Try an overshank coupler? Try the centershank first: #38. Any reason you chose to put scale couplers on a BB? A regular #148 whisker coupler in a snap together coupler box would have been way easier.
Kadee now makes snap together coupler boxes and whisker spring couplers that obviate the need for those whacky hairsprings (Kadee calls them torsion springs). Never again say I.
#252 is the snap together version of the #233 you fitted. Kadee has not fully amended their conversion charts to include the whisker coupler versions. You kind of have to know which whisker and snap together gearboxes are the same geometry as the listed recommended conversions. Basically, the traditional brass spring (either the #5 style box spring or the weird and mind blowingly badly conceived hairsprings you had so much fun with, as did I fitting same to a Bachmann Spectrum FM H16 44 pair of locomotives) has been or will shortly be replaced by the steel wire whisker spring couplers which work better and are far easier to instsll.
I have not looked at Kadee conversion site to see if a whisker coupler and snap gearbox are available for your application. Whoops, just did, the #37 is undershank which explains your problem (Even though Kadee recommends that one for your application):
https://www.kadee.com/documents/coupler_handout.pdf
https://www.kadee.com/documents/coupler_primer_handout_new.pdf
Some Athearn models work better with Bachmann EZ Mate II couplers with their thinner shanks. These also come in center shank, under or over as well as short, medium and long.
In the past I have reduced the thickness of the coupler shank by filing the appropriate amount of material off the bottom of the coupler and then installing it with a shim on top of the same thickness as the amount of material removed.
If your coupler is too low, remove the material from the top of the shank and place the shim underneath.
Grizlump (grouch German)
and thank you for your replies. The reason I fitted #37’s is because they are what the Kadee website & download states to use. The instructions and diagram are quite precise and the T-shape (as shown) is an exact match for the Chassis die-cast on my model.
Possibly, the Kadee info is incorrect or intended for a slightly different version? If push comes to shove, I will file the chassis down or try a different combination.
However, as stated this was my first venture and having got a bit of experience and looked at all the different diagrams that were enclosed with the instructions, I am confident that I can make an informed choice, for my next purchase.
I.e. I will obtain a multi-pack of #148’s. I have followed threads about KD’s for sometime now. The Whisker design seems much more suitable.
Thanks again, regards Paul
Since the underset coupler sits too high a I highly recommend against filing anything. You actually want a centerset coupler if it will work at correct height. Under and overset couplers are made in order to allow you to adjust for a particular chassis height. Sounds like your issue is just the wrong type of coupler for your particular locomotive. Kadee publishes the standard conversions for unmodified models. But they make three “sets” of couplers each in three shank lengths (9 variations) for each coupler they make and that’s for this purpose.
I ran into the same thing when converting Athearn BB GP38-2, GP40-2, and GP50. It’s the design of the frame. The problem is, the truck bolster is too high. There have been several articles written about lowering the Athearn truck height, but I usually filed the coupler mounting pad, drilled a hole, used a 2-56 tap and screw, and screwed the coupler box to the thinned pad.
Or, you could cut the frame pads off and body mount the coupler.
If the truck bolster is too high, thus raising a body mount coupler, then you’d just shim down the coupler mount, no? Filing anything off under the coupler mount would just compound the problem. Or am I not understanding the geometry again?
Bolster height won’t affect truck mounted coupler height.
If the underset coupler is too high then switching to a centerset should lower the knuckle by enough to line things up.
On this particular frame, the coupler mounts on TOP of the pad. This makes all the normal solutions backwards.
Kind of weird!
Here is a pic of a Athearn GP40-2 frame showing the pad…
As far as correcting the Athearn truck height, here are a couple of photos of a how-to that I posted on the old Atlas board around 11 years ago…
That part is now clear. You’re raising the axles relative to the chassis which holds the coupler mounting pads. Thus the coupler mounting pads drop as the axles ride higher into the truck.
You mentioned a second method. How would you lower coupler knuckles by filing the coupler pads? I’m not following the geometry there,
Thanks, that explains my failure to understand. I just fit new #148 Kadees to a BB F7 without difficulty. No filing required. Different chassis no doubt.
First you must understand that our coupler conversions are base on the single model we have on hand and we found that many Athearn locomotives and rolling stock had many coupler height differences even in the same production run. So we list a coupler recommendation on the actual model we have which could differ from the same model you have.
Updating our older conversions is not a very high priority right now.
A #37 is a medium underset coupler that raises the coupler head, a #32 is an overset coupler that lowers the coupler, and the #38 is the centerset.
Each offset coupler is .050" higher or lower than a centerset coupler, the thickness of the coupler shank.
As previously mentioned you can relpace any 30 series coupler with a combination of a #252 draft gear box and a whisker coupler. NOTE that the last digit in each series are the same configuration. So a #37 is the same as a #147, #38 the same as a #148 and so on.
I do think we’ll make a standard package of #252 boxes and whisker couplers.
Sam Clarke, R&D Kadee Quality Products.
You publish enough information online about your array of couplers and boxes to allow a hobbyist to find what we need. Some combinations of couplers and boxes can take a while to deduce but generally speaking it’s all there somewhere.
Not sure what we hobbyists with a penchant for acquiring older models would do without the resources we have available to us from Kadee.
Frankly, I pretty much upgrade many brand new models with Kadees.
Thanks from all of us.
Back in the day when these where the best engines and only more modern EMD’s on the market(other than the Roco/Atlas or brass), we would grind down the mounting pad with a milling bit in the dremel motor tool. Then drill and tap the hole to 2-56. After slightly shortening a Kaydee #5 box, you would test mount the coupler and check it with the Kaydee coupler height gauge. This also helps set the trip pin height if your keeping that feature for its remote uncoupling abilities. Back then, Kaydee was all we had, #5 was the go to coupler, no wisker spring options back when these engines were first on the market. Doing the couplers was part of the process of also hard wiring the trucks to the motor, tuning the trucks to run quieter, and redoing the headlight to light up the lenses instead of the whole darn cab. Even a preteen with a summer job cutting grass could afford these when they were new. Cant do that as easilly now. As also mentioned, you can cut off the pads and build up new ones that are attached to the body itself. I never messed with lowering the truck bolster height, If it want that much of a difference, I will buy brass or a more recent model. Mike
Never understood how this was supposed to work.
Looks like you have to remove the shell to install the coupler. If you permanently install a plow it becomes impossible.
The shell does need to come off to mount the coupler. I have body mounted the front coupler if a snow plow is installed. Also, you will probably remove the trip pin when a plow is used, then you can easily remove the shell by just sliding the coupler out while still attached to the frame.