OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Scott Bonnar 45 project

Hello.

I recently aquired this SB45 from a bloke down the road.



Long story short - he had bought it from someone, it wouldn't go, they established it was the coil, couldn't get a replacement and gave up.
Then he started pulling it to bits with the intention of using the handle and rear roller as a lawn roller.
Which never happened and so in the end I ended up with the whole thing for nothing.
In pieces....

So I'm slowly putting it back together to see how everything fits and if anything's missing.
At this stage I haven't looked at any diagrams or manuals, just plodding along over a couple of beers and trying to work out what goes where.




This is where I'm up to at the moment.



Most bits seem to be there but this is rather worn....
(Please fill me in on what these parts are called as we go )


I have a lathe so making a new piece isn't a problem.
Does it just sit there like that against the shaft with a bit of grease or what's the go there?
Clearly it's been overheating and melted against the clutch.
Would making one from brass or something similar be better or should I just stick to plastic/nylon?




Does the bolt going through here just rest against the steel profile or is there a bearing or something to go on the inside?





I also seem to be missing one of these knobs but that's no big drama as I'll probably have something laying around to replace it with, or I can make something up.






I'm not doing a full nut and bolt resto here, just want to get it working first.
Maybe later I'll look at a respray etc, but that's in the future.




Well, that's all for now.
Comments, advice and suggestions welcome.


Cheers.

Hi Platypus,

A nice little project you have there I've just about finished a SB45 resto myself, and it's been very enjoyable and not at all difficult.

The melted piece of plastic is the thrust pad. I've noticed a few other members have had the same trouble. It's caused by an alignment/adjustment issue with the clutch assembly, which causes friction against the thrust pad, resulting in it melting. It should have some clearance between the pad and the clutch cone. Deejay covers it very well in this post HERE

Here is a picture of my Rover also..



Almost all parts are available from the OutdoorKing store and are competitively priced. The thrust pad is available
HERE. The early SB45 thrust pads were made from brass, but the plastic ones are fine if the adjustment is correct. I'm not quite sure what you mean regarding the drum clutch release lever but you can see it in my photo also. If you'd like some pictures from inside the chain case, just let me know. The exploded parts diagram will also help.

Michael

Hello.

Thrust pad... ok I see.
So it should be more or less wedged in to the metal bracket and not touching the shaft or the clutch assembly.

Yeh I'll just make one myself.
I enjoy making bits and pieces like that.





As for the clutch release lever, yes I was wondering if it should just have a nut on the inside, like in your photo.
Very good.
Thanks.

Yes, the thrust pad sits inside the clutch fork and doesn't touch the inner clutch cone when it is engaged and cutting. When you disengage the clutch, the fork moves the thrust pad along the drive shaft until in contacts and pushes the inner cone in.

And I agree it looks like you're just missing the nut from the drum clutch lever.

Keep us updated on your progress, it'll be good to see it all back together and ready for work

Hi Platypus, I would encourage you to purchase this part, as they are not expensive and without one to use as a template for fabrication, and the correct material, you will not achieve the correct cutter clutch adjustment that is required....and to replace it you need to remove the engine and clutch assembly, which is time consuming.
Also, regarding the primary thrust pad, it is a sliding fit into the clutch fork.

Time stands still when I'm in the shed.

Fabricating that part won't really be a problem.
I see what you mean about it being cheap though.
I'll be needing a few parts for this project anyway so I might end up ordering one along with the other bits and pieces.

I enjoy fabricating things and one of my hobbies is building rather large radio controlled cars using whippersnipper or chainsaw motors.
I fabricate all the drive and steering parts myself, and use gears and sprockets from angle grinders and the likes for transmission.
I'll get some pics and videos up in the off topic section some time when I'm on the desktop computer.