# Back-to-Back Problem



## sandbarn (Feb 13, 2010)

Well, it’s Thanksgiving morning. The turkey’s in the oven, and will be for the next 4 hours or so. The kids will be here in about 2 hours. 
I find I have time to ask another question I’m sure most of you have already overcome. I have some wheel back-to-back issues with my Bachmann 4-4-0 and with the tender of my Bachmann 2-8-0. I think I could figure out the tender issue but the 4-4-0 is another matter. Both of the problems are with the back-to-back being too narrow. The 4-4-0s problem is with the rear drive axel and I have no idea how to re-space a drive axel







. Actually I’m not too sure about the tender axel either







.
I’ve read you guys talking about having to do this with various pieces of equipment to meet some organizations’ standards (I won’t mention any acronyms







) but I can’t find any reference to the actual nuts and bolts, hands-on method of spreading the wheels without breaking the wheel or axel. Can anyone help?


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## Greg Elmassian (Jan 3, 2008)

For freight, passenger and trailing and leading truck wheelsets:

The nicest way (most controllable and least damaging) is a press:

to increase back to back, put one wheel in a slot and push the axle tip while supporting the back of the wheel. To decrease, put the the outer wheel on top, and press the other wheel closer.

Harbor freight, $60, worth the money. 











Barring that, you can try to do this with a vise, but you need a socket over each wheel and a lot of opening in the vise to decrease back to back. Increasing it means you have to have a way to support just the back of one wheel and press on it's axle tip.

Now, there are some wheelsets that you can actually pull/push on and twist and you can move them. Put a spot of acc on the area that moved so it does not move back on it's own. Also watch that you don't pull the wheel off the central plastic insulator.

On locos, it's variable, depending on how the wheels are attached to an axle. I have some old big haulers up on a shelf I could look at, but there are many more people here with more experience on this particular loco. 

Regards, Greg


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## Ironton (Jan 2, 2008)

If you have a drill press you can use it just like Greg says. Take it slow and careful. That is what I use.

I got a couple of 1-2-3 blocks to use as support. Then I got a small piece of drill rod slightly smaller in diameter that the axles I was working with. To remove the axle or enlarge the back-to-back just slide the two blocks so the wheel set is suspended over the large hole in the middle of the table, or you could use a vise widened to more than the diameter of the wheel and arrange the blocks perpendicular to the jaws if the depth is enough. Then slowly lower the drill rod chucked in the drill press until it touches the axle end. Now press until you reach the desired back to back. To tighten the back-to-back, just set one wheel with the axle in one of the holed in the blocks and push on the opposite wheel with the jaws of the chuck.

Just what I did. Use at your own discretion.


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## sandbarn (Feb 13, 2010)

Rich,
I have a drill press. It's a Shopsmith Mark V thats about 35 years old. It may work but I'm a little concerned about it's stability for percision work. 

Greg,
I went to HF and found the press. Only 47 bucks. Wow, I'm getting deal. But shipping and tax. Yup, 60 was about right. I ordered it even though it wasn't the deal I though it was. But I think I'll get that much use out of it, easy... Bachmann dosen't seem to have any calipers in their factory and since I'm working in 1:20.3 their locos are all I can afford for now (I have dreams of Accucraft).

Hopfully over the weekend someone will chime in about re-gauging drivers.

Thanks to both of you though, your instructions were detailed enough that I'm sure I can do normal axels.


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## John J (Dec 29, 2007)

Or you can build one of these.

This works great on Rolling stock wheels and axels.


First you get a "C" clamp large enough for the wheel set to fit between the jaws. Make sure the meatal piece that is on the end of the screw has a indent in it. ( See Step 2) 











Then with your dremel tool or what ever motorized cutting tool you have Notch the fixed end.

Note the metal cone on the screw end. It has a intent in it.

If you can't find one with the indent you can always drill one after you notch the fixed end. 












This is how you narrow the back to back space. 













This is how you increase the back to back space 












You will notice on the wheel set that one wheel has a insolator bushing. 

That is the wheel that will adjust easiest.

JJ


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## Pete Thornton (Jan 2, 2008)

I have a wheel puller that was designed for O-scale Lionel trains. It isn't big enough for a loco whell, but it handles the small stuff. It's like JJ's C clamp in principal, but it has 3 prongs to go round the backl of the wheel to support it while the center threaded rod pushes on the axle.


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## Greg Elmassian (Jan 3, 2008)

That is just way too cool JJ, great idea! 

Are those your pictures? Can I use them on my site? (giving you credit of course). 


Greg


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## John J (Dec 29, 2007)

Yes Greg.

All that is mine. The Idea, The pictures, everything.

If you want I can send you the pictures.

You may use them on your Website if you wish.

JJ


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## Spule 4 (Jan 2, 2008)

VERY cool JJ!!!! No need to buy the NWSL one! 

EDIT- Bigger wheels = bigger C clamp?


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## East Broad Top (Dec 29, 2007)

I'm a little lower tech--I just hang the wheels in the top of a vice and gently tap the end of the axle to adjust the gauge. Tap the end nearest the wheel that's hanging in the jaws to widen the gauge, or flip the wheel and tap the end farthest to tighten the gauge. 

As for the locomotive drivers, that's a tougher nut to crack. If the wheels are too tight back to back, you may be able to put some kind of shim spacer between the wheel and the end of the axle, but that works only if the wheel itself has some kind of end on it that presses up against the end of the axle. I don't think that's the case with the Bachmann 4-4-0 drivers, I think the wheel has a "D" shaped opening all the way through, and it's held in gauge by the shoulder on the backside of the driver. If that's the case, a small shim at that shoulder should widen the gauge for you. If they're too wide (fairly uncommon, but "if"), then you can file a bit of the end of the axle and flatten a bit more of the axle where it's "D" shaped so the wheels can squeeze tighter together. 

Later, 

K


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## Greg Elmassian (Jan 3, 2008)

I would love to JJ, please send highest resolution you have. 

A simple, effective way that everyone can afford. 

Regards, Greg


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## Totalwrecker (Feb 26, 2009)

Posted By John J on 26 Nov 2010 09:30 AM 
Yes Greg.

All that is mine. The Idea, The pictures, everything.

If you want I can send you the pictures.

You may use them on your Website if you wish.

JJ 
Dang JJ, ya shoulda sent that to GR for their handy tips reward.

This is a great solution, I was on the look out for a big old vice, but don't have much space for one. 
Your device can be used at the bench.
Great!

Thanks very much.
John


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## John J (Dec 29, 2007)

Posted By Greg Elmassian on 26 Nov 2010 09:41 AM 
I would love to JJ, please send highest resolution you have. 

A simple, effective way that everyone can afford. 

Regards, Greg 
I will have to re take the pictures.

JJ


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## John J (Dec 29, 2007)

Posted By Totalwrecker on 26 Nov 2010 11:19 AM 
Posted By John J on 26 Nov 2010 09:30 AM 
Yes Greg.

All that is mine. The Idea, The pictures, everything.

If you want I can send you the pictures.

You may use them on your Website if you wish.

JJ 
Dang JJ, ya shoulda sent that to GR for their handy tips reward.

This is a great solution, I was on the look out for a big old vice, but don't have much space for one. 
Your device can be used at the bench.
Great!

Thanks very much.
John



What the C clamp is sitting in for the taking of pictures is a PAN A VISE. The sucktion cup vise that is suppose to stick to smooth surfaces. 

I think now that I have posted it here GRM will not want it. ( It has been posted several times.)


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## Totalwrecker (Feb 26, 2009)

Yeah that's why I used past tense, once here it's been open sourced. 

I chose the Pan o vice with the screw base.... my work bench surfaces were never that smooth (for suction) 

But thanks for posting it again for this slow guy! 

John


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## Greg Elmassian (Jan 3, 2008)

Like the Panavise too, suction base came loose too often, clamp base did not fit everything, they make a really nice low profile weighted base that now is my favorite. 

They might want JJ's idea for their "tips" column though: 

*http://grw.trains.com/Product%20and...olumn.aspx* 


Regards, Greg


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## sandbarn (Feb 13, 2010)

Well guys I got the press that Greg recommended Thursday and started working on re-gauging the tender wheels yesterday. The re-gauging actually went very easy. I followed your directions, Greg, and it went quickly and easily.
However…. Setting the proper back-to-back turned out to be complicated by the fact that some of the axels had wheels that were not properly aligned (wobbles). I’m using the back-to-back measurement listed in the NMRA wheel standards for Fn3 which is 1.580”. When I set some of the axels to that value they work perfectly through my switches (#4 and #6 from SwitchCrafters). However two of the axels have wobbles from one side of the wheel to the other that ranges from 1.568” to 1.590”. I tried bending the wheels back into alignment with my fingers, but that didn’t seem to work at all. Is there anything I can do to fix these, or am I just SOL and need to buy new wheels and axels from another source?
Any ideas?


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## John J (Dec 29, 2007)

Which Wheel has the woble? Is it the one that is solidly fixed to the shaft or is the one with the bushing? If it is the one with the isolator bushing it could be the busihing is distorted. Or the wheel is cocked on the bushing. And lastly the axel it shelf can be bent. I have had that problem striaght out of the package with LGB wheels. Chuck the axel into a electric drill and turn it very slowly you might see what is bent.


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## sandbarn (Feb 13, 2010)

John, 
I checked the axels like you suggested and they all look okay. On each of the axels that have a problem only one wheel wobbles. Also both wheels have isolator bushings. 

Would I just be better off getting new wheels from Sierra Valley or Gary Raymond ($17 seems reasonable). If so, is there an advantage to one or the other of their wheel plattings or no platting, just steel? I'm running battery power on aluminum track.


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## East Broad Top (Dec 29, 2007)

Two things... 

First, the NMRA standards for large scale (and Fn3) for back-to-back is 1.575" (40mm). This is identical to G1MRA. Tolerances for NMRA range from 1.590" to 1.560". 

http://www.nmra.org/standards/sandrp/pdf/S-4.2 2010.02.24.pdf 

(Sorry, I worked long and hard on those; I hate to see the outdated values kicked around.) 

Second, from the measurements you give, the wobble (while not ideal) is at least "within tolerances." If it's not causing derailments and isn't manifesting itself in any kind of annoying wobble, I'm not sure I'd worry too much about it. I run a fair amount of Bachmann wheels with similar slight wobbles to the wheels (alas, it seems to be somewhat inherent in a percentage of their wheels) and while I weed out the most agregious offenders, I don't really notice any other side effects. Certainly a new set of wheels would solve the problem. It's your call. If the wheel wobble is giving you concern, I've found replacement to be pretty much the best route. 

Later, 

K


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## John J (Dec 29, 2007)

I agree with EBT that if it is not causing derailments then it is not a issue. 

JJ


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## sandbarn (Feb 13, 2010)

Kevin, 
Sorry about the wrong back-to-back standard. Some how I got, and was using, the standard from July 2009 instead of the one from February 2010. I just deleted the old one and printed the new one. (my goof). 
When I look at the tender slowly rolling on the track I can see the wobble. Even though it may not effect operation in any way, I just don't like the way it looks. Think I'm going to order some Sierra Vally unplated wheels and replace them all. 
Your info about the drivers being out of gauge did give me pause. I'm not sure I'm ready or skilled enough to tackle that yet. The 4-4-0 will just have to bounce through the switches for now. 
Thanks for all your help


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## Greg Elmassian (Jan 3, 2008)

I agree, I don't like the wobble on locos. When you consider unplated steel wheels, be sure to likewise consider your environment. Some places get a lot of rust if you have high humidity or leave the loco out. I have that problem, and found out some of my rolling stock was equipped with steel wheels. The rust was bright orange. 

Regards, Greg


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