I don’t have a mill for removing part of the metal chassis for DCC install. What else can I use while preventing metal bits from getting into the trucks?
Remove the trucks. A couple times I have removed the trucks and everything else to grind metal off with a belt sander or cut a small part of with a Dremel and diamond cutoff wheel. Don’t try to cheat. It is not worth it. I never did.
I also did some grinding with a four inch Harbor Freight rotary grinder some years ago.
Choose proper kind of grit and keep a bowl of cool water. Measure often.
Rich
Agree with Rich. If your modifying the frame, you need the bare frame alone, no other parts attached.
I’ve used a hacksaw, and files for bigger pieces, one major overhaul I did required I use my 4" grinder, or it would take forever.
I use a Dremel for small ares.
Mike.
Thanks Rich, I agree, removing the trucks would be most beneficial. I’m not sure how to remove the trucks and hope it is possible without disassembling the drivetrain… Off the internet! 
Even if you had a mill, you would need to strip down to the bare frame.
you can’t remove the metal shavings . You need to wash with soap and water, then blow dry.
What manufacturer of loco are we talking? Right off hand, I don’t know of any that you can remove the truck, without removing the drive shaft, and worm gearing, or whatever drives the truck.
That’s not a big deal.
Mike.
Thanks Mike, you always provide great advice! I’m a mechanical klutz and not sure I want to strip things down the bare frame… The decoder will fit in the space for the current light board so the key decision is where to put the speaker. Milling the frame is one solution but perhaps there are other solutions like a small sugar cube speaker in the cab… I’ll need to check that out as it would simpler and easier.
It is a Life Like P2k GP30. There is a nice diagram on Hoseeker.net on page 2 but I don’t see how the trucks are held in place.
I’d visit a couple local machine shops. If they’re busy and not interested, they will want $75 or $100. If they are sympathetic to model railroading and realize it’s a 10 minute job, it should be a lot less. Bring a kid, if he’s not yours, don’t mention it.
Great suggestion Henry! My kid is 35 and lives 280 miles away so will need to adopt a local kid for the task… Maybe can even get tears if I throw in a ten spot!
Yes, I have stripped it to bare frame. No motor, drive parts at all. Keep all the screws together. They may be Metric and not easy to find locally. Some are tricky. I had to search around but I have been a machine mechanic for fifty or so years.
Rich
Looks like my Proto GP9. #17 covers the worm and clips on to the top of the truck, as I recall. Remove that and the truck just falls out except for any wires, which you are going to replace anyway.
The engine is held in by Athearn type rubber mounts #6, which grip the sides of the engine and have mushroom projections which press fit into the bottom of the chasis.
Pop off the worm gear cover, that’s it. Part #17. Remove the worm gear, becareful of the little thrust washers on each, and the little brass blocks, the truck drops out.
If you coming up with another way to hide the speaker, the milling you need to do is on part #18. There might be enough space for your speaker on top.
The decoder will pug into the board where it show the 8 little pins, after you remove the jumper board.
Mike.
Here is a link to one installation method on the P2k GP30 with several pictures.
http://tcsdcc.com/installation/ho-scale/life-proto-2000-gp30/wdk-kat-3
They used a sound decoder, a stay alive and a large speaker. I’m thinking the decoder could fit where the original light board resides and perhaps a sugar cube could be installed in the cab or over the tab for the front trucks. What do you guys think?
For a sugar cube, you might be able to use the little space on top, behind the board/decoder. That will get the speaker right under the fans, so you can hear it.
Mike.
Sugar cube may also fit between the two pairs of notches on top of the chassis and would put the speaker below the fans. I thought the sound would project well through the openings of the cab (with cab mount) or out through the front truck if mounted on top of the front truck clip. Agree or would it be poor quality sound?
In my GP9 the slot for the circuit board was shorter than the standard drop in replacement boards for factory circuit boards. I put a sugar cube in the cab, because I milled the nose and there still wasn’t room.
Good point Henry, I need to take some measurements to ensure there is sufficient room for the decoder and speaker. Thanks for sharing your experience with the GP9!
Hi,
I just did some decoder and speaker installs in Life-Like SD-7s and a GP-9. Somewhat similar designs. Here’s what you see when you remove the worm cover housing, which also has the fingers that retain the truck to the frame:
L-L_SD-7fw by Edmund, on Flickr
I clean out all the old grease, check the gearing and wheel gauge and run the locomotive on roller-stands to sheck for binding and current draw. This is a good time to put a little light oil on the motor shaft, too.
SD_9-decoder-4 by Edmund, on Flickr
I solder new, extra flexible silicone wire to the truck pickups. Sometimes the old wiring is stiff and/or frayed. For the age of these Life-Like locomotives, they are surprisingly robust and smooth runners. Very low current draw, with a few exceptions, too.
In the case of the SD-9 all I had to do was file away a few mounting bosses that held the old board and the headlight wires. Then I planned out my decoder/speaker/headlight layout:
[url=https://flic.kr/p/2f
Thanks for showing the parts from an actual locomotive, very helpful!