How difficult is it to convert trucks to use roller bearings?

I don't think you want roller bearings.  Ball bearings are the way to go.  I prefer flanged ball bearings.  The flange creates the space required to keep the wheels from touching the side frames and keeps them from going too deep into the journal hole.


I buy mine from Boca Bearing but I buy them 200 to 300 at a time.  This gives me a better price break.  VXB is another source but I seem to get better pricing from Boca.

If you're only looking, for say, a dozen, ebay might be the way to go.  Look for FR133-ZZ.  This equates to a flanged, shielded, ball bearing w/3/32" ID and a 3/16" OD.

Hope this helps.


Everytime I read this forum I am simply amazed!!!!! I have to ask, how do you and where do you place the bearings? Just when you think there is no possible way to do something someone has already thought it out, bought it, engineered it and done it! Simply amazing!

Engines of any sort, steam, diesel or electric are just fascinating pieces of equipment.

I bore out the side frame journals with a series of reamers until I get to few thousandths under 3/16" and then I press the bearings into the side frame.  One thing that is critical, the shoulder your axles needs to be 3/16" diameter.  If the shoulder is smaller you'll need a different bearing.  Same thing if you axle shoulders are larger.

You can use twist drills but they tend to grab the material you're boring out.


Alternatively, I use a 2x5x2.5.  You need to bore the 5mm hole in the journal or side frame as Jay describes and the axle ends need to be turned down to 2mm.    These bearings are available for as little as $0.10 ea in quantity.  The boring requires a jig for a drill press to hold the side frame or journal steady and square. 

Before I went this far I would try some light oil on the axle ends.  In over 45 years in O Scale 2 rail I have never had to convert freight car trucks with ball bearings to get them to roll smoothly.  If you attempt to install bearings I hope you have a good drill press in your shop.

Ball bearings may make some sense on models used on a commercial model railroad that see many hour of running time, otherwise proper lubrication should be a sufficient way to get your cars rolling better.

Just my two cents worth.


Interesting!  I was only thinking about locomotives (mostly diesel) where the axle loading goes way beyond anything a car, freight or passenger, would have.  Freight cars?  Probably not worth it.  Passenger?  Maybe.  Never occurred to me we would be talking about anything else.  In retrospect, I should have considered the cars.  The not so funny thing for the opening it says, "Cars".


 I hope anyone who reads this and run long trains will try this. Connect all the cars you wish to run and try to pull them up any hill on your layout. When I do this outside with my G scale, I am amazed that these toy trains work so hard. I can only imagine some club that runs for hours, burning up stuff hauling heavy trains? So I always do this before deciding on what power to add to the train. I have less than 2 % grade outside. When I put about fifty cars together, the effort to move them up the hill is big. The  high track going into my shed approaches 3%. I break trains apart before attempting that run. I started putting bearings into my USA trains (heavy) metal cars. They are already in the Accucraft passenger cars. So I can't help but want them inside on my O scale layout even though it's much flatter.

" on Sour mash and cheap wine " ??

Why go back to DCC when I have DCS!

I experiment with this was a little different I put the roller bearings from RC race cars in O gauge freight wheels. This way not only bearings, but also independent rolling. No resistance on curves. 

P.S.            I just do what RRJJF posted


I wasn't going to comment, but I agree with Joe and Jay.

I did my "Log Mallet" with roller bearings on each driver axle.  Understand, I am not a world-class machinist, but I make my own mainframes.  A ball bearing must be precisely aligned, or it will have more friction than a solid bearing.  My alignment was not good enough; the six axle Mallet runs ok, but not as good as similar solid bearing models.

A sprung or equalized truck will give you fits.  The bearing has to "rock" as the wheels go over bumps.

A famous collector wanted to commission me to put ball bearings in his PSC Pullmans.  I turned him down.  He said "you don't understand; I will pay big bucks for this!"  I still said no. (It wasn't Jim).

Is axle loading actually an important factor in the operation of our models? Suppose your 4-axle diesel weighs five pounds, then the weight carried by each of the eight journals is only 0.625 pound, or about 10 oz; and if it is a 6-axle diesel, then only 0.416 pound, or 6.6 oz. My F units are fitted with brass trucks and brass journals and seem to run perfectly well with just a drop of oil from time to time. I kind of have the feeling that ball bearings have a big "wow" factor, but may not be that significant an improvement for operation. But I could very well be wrong.

Yes, it is.  I've had to replace solid bearings on heavy models.  Over time the rotating axles will create oblong hole in the journals.  This is especially true if you lubricate without cleaning.  The dirt, dust, grime, whatever, becomes a cutting compound.  The lubrication actually exacerbates the attraction of the contaminants.  Bronze bearing material is better than brass but even the bronze will wear.

Same thing happens with the side rods on steam engine models.  This is especially true with the newer models with very thing rods.  The older KTM models and other early models were far more robust and last far longer.


Good afternoon. Just to add to what Jay already said above, it most ceryainly can be done. I have found that making a mold for the side frame to slip into is an easy way of making sure the side frames sit flat for drilling and to help keep everything square. I use all ball bearings in my walthers Milwaukee cars as these cars tend to weigh about 3-4 pounds a piece. I can literally push a 5 car train down the tracks with my pinky and they just keep rolling. Definitely the way to go with most any passenger car. 


Photos (1)

  This goes beyond just 2r.  I've been toying with the idea on cast post war cars with straight axles ever since I got some modern cars with ball bearings and my car limits more than doubled.

  A good axle seat in the i.d. (long enough) may enable a mounting similar to a "pillow block" if your good at machining (powered or by hand). It would let sprung axles achieve an angle too. Pin the race o.d. at 9&3 o clock ?

"Still trying to not shoot my eye out"


"Nursing insomnia one railcar at a time"

My aroma therapy? Smoke Pellets.


bob2 posted:

More pictures of the Milwaukee cars?  I had no idea they could look that good.  I am working on an Erie-Built, and may opt for Milwaukee cars.  Especially a Skytop!

Not a problem. As soon as I get home tonight I will line up the 6 complete cars I have and get ya some photos. Both the Skytops were entered into the O scale meet contest in chicago.  


Can I post on to this topic? I don’t want to inundate this topic on unrelated material or is that ok to do? Still new to how all this works. 

I kind of have the feeling that ball bearings have a big "wow" factor, but may not be that significant an improvement
for operation. But I could very well be wrong.

Well I am eyeing one of my biggest offenders - the ones who have a LOT of resistance... the MTH Aerotrain cars.... all Ten of them!

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