Friday, April 10, 2009

Rollin' on Dubz - rewheeling a DF

DB says:

I got a cryptic email from Mo’druff this morning that started me wondering about wheel sizes on my diesels. I remember the first time I saw a real DF and the wheels looked huge compared to DJs and DGs. Not so on my wee models.

Now we all know that size isn’t everything, thank goodness, but I did buy a pair of Kato SD90MAC bogies a few years back, and for those unfamiliar with the with weird foreign diesels, SD90s have bigger wheels than your average chassis used in NZ120… So as we struggle with tiny-looking bogies in NZ120, could these ones with their larger diameter wheels help us?

My first thought was: could a SD90 bogie fit under a DF with the old SD40-2 sideframes? Unfortunately the bogie bits aren’t swappable in the frame because of gear tower, gearing and sideframe design differences. So I tried putting the SD90 wheelsets into the SD40-2 bogies, and while they seemed to fit, the differences in gear sizes made the wheels difficult to turn. OK, so that won’t work, but the real discovery came in finding that the wheels are mounted on plastic axles that are quite interchangeable.



Thus I could use the entire old SD40-2 mech (including its matching axles and gears) except for some larger diameter chrome-plated spinner rimz. So I swapped the big wheels onto the DF axles, popped them into its bogies (trimming some plastic to give clearance for larger flanges) and made a subtle change for the bigger. If only it was only that easy in real life.

FYI: Wheels seem swappable between Kato and Atlas locos too - with my new DX dash-8 anyway.

4 comments:

Amateur Fettler said...

Looks good....but do you think (for the effort expended) it does actually make an appreciable difference?

Kiwibonds said...

excellent question. To be honest, with *that* DF, I doubt it, but I'm going to reserve judgement.

Ben Scaro said...

Just for information, the same trick can be applied to old Bachmann (pre-Spectrum) diesel trucks.

With these, you can swap out the old 7.47mm wheels (which are a pretty decent size for TT anyway, now I think of it) for 8.1mm wheels as used on the 0-6-0 and 2-6-2 steamers. The next diameter up in Bachmann wheels is 8.8mm but that was a wheel used on the 0-4-0 shifter and docksider and Bachmann haven't made these since 2003. I think you can also add the 7.47mm or 8.1mm wheels to the Spectrum GE units too, if you carefully widen the holes in the truck frame that the wheels sit in.

The SD90MAC exercise does make me wonder what other larger diameter wheels could be used.

I think the 7mm wheels do look better, FWIW.

Motorised Dandruff said...

The big probelm I have with Bachmann is that ,unlike Kato an dAtlas, you can't get the spare parts easily. CF this with Kato where I can get stuff to my door at the arse end of the world in 8-9 days for online ordering.