I like to wieght my cars according to formula.
Do passenger cars follow the formula 1/2 oz/in + 1 oz.?
I would need to add 3.25 oz to my “empty” (no interior) passenger cars to reach 6.25 oz. ea.
That’s generally the formula that I’ve been using. My Rivorossi passenger cars were “featherweights” out of the box.
I did the trick of filling in all of the pockets in the floor with BB gun pellets (Walmart sells them) and smothering them with glue. To make up for the rest of the weight all that was needed was a long flat weight and the cars roll nicely coupled to my Walthers Budds.
The Walthers Budd cars are easy as they’re reasonably close to the proper weight and can be left as they are. I experimented and weighted one down using the same trick as above. Rolling and tracking quality improved. Nice not seeing a “wobble” when it rolling over switch turnouts.
That’s the NMRA Recommended Practice 20 for HO. I use it for my passenger cars. The weight helps keep them on the tracks when backing, especially backing up thru turnouts. A full length 80 foot passenger car wants to weight about 6 oz.
The BB’s in the floor trick works. I used sheet lead flashing, available from my hardware store. It cuts easily with snips and lies down flat so it doesn’t show thru the windows. The IHC cars are very light out of the box. They run better weighted.
Something I usually mention to modelers in general dealing with rolling stock weight.
Be careful about adding “too much” weight to your cars as it puts an unnecessary strain on locomotive motors, even if they’re of high quality.
For example: A modern HO Atlas FP-7, according to the MRR Review a few years back, can pull 25 free rolling freight cars on straight, level track.
My wife’s cousin decided that his HO open bay hoppers needed some “prototype” weight. He often ran them in a 30+ car unit train. So he loaded them up with extra metal weights in the bins and applied real crushed coal on the tops. Didn’t use a scale. Afterwards things got interesting. In a nutshell, a SINGLE 6 axle genesis locomotive or a single Atlas SD24 would sit and spin its wheels on that train! It now takes 3 locomotives to move that 30 car monster! In a nice, polite way I said to him “THAT IS WAYYYYYYY TOO MUCH WEIGHT ON THAT TRAIN FOR YOUR ENGINES![:O]”; in attempt to make him realize that what he had was a “Texas style Tractor Pull Contest” to see which locomotive motor burns out first. [C):-)]
He laughed when I told him how many cars his Athearn and Atlas engines, individually, should be able to pull. His attitude was that his locomotives were of high quality, so they should be able to “pull a heavy load” like the prototypes. I told him about the NMRA weight formula and he now plans to “lighten the loads”. If his locomotives could talk, they’d be barking some thank yous to the NMRA![:o)]