Confused About Kato SD70MAC Coupler Conversion

[freescopesdad]

I have the latest release Kato SD70MAC (Alaska RR) on pre-order, due in October. MT specifies the 2004 coupler for this conversion in their chart, as does my dealer, but numerous sources have concluded that the coupler height is too high. Both YouTube and various forums recommend a range of solutions, 1015, 2003 in particular, with varying installation methods and minor trimming of the pilot box. I've also seen postings alluding that Kato is (was) aware of the issue, but not sure if they or MTL have made any modifications to the mounting geometry. I guess I can buy a pair of each and see which one works best, or perhaps the experts here have already solved this riddle and can save me the price of dinner (which I will donate to The Railwire). Thanks.

[peteski]

I seem to have vague recollection that the solution involved mixing/matching the coupler box from one type of coupler and the coupler itself from another set. Hopefully someone will have more specific info.

[Sokramiketes]

On my last run Alaska units I slide in stock 1015 style couplers. 

[martin station]

 It's been awhile but I seem to remember putting a 2004 coupler in a 1015 coupler box. I seem to recall that I did that on advice I got from someone here. Using the 1015 box kept me from having to trim the lower corners of the opening on pilot, then I just reused the Kato coupler clip that held it in place.
Ralph

[Albert in N]

   First, I own at least five various Kato SD-70 M (& Mac) N scale locomotives.  The recent ones (as well as other Kato N units) require a lot of filing, fitting, and use of MTL screw mounting with various results.  I have not tried mounting coupler components into a different MTL coupler box, but understand that is the preferred method.  After fussing with my SP SD70M set, I tried MTL 905 Z and Nn3 scale couplers.  They are assembled with two pair per blister pack.  These readily replace the Kato couplers using the original Kato coupler clip.  It works for me!  My poor old Fujifilm digital camera is showing its age like me, but a picture is better than many words.






BN MAC has Katos, SP Ms have MTL 905s, UP Ms have MTL 1015-1s

[jagged ben]

It's been awhile but I seem to remember putting a 2004 coupler in a 1015 coupler box. I seem to recall that I did that on advice I got from someone here. Using the 1015 box kept me from having to trim the lower corners of the opening on pilot, then I just reused the Kato coupler clip that held it in place.
Ralph

That's the right idea but you got it backwards. It's a 1015 in a 2004 box.  As attested to by all the extra 2004 shanks and 1015 boxes in my coupler parts box.

[samusi01]

70MACs: all of mine are using 2003 - more or less the 1015 in a 2004 box, but the 2004 box requires less work; I weld my 2003 boxes with a soldering iron and then drill out the box with (I think) a #56 as the lid has no hole. Pile of work for an install but it reduces the number of odd spare parts laying around.

[freescopesdad]

samusi01, that's certainly not the answer I was looking for...   

[peteski]

samusi01, that's certainly not the answer I was looking for...   

At least there are multiple options available, with different  costs and difficulty levels.  That's always better than no options. 

[samusi01]

that's certainly not the answer I was looking for...

no reason to do it the easy way when you can do it the hard and frustrating way. explains my general approach to modeling.

[jagged ben]

no reason to do it the easy way when you can do it the hard and frustrating way. explains my general approach to modeling.

   Adds to your sense of accomplishment.

[martin station]

That's the right idea but you got it backwards. It's a 1015 in a 2004 box.  As attested to by all the extra 2004 shanks and 1015 boxes in my coupler parts box.

Jagged Ben, Thank you! I would write that down so I wouldn't forget it the next time....but then I would just forget where I put it!!
Thanks, Ralph

[robert3985]

EDIT:  It's been pointed out that I'm "way off the mark" with the spacer/drill & tap explanation for recent Kato modern diesel models, and that the Kato coupler box is actually "too low" as opposed to the OP's description.  Okee Dokie...I haven't done any coupler conversions on "recent" Kato engines other than steam engines, so my recommendation is to go with Z-scale couplers and save some money by getting 903's and putting them together yourself.  A coupler pocket that's too high is much easier to fix than one that's too low.  Also, I've got several engines that have 00-90 coupler mounting screws that come up through the end platforms, where they get cut off and filed so that it's virtually invisible after a bit of paint.  I don't consider this to be "destroying" platform details, although not an improvement. Several of my cabooses suffer from protruding coupler mounting screws on their end platforms too, that get flush cut and filed. Looks like @jagged ben 's got the answer if you want to stick with N-scale couplers!

What's the big deal?  A coupler pocket that's too high is easy-peasy to fix.

First, run the engine up to your trusty MTL coupler height gauge and measure how high it is with your digital calipers you bought for $20 from Harbor Freight.

Second, after you get your measurement of how much the coupler needs to be lowered, find a piece of Styrene that's within a couple of thou of that measurement and cut it to size, drill a clearance hole in it at the appropriate location (to clear a 00-90 screw).

Third, drill and tap (if you need to) a mounting hole in the correct location on the top of the coupler opening, and...

Fourth, mount your coupler with the included 00-90 screw.

You might have to cut & trim a bit if you want to retain the stock Kato mounting protocol.

You'll probably have to paint at least the part of the Styrene spacer piece that shows above the coupler box with an appropriate color, but that should fix the problem.

I've had to do this to any number of my locomotives over the years when converting them to MTL couplers, and it doesn't take long nor is it complicated.

Photo (1) - Showing spacer between coupler pocket and top of coupler opening on one of my old Life-Like switchers when I had to lower the new MTL coupler to the correct height:


However, I like the idea of replacing the Kato couplers with MTL Z-scale couplers, which is what I did for a long time until I went with modified MTL True Scale couplers in 3D printed coupler pockets. MTL Z-scale couplers work just fine with most other knuckle couplers derived from the original MTL N-scale design, and are strong enough for trains up to at least 60 cars, which is where my testing stopped. As an added benefit, the MTL Z-scale couplers look exponentially better than MTL regular N-scale couplers since they're only a few thousandths off of being the correct size for a scaled-down prototype coupler.

Cheerio!
Bob Gilmore

[jwaldo]

What's the big deal?  A coupler pocket that's too high is easy-peasy to fix.

First, run the engine up to your trusty MTL coupler height gauge and measure how high it is with your digital calipers you bought for $20 from Harbor Freight.

Second, after you get your measurement of how much the coupler needs to be lowered, find a piece of Styrene that's within a couple of thou of that measurement and cut it to size, drill a clearance hole in it at the appropriate location (to clear a 00-90 screw).

Third, drill and tap (if you need to) a mounting hole in the correct location on the top of the coupler opening, and...

Fourth, mount your coupler with the included 00-90 screw.

You might have to cut & trim a bit if you want to retain the stock Kato mounting protocol.

You'll probably have to paint at least the part of the Styrene spacer piece that shows above the coupler box with an appropriate color, but that should fix the problem.

I've had to do this to any number of my locomotives over the years when converting them to MTL couplers, and it doesn't take long nor is it complicated.

Photo (1) - Showing spacer between coupler pocket and top of coupler opening on one of my old Life-Like switchers when I had to lower the new MTL coupler to the correct height:


However, I like the idea of replacing the Kato couplers with MTL Z-scale couplers, which is what I did for a long time until I went with modified MTL True Scale couplers in 3D printed coupler pockets. MTL Z-scale couplers work just fine with most other knuckle couplers derived from the original MTL N-scale design, and are strong enough for trains up to at least 60 cars, which is where my testing stopped. As an added benefit, the MTL Z-scale couplers look exponentially better than MTL regular N-scale couplers since they're only a few thousandths off of being the correct size for a scaled-down prototype coupler.

Cheerio!
Bob Gilmore

At the risk of derailing the topic, I want to know more about the rolled-up cover on top of the nose grille. It looks great, and I'm pretty sure LL never included it!

As to the actual topic I'm going to second MT Z scale couplers. Their thin boxes mean they can be easily shimmed to move the coupler up or down to the right height, they look more prototypical than the N scale couplers, and they couple just fine to all but the chunkiest N scale couplers (looking at you, Bachmann). They also have an assemble-it-yourself version that costs significantly less, if you have the right combination of finesse and masochism to undertake that kind of micro-surgery.

[jagged ben]

What's the big deal?  A coupler pocket that's too high is easy-peasy to fix.

....

That's all great advice for some other model, but just to be clear it's actually way off the mark for recent Kato models in question.  A key point being that the Kato coupler opening is actually a bit too low, not high, for any MT coupler other than the aforementioned 2003 or 1015 in a 2004 box.  (It's only high for the 'underslung' 2004.)  The beauty of the solutions offered is they produce a coupler conversion at the right height without needing to take a knife or a tap to anything; you reuse the Kato coupler clip.  It's a 5 minute conversion per coupler (if you know now to assemble any MT coupler) for an extra $4.50 in MT parts.  My time is worth a lot more than that. 

We share tips like this on this forum to save people time and grief.  In this case the solutions already given are the most helpful to the OP.