ON BB athearn SD40-2 for milwaukee road fuel tank mod?


B

blues90

Member
I have 2 SD40-2's one has the newer frame mount by the couplers and hex drive but is not the newer rtr series. the other is an older model year that had the four pins securing the shell to the frame . On the older one I removed the pins and used the cast metal buffer plates and added a styrene block to it is now mounted by the couplers .

I wanted to shorten the fuel tank to the 16 feet but see that if I do this there will not much frame left so the frame may break .

I thought I could get a later rtr frame but don't know it that will work with the older BB trucks and I don't see any photo's of that frame or trucks .

I already changed the 88" short hood to 81" on the older model .

Does anyone know if I did find the newer rtr frame if the old trucks would fit .

I thought maybe if I either made the tank 16' 6" the frame may be strong enough and if not make 2 U shaped brackets that would screw mount from the bottom of the frame and just fit inside the shell so each bracket would clear the flywheels sort of a version PK2 used as a weight. I would use the U brackets to add strength to the BB frame .

I can't afford a new or used RTR SD40-2 .
 
Hi-

One problem with the older Athearn BB locos is the frame-it's not as solid as it looks. Then, when you start modifying it, its problems start to show. I have an Athearn frame that came in a deal-the frame came busted and I have not been able to put it back together successfully.

The way I see it, you have a couple of choices. The easiest is to do nothing and just live with it. The second is to make a slightly different modification to it. What I am proposing is that you don't try to cut the tank to the correct length, just shorten it enough to make it noticeable that it's a shorter tank. Perhaps just take off a scale 3 feet on each side of the tank?

There is always fabricating a new frame from brass; getting a junk Athearn SD frame and modifying that tank to the correct length after removing from the frame. Then attach the modified tank to the new frame.

I used to model the MILW and never got an Athearn BB SD40-2 because of the fuel tank problem.

Photoman475
 
Aren't all the frames even Kato made of the same sort of cast metal as Athearn ? I do have an extra SD40-2 frame sitting here I can use and see what happens . I recall once I got two SD40 T2 BB and they have the same frame as the 40-2 , one was broken and they gave me another frame and I bought an extra one. The BB SD40-2 frame is made similar to the GP38-2 and they seemed to drop the motor deeper into the frame compared to the older frames . I suppose this was needed to fit the newer scale width hoods.
 
What about splicing the frames at the breaks using brass angle screwed to the ends of the cast metal parts? I used Athearn BB Alco PA frames for some Bachman E7A bodies that I wanted to run better. I simply cut the frame at one point and used brass angle screwed to the stubs of the die cast frames. Where necessary, I filed/ground one leg of the angle flush with the frame. (I extened the drive shaft from the motor to the gear tower of the truck. Since the Alco trucks have drop equalizers an the EMD trucks do not, I simply painted the drop equalizers "out" with Grimy Black paint. Just a thought...
 
I've never tried the brass angle and screw method. What size screws did you use, and how well has the frame held up on the reworked Es?

As to Kato locos, I have an Atlas which may have been made by Kato back in the 1980s. I would not dare to guess about what current production Katos have. They are way too expensive for this modeler's budget!

Photoman475
 
photoman475 said:
I've never tried the brass angle and screw method. What size screws did you use, and how well has the frame held up on the reworked Es?

As to Kato locos, I have an Atlas which may have been made by Kato back in the 1980s. I would not dare to guess about what current production Katos have. They are way too expensive for this modeler's budget!



Photoman475
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I have extended athearn F7 frames to make FP7's and did a similar thing . I used square brass tubing and cut the frame so enough of the frame rails where left in front of the fuel tank . I then filed the frame ends on both sections so they would fit snug in the square brass tubing ie so the brass fit flush on the sides and bottom of the athearn frame so the shell would fit flush to the frame rails then once it was square I used epoxy to glue the brass to the frame and it's held up for over 20 years. This would be similar to the PA frames but on an athearn SD40-2 frame which seem to break right at the fuel tank is an entirely different frame , you have the flywheel at each end right there and maybe just enough room under the flywheel to fit a flat brass sheet about 5/16" wide and 7/8" long and as thick as possible so it clears the flywheel and use 4 screws , 2 at each end drilled and tapped into the frame looks like there is enough room for 2-56 screws if counter sunk or go down to the next smaller size . I would first see how much room there is under the flywheels for the brass sheet thickness and then remove the paint from that area of the frame and then after the plate is made and frame drilled and tapped all ready to go apply two part epoxy to the frame and screw down the brass plate. I would also apply some epoxy to the area where the break happened for added assurance.

To add , I am with you on the prices of the new Kato and even Athearn units made today . No way I could afford one these days , I had a few PK2's and atlas C424's , RS 11's and RS3 and RS1 , and a kato SD40-2 and NW2 and a few stewart AS16's and F7's and F3's and a U -boat all with kato drives but had to part with them all and at the time I got them they were on sale or in a very old hobby shop where the owner was selling out and I got to know him . Most I paid $50 each for even though they listed at close to $100 each or more.
 
I've done a few MILW frames, at least 3, and just chucked them up in the mill and cut the tank down. It leaves about 3/16" metal connecting the frame to the tank. Not much, but I've never had a problem. I have an extra frame around but the coupler pads are cut off. It is from before I had access to a mill so it's cut with a hack saw. You can have it if you cover shipping, send me a PM for details or if you want a photo.

The trucks from a newer SD40-2 will fit just fine on an older model and vice-versa. I actually prefer the older shells since now they make the pilots a foot thick.
 
kjd said:
I've done a few MILW frames, at least 3, and just chucked them up in the mill and cut the tank down. It leaves about 3/16" metal connecting the frame to the tank. Not much, but I've never had a problem. I have an extra frame around but the coupler pads are cut off. It is from before I had access to a mill so it's cut with a hack saw. You can have it if you cover shipping, send me a PM for details or if you want a photo.

The trucks from a newer SD40-2 will fit just fine on an older model and vice-versa. I actually prefer the older shells since now they make the pilots a foot thick.
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I have one spare BB SD40-2 frame that I got years ago , I do thank you for the offer though. The stock tank is 19 scale feet long and from what I've read the Milw tank is 16 feet I can see where you get the 3/16" which would put the cut just shy of cutting away the area cast into the frame to clear the front fly wheel. I don't have a mill but I use a table top drill press and a 1/4" dia cutting bit to get close then file the rest away .

I would like to see one of the frames you milled just to get a better idea if you have the time .

I didn't know the newer shells like the athearn RTR units had such thick pilots . I've never seen one in person . I do like the fact the new shells have removable short hoods and a frame that is made to use different tanks . It's easier than cutting off the old BB low hood and fitting a cannon 81" short hood. Not that doing so is all that difficult . I have done it many times . I like doing mods .
 
photoman475 said:
I've never tried the brass angle and screw method. What size screws did you use, and how well has the frame held up on the reworked Es?

As to Kato locos, I have an Atlas which may have been made by Kato back in the 1980s. I would not dare to guess about what current production Katos have. They are way too expensive for this modeler's budget!

Photoman475
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I'd have to look, but IIRC, the screws were 2-56 self-tapping screws (used after pilot holes were drilled first). As Blues90 said, 2 screws at each end of the brass angle. I think it's been about 25-30 years (although the units were in storage for at least 20 years, between layouts.) They still hold together fine. I don't intend doing any drop-tests off the top of the layout, of course. If the frames are broken off flush with a larger section, you would probably have to do some engineering, just as Blues90 said. Adding some 2-part epoxy, probably with a metal particle filler wouldn't hurt, if needed. (Devcon Plastic Steel...if it's still available, or somesuch has held the boiler and frame sections of my stretched Mantua steam locomoitves together for about 35 years or so.) Best of luck!
 
Here are a couple photos. One is the pilot of an Atlas GP40 next to an Athearn SD40-2. It is not as bad as I was thinking, it is twice as thick as it should be but the Proto 2000 GP38-2s are really bad. Another is the frame of EMD 6381, a former Milw unit. You can see there isn't much metal left but as long as you don't try to press the old style motor mounts in without supporting it, it should last a long time.

The rest of the 6381 has the right radiator but wrong nose and fixing it will require repainting so it will probably become GATX 6304, another former Milw unit. Lately, the biggest thing that bugs me is the wrong wheelbase and goofy stepwells on the SD40-2. They aren't an easy fix though.
pilots.jpg frame1.jpg
 
kjd said:
Here are a couple photos. One is the pilot of an Atlas GP40 next to an Athearn SD40-2. It is not as bad as I was thinking, it is twice as thick as it should be but the Proto 2000 GP38-2s are really bad. Another is the frame of EMD 6381, a former Milw unit. You can see there isn't much metal left but as long as you don't try to press the old style motor mounts in without supporting it, it should last a long time.

The rest of the 6381 has the right radiator but wrong nose and fixing it will require repainting so it will probably become GATX 6304, another former Milw unit. Lately, the biggest thing that bugs me is the wrong wheelbase and goofy stepwells on the SD40-2. They aren't an easy fix though.
View attachment 42836 View attachment 42837
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I see the opening in the frame where the flywheel cavity cast into the frame . I wonder if it would show much if just part of the bottom section was left , cut as an angle so the opening would not show. Basically at that point not milling the tank flush with the bottom of the frames side rails , leave a slight say 45 degree section of that area from the opening so it still meets the frame rails that reach to the front truck . ie you would not have the opening seen at the front of the fuel tank , instead you would have the opening closed and a slight 45 degree section left maybe 1/8" long between the inside of the frame rails rather than the frame rails being the only support.
 
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