How to cure wobble on Bachmann LMS Jubilee Chassis

[Crewlisle]

I have a Bachmann Jubilee chassis which is very responsive to my controllers (both DCC & H&M Duette which I use for testing) with a smooth running motor - until I place it on the track!  When moving it has a slight wobble which increases as it speeds up.

 

Any ideas how I can eliminate the wobble to avoid a new replacement chassis?  I have fitted a Bachmann/Mainline Jubilee body & tender to a new DCC replacement chassis & I do not want to do it again.  It is not for the faint hearted!

 

Peter

 

 

[cypherman]

Hi Crewlisle,

Is this an old Bachmann split chassis model that was originally a Mainline product. If it is it is probably suffering from the Bachmann wobbly wheel syndrome that especially effected their 4mt 4-6-0. It is caused by the plastic inner part of the main wheels(This is the  part that is the wheel weights and spokes) warping and therefore warping the metal part of the wheel. If it is this then the easiest fix is just to remove the plastic inners and in the main the wheels straighten out. A little bit of judicious tweaking may be needed to get them perfectly flat. Bachmann have long since run out of the spare plastic inners so none are available from them. It is a pity that Bachmann chose to go this way as the original Mainline wheels were all metal and did not warp. They just has problems with the plastic axel centres. But that is another story.

[34theletterbetweenB&D]

14 hours ago, Crewlisle said:

...  I have fitted a Bachmann/Mainline Jubilee body & tender to a new DCC replacement chassis...

Or, if this is the current steel axle wheelset DCC ready mechanism as I suspect the above quote indicates, then we are looking for a mechanical cause specific to such a mechanism. I would start by sighting along the treads and flanges with a straightedge, and inching the mechanism round looking for a deviation. Once found, then it is determining the cause. You may get lucky and find something like a pick up wiper snagging an irregularity on the wheelback, or a momentary catch in the outside rods as the cause of a 'kick'. Usually though what goes with the description 'wobble' is a wheel not concentric and/or perpendicular to an axle. May be possible to reset the wheel, but if not a replacement wheelset would be the way forward.

[Rowsley17D]

If the wheels turn out to be okay, I suggest doing what I did with a Hornby Black 5 which had front-end waddle. I glued a small piece of foam on top of the bogie truck, no waddle now. There are better ways of doing this with engineering but the foam way was quick and easy.

[Il Grifone]

Most wobble is due to wheels not being true (with care they can be realigned, but it's trick and needs care. It's just as easy (easier?) to make it worse. But, first check there is nothing snagging the mechanism. Some manufacturers don't seem to know how the valve gear works and set it every which way.

 

https://en.wikipedia.org/wiki/Walschaerts_valve_gear

[Crewlisle]

Thanks for all your suggestions but I think I have found the problem.  I thought I would start with a simple squareness/condition check of the driving wheel axles.  I removed the coupling rod wheel screws from both the front & rear sets of drivers & removed the wheel sets from the chassis.  Just holding each wheel between thumb & fore finger & twisting them in opposite directions I could check if the axles were broken.  The front pair were solid but I felt a small movement on the rear pair.  Closer inspection showed that the nylon axle in the middle had developed a small crack along its full length.

Fortunately, I had a broken Bachmann Jubilee chassis.  I removed the set of rear drivers & fitted them in my defective chassis.  The wobble had been reduced by about 90% to an acceptable level but as a final check I loosened the screws holding the two halves of the chassis together, placed the loco on a flat test track on the table & pushed down to make sure the two halves of the chassis were aligned correctly.  I re tightened the chassis screws, not too much as they are fitted into small diameter plastic bushes & which are easily sheared.  I will now go ahead & renumber it 45723 Fearless.

 

Peter

[kevinlms]

5 hours ago, Crewlisle said:

Thanks for all your suggestions but I think I have found the problem.  I thought I would start with a simple squareness/condition check of the driving wheel axles.  I removed the coupling rod wheel screws from both the front & rear sets of drivers & removed the wheel sets from the chassis.  Just holding each wheel between thumb & fore finger & twisting them in opposite directions I could check if the axles were broken.  The front pair were solid but I felt a small movement on the rear pair.  Closer inspection showed that the nylon axle in the middle had developed a small crack along its full length.

Fortunately, I had a broken Bachmann Jubilee chassis.  I removed the set of rear drivers & fitted them in my defective chassis.  The wobble had been reduced by about 90% to an acceptable level but as a final check I loosened the screws holding the two halves of the chassis together, placed the loco on a flat test track on the table & pushed down to make sure the two halves of the chassis were aligned correctly.  I re tightened the chassis screws, not too much as they are fitted into small diameter plastic bushes & which are easily sheared.  I will now go ahead & renumber it 45723 Fearless.

 

Peter

Not 45736 Phoenix then?

[Crewlisle]

23 hours ago, kevinlms said:

Not 45736 Phoenix then?

 

Kevin,

 

Very good.  No, Fearless was my last ship when I was in the Navy.  I sometimes mention for a laugh when having any general conversation with people I don;t know by saying, "I starred in a James Bond film."  Then adding ,"Along with about 500 others!".   Fearless was in the 1976 film 'The Spy Who Loved Me'.  It was only for about 2 minutes at the end of the film but the special effects team were onboard for about 4 weeks making the escape gondola & filming many takes of it coming into the landing craft dock.  None of the stars came onboard; the onboard scenes with the film stars were filmed in the studio.

 

I have other locos named after other ships & establishments I served in including the aircraft carrier HMS Hermes as Warship Class D823 & Jubilee 45687 Neptune, the submarine base on the Clyde.

 

Peter