What do you have to do to install a Decoder in an older split chassis British Loco (Bachman)

Hi David,

No more difficult than a regular chassis (I've done 20 or so split chassis conversions). If the axles and gears are split don't bother. Easy to check. Hold each wheel in one hand, if the opposite wheel rotates or moves using your fingers it's a goner unless the correct axles are available. Could be the reason it waddles. My advice here would be to stop the conversion unless the client wants to come up with the spares and/or a new chassis/axles/wheels or wants you to do it.

Older Bachmann models often have a different stub-axle/gear design to the newer ones, replacement gears often do not fit the old stub axles, which means new axles and wheels. Voice of bitter experience here- I've had to bin the innards of 6 older Bachmann split chassis models because of this issue.

The other thing to look out for are the plastic spacer nuts that keep the two halves isolated. There are 3 (one top, one at each end on the bottom). On older models they split. This is a part common with Bachmann USA, they normally have spares. Don't loose those 2 white plastic spacers that go between the chassis halves.

Wire the orange and grey wires to the terminals using heat shrink to cover. Coat the sides of the terminal pockets in the chassis halves with 2-part epoxy or liquid insulation. Belt and braces approach.

Drill and tap a hole in the top of each chassis where there is enough meat for the screw. I use 2/56 brass machine screws file to the correct length. Top of the side tanks is a good spot. Recess the hole slightly and or file the top of the screw so it doesn't rub on the body. Solder the red and black wires to terminal washers and secure.

I normally use a female plug wire harness if space permits. An N-scale decoder works with this locomotive (use the smallest you can). A decoder with a JST plug also allows soldering without connecting the decoder.

That's it, apart from finding some space for the decoder/speaker. Cab is the logical spot, although you can mill the space between the chassis in the boiler area and slot the decoder in there. Wouldn't recommend it though.That half-bodied crew normally hide a small decoder sitting between them. You may have to mill a bit of metal off the top of the chassis in the cab. You should be able to get a small round or rectangular speaker in the smoke box or bunker, as there is enough meat there for some milling. Bunker is the easiest. Or just sit it on top of the decoder. Hide with a strip of grey craft paper each side.

Or as John said, a decent chassis is the best solution.

Nigel

I think Bachmann have converted all their previous split chassis models to a proper chassis now.  Most recently the Ivatt 2-6-2T. The Mainline axles had cylindrical bosses IIRC, Bachmann's were square to prevent rotation which is fine as long as they're not cracked. 

Quite right John. I went through 4 Bachmann Manors and an early 57xx (plus that LMS 4-6-0 something), all had split axles, and waddled along like geese. I did get a set of replacement axle holders (round axle holes) for the Manor, different diameter to the stub axles (too big). I then got a new set of wheels - square axles. To match the latest axle holders. Which were not available. Definitely a "well I never" moment. Enough already! Life's too short!

Bottom line - Bachmann split axle holders? Where's the barge-pole? That said, Bachmann USA axle holders seem to be made of sterner stuff.

Nigel

I've said before that you get to a certain age and time takes on a whole different value.  When you're 30 it's fine to faff about with lost causes.  Now, though, I prefer to tackle things where I have a chance of winning.

Interesting that US models use a similar split chassis design. So why on earth couldn't Bachmann use the same material?

John

Having done a few split chassis conversions myself, the easiest were probably the two Lord Nelsons; they both had the extra pickups arranged from their front bogies, which meant it was very easy to solder the decoder track wires to those contact points on the chassis.

The Ivatt 2-6-2T was also in the same category, but the triangular valve gear retaining bracket required some care.

The 57XX pannier still waddles, but runs smoothly enough, and the 04 diesel shunter took a bit of adjustment before it ran smoothly.

I'm not sure I would convert any more split chassis, although I did look at my early BR Standard 4MT, but decided it was too rough a runner to make it worthwhile.

The conversions are not really difficult. The hardest bit is finding somewhere discrete to hide the decoder. Newer, non-split chassis from Bachmann are still better runners, though.

p.s. If you wade through my workbench topic, i did a blow by blow account of one of the Lord Nelson conversions. I am at work so don't have time right now, but I'll edit this and post a direct link to that thread later on.

Better to take the pick-up directly from the chassis rather than relying on those fragile front bogie wheels wipers, and wires that have to move with the bogie (as I found out with Bachmann's City of Truro and Hornby's Dean Single, neither of which are split chassis but being 4-4-0 and 4-2-2 the manufacturers felt obliged to maximize pick-ups, WOT with live frogs). I'm not sure I would want to rely on electrical pick-up from a bogie that bounces around, even with additional weight.

The driving wheels and stub axles are all live with a split chassis, if you have a look at the inside of the axle slot you'll see it's copper lined so that it acts as a bearing. If the copper is worn and the axles are riding on ZAMAC it's perhaps a tad too old for this new fangled DCC stuff….

Drilling and tapping 2 holes is 5 minutes work and can be done with an electric hand drill (the hole, not the tapping). If you don't fancy tapping, a self-threading steel screw works fine (once, keep taking it out and screwing it back in will strip the threads, ZAMAC is a friable alloy).

Nigel

Nigel, I think you might have misunderstood: the front bogie wires on the LN and Ivatt locos are soldered to copper tags that are screwed into the split chassis. Soldering to the tags makes it easy to link the decoder to the chassis, as well as the bogie. It removes the need to drill and tap holes.

Hi Jeff,

I understood how it was working from our previous discussion. Your method is fine for a 4-6-0 or 4-6-2 that's already been wired with solder pads attached to the split chassis. My comment about pick-up from the bogie is that it's unreliable. My objection? Your method won't work without those convenient solder pads. It certainly won't work with a pre-DCC 0-6-0 and drilling and tapping really is the only reliable method.

Trying to put solder pads on ZAMAC is not easy, and requires special aluminum and zinc-rich solder and a witches-brew flux that needs a respirator and positive ventilation to get rid of the fumes. I've done it (once, I have the gear), but never again. Using regular solder/flux will normally give a cold joint at best, normally it won't work. If it "seems" to work it's because the joint adhered to the very thin layer of copper (less than 50 µm) that the ZAMAC is coated with (those bearing surfaces, it's easier to coat the whole chassis than just the bearing surfaces). It will fail very quickly.

The other concern I have with a live bogie is that a wheel bouncing around over turnouts and frogs can cause a short where a dead one wouldn't. Keep the wheels dead and most of that goes away, even with a bogie derailment where the wheels touch the opposite rail. One of the reasons I ended up getting rid of the pick-ups and having a dead bogie with the City and the Dean Single. Getting a spark from a DC setup versus shutting down a block (and other locomotives) with DCC…

I would still drill and tap even with solder pads conveniently available, it's a lot more permanent and robust and carries zero risk of a cold solder joint. Minimal investment - $8.50 for a 2/56 drill and tap set and $5.00 for cutting oil - and it's dead easy. 

Nigel