Author Topic: Scale Trains SD40-2 Fuel Tank height fix?..  (Read 2773 times)

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GM50 4164

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #30 on: March 24, 2024, 05:01:10 PM »
+1
Seems like most are limited to sound equipped versions. The DC version doesnt have speakers, so no push down from something thats not there.
Out of the 4 I received, all DCC ready, 2 had issues with the fuel tanks. Both have been resolved while modifying the fuel tank to carry more weight.


Benjamin H

turbowhiz

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #31 on: March 24, 2024, 10:54:58 PM »
+6
https://www.scaletrains.com/blog/time-to-model-correcting-fuel-tank.html

Here's ScaleTrains offical fix page. Hopefully next run the modify the frames themselves.

Absolutely insane to suggest filing down the inner section of a sound equipped model without removing the speaker... Note the how the contacts in my pre-modified example sit below the frame section before any material removal. I don't see how you could effectively protect the speaker with tape in this case.



If you want to properly fix the fuel tank height for correct prototypical look, you do need to remove a fair bit of material from this section (.5mm+ to be exact). I would very very very strongly recommend entirely disassembling the model before attempting any filing to this section, sound or not. You will get filings into all sorts of places you'd rather not, along with very easily risk damaging things. Its just not worth a shortcut.

If there is interest in a more complete how to, I'll put together the post. I have all the backing pictures, but that said, its not really anything too complex.




robert3985

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #32 on: March 26, 2024, 10:15:31 PM »
0
There's no way I could've performed any of their fixes since I absolutely could not budge those #^#&% screws.

-Mark

Yeah, mine were difficult to get out too.  Consistent pressure on them with the proper sized Phillips Head screwdriver (so as not to strip the Phillips Head) did the trick since I've had to deal with screws and parts attached with both Loctite and canopy cement before, so I thought maybe the constant pressure technique would work on these...and it did. 

They don't "break loose", but just get progressively easier to unscrew after they initially start to turn...sorta like unscrewing the lid from the well-used molasses jar that's been in the cold storage cabinet in the basement...sorta.

They didn't react like Loctite, but like parts I've removed that were glued on with canopy glue...which never "dries" into a rigid adhesive, but remains slightly flexible. 

I don't know exactly what the glue was that was used in their assembly in China, but, it was "like" canopy cement...so, that's what I said it was in my explanation link on how to "fix" the problem.

Cheerio!
Bob Gilmore

learmoia

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #33 on: March 27, 2024, 01:26:30 PM »
+2
I went back and looked at the photos of sample models on the ST website.  All photos clearly show the low/slanted fuel tank issue and none of them/us caught it.
~Ian

tehachapifan

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #34 on: March 27, 2024, 03:59:25 PM »
0
posted in wrong thread, sorry!

DeltaBravo

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #35 on: March 27, 2024, 08:28:05 PM »
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I tried the constant pressure on the screws and one snapped off with half the shaft still in the frame.
David B.
 
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peteski

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #36 on: March 27, 2024, 09:40:22 PM »
0
I tried the constant pressure on the screws and one snapped off with half the shaft still in the frame.

Seems that there is no consistency in the assembly process. Some screws just come out easily, others have flexible compound applied, while others seem to have been "Loctited" with the permanent threadlocker.
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robert3985

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #37 on: March 28, 2024, 10:29:10 AM »
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Seems that there is no consistency in the assembly process. Some screws just come out easily, others have flexible compound applied, while others seem to have been "Loctited" with the permanent threadlocker.

Yup.  Looks that way. Probably not an assembly procedure that's "approved", but a stop-gap measure by a worker or supervisor to keep the line going, with no thought about what's actually causing the screw-setting problem.

Seems like most are limited to sound equipped versions. The DC version doesnt have speakers, so no push down from something thats not there.

Out of the 4 I received, all DCC ready, 2 had issues with the fuel tanks. Both have been resolved while modifying the fuel tank to carry more weight.

The interference on the DCC-sound equipped model I fixed was not from the speaker being improperly positioned, but from a hardened glob of flux/solder residue swiped on the frame/speaker-enclosure from whatever is used to solder the wires to the speaker solder-tabs...really close to one of the speaker solder-tabs.

It would be interesting to know what the problem was and what the "fix" would be to non-DCC versions if the "problem" is the front of the fuel tank dragging, which is what the problem on the sound equipped versions seems to be, added to the fuel tank just being unprototypically too low even when properly installed.  On versions with no speaker installed, there wouldn't be an opportunity for swiping a glob of flux/solder on the frame/speaker-enclosure since there wouldn't be any speaker solder-tabs to solder.

Cheerio!
Bob Gilmore

John

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #38 on: March 28, 2024, 12:39:13 PM »
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Maybe this problem is specific to an individual assembler?

turbowhiz

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #39 on: March 28, 2024, 02:02:02 PM »
+1

It would be interesting to know what the problem was and what the "fix" would be to non-DCC versions if the "problem" is the front of the fuel tank dragging, which is what the problem on the sound equipped versions seems to be, added to the fuel tank just being unprototypically too low even when properly installed.  On versions with no speaker installed, there wouldn't be an opportunity for swiping a glob of flux/solder on the frame/speaker-enclosure since there wouldn't be any speaker solder-tabs to solder.


I suspect why it’s the front of the tank that’s drooping is likely related to the workmanship with respect to the fuel tank filler found in the front of the tank, and its relationship to what seems to be a casting draft found only on the front surface of the inner frame section. Your solder experience is more likely to be a one off then something seen consistently; My example was clean.



The fuel tank filler is just a section glued into the tank. Easily it could be glued just a hair back from the front of the tank, and it will readily interfere with the draft even on a stock frame.

Picture of tank w/filler section removed. Note the loads-o-glue on the front section of the tank used to hold it in:


This draft progressively interferes with the fuel tank filler section. For my tank height modification, I needed to form an equivalent angle of removed material on the fuel tank filler so that the tank fit properly. I also found the filler section just a very tiny bit proud of the tank mount detail, but that doesn’t come into play until you’ve milled the frame for sure.

Picture of draft added to filler section: (weight in this filler section is not stock, I added it)



You don't need to remove the filler section to add the angle to it.. You can file it to shape in place. That said, I wanted to add weight and I also needed to correct its height, so I removed mine. It took a great deal of force to pop it out of the glue, and it launched itself when it finally did break free necessitating a workshop search and find.

GM50 4164

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Re: Scale Trains SD40-2 Fuel Tank height fix?..
« Reply #40 on: April 01, 2024, 03:46:09 PM »
0
I suspect why it’s the front of the tank that’s drooping is likely related to the workmanship with respect to the fuel tank filler found in the front of the tank, and its relationship to what seems to be a casting draft found only on the front surface of the inner frame section. Your solder experience is more likely to be a one off then something seen consistently; My example was clean.



The fuel tank filler is just a section glued into the tank. Easily it could be glued just a hair back from the front of the tank, and it will readily interfere with the draft even on a stock frame.

Picture of tank w/filler section removed. Note the loads-o-glue on the front section of the tank used to hold it in:


This draft progressively interferes with the fuel tank filler section. For my tank height modification, I needed to form an equivalent angle of removed material on the fuel tank filler so that the tank fit properly. I also found the filler section just a very tiny bit proud of the tank mount detail, but that doesn’t come into play until you’ve milled the frame for sure.

Picture of draft added to filler section: (weight in this filler section is not stock, I added it)



You don't need to remove the filler section to add the angle to it.. You can file it to shape in place. That said, I wanted to add weight and I also needed to correct its height, so I removed mine. It took a great deal of force to pop it out of the glue, and it launched itself when it finally did break free necessitating a workshop search and find.
I ended up replacing that small plastic piece with weight like yours as well. I felt I would benefit more by removing the plastic filler altogether. I also filled in the speaker cavity with weight on 2 of my 4 units. The others have sound so just the small place up front was used.

A TCS KA-N1 stay alive can be secured in the nose directly above the front worm gear!


Benjamin H