Overhauling an old A3 and B12

[Mersey508138]

Hi Jim

I look forward to seeing your update.

[Jim de Griz]

First fit is a 'measured' success.

To be fair, Peter's Spares are very upfront that the motor will need some fettling, which given it is supposed to be compatible with 30+ years of Hornby products is pretty reasonable.

First push fit had a slight alignment problem.

A little 'gentle' persuasion got it into position, but the mounting plate is slightly bowed.

Running at speed is good, responsiveness is excellent, slow speed running however shows there is a stiff spot roughly once per rotation and I think that also accounts for the odd stall.

I'm going to take the motor out and have another go at giving the mounting plate a 'recommended bend', see if I can't remove that stiff spot.

I'm also going to have to order a retaining screw for the coupling rods as somehow I've lost one....

Jim de Griz

[Mersey508138]

Hi Jim

Sounds like the recommended bending of the base plate will do the job, if I remember correctly from bill's video there is mention that having the base of the motor fitting lying flat on the chassis helps to improve running quality aswell.

[Jim de Griz]

I played a hunch and took off the coupling rods.

Now noting this is a bench test with my spare controller (can't set the layout up right now to do a proper test)...but with the coupling rods off, there doesn't appear to be a tight spot anymore. Which suggests the problem isn't with the motor assembly, but with the wheels and coupling rod.

Obviously I need a new retaining screw before I can test properly, but after applying a more force than I was particularly comfortable with to get the wheels squarer and testing with the front and rear wheels only coupled, she does seem to run alot smoother.

That might change when I have all three axles coupled up, it might change when I place her on the railway to test her on real track with my regular controller. But, for now at least its a positive development that didn't require me to do any additional soldering

Given I fitted new pick ups on both sides of the chassis, I'm really wishing I hadn't taken the wheels off! Still hindsight, 20:20 and all that. Lesson learnt.

Jim de Griz

[Mersey508138]

Hi Jim

It sounds like the quartering on the centre driving wheels might be slightly out. I've had quartering issues on a few of my locos lately ( 1 of which was my only B12 with a chassis.like your loco ) which was a major butt pain but I have finally managed to sort it out.

I decided to give it a full strip down and clean up last week, a lot of cotton buds were used ( about 10 or 12 ) aswell as roughly a cap full of enamel thinners ( perfect for a chassis clean down ).

The quartering issues arose because initially I tried to set the wheels with the chassis the right way up, big mistake because I couldn't see through the chassis block but once I had turned it over, setting the wheels was done fairly quickly.

[Jim de Griz]

Thanks Mersey, you were right, the quartering wasn't quite right. I've done a bit more work on that and on squaring up the wheels.

Screws have arrive and I am still testing on a test bed, but she is certainly running smoother in both directions. Close examination suggests there is a similar issue with the rear axle bearing as on my Flying Scotsman (wobbly wheels), just nowhere near as bad. That won't be helping, but the signs are certainly improving.

Odd one, one of the coupling rod retaining screws undid itself during testing! I've not been able to replicate the fault, but I assume that is how I lost the original. Something for me to keep an eye on I guess.

Jim de Griz

[Mersey508138]

Hi Jim

Those coupling rod screws can be a pain to tighten up, the thing I found is that the head of the screw is only just big enough for a jewellers screwdriver to fit in them.

I remember a few years ago, I had a rod screw do exactly the same thing on an old triang Princess Victoria locomotive, I managed to sort 1 side out by removing the distance piece and replacing it with a couple of small diameter washers and luckily I was able to complete the same modification on the other side of the loco.

I tightened the screws which were the same tyoe as for the B12 but still the valve gear fell off, dicey as this will sound, I had to put a dab of superglue on the back of the centre driving wheels then fit the coupling rod and valve gear before the glue set,luckily it worked and the valve gear never came loose after that but eventually the loco succumbed to a number of issues including failed isolation centres for the insulated wheels, motor burn out and worn driving wheel slots.

I think the A3 & B12 have the same kind of thing where by the axles are fitted straight through the chassis and essentially the chassis block is basically the bearing. I have an idea but it's knowing whether it will work or not.

The idea is to find some copper or brass tubing that is just slightly bigger in diameter on the inside of the tube than the driving axles and fit 3 pieces ( 1 of which will be shorter than the other 2 pieces ) into the chassis, these pieces of tubing would then become the bearings.

The shorter piece of tubing then needs to be cut in half would be fitted to the axle which has the gear on it once the gear has been removed, there will likely be some trial and error required to get the geared axle to turn freely but it would ensure that the chassis lives on a bit longer because the only other option would be total replacement of the chassis with the updated version with a type 7 motor although the good news is that the tupe 7 motor chassis will take thr Peter's Spares replacement motors which like the R150 chassis is a straight forward replacement.

[Jim de Griz]

Its reassuring to know I'm not the only one that has had that issue, I'm holding onto the superglue as my do or die option for now, hopefully I just didn't tighten it up properly last time. Like yourself, I've found the jewellers screwdriver is the only tool for the job and even then it is fiddly.

I think your right on the 'bearings' for the main wheels, which I gather is exactly the problem, there is no part to remove and replace. As discussed, I'm not willing to replace the chassis block so trying to create a bearing as you describe might be the only way....I wonder if there would be enough clearance to fit top hat bearings or similar...that would mean fitting new pick ups but as I've already done that on the B12....

Might be something to experiment with on the A3 if she gets any worse, though I'll need a press or something to get the wheels back on square before I risk taking them off. (That's on the list to acquire anyway for the long delayed J69 build)

That said, onto the good news!

My railway is still packed away, so I set up a little test track with my usual controller and I'd say that electro/mechanically the B12 chassis is now at 95%.

There is hardly any wheel wobble and the stiff spot is completely gone, as has the stalling. Slow speed running is excellent and the motor is so responsive I've been running purely in the 'high resistance' setting. (Most new RTR locomotives need this setting as well)

She might benefit from tender pick ups, but the pick up from the bogie is doing the job of getting her over point work. Once I've got a quartering press I'll have another go at squaring up the wheels which will hopefully reduce the wheel wobble further. Other than that, I think the chassis block is as good as it will get.

Thank you everyone for your advice and assistance with this, I must admit to taking a lot of satisfaction from breathing life back into this locomotive after it has been on the repair bench so long.


In further good news, it has stopped raining for more than 30 minutes and gotten warm enough I might actually be able to put the first coat of paint on the bodies. Wish me luck

Jim de Griz

[Mersey508138]

Hi Jim

I hoped to have good news for you aswell, I have managed to purchase some copper tubing of the size I was describing yesterday in regards to making a bearing for the driving axles.

It turns out I have ended up purchase copper tubing that is the same size as the axles. Measuring the axles just now has yielded the result that they are 4mm in diameter so the tubing needs to have an internal diameter over 4mm.

[Jim de Griz]

Thank you for giving it a go, I had my fingers crossed for you.

I imagine finding a tube that is the exact dimensions required will prove quite tricky. Would need to be both very thin and very strong to avoid becoming distorted when it is pushed into the chassis block.

Jim de Griz

[Mersey508138]

Hi Jim

From what I can remember the chassis block will need to be opened up just enough with a drill to still allow a secure fitting.

The size of tubing I purchased fits nicely over the newer axles for the more up to date locos where the wheels on both sides are isolated due to plastic spokes but for the wheels on the older ringfield and triang locos it needs to be literally next size up from what I purchased yesterday, the internal diameter of that piece is 3.97 mm according to the label.

[Jim de Griz]

That makes sense, I suppose I'd need to look at a suitable jig to hold the drill perfectly perpendicular to the chassis block and a suitable drill bit as well.

I must admit to not knowing how tough the chassis block is?

Jim de Griz

[Mersey508138]

Hi Jim

I can definitely vouch for how tough chassis blocks are because back in 2004 or thereabouts, I decided to convert a tender driven GWR 2 - 8 - 0 into a loco driven engine, the 3rd driving axle was chosen as the site for opening up the chassis to facilitate the addition of drive gears and motor fitting. Little did I realise how hard it would be.

I started drilling using an old manual drill to mark out the chassis and start drilling through ( working my way up through the drill sizes as I went ), but also I broke a few drill bits. All in, the conversion took about 3 weeks to carry out, wire up and begin testing without the loco and tender bodies fitted as I had wired the tender for power collection too.

The 1 result it did yield was that extra weight was required for the loco to haul anything but needless to say the loco was eventually heavy enough to haul upto 8 or 9 coaches depending on their total weight or upto 25 wagons. Unfortunately the GWR 2 - 8 - 0 is no longer in service and parts of it were used on other projects but from my experiences I was able to get some sort of idea of chassis toughness.

Triang chassis are a bit tougher than the up to date chassis and can take longer to cut with a hacksaw if they are being modified for a project, than the newer chassis take to cut if forvthe same reason.

In respect of drilling triang chassis I can imagine that possibly careful drilling would be required as I have never drilled a triang chassis for modification of axle bearings but have on occasion had to drill out snapped screws or bolts, not an easy task.

[Jim de Griz]

Hi Jim

I can definitely vouch for how tough chassis blocks are because back in 2004 or thereabouts, I decided to convert a tender driven GWR 2 - 8 - 0 into a loco driven engine, the 3rd driving axle was chosen as the site for opening up the chassis to facilitate the addition of drive gears and motor fitting. Little did I realise how hard it would be.

I started drilling using an old manual drill to mark out the chassis and start drilling through ( working my way up through the drill sizes as I went ), but also I broke a few drill bits. All in, the conversion took about 3 weeks to carry out, wire up and begin testing without the loco and tender bodies fitted as I had wired the tender for power collection too.

The 1 result it did yield was that extra weight was required for the loco to haul anything but needless to say the loco was eventually heavy enough to haul upto 8 or 9 coaches depending on their total weight or upto 25 wagons. Unfortunately the GWR 2 - 8 - 0 is no longer in service and parts of it were used on other projects but from my experiences I was able to get some sort of idea of chassis toughness.

Triang chassis are a bit tougher than the up to date chassis and can take longer to cut with a hacksaw if they are being modified for a project, than the newer chassis take to cut if for the same reason.

In respect of drilling triang chassis I can imagine that possibly careful drilling would be required as I have never drilled a triang chassis for modification of axle bearings but have on occasion had to drill out snapped screws or bolts, not an easy task.

Regrettably, that sounds like a job that is beyond my skills or the tools I own. Maybe something to consider in the future when I've gained more experience/skills.


With the good weather I've been able to get the main coats on the bodyshells.

Not a perfect job, there will be touching up to do, but the main blocks of colour are done and I've put a layer of satin varnish on to protect the paint while I start with the Pressfix lining.

I had high hopes of getting both engines 50% done today, but in the end only the B12 has one side complete. The lining round the splashers has proven very awkward, the shapes available are a little too small so I had to stretch them. A little touching up with a brush will be needed.

Incidentally 8516 was chosen as there is a picture of her hauling a 'through' train near Sheringham from the interwar period. I gather she was a Stratford engine so more than likely heading to Liverpool Street than King's Cross, but it is a close enough link for me to justify choosing her. Incidentally, I gather she was in BR days assigned to Cromer Beach, strengthening the link.

Jim de Griz

[Jim de Griz]

Well colour me embarrassed.

The lining isn't undersized for the task at hand, it fits perfectly, assuming you've noticed the (bronze?) rims on the upper edges of the splashers.

Bit of emergency surgery with water, white spirits and a sharp knife got the lining up (I've used the spare parts on the sheet already) and I've managed a 98% successful transplant and repair, assuming the varnish I've used to stick the lining down in its new location holds. As with previous, a little touching up with black paint should hide the imperfections.

Now to figure out what I should be painting the rims.

Jim de Griz