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Collection, Preservation and Display of Old Lawn Mowers

43S Engine/Clutch alignment


I'm in the process of fixing up a second Suffolk Punch 43S and have hit a bit of a stumbling block towards the end. When attaching the engine and inserting the centrifugal clutch into its housing, it  does not seem to want to align correctly and once the engine bolts are fastened, it makes the chain very tight, making the blades stiff and also will mean that when the engine is running the blades will always turn. Clearly the clutch isn't aligning properly, but I can't seem to adjust this. There weren't any shims under the engine and I've tried adding some in various places but just can't get it right.


Any advice?


wristpin Sun, 02/01/2022

Might not be an alignment issue but just clutch shoes partially binding on their pivots or the clutch drum shaft partially seized in the spherical bush Another thought is that the combination of cutting cylinder and bottom blade wear may just be making the chain too short. If the latter, raising the engine on even thin shims will worsen the issue. 

m.watson121 Sun, 02/01/2022

Hi, thanks for that. 

So the spherical bush is brand new as it was just replaced as I was doing this job, so I think we could possibly rule out the drum shaft being seized in there. 

I'll have a look into the shoes binding on the pivots as my next port of call, as the cylinder and bottom blade are fairly new and not well worn.

Thanks again

wristpin Mon, 03/01/2022

Another point to check is that the clutch components are running true. Earlier machines had cast steel machined clutch back plates and drums which almost always ran true. Later machines had a cast alloy back plate and pressed steel drum welded to it’s shaft often exhibited a degree of run out in one or both components. When scrapping an early machine with the cast steel and machined back plates and drums , I save those to replace unsatisfactory later ones.