JLTRT Class 40s conversion to S7

[richard carr]

I'm taking a little break from the 9fs and tidying up a few lose ends, two of which are a pair of JLTRT Class 40s that I bought on ebay back in 2019. Both are finished in BR Blue one is 40075 a discless disc head code example and the other is 40135 in its final configuration with water tanks removed . The paint work and weathering finish on both locos is excellent. Both of course are finescale so the little job now is to convert these to S7.





When I collected the locos from the seller at Kettering I did ask why he was selling them and he replied that they wouldn't stay on the track, the pony wheels regularly derailed, fortunately I have a solution to that problem.

40135 is powered by a pair of ABC power bogies, these aren't going to work with conversion so the first thing is to remove them.



This just involves undoing a few screws and removing the pick up and motor wires from the decoder.

 

[richard carr]

SOme progress has been made so I now need to get some S7 wheels ready for the first loco.
The S7 Group have been producing diesel wheels for a few years now and they are nice, they are made by slaters but with a few tweaks for S7 and aimed at specific loco types. The 3 foot 9 inch wheel that a class 40 needs is really aimed at a class 47 so comes complete with the 4 lifting holes, but you won't be able to see those once the wheels are behind the bogie frames.

I have though identified a few issues with these wheels, not so much the wheels but the axle and the axle screw.

Here is a wheel fitted to an S7 axle with the screw fitted you can see that the screw cannot go fully home it should be flush with the boss of the wheel.



This means the wheel is lose on the axle end and you can pull away from the axle like this



That isn't something anybody wants.

To fix this I find that 3 things are needed, first the square end to the axle needs to be shortened by 0.7 mm so it looks



like this. You then need to thin the neck of the screw, I do this by putting it in a mini drill and taking a file to it to just thin the area where the tapered head begins, I then shorten the screw by about 2mm.




Have any other S7 members had a similar problems, can't we get slaters to sort this out ?

Richard

 

[Ian@StEnochs]

I have had a similar problem when thinning standard O wheelsets down to S7 standards. My solution has been to countersink the end of the axle on the lathe. This retains the square but gives space for the head of the screw. Sometimes the countersink needs deepening too but I do that on the vertical drill. I have two countersink bits one I use only for the brass and the other for the steel.

The latest Slaters screws have quite a thick head so I usually turn a wee bit off the face so that they sit flush or just proud of the wheel depending on prototype. The hex socket is much better than on the old screws and doesn’t give me the same problem with the key slipping.

Ian

 

[Eastsidepilot]

If the threaded bore is not long enough for the screw and you don't want to cut the screws down then you'll need a 6 B.A. tap but check that the counter bore is long enough for the tap first !

Col.

 

[Tim Humphreys ex Mudhen]

Richard,
I've had a couple of instances of this and its been due to the screw thread bottoming out in the hole. Solved by filing a little off the screw thread.
atb
Tim

 

[Cliff Williams]

Nice locos, any plans for the redundant ABC class 40 bogies?

 

[richard carr]

Cliff

No they are for sale.

Richard

 

[Cliff Williams]

Pm sent Richard

 

[richard carr]

WOrk has been progressing on the conversion, the 2 bogie chassis's are now complete, heres the motorised chassis.



One thing I would always recommend doing is to get some weight into the chassis, I have already added the first piece of lead and two more will go in beside the radial truck and a piece at the back. You really do need some on the motorised chassis to balance off the weight of the motor.
Here's the non motorised chassis






The other thing you need to do with a conversion to S7 is to file back the sides of the frames, it really is tight otherwise.





The final thing I'm doing is making up some new screw couplings, for some reason, the builder didn't used those that are supplied with the kit, the kit ones are accurate and look really nice much better than the ones that came with the model, fortunately I have a few spare from TAA wagon kits.

 

[richard carr]

I have now moved on to converting 40075, unfortunately it has not been as well put together as 40135, there is a fair bit of damage to the bogie side frames, to point where I will need to make a call to Laurie at MM1 and order some new ones.



The body and the insides are fine, again with nice ESU decoder.



I have had to hack away at the decoder support as the only way to get the second bogie off.



The bogie looks quite good here but once you look closely you can see it could have been put together better.

I'm not sure who's gearboxes these are but they run very smoothly


You can see the damage around the extended axle of the pony wheel.



Another view of it



The inner bogie falls apart removing the wheels and bearings, but fortunately I don't need those.



The outer frames are still intact but only just.

 

[Eastsidepilot]

Richard, glad to see I'm not the only one with a 'tidy' workbench

Col.