Tuning couplers

I don’t like the slack action in Kadee’s S scale couplers, so I’ve been modifying them to remove it.

On the underside of the coupler shank, there’s a projection that fits into a slot in the coupler box to aid in centring the couplers. I slice this off and sand/file the area smooth:

Kadee coupler modifications.

There’s also a small projection at the back of the shaft. I remove this, too:

Kadee coupler modifications.

Then, instead of adding the centring spring, I cut a piece of .080″ x .080″ styrene strip and use it. I cut this so it’s just a touch shorter than the opening for the spring (minus, of course, the post in the coupler box). This prevents the coupler from sliding forwards and backwards in the box:

Kadee coupler modifications.

This means my couplers do not automatically centre. But that’s fine. With all track a reasonable reach from the front edge of the layout, I can manually line up knuckles before coupling – something that brakemen have to do on real railways on occasion. The extra time to line up couplers represents the time a brakeman would spend visually checking the alignment, pulling the pin, etc.

4 thoughts on “Tuning couplers

    • Hi Gene:

      I’ve had a lot of experience with the couplers from Sergent Engineering. When I started working in On2, I used Frank’s S scale white metal kits – and then switched to the HO die cast couplers. Sharp-eyed readers will spot the die cast couplers on the fronts of these two Forneys.

      The HO die cast couplers were fantastic on my On2 equipment. If one is manually uncoupling (e.g.: using a pick or wand instead of relying on between-the-rails magnets) then the Sergent solution, using a steel ball in the coupler and a magnetic wand, is the best I’ve ever experienced. And I am using manual uncoupling – I’ve cut the pins off all my Kadees.

      Based on my experience, I would definitely consider switching to Sergent couplers if Frank produces the S scale couplers in die cast. The white metal versions looked great but I could never get them to work properly. It was not an issue with the couplers, but with my ability to assemble them.

      I’ve read on the S Scale Yahoo Group that Frank is considering doing the S scale couplers in die cast. But I note that he has no S scale products listed on his web site these days, and I expect all his energies are being put – wisely – to introducing more products for the much larger HO market.

      Thanks for asking – it’s a good question.

    • Hi Michael:

      The projections work with the spring to centre the couplers. If you don’t remove them, when you replace the spring with a piece of styrene the coupler will no longer swing side to side.


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