Large Scale Central

Problem: Tight back to back gauge on Aristo locos

Problem Solving
#1

I thought I’d “launch” the forum, ha ha.

This is a typical problem, the back to back gauge is very narrow on “new” Aristo locos. I will confine myself to the Aristo locomotives using the “new” “prime mover” gearbox. This is the “modular” system where the gearbox is totally enclosed, with hex recesses on each end for the drive and 2 metal half axles affixed to the center plastic worm gear.

I’ve never seen one out of the box with the back to back too wide. The wheels have a tapered opening for the axle shafts, and the ends of the axle have a matching taper.

The problem here is how to space the wheels out further.

  1. Shim the wheel.

One way is to try a thin shim on the end of the axle between the axle and the wheel. There is a common problem with wheels slipping on the axles already, and Aristo often puts Loctite red here, so I think this is a poor solution. Also unless you can make a “perfect” shim, you will probably get more wheel “wobble” / runout.

If you want to try this, try making a pie-shaped shim, then cutting the tip off. This should give you a good start at covering the end of the axle well.

I would recommend “lapping” the wheel to the axles first, to improve the fit. I use medium valve lapping compound.

  1. Remove material from the back side of the wheel.

This is actually pretty simple and easy. You remove the wheel and put it in a lathe (oops you need a lathe buddy), and remove material from the backside of the wheel. The upside is the ease to do this. The downside, besides needing a lathe, is that Aristo wheels are steel, and you will have turned off the plating. It’s not a big deal since it’s on the backside, and the plating wears off the tread anyway.

  1. Shim the half axle out.

This is the most elegant way, but the most time consuming, and you have to buy shims. Outback turnouts in Australia makes shims (I believe he still has them) or you can make your own shims. You take the gearboxes out, unscrew one half axle from the worm gear, put a shim in place and put it back together. The downside is that you have to remove the gearboxes and pull them apart. The upside is that everything will still run true and you do not need a lathe.

Well, that’s my problem solving info I have discovered when I started figuring out why my locos had so much trouble at switches and picking points, etc.

Regards, Greg

Building a 1:20 Mikado
#2

Same as you Greg. I got so peeved on how Aristo quality was on there wheel. My Pacific is an older run and I rebuilt it about 3 times now…Bushing wore out and etc… but the worst problem was the darn drive axles… Either to wide on gage or to narrow on gage… I even tried to shim the wheels to the axle if to narrow…Then the screw would work out and quarter would get out. I Findley took mine apart again and I knocked out the pin in the center plastic shaft coupling. then slotted both pin holes on the plastic housing… put a little J B weld on shaft and press wheel and shaft back in. Insert pin before it set up. ck the gage and quarter align. Findley got it right and run great now thru all Switches and tracks Now not going down the track side ways… hahahaha. With like you … No lathe so had to punt. Good post Greg…

#3

I cheated; I didn’t use a lathe. :wink:

I soldered leads from my power supply to the back of the motor, then clamped the block on it’s side in my vise. I used a Dremel tool with a grinding wheel as well as a file - while the wheels were going. It’s not quick, and the screws keep coming loose, but eventually, they’re ground down enough.

And, while I was grinding the backs off, I also ground down those HUGE flanges.

My way is not nearly as accurate as a lathe. :smiley:

#4

I would venture that as long as it’s relatively smooth, it will work fine, you’re only using the backsides through switches.

How is it working for you Bruce?

Regards, Greg

#5

Greg, it’s still a project loco. I’ve been working on building a new tender lately, so I haven’t gone back to the drivers. They work fine on my straight test track - but they did that before I ground them down, as well. :smiley:

The Pacific really loses out when I compare it to the quality and detail of my Bachmann Consolidation; I had been prepared for it to be better, just based on all the criticisms of Bachmann than I’ve heard over the years.

I expect it to be a strong puller once I get it modified.

My next trick will be to re-quarter all the drivers. I really wish they had keyed the drivers to make this easier.

#6

I’ve taken most all wheels off my locos and had a buddy of mine that has a lath and turn the back side of the wheels and also trimmed the flanges fo thin them down and reduce the height also. Locos running much better through the turnouts now especially the SD45 and -9s Later RJD

#7

Hi Bruce - Do tell: how’s that Consolidation now, two years later?

#8

John Le Forestier said:
Hi Bruce - Do tell: how’s that Consolidation now, two years later?

I think it turned out rather nicely.

LOTS more here: http://www.largescalecentral.com/LSCForums/viewtopic.php?id=11198

#9

She looks luverly… v admirable TT as well… now back to that B’mann loco, if I may… she still running well?

Woah… I thought we were talking about a Connsy… she lookes more like my old friend Mike now… Good work!
I am most curious about her running characteristics…

#10

Well, in my opinion, the Connie is one of the better deals in 1:20 scale. It has sprung drivers and pulls like a champ. Yes, there is a weakness in the gear strength, but that CAN be fixed. I have a BBT drive in mine and it works great.

#11

Yeah, Bruce… That’s my impression too. Some guys say that B’mann drives have improved; they’re still not good enough. B’mann isn’t the only culprit. Large scale gives you a whole new hobby - taking products apart and making them work!! The BBT replacement drives are great.

Thanks for yr answer - it’s pretty much what I thought you’d say.