old Bachmann 'blinky' SD40-2 chassis white gear replacement ?

[scaro]

Hi

Thinking of using this chassis for something in TT because it lines up perfectly with a B-B Baldwin, if you drop the middle axle. And I have four of them! However, these ancient locos feature Bachmann's legendary cracked white gears.

Wondering what people use as replacements, or if there are totally different generic gears available that would mesh well with Bachmann's white gears? Do they conform to any industry standard for gears?

The existing gears that don't have half axles pressed into them seem to be in okay condition.

In my case, the whole front and rear axle on each truck would probably be replaced anyway. I need bigger wheels and Bachmann's 'press-fit' muffs / half axle setup doesn't sound reliable for something of 12mm gauge. 

[randgust]

If the axle spacing for TT works out on an N-scale six-wheel EMD truck - I'd think it would work equally well for a Kato six-axle, or an Atlas.    There was a mid-production Kato that had a gear tower rather than a truck pivot....

http://www.spookshow.net/loco/katosd4x.html

This was the debate that Ron Beardon and I got into building the TP56 Critter, and Ron won with his adaptation using that Kato truck design.   I tried to adapt an old Roco E-unit truck with a tower, it worked, but not as well as his.

You might have four Bachmann's, and that's a pretty good pile of donor parts, but if you're having to nearly scratchbuild anyway, start with the best mechanism stuff you can find.

[mmagliaro]

If you can measure the diameter, bore, number of teeth, and thickness of the gear, you can go to my favorite gear maker in Czech Republic (or Poland... I still cannot actually figure out where they are making and shipping these from) and buy some very nice replacements
at a good price.
(I know I mention them all the time, but people don't seem to know they are there... and no, I don't know these people personally and I'm not getting some sort of "kickback" from this.  It's just that I've ordered gears from them a half dozen times and they always deliver well.

https://shop.kkpmo.com/index.php

[peteski]

if you feel up to it, you can fix them (permanantly).  See https://www.therailwire.net/forum/index.php?topic=49440
I cover 2 ways of doing the repair. The write-up is pretty thorough, but if you have any questions, post them in that thread.

[Albert in N]

Since these dated back to 1986, some may not know about the Bachmann blinking strobe light SD40-2.  This roof strobe blinks going either direction.  Going backward, the rear headlights are fairly decent.  Yet going forward, the light shines through the windshield, but no holes for actual prototype headlight.  Yes, the model sits high and seems toy like, but is fun retro N scale running.  I tried to take a photo of the lighting but difficult.  The second photo dimly shows the strobe.  Since the lighting brightens with track voltage, I could only run it slow or the camera would show a NS black blur.

[ChristianJDavis1]

Does the Spectrum version also develop cracked gears? I just recently acquired one from a collection, and if the gears are good, maybe that would be cheaper than custom gears?

[peteski]

Does the Spectrum version also develop cracked gears? I just recently acquired one from a collection, and if the gears are good, maybe that would be cheaper than custom gears?

Both, the white and the black plastic gears are prone to cracking.  But I recently discovered yet another iteration of Bachmann wheelsets.  Those use black gears, but the metal half-axles at the backs of the wheels are smaller diameter than the original design.  Since now the axle tube of the gear has more "meat" on it, it does not seem to be prone to cracking.  I was going to mention this in my repair thread, but I didn't think there would be much use for that info.

So if your loco has these new wheelsets, those should not be probe to cracking.  And also, not all the older-design gears crack.  The machined metal half-axles were manufactured to very sloppy tolerances. If they are on the smaller side then they will not crack the gears, but it they are on the larger side, they will crack them.

[scaro]

Thanks everyone. Some useful stuff to follow up.

Regards, Ben