NS Heritage SD70ACE DCC Sound Value

[bigreddnz]

Hello there

I have a Bachmann HO SD70ACE DCC Sound Value model in NS Heritage color scheme (Illinois Terminal), on which I need to replace the front truck, as the original truck is defective and derails. As I'm not sure on how to do this, I wonder if there is anyone in the community who would be able to provide me with some guidance as to how to undertake the replacement, without me breaking the model as I don't know what I'm doing.

Specifically:
- changing the sideframes on the truck - the replacement truck has black sideframes but the original model has silver sideframes, so I need to remove the sideframes from the original truck and then fit them to the replacement truck. I've looked at how the sideframes are mounted but I can't see any easy way of removing them - I'm sure there is but I don't want to break them trying to remove them without knowing how.

- removing the body - I can see a couple of small screws on the underside, but if anyone could advise the correct way of removing the body please

- removing the front truck and then fitting the replacement front truck to the loco frame

I'd be most appreciative of any advice and guidance that the community can provide.

Many Thanks
Arthur

[James in FL]

Did you check the exploded view?

https://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_SD70ACe_(DCC_SOUND).pdf

[jonathan]

Arthur,

First, I don't own this locomotive.  However, I have disassembled many, many Bachmann locos. They all seem to have similar construction.  I have studied the diagram.  So... I will offer my two cents, keeping in mind I may be way off base.

The shell:

It appears you will have to remove the couplers, as they are attached to the frame.  Some Bachmann locos will allow you to lift off the shell after the couplers are removed.  If it doesn't release at first, look for a couple of screws under the frame, between the fuel tank and the trucks.  DO NOT remove any screws on the fuel tank.  They have other purposes not associated with removing the shell.

The truck:

The construction reminds me of how the old Athearn diesels used to be made.  There should be a housing/clip over the worm gear, on top of the truck.  Removing that clip usually releases the truck.  ALSO, probably there are two wires, associated with the truck, that are attached to the mother board by two plastic tabs.  Those are pretty easy to pull off. The wires can then be released. Remember how they are oriented, as the new truck will need wires attached in the same way.

The side frames:

In the past, large diesel side frames were press fit onto the truck.  A gentle pressure with a jewelers screwdriver, between the side frame and the drive wheels MAY do the trick.  Look closely. Things may have changed over the years.  Also, the tabs that hold the side frames used to have a bad habit of breaking off pretty easily.

Derailing:

I have a small suspicion, as you disassemble your loco, you may find the reason the original truck is derailing.  Could be as simple as a wire wrapped too tight or the worm clip not seated correctly... something simple like that.

Disclaimer:

Again, I don't have this loco.  However, this is how I would go about trying to take it apart.  

Regards,

Jonathan

[bigreddnz]

Hello Jonathan.

Many thanks for your most thoughtful reply and guidance. I'll give that a go.

[bigreddnz]

Did you check the exploded view?

https://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_SD70ACe_(DCC_SOUND).pdf

Hello James. Yes I did have a look at the exploded view but it didn't really show the best way of dismantling the loco. But thanks for your suggestion.

Cheers
Arthur

[robby]

I'm hoping adding to this thread is ok. I have one of these in Jersey Central which leans a little and rocks when I apply the throttle. I've heard this can be fixed by replacing the worm gear covers. Are the current worm gear covers available on the website a correct fix?

[jward]

Looking at the drawing i am wondering why Bachmann changed the truck mounts. On earlier diesels, there was a bolster above the worm gear that had a screw you could adjust similar to a freight car. The mounting shown in the drawing, while similar to what almost everybody else out there is doing, does not allow you to adjust the rock of the truck like the older ones.