Hi,
I had installed my Kadee uncouplers on top of my ties, as directed by the Kadee instructions, however some of my engines would scrape the bottom of their trucks on the uncouplers (the uncouplers were slightly above the top of the rails). So I cut out the ties and installed the uncoupler on the top of the roadbed. Now the couplers will uncouple the couplers, however the couplers will not move outboard enough to allow me to back the now uncoupled cars without recoupling the couplers. Do I need to shim the uncouplers until they are fluch with the tops of the rails?
Thanks, Hansel
To get the desired uncoupling action without running aground with low-hanging gearbox covers, the top of the Kadee magnet should be even with the top of the rails. Just measure from the bottom of your cut-out ties to the railhead, measure the thickness of the magnet and insert a shim of appropriate thickness (which could simply be a thick bead of grey latex caulk.)
The Kadee magnets are about .110" thick, so a top-of-the-ties installation would put them very slightly above the railheads on Code 100 track, and .027" (more than RP-25 flange height) above code 83 railheads.
My own preference is for under-the-tie magnets, which don't require any special track modifications and can be put in places where between-the-rails magnets cannot be used. (One club I belonged to had an uncoupling magnet under the middle of a double slip switch!)
Chuck (modeling Central Japan in September, 1964)