Hornby diesel locos - buffer height? (And replacement wheels?)

[SteveyDee68]

Yet more assistance sought!

I recently won a Hornby class 25 and a class 29 from a well known auction site (before scoring a Lima class 33 and a more modern Hornby class 73 more or less by accident!) and upon opening have noticed that both Hornby locos appear to tower over my (mainly) Bachmann rolling stock. The loco buffers only just contact the wagon buffers.

I know that back in the Hornby Triang days that all their products were top heavy - I have an old van that stands head and shoulders above any other stock - but I thought Hornby had sorted this out a long time ago.

So, are the buffer heights of these two locos correct, or if I park them up next to a Bachmann class 25 am I going to see a noticeable discrepancy? If the latter, any suggestions about how to remedy?

I did do a forum search using the new software and I found a thread from 2017 asking how far a class 25 can be improved, but it doesn't mention ride height. Nor does it mention replacement wheel sets to get rid of the awful traction tyres. Fitted on the power bogie, so any advice on that also sought (if simply which manufacturers to contact).

Many thanks to the collective wisdom in advance, and congratulations to Andy on the new website design.

Regards

Steve S

[mossdp]

Older Hornby models had an incorrect buffer height. I think this was to allow the coupling hook to pass under the buffers without jamming against them on sharp curves that were followed immediately by a sharp incline. Some diesel models can have the height reduced a bit by removing a little from the top of the bogie supports either side. On some models, the under frame fuel tank or battery box detail has been made rather too deep to compensate for the increased height so it will be rather near the track following adjustment.

[mossdp]

On many older Hornby models with traction tyres, you can replace traction tyred wheels with those without traction tyres but also have a gear moulded on them. On diesels, this sort of wheel was often used on the trailing bogies so you need some additional spares of the wheels like that. If you remove the traction tyres, you will need to add quite a bit of extra weight to the model to restore adequate pulling power.

[34theletterbetweenB&D]

How far do you want to go with improvement, and toward what end, is where I would start?

Between the 25 and 29 you will probably have sufficient traction tyre free wheelsets to swap around as mossdp suggests, and thus make one of them all metal tyred. If traction isn't enormously important that might suffice for a loco that isn't ever going to pull much. While in pieces you can go to work on the bogie to body interface to correct the height. You need to measure beforehand to know how much to cut away to get the buffer centres 14mm above rail.

If one of them is intended to pull real loads, I would go looking for a s/h Bachmann 24/25 mechanism to install. I have done this on the 29 body and it needs some filing of the chassis block to reshape it to conform to the vertical taper of the body sides, but is otherwise a simple adaption as the Hornby parts can be made to clip over the stripped Bachmann mechanism. You end up with a model that is to all appearances the Hornby on the outside, but actually performs really well.

[The Johnster]

These must be quite old models, as I think Hornby's stuff has been correct height since the end of Triang Hornby days.  A good rough guide when you are browsing on 'Bay is to look for stock with NEM type couplings as this is much more likely to be current spec, and I discount any that don't have NEMs.  Older models are ok if you're into that sort of 'retro charm', but bringing them up to modern compatibility in terms of wheelsets, buffers, and couplings, and ride height in the case of Triang Hornby or Triang stuff, might be more trouble than the model is worth; only you can decide if you want to make a 'project' of it, but as well as the ride height, you will have to mount modern couplings and replace the wheels at least.  Modern finishes and printing is much better than it was in those days as well; Triang Hornby's idea of rail blue was more suited to a Hockney painting than a locomotive, so we might be looking at a repaint as well, and transfers.

Don't forget that, once you've lowered the ride height and got the buffers the correct level above the railhead, your couplings are now too low, and must be mounted higher on the bogies; this is by no means simple as you have to cut a sort of platform in the bogie from underneath and drill holes for the fixing lugs and screw.  

I know this is all a bit negative and not what you want to hear!  

Traction tyres are another issue; I think they are the Devil's expectorant, remove any that come into my possession immediately, and offer them the opportunity of an exciting new career in the landfill industry.  They will, IMHO, ruin any chance you may have had of the loco running smoothly at low speeds, and spread muck all over your layout.  They may also cause pickup problems by lifting the bogie off the rail over dead frogs.  Unfortunately the old ringfield 'pancake' motors of diesel outline models of this era left little room for ballast where it is needed, over the driving wheels, and plenty where it isn't and will make the situation worse.  It won't be an issue on many BLT or shunting problem type layouts, but will if you run anything like even half scale length trains or have gradients.

Traction tyres were put on locos that weren't powerful enough in the first place and had to be run at very high rpms to develop any performance at all (which meant gearing down through cheap plastic spur gears that split and caused more trouble than they were worth), and were to my mind a very poor substitute for more traditional open frame worm and cog mechanisms that were too expensive to produce competitively back in the 80s; the modern situation is much, much better!

Your Lima 33 is probably a better deal, unless it is one of the very early HO scale ones; you will be able to tell this from the roof height compared to more modern versions, as the whole thing will look too small (because of course it is).  But my comments about cheap and nasty plastic pancake mechs and traction tyres apply to this model as well, plus Lima used a sort of brass alloy for their loco wheels which could not have been better formulated to both pick up crud and ruin pickup and to distribute said crud around the layout.  Added to this, Lima mechanisms will propel the model at insane speeds.  

Despite this, and all the drag of those plastic reduction cogs, Lima chassis can be made to run very smoothly and controlled at very low speeds, so long as they are kept scrupulously clean, and they need a lot of attention to be kept this clean, like 2 or 3 times a running session in the case of my old Lima Western; I still have a 117 dmu bashed into a 116 that gets an occasional run and this is a little better, but again needs a lot more cleaning than any of my other locos.  But you must remove the traction tyres IMHO.

[DCB]

You may be looking at this from the wrong end.  You need a common buffer height not necessarily the scale one.    Buffer centrelines are often quoted as 3ft  5 1/2" fractionally under 14mm from rail height.   Triang raised this by about 1mm from scale by a variety of strategies to clear their ugly great tension lock couplers, sometimes the whole thing is 1mm too high, others just the buffer beam.    Hornby Dublo and Peco stuck with around 14mm.

If you lower the body onto the bogies you may well have to cut away parts of the buffer beams to allow the couplers to swing, I had to do this when I lowered my Hornby coaches.  The old metal Hornby couplers can be bent to clear, but the plastic ones can't so maybe retrofit the old ones.

A problem a lot of layouts inherit is that a lot of trackside bits and bobs suit the Triang buffer height and the buffer centre line needs to be above your platform  surface by 1mm or maybe a bit more and when you lower the locos the buffer centre line is often below below the platforms which looks worse than  when you started.   I would set your own buffer height and adjust stuff to suit, bigger wheels in Lima coaches, smaller ones in Triang.   I have lowered my Triang Coaches by sawing away 1mm of the bogie pivot tower.

Hornby compounded the buffer heigh issue by fitting undersize wheels to many diesels, the class 47 benefits from a Saint tender drive unit in place of the 47 one, a bit of filler sorts the spokes, or I think A4 tender drive wheels fit and I'm pretty sure the other Hornby locos had the same stupid little wheels.  the wheels have traction tyres but all you need is a lathe to turn the tyres down to get rid of the grooves and some spare wheels maybe A4 for the trailing bogie. Then you have to lower the body about 2mm onto the bogies and lower the coupling.  It looks a lot better but Life is too short. 

On the flip side many China Hornby Steam locos don't stand high enough.  The King should tower above A4s etc as they were almost 13ft 6 high, the Bachmann 2251 is the same, the Margate King and Hall were a lot better but progress is progress.

[SteveyDee68]

Thanks for the all the responses.

 

I plan to ditch the traction tyres asap, as per many negative comments about them on the forums.

 

I've  already "fettled" my class 25 for better bogie movement - someone had added extra lead/plasticine weight, but it was pressing against the ends of the motor bogie - so am not averse to "tinkering" with models if they weren't too expensive in the first place! No way am I butchering Bachmann locos until I have seriously raised my skill levels!

 

My aim is to have "reasonable" detailed locos that run well enough for an inlenook inspired "mini" (rather than micro) layout, using tension lock couplers for ease of use, so the info regarding coupler height is also very useful.

 

Thanks again fo the help.

 

[Il Grifone]

The buffer centreline  should be  3' 5½" above the railhead generally. It does vary slightly and there is a tolerance for loading and tyre wear. Nothing like Tri-ang's 2mm, which some of Hornby's models have inherited, however. I have a Tri-ang Hornby E2 buffered up to a Hornby 3F  in front of me now. The latter, despite her later SSPP chassis (the one with the sprung rear axle ), stands 2mm higher than the former at the buffers. It is on the list to modify as it looks ridiculous.

 

The bar of the tension lock coupling (these should share the  new career of  the traction tyres mentioned above IMHO) should be 10mm above railhead. The actual value is not critical, but must be the same on all stock and the dropper must clear rhe railhead. Lowering the body of a diesel will not affect the coupling height as these are mounted on the bogies and, in any case a little judicious bending will sort out the problem.  (The hook has to be horizontal and might need removal and soldering at a different height). I prefer to remove the hook altogether on locomotives anyway,

Edited February 3, 2019 by Il Grifone