RMweb Gold JohnR Posted March 30, 2019 RMweb Gold Share Posted March 30, 2019 What's the best way to add weight to these locos? Any tips on material to use and where to put it? I know these are tricky to balance so any tips will be useful Link to post Share on other sites More sharing options...
cypherman Posted March 30, 2019 Share Posted March 30, 2019 Which M7 do you mean. The older one or the new one. In the older one I would use a little bit of steel/brass tube glued into the boiler over the driving wheels . With enough cut away to avoid the engine Link to post Share on other sites More sharing options...
RMweb Gold JohnR Posted March 30, 2019 Author RMweb Gold Share Posted March 30, 2019 2 hours ago, cypherman said: Which M7 do you mean. The older one or the new one. In the older one I would use a little bit of steel/brass tube glued into the boiler over the driving wheels . With enough cut away to avoid the engine Sorry I didnt make it clear - its the newer 2006+ model. The old Triang one didnt really have this sort of problem, and there was plenty of space to stick anything in to make it heavier if necessary. Link to post Share on other sites More sharing options...
DCB Posted March 31, 2019 Share Posted March 31, 2019 Probably easier to fit a Black Beetle or similar to power the bogie. My old 1970s M7 was/ is a total nightmare, it needed a split axle pick up bogie and a lot of fiddling to make work and it still slips to a halt if there is a dip in the track. Link to post Share on other sites More sharing options...
SRman Posted March 31, 2019 Share Posted March 31, 2019 (edited) The newer M7 suffers from poor balance and weight distribution, even worse if you bought a factory DCC-fitted example. In hindsight, it would have been better if Hornby had fitted the decoder socket at the rear (in the bunker area?), and added weight at the front, over and ahead of the driving axles. There are two weights in the side tanks (one in each, unless you have the aforementioned DCC-fitted model, in which case there is only one weight in one tank). I have not done this yet, but I will one day replace the tank weights with something heavier (real lead). My own models are fitted with TCS DP2X-UK direct plug-in decoders, which means I did not have to remove any tank weights. If at all possible, add weight over the decoder socket, but there is not a lot of room there. If you are really keen, remove the decoder socket altogether and wire everything directly for DC operation, or hardwire a decoder in and place it at the rear of the locomotive, then pack more lead in the area vacated by the socket. Edited April 1, 2019 by SRman 2 Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted March 31, 2019 Share Posted March 31, 2019 On 30/03/2019 at 11:21, JohnR said: What's the best way to add weight to these locos? Any tips on material to use and where to put it? ... The crucial question is how far you are prepared to go in dismantling this very good looking model, in order to replace components with the most dense available ballast, which for practical purposes is lead? The weighting efforts should be concentrated forward of the rear driven axle centre line. If you can add enough weight forward to get the centre of gravity forward of the midpoint of the coupled wheels, then you can add weight just to the rear of the axle centre line to bring the CoG to the center of the coupled wheelbase, but no further back that that. On the mechanism the bulky and light mounting arrangements for the decoder socket can all go: rearrange the wiring into the firebox end of the boiler, stuff the vacated volume in the smokebox with lead. It is possible to glue a strip of lead sheet on the underside of the keeper plate. On the body removing the plastic chimney and replacement in turned brass or whitemetal, and likewise the forward air tank in cast lead, add as much detail around the front platform as feasible in metal, inside the weights in the side tanks can be removed and lead sheet substituted at the forward end only, ahead of the rear coupled axle centreline. The ideal arrangement of an 0-4-4T is motor in firebox driving the rear coupled axle, and as much metal construction as possible forward of the rear coupled axle and all voids in this location packed solid with ballast. As already observed above, light tackle like the decoder socket should go in the bunker. 1 1 Link to post Share on other sites More sharing options...
RMweb Gold JohnR Posted March 31, 2019 Author RMweb Gold Share Posted March 31, 2019 Thanks. Ideally I dont want to dismantle it in that way - its far better than anything I managed to turn the Triang model into back in the day. I'll move the DCC socket (I''ve not fitted a decoder into it yet, but do plan to someday). and try to stuff lead in where I can following your suggestions. I didnt think of sticking some on the keeper plate! Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted March 31, 2019 Share Posted March 31, 2019 I think it's a cracker, remains a very classy model for appearance, and while the mechanism layout and thus weight distribution is far from optimum, the mechanism is a sweet running job. (I wait with interest to see if Bachmann will turn in a better arrangement now they are venturing 0-4-4-T - wards...) Something I forgot to mention in my earlier post: the pick up wipers on the bogie. These need to be adjusted to barely graze the wheelbacks, and a rub over with soft graphite on the wheelbacks won't hurt. I have had three of these to look at over the years, and on all of them the bogie wheels were visibly retarded by the wipers - often only in one direction on each wheelset - with consequent significant loss of pulling power. Optimally adjusted in this respect, even without added weight I could get them to pull 12 of Bach's BR mk1s, on level track. Any adverse gradient with anything approaching this sort of load immediately caused a slip to a stand of course... 1 1 Link to post Share on other sites More sharing options...
SRman Posted March 31, 2019 Share Posted March 31, 2019 Adding slightly to 34C's post above, you will probably find that on an uphill gradient, the model will pull better bunker first, because the weight is being transferred onto the driven axles. I totally agree with him regarding the lovely appearance of the model and the smoothness of the mechanism. Incidentally, this weight distribution problem is not confined to Hornby's M7; a couple of other 0=4=4T models also have similar problems. In my experience, these include Hornby's more recent SECR H class (no room at all ahead of the second axle as it is completely full of motor!), and Kernow's LSWR O2 locos as well (I haven't attempted anything with mine, yet). 1 Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted April 1, 2019 Share Posted April 1, 2019 13 hours ago, SRman said: ...Incidentally, this weight distribution problem is not confined to Hornby's M7... Thus my interest in seeing how Bachmann arrange the internal layout on the two 0-4-4T they have underway. Will they do better in weight distribution? It is certainly possible to better what has been done in RTR OO to date. 1 Link to post Share on other sites More sharing options...
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