Bachmann Class 08 Coupling Rods/ Cranks

[drgj]

I did post this in the drive systems forum. I tried to delete that one but coudn't.

 

I have an early Bachmann O8 . It runs very smoothly slowly but at higher speeds not so well (I suppose higher speed is not strictly needed but was just testing it. I found that as the loco moves, the coupling rod on one side flicks  back and forth along the length of the centre wheel crank pin ( looking from above). On close inspection the crank pin on one end wheel is not vertical compared with the surface of the crank/ balance weight or maybe the whole balance weight is off.  Is this fixable? I notice on the Bachmann site that you have to buy the whole wheel set and cranks/ coupling rods.

 

Thanks

Dave

[34theletterbetweenB&D]

I would be very cautious, as attempting any adjustment of a crank pin in a fly crank risks damage to the fly crank, they are not as robust as wheels in my experience. My first thought for rectification would be to obtain a spare crankpin and substitute it. And I would only do that if the running was degraded within the scale speed range of 0 to 15mph of a gronk...

[drgj]

Thanks. Maybe replace the whole  pin/ crank assembly. I am not sure if it is even the problem. There seems to be a lot of play in the rod joints although not much more than another one I have.

 

Dave

[PMP]

The Bachmann rods are perhaps the weak point of the model in visual terms, so I swap the rods as shown below.

You can remove the rods and cranks from the wheel assembly quite easily. The issue with a crankpin alignment is it won’t be a simple adjustment as they are permanently fixed with the rods into the plastic moulded crank. One thing to check is are the rods straight, with no curves or twists in them.

I replace rods and crankpins using Romford crankpins and Brassmasters or Hornby rods as in the following link:

 https://albionyard.com/2012/03/04/trinity-08-brassmaster-rods/

This conversion also removes the sag in the horizontal alignment that some of these models develop over useage too. If you do not want to do similar conversions, the easiest option is to swap the wheels with those on the Bachmann spares pages.

 

Edited February 26 by PMP

[drgj]

Thanks for your reply. Will have a look at your page. Yes the rods on mine also have the horizontal sag which doesn't look very prototypical. Does your conversion still allow the loco to negotiate the same radius curves?

 

Dave

Edited February 27 by drgj
extra question

[Enfys_Rainbow]

Are the Brassmasters rods still available?

[PMP]

On 27/02/2024 at 07:57, drgj said:

Thanks for your reply. Will have a look at your page. Yes the rods on mine also have the horizontal sag which doesn't look very prototypical. Does your conversion still allow the loco to negotiate the same radius curves?

 

Dave

The minimum radii I use is Peco streamline medium radius, and no problems with those.