know I didn't care for them).  MTL's newest metal wheels are constructed like any other aftermarket metal wheels.  Turned brass wheels and meta axle with one wheel insulated.  One thing that then seem to have messed up is the wheel face if flat, not dished like all their previous wheels and the competitor's wheels.

The new wheels (36") have been used on their recent car releases. Not sure if they are available in bulk. The axle length is 0.542"

[bbussey]

ESM wheels are available with a .540" axle.   

[Lemosteam]

It may be that when the old axles are removed that the truck frame remains a bit wider from that.  I always try to squeeze the frame a bit after removal and before I install a new wheelset.

[bigdawgks]

@Lemosteam If that is to be believed then it seems all the more reason to make the replacement axles at least as long as the originals, not shorter like MTL has done.

@peteski I am aware of new MTL stock coming with well fitting, turned all metal wheelsets and thus my suspicion was that the 403 design would not longer be produced. I can absolutely understand why they would be ill-received and the change of design on new productions by MTL seems to support the idea that it was not a success.

@bbussey Oh I am well aware of your wheelsets and they are my go to choice. I am glad bulk packs are finally available because if my club votes to replace all our MTL wheelsets we might clear out your inventory. 

[Lemosteam]

@Lemosteam If that is to be believed then it seems all the more reason to make the replacement axles at least as long as the originals, not shorter like MTL has done.

@peteski I am aware of new MTL stock coming with well fitting, turned all metal wheelsets and thus my suspicion was that the 403 design would not longer be produced. I can absolutely understand why they would be ill-received and the change of design on new productions by MTL seems to support the idea that it was not a success.

@bbussey Oh I am well aware of your wheelsets and they are my go to choice. I am glad bulk packs are finally available because if my club votes to replace all our MTL wheelsets we might clear out your inventory. 

One-one-hundreth of an inch is likely within design tolerance for those axles.  Try measuring the truck frame measurements at the journal ends before and after removing an axle.  Might be just enough to contribute to the additional clearance.  Then try squeezing the frame before you put the new axle back in.  The frames can deflect quite a bet in Delrin.

[bbussey]

@Lemosteam If that is to be believed then it seems all the more reason to make the replacement axles at least as long as the originals, not shorter like MTL has done.

My guess would be that the shorter axles are by error rather than by design.  Hopefully for MTL it's just a bad batch.

@bbussey Oh I am well aware of your wheelsets and they are my go to choice. I am glad bulk packs are finally available because if my club votes to replace all our MTL wheelsets we might clear out your inventory. 

We've got plenty!    Plus, I can restock in 10 weeks if we get deluged with orders unexpectedly.  But the inventory should last through this year.