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Converting a Bachmann N into a U.


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Has anyone tried or succeeded in converting a Bachmann N class loco into a U.  Both locos look very similar and the (old ?) Wills kit was capable of being used for an N, U, N1 or U1 and originally was meant to be used with a chassis from a Triang 2-6-2 tank loco.  The driving wheels of a U are of a bigger diameter than an N.   Are there any other significant differences ?  Could the Wills body be fitted to the Bachmann N chassis ? or would it be better to modify the Bachmann body into a U ?.  What would be the problems of fitting larger diameter wheels to the Bachmann N chassis or is that impossible because of wheelbase spacing ?  Obviously the loco body would sit too high, could it be 'carved up' a bit underneath to sit lower. 

 

In the 'old days' it was common to use a Triang chassis under a kit body, or to fit better wheels (usually Romfords) to a Triang chassis, but in these days of more accurate chassis no one seems to use a modern Bachmann or Hornby one as the base for something else, or have I missed something ? 

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The chassis is the problem, bigger wheel diameter for the U with different wheels spacing, U's have wheel splashers, bigger for the K (SECR) rebuilds with lower footplate, and less front drop, oh - and different slide-bar, 3-bar instead of a single.:sungum:

 

Edited by bike2steam
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  • 4 months later...

I have done this by cutting the Bachman chassis, reattaching with sides of plasticard (included any as converting to EM). Then needs new running plate with splashers and cab side to match. And new larger wheels and rods for new wheel spacing.

I honestly question the sanity but I had an N spare! Do not buy one expecting an easy conversion as it is quite a challenge

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DJH Kit isn't that accurate but can appear at a reasonable price, even with wheels. It is a relatively easy kit to construct. Decent motor /GB from DJH (costs) but better IMO than hacking a RTR N.

I should finish my two; U and a U1. Yes, I should! Valve gear puts me off.

Phil

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  • 2 years later...

The Bachmann N is a much better candidate for conversion to an 'as built' U Class rather than a 'Rebuilt River'.   The conversion would benefit from a replacement chassis due to the wheelbase difference, and the SEF chassis with Bachmann valve gear is what I will use.  It will also need a new running plate because the U Class running plate is higher and runs under the cab further than the N Class.  The cab looks reusable with a new front.  To try to illustrate the differences, I've scaled and traced an Eastleigh Weight Diagram for the U Class, and superimposed it on one for the N Class.  The N Class happens to have a rebuilt front end, so is longer. 

UClassTraceoverNClassWtDiags.jpg.9b9c7e85e9b154d1f9ae988fd9521a64.jpg

I've started a thread on Western Thunder to collect the changes that would need to be made ready for my own conversion:

https://www.westernthunder.co.uk/threads/converting-a-Bachmann-n-class-to-as-built-u-class-in-em-gauge.11833/

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On 01/07/2021 at 20:42, Mallard60022 said:

DJH Kit isn't that accurate but can appear at a reasonable price, even with wheels. It is a relatively easy kit to construct.

 

The DJH kit isn't really sure whether it's an 'as built U' or a 'Rebuilt River U'.  The running plate and cab have the width of the 'as built U', but the height of the running plate more like a Rebuilt River.   Built as per instructions the buffer beam, cab and footplate are likely to be 1mm too high - though that's not a lot in the grand scheme of things.  I turned my DJH kit into a Rebuilt River with the addition of scratch built cab and running plate, and although a runner I'm also stuck on building the valve gear, in my case for an SEF chassis kit.

PA160338.JPG.7b1f6d5bfd941e71a8dc26c2699caa88.JPGPC200361.JPG.50bd0c0c04c6f99385aa440cb7f974ec.JPG

Rebuilt Rivers are wide and the cab is very clearly cut down from the enclosed cab of the tank engine.  This one will be 31792 when it was a Yeovil engine with a fairly regular turn on the Salisbury & Dorset.

 

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On 18/07/2023 at 10:57, Steve Smith said:

The Bachmann N is a much better candidate for conversion to an 'as built' U Class rather than a 'Rebuilt River'.   The conversion would benefit from a replacement chassis due to the wheelbase difference, and the SEF chassis with Bachmann valve gear is what I will use.  It will also need a new running plate because the U Class running plate is higher and runs under the cab further than the N Class.  The cab looks reusable with a new front.  To try to illustrate the differences, I've scaled and traced an Eastleigh Weight Diagram for the U Class, and superimposed it on one for the N Class.  The N Class happens to have a rebuilt front end, so is longer. 

UClassTraceoverNClassWtDiags.jpg.9b9c7e85e9b154d1f9ae988fd9521a64.jpg

I've started a thread on Western Thunder to collect the changes that would need to be made ready for my own conversion:

https://www.westernthunder.co.uk/threads/converting-a-Bachmann-n-class-to-as-built-u-class-in-em-gauge.11833/

Is that a rebuilt River?  The new builds look to have the running plate raised above the wheels and a much deeper front frame drop.

I want a U as they were regulars on the MSWJR, and  I vaguely remember them from my pre primary school days and it will be usable on my 1957/62 WR layout.

I have acquired a Wills Finecast kit for the Southern Moguls which allegedly can be made up as a U class. so I am searching for inspiration . Can any one throw any light please.

Edited by DCB
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2 hours ago, DCB said:

Is that a rebuilt River? 

The partially completed model is of a Rebuilt River, whilst the drawings compare a 'new build' U Class to an N Class.  The new build U and rebuilt River U are the same apart from the rebuilt Rivers having a much wider cab and running plate which is set quite a bit lower necessitating larger splashers, and of course that very different arrangement of cab windows.  The cab front of N and rebuilt River U although sharing a similar arrangement of windows differ as the rebuilt River cab is wider.    

 

My purchase of the DJH kit occurred before SEF brought out their kit for the River Class tank engine, and that I'm sure would have been a better starting point for a rebuilt River.  The intention of SEF at the time was to go on to do the U Class to a much better standard than the old Wills Bodyline kit, but Bachmann bringing in their N Class stopped them taking it forward.  As to how easy it would be, it really depends on whether or not the River tank kit components were designed with a rebuilt River kit in mind, and only Dave Ellis will know that.

Edited by Steve Smith
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  • 2 weeks later...
On 18/07/2023 at 12:39, DCB said:

I have acquired a Wills Finecast kit for the Southern Moguls which allegedly can be made up as a U class. so I am searching for inspiration . Can any one throw any light please.

The Ex-Wills Finecast kit was my original intention for an as-built U and I did pick one up off Ebay.  Dave Ellis sent me a U/U1 chassis kit for it after I re-typed the SR Mogul instructions for him.  He very kindly added a few improved mouldings from the River kit.  The Wills kit expects larger wheels to be fitted to the Triang chassis raising the whole thing by 1mm.  Parts are only provided for an N or N1 Class running plate so the rise measured at about 5.3mm will be too low if used to make a U.  The instructions state that "Very small splashers should be made from card for the U and U1, it is not necessary for the driving wheels to recess into these however."  This would leave cab and buffers 1mm too high, and perhaps higher if those 6' wheels don't touch the thick cast running plate!  The running plate drop position under the cab seems to be something of a compromise between U and N.  There is a cast left and right running plate each incorporating a cab side making modification of the drop difficult.  The higher running plate gives the as-built U something of a 'Baby Arthur' look that I would definitely want to capture in my model.   Interestingly the cast spectacle plate provided is for a U rather than an N.   I can PM you a copy of the re-typed instructions if it would be useful.    Needless to say the Triang 2-6-2 chassis originally intended for this kit can't be correct for both N and U, and as this is a 'Bodyline' kit may not be correct for either (see T9 etc.).  

 

I'm of the view that the DJH kit (modified DLT style with an SEF chassis) would be a better route to a new-build U to modern standards of accuracy.  This should be the link to the page of DLTs SR loco build thread with the start of his U Class build:

DLT's U Class Build

 

Of course what I'm contemplating for my spare Bachmann N Class body and tender might also work, but that remains to be seen, and seen to be believed!

 

Edited by Steve Smith
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The problem with these kits is that they try to be "all things to all men" and use standard parts for N & U locos.  So the result is always going to be a hybrid of some sort.  I guess it depends how accurate you want it to be.

When I built the U-class, I realised that there are MANY differences from the N, and from the rebuilt-River version.  I had to consider the kit parts as an aid to the build. rather than a "kit" as we think of them.

Sorry, that's not very helpful!

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HI,

 

It is a puzzle why Bachmann have not re-tooled the "N" class so create the U and the two three cylindered versions. There are three versions of the "U" - new contsruction, "River" conversions of which there are two variations. From a business perspective, the "U" seems a good proposition given the variations. The footplate and cab would need investment and the chassis to deal with the centre to trailing wheelbase change, although the lattter could be ignored......

 

I used a heavily modified SEF white metal kit and the SEF chassis kit to produce 31806.

I am aware that 31806 does not seem to have been paired with this type of tender although its fellows were.

IMG_8094.JPG.66b6c43962d4ea4b777cf1ab27c0cb47.JPG

IMG_8095.JPG.295d36496b6f410481a48a9b9a0a771b.JPG

IMG_8097.JPG.46e2113e40b43c01b347fb2cb1d33ff7.JPG

 

 

Kind regards,

 

Richard B

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On 01/08/2023 at 13:29, 30368 said:

I am aware that 31806 does not seem to have been paired with this type of tender although its fellows were.

.

That really looks the part, and I'm impressed that the footsteps are nicely lined up - that's a Maunsell feature.   One of Dave Ford's Dorset Walks (filmed last year), shows him returning from Swanage to Corfe Castle behind a gleaming 31806 running with a 4000 gallon tender - a prototype for everything! 

https://youtu.be/srwfnCJ5pZc

I'm planning on modelling 31614 which had the same sort of tender.  This was a Bournemouth and later a Yeovil engine, and was photographed at least once in the Salisbury bay platform with what is described as a Bournemouth train.

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