Wobbly wheels on split chasses - solutions?

[peterws]

The perrenial question; get rid! Buy new, or buy judiciously. But I been thinkin' there's got to be an answer.
I love my Mainline stuff, and currently have a J72, GWR Mogul and a Bach. J39 which could all use a bit of TLC in that department.
Anyone tried peening? In several places, this might effect a decent solution. But as always, who's tried it/gonna be first?
Everybody takes a step back . . . . .

[Bigmet]

I wouldn't go anywhere near the driving wheel assemblies of these with a hammer. Degreasing the pieces and reassembling with an adhesive - my choice was 24hr curing Araldite - did the job on mine, until all the essential plating for conduction was worn through.

The 'problem child' for my interest was the J39, Bachmann not having renewed it with a conventional wiper pick up mechanism. My quick cheap and dirty fix is a Bachmann J11 mechanisn wedged in it. Runs beautifully, appearance not that special with quite a lot of the drive on view. But, something better may yet occur to me.

[peterws]

Yeah; had to refix my Mogul wheels since I replaced the tyred ones with non-tyred. Got a new black central piece and glued the wheels in with UHU non-solvent which worked better than superglue, even loctite slow, which enables a small time for adjustment.
Was thinking of peening the housing, not the wheels. It'd raise the surface,narrowing the running gap, and allow lube to work its magic for a bit longer.
Maybe . . . .but I'll start on the J72, my most expendable.

[GeraldH]

I've used a similar approach to Bigmet, my choice of epoxy has been JB Weld, but this may not be better than any other epoxy. I use the standard slow setting one which gives one more chance of adjusting the quartering before everything sets solid. Superglue has not proved as good. Degreasing is very important and let the degreaser dry/evaporate before adding the glue. Graphite powder is conductive and quite an effective lubricant on Mainline axles.

[Bigmet]

...Was thinking of peening the housing, not the wheels. It'd raise the surface,narrowing the running gap...

One potential problem to be aware of in the mechanism castings are voids in the casting. I have taken a saw to five different Bachmann mechanism castings for varied purposes, (altering the wheel arrangement, shortening the chassis, adjusting for fit in a different body, adding weight for tractive purposes, etc.) and never failed to find voids. Now that said I never cut into or close to any of the axle locators, but I see no reason why voids may not be present near these.

Secondly the chassis half castings are not precision items. I'd check very carefully before attempting any adjustment to make the axles a less slack fit, that both halves are starting from the same wheelbase dimensions.

Treat the plastic 'through plugs' that align the chassis halves very gently, especially when reassembling: the plastic embrittles with time and overtightening a screw can readily pull off the square head of the plug.

Unrelated but may be useful. Something else that really surprised me was that the casting metal took a much sharper edge than any of the H-D, Triang/Hornby, Wrenn, mechanism castings I had previously cut. I wounded myself a couple of times on the Bachmann product before taking care to always round-off all cut edges, just like my Pa had taught me when first shown how to go about cutting steel.

[peterws]

Every railway modeller has battle scars to prove his pedigree. My last was a deep slice to the thumb with a Stanley knife, cutting thick card, with some force, to do it in one, using a metal ruler. You can guess the rest, but it turned out much better for me than expected.
Better to use a decent size metal spirit level, on its side. But we're always learning aren't we?
Have to admit to loving the Mainliners, though. The company which woke Hornby up!

[Bigmet]

...Have to admit to loving the Mainliners, though. The company which woke Hornby up!

Shame that their parent 'pulled the plug' before they could progress to a conventional wiper pick up mechanism for steam, and the centre motor drive for D+E traction. We could have had competent HO technique mechanisms in RTR OO 20 years earlier*.


All my Bachmann purchases with the superior mechanisms that were introduced as 'Blue Riband' from the late 1990s are still running well, exactly as when first purchased. The oldest are a pair of Peak mechanisms now 32 years old, and of the steamers the WD 2-8-0, now 25 years old. (I will refrain from mentioning the prices back then, as it might make some cry.)

The Hornby and Heljan mechanisms of similar construction all promise the same longevity, and I haven't seen anything to concern me among the few items I own from the likes of Dapol, Oxford Rail, Planet industrials, Sonic. (Current RTR OO brands not mentioned have yet to make an item of interest, get on with it guys!)

For comparison the longest life I ever got out of a Bachmann split chassis steamer before it needed dismantling for cleaning and relubrication of the conduction path was just over a year, and the best life was six years before complete wear out, most fell well short of that. I wouldn't expect the Mainline steam loco drives to do that well, other than the lightweights like the J72. That assessment is made on the basis of the very good looking Replica B1 with a mechanism based very closely on Mainline's method, which went all to pieces inside four years - still looking lovely on the outside...

I am an enthusiast for timetable operation, and operate every day, so need models with endurance. Pretty confident today's RTR OO will 'see me out'.

*What I still have operating from Mainline is the Airfix GMR designed N2 which was released by Mainline when they took over that range. The open frame five pole motor based on the MW005 makes a racket due to wear but it runs reliably. I had to rework the pick up wipers once the wiper pressings eventually cut their way through the plastic studs on the all plastic chassis, and while about that skimmed down the flanges to enable operation on code 75 track. But apart from that it's as purchased forty something years ago. So better mechanisms were within reach of Mainline back then, pity they didn't make the leap forward to give all their models robust and reliable mechanisms, based on what Airfix GMR demonstrated. And of course Hornby still have the N2 in their range, design essentially unchanged but now with their quiet running black can motor, so it doesn't make coffee grinder noises.

[Bufferstop]

That assessment is made on the basis of the very good looking Replica B1 with a mechanism based very closely on Mainline's method, which went all to pieces inside four years

Indeed many Replica chassies had the legend "Made by Bachman" Stamped into them, or had a blank panel where the Bachman brand had been ground off the tool. Replica seemed to specialise in getting other manufacturers to produce short runs of slightly modified versions of their own products.

[Mountain]

Peters Spares sell replacement plastic axle inserts for soms Mainline/Replica/Bachmann split chassis. Am sure they do a J72. Hope that helps? Enables one to keep those lovely locos on the rails for years to come!

[peterws]

Problem is wear on the chassis housing the wheels. So much so that I used a small piece of brassstrip to shim one. That helps, but isn't ideal.

[Bufferstop]

In the end we have to accept that split chassis produced in the manner chosen by Mainline was a poor choice. Split chassis was devised for motor bogies and small chassis where lack of space meant there was little space for conventional wipers. The material used for the insulating axle/wheel mouldings had been used for many years in rotary switch mechanisms where its propensity to split and swell in the presence of mineral oils was the downfall of many designs, made even worse by the impossibility of smoothing it down to its original size, despite the manhours wasted trying to avoid the replacement of an expensive sub assembly.

[Bigmet]

Problem is wear on the chassis housing the wheels.

Wear to all the plating in the conduction path was a killer especially on the heavier Bachmann split chassis locos like the A4 and V2. Once the driven wheel tyre plating had worn through to the mazak after about 6 years use, current collection was unreliable. But since they were cheap whan introduced I felt that I had my moneys's worth from them; and I have made extensive use of the salvaged parts, the Mitsumi FK 130 motors appear 'unburstable', and all sorts of Bugatti styled streamlined locos can be had by use of old A4 bodyshells.

[Bufferstop]

I've just watched a video on overhauling a split chassis, (no names no pack-drill) I spotted a mistake being made in the reassembly with no recap to fix it, so either it was fixed in the editing or there's a fault waiting to happen. Each through, threaded hole into the plastic takes a screw from each side, one long one and one short one. I spotted two long ones going into the same hole, if they are long enough to touch they form a perfect short circuit between the two sides of the chassis. Be extra careful to get all parts, even screws, back where they came from.

[Bigmet]

I've just watched a video on overhauling a split chassis, (no names no pack-drill) I spotted a mistake being made in the reassembly with no recap to fix it, so either it was fixed in the editing or there's a fault waiting to happen. Each through, threaded hole into the plastic takes a screw from each side, one long one and one short one. I spotted two long ones going into the same hole, if they are long enough to touch they form a perfect short circuit between the two sides of the chassis. Be extra careful to get all parts, even screws, back where they came from.

Was that on a Mainline origin design of a split chassis mechanism?

TTBoMK Bachmann's construction only has a single screw into the plastic insulating connector 'plug' that links the chassis halves, so not subject to this problem. Their replacement problem is that the square cap of the Bachmann plug very readily shears off if the screw is slighly overtightened...

[Bufferstop]

Got it. The Collet Goods to be precise. Mine wouldn't allow two long screws to be tightened, but I've seen other examples where they touched and some where they would never touch. They didn't seem to grasp that the screw lengths mattered. The quality control bods probably knew what to do when they got a dead 'un, just change the short screw, but they wouldn't want to do anything about it. Faults found and fixed probably look good on their stats.