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Replacing Trucks w/ Truck Mounted Couplers on Freight Cars

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  • Member since
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  • From: Chamberlain, ME
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Replacing Trucks w/ Truck Mounted Couplers on Freight Cars
Posted by G Paine on Wednesday, July 6, 2011 1:04 PM

I have just finished replacing the trucks on an old HO scale Tyco reefer. My aim is to convert the friction pin connected trucks with truck mounted couplers with screw connected trucks and body mounted couplers. I will make a separate post on the coupler mounting when I have finished the installation.

Parts of this can also be used to replace a screw connected truck when the threads have stripped.

Some "toy train" freight cars sit too high when compared with similar model train freight cars. The first thing I did was compare my Tyco swift reefer with a red Walthers reefer

They were similar in height. Probably, the older Tyco car with a 1937 build date should be a bit shorter than the Walthers car with 1954 build date, but for this project I feel it's close enough.

Next I removed the old trucks by inserting a screw driver under the truck and giving it a twist to pop the trucks off. The old trucks will not be used.

Many cars are too light; I weighed the reefer with the new trucks and couplers on the scale, and it was an ounce too light. I removed the bottom of the car by prying with a screw driver until it popped off the 4 mounting pins. I added additional weight using a steel weight that was left over from another car. I was careful to keep the weight away from the holes where the truck screws could stick through.

Then I checked if a piece of 1/8" styrene rod would fit in the truck mounting hole; I found the hole was too large. Usually, I would drill out the mounting hole with a 3/16" drill and fill with 3/16 tube (Evergreen 226), but all I had was 1/4". With 3/16" you can preserve some of the existing truck bolster, and get a better flush mounting surface for the truck and pin. When I drilled the 1/4" hole, some of the bolster was damaged. I cut the tube to length, glued it unto the bolster, leaving it flush with the bolster top, and let it set overnight.

When the glue has set, I drilled the hole out with a 1/8" drill. I cut the 1/8" tube (Evergreen 224) so that it would stick out above the bolster surface about 1/16". I glued this part in and let set overnight to ensure in was hard in place before drilling and tapping. I drilled the hole with a #43 drill and tapped with a 2-56 tap. Kadee sells a kit #246 that includes the 2-56 tap, the #43 tap drill and a #50 clearence drill.

The above paragraph is also a procedure for replacing truck mounting where the threads are stripped. There are many other ways of doing this; this how I do it.

The new truck bolster looks like this:

I used trucks from my parts box; there are trucks available from many manufacturers. Get ones with metal wheels for better running. Before mounting the trucks, check that the wheels are in gage with an NMRA standards gage and that the wheels spin freely. If they do not, use a Truck Tuner to recountour the truck bearing. Truck Tuner is available from Micro-Mark,8241.html
See Walthers for the HO NMRA standards gage; all hobby shops should have this item!

Install the trucks using 2-56 screws. Tighten the screw until it is tight (do not force it), then back off about 1/4 turn, and adjust so the truck turns freely, but does not wobble. For the other truck, tighten as above but leave it looser so it does wobble a bit. This mounting will pervent or lessen the car wobbling as it goes over the track.


In a couple of days I will post part 2 showing how to install a body monted Kadee #5 coupler and coupler box.

Part 2, installing a Kadee #5 coupler box and coupler is posted here

George In Midcoast Maine, 'bout halfway up the Rockland branch 

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Posted by cmarchan on Wednesday, July 6, 2011 1:42 PM

G Paine,

Thanks for sharing; this is a "clinic" that'll make a great addition to anyone's skill notebook. Very nicely done!

I look forward to your coupler installation demonstration.

I just upgraded two AHM cars; one triple dome tank car (Ethyl Corp)and a 40' box car (Domino Sugar). I did not have to replace the trucks; I cut off the couple boxes and retained the trucks. I body mounted Kadee # 5 couplers with boxes; shims made from styrene were placed between the coupler boxes and the car underside; .020 for the tank car and .040 for the boxcar. The wheelsets were replaced with metal wheelsets from Walthers.

Carl in Florida - - - - - - - - - - We need an HO Amtrak SDP40F and GE U36B oh wait- We GOT THEM!

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Posted by G Paine on Wednesday, July 6, 2011 2:23 PM

Thanks for the good words, Carl. What you descrbe is about the same as what I am doing on the reefer coupler installation. I just need to run the car bottom thru the paint shop, put the couplers on and Photoshop the remaining pictures...

George In Midcoast Maine, 'bout halfway up the Rockland branch 

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Posted by Chen on Thursday, November 27, 2014 2:15 PM

I bought an AHM car, and had bad truck & coupling.  Alternative quick fix is:  purchase Kadee 502(Bettendorf Truck) kit,  2-56 screws, and 2-56 lock nuts. 

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Posted by dknelson on Thursday, November 27, 2014 4:07 PM

Sometimes the problem with AHM cars was not the trucks but the blankety blank wheels.  The next problem is that due to a somewhat proprietary design, not all replacement wheels will just pop into an AHM truck.  So in the end a complete replacement with a quality truck is likely the way to go.  

I am in the midst of what should be a simple project involving an AHM tank car -- but with a tank car the mounting of a Kadee coupler draft gear box is not so clean and simple, and moreover the car is seriously underweight -- and is the very devil to pry open without damage.  It is an interesting enough car that I am willing to give it a try.

I have also been upgrading an old Athearn 62' tank car which is similarly underweight -- only to learn that the weight that Adair Shops makes for this very model is out of stock at Walthers with no expected date of shipment.  I think Adair ships on a very irregular calendar and I suspect old Blue Box kit weights are now low on their work schedule.  Ah well.  At least these simple projects get me tinkering at the workbench rather than watching chipmunk videos on YouTube ....

Dave Nelson 


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Posted by ruderunner on Friday, November 28, 2014 6:28 PM
For weight in a tanker, how about drilling a hole in the bottom, adding BBS then plugging the hole No it won't be secure but it won't spill on the layout

Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction

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Posted by riogrande5761 on Sunday, November 30, 2014 11:43 AM

If I was really sentimental, or there was a car that was quite unique and no better alternative, it might be worth it to do that upgrade.  For example, I think Bachman or Lifelike made a cylindrical hopper I have never seen done in a higher quality model, that one might be worth the upgrade, but many other models it would much more easily be replace with an Athearn or or Accurail model for cheap which already have the body mounted couplers.  YMMV.

Rio Grande.  The Action Road  - Focus 1977-1983

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Posted by MisterBeasley on Sunday, November 30, 2014 12:38 PM

I have a lot of old rolling stock with Mantua-Tyco trucks and truck-mounted couplers.  I've got sentimental attachment to them.  I originally just cut off the couplers and replaced them with body-mounts using Kadee draft gear boxes, but then I realized that those old trucks with plastic wheels had a lot of rolling resistance, so it was time to upgrade to metal.  I bought a bunch of Intermountain wheelsets in bulk.

Unfortunately, the old trucks are all metal, press-fit together, and they're not coming apart.  (Well, let's say they're not going back together.)  I found Tichy trucks without wheels for a good price, and I've got most of those upgrades done.

When I got the Tichy truck frames, my first step was to paint and weather them, so as each one goes on it's ready for the layout.

It takes an iron man to play with a toy iron horse. 

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Posted by JACOB LONGANECKER on Tuesday, August 11, 2015 11:36 PM

The BB's idea is a pretty awesome one that I never considered, but I will employ ASAP on all tank cars, RTR or not.  One thing that might help keep them from rolling around all over inside is after adding the amount needed to bring the weight up to spec, tip the car on it's end and add white glue either full strength or 1 part water to 3 parts white glue into the tank.  Use duct tape or something similar that will make a good temporary seal and set the car back right side up.  Shake the car back and forth longways to distribute the BB's and glue and let set for a day or so.  After that, you should find the glue has 1. sealed up the hold, 2. will hold the BB's in place so that won't be temped to shift during evelation changes (although the BB's shifting could add a certain level of realism to a consist if you dare).

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Posted by Catt on Wednesday, August 12, 2015 9:56 AM

Unless the trucks are totally wrong or in bad shape I keep the origonal trucks and just replace the wheel sets with Intermountain metal wheels after using a truck tuner first.I have on occasion just used the truck tuner and put the plastic wheels back in temporally if I were out of metal wheel sets.Using just the tuner can make a huge difference in rolling quality.

Johnathan(Catt) Edwards 100 % Michigan Made
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Posted by dstarr on Wednesday, August 12, 2015 11:59 AM

Nice writeup.  Good photos.  I might add a couple of things.  You don't really need to tap plastic.  Ordinary machine screws, or self tapping screws will bite into the plastic and cut their own threads.  If your couplers come out low, ordinary #6 flat washers from the hardware store do a fine job shimming the car up. You don't have to buy Kadee washers. 

   Like you, I go to the trouble of spray painting the underside of cars.  Even though you cannot see the underside while the car on on the layout, I think it improves the looks of them.  I use Rustoleum or Krylon auto primer, sometimes the dark gray sometimes the light gray.  Painting glossy black trucks with either rust or grimy black helps the looks a lot and does not require artistic talent.  For the more toylike trainset cars, an overall coat of DullCote will flatten the gloss paint and tone down the bright colors.  I run a fair number of  trainset cars and with a bit of paint they look just fine on the layout.

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Posted by hon30critter on Tuesday, January 1, 2019 11:00 PM

Clickable link.

Yes, this is an old thread but George just referred people to it so I decided to make the link to the Kadee coupler box installation work.


I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by doctorwayne on Wednesday, January 2, 2019 7:42 AM

Those are very nicely-done write-ups on both the truck installation and that for the Kadee couplers, George!

And Dave, thanks for the working links to both of those older threads, as they provide good information, especially for newcomers who have these older type cars and want to upgrade them as they get deeper into the hobby.


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Posted by G Paine on Wednesday, January 2, 2019 9:35 AM

Thanks for updating the link Dave. I am surprised Photobucket is still hosting and displaying my images; I left them years ago when they wanted to charge money for everything

George In Midcoast Maine, 'bout halfway up the Rockland branch 

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