OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Scott Bonnar Model 430 Diplomat clutch issues

Hi Bruce, hope the pictures I have sent with the help from Deejay, they may help you as to what the model is of the Diplomat and help me to get the flat clutch plate off and renew the Gasket.
Thank to you both.

jray

pics for bruce

Hi jray, I have put all the pics into one post....(just a matter of posting all the [IMG] strings into the one post) to make it easier to see the problem you are having.
I can identify your model for you, it is a Model 430 Diplomat Scotty, and this particular model, along with the 590, won an Australian design award for being the first cylinder mowers with a rear mounted catcher, to allow you to mow up to a fence line or wall without removing the catcher. The only difference between the 430 and the 590 is basically the width of cut, much like the 17" and the 20" Scotty Model 45's.
Thanks for posting the pics, and it's now over to Bruce to help with the clutch problem, as I have had no experience with these particular models.
Best of luck with it, and we hope to see you posting in the future.

jray,

The drum pulley from memory is left hand thread so if you get a couple of bolts and put the into the two holes (try to get ones that are a neat fit) and then get a screwdriver and do it up to remove it. Don't forget it is left hand so you need to do it up to undo it.

It might be a good idea to hit the centre part to releave the thread.

If you are going to work on this or other belt-drive SBs from time to time you might want to make a tool for dismantling this clutch (same one will fit the reel's drive pulley by the look of it, but you'll need a different sized one for the engine pulley). Just find or cut a piece of quarter or three-eighths inch thick steel plate about 2" wide and a foot long, drill two holes in one end exactly the right distance apart, and weld a couple of pieces of steel rod (or bolts with the threaded part cut off)into the two holes so they stick out the right distance to reach the bottoms of the holes in the clutch. Use the biggest rod that will it into the holes in the clutch, and make them a close fit in the holes in the steel plate. Weld them on the back of course, not on the side that has to fit flat against the clutch. The tool you make will look like the standard tool that comes with a big angle grinder to change disks. You might also put a pair of holes and pins in the opposite end of the tool, to fit the engine pulley.
And don't forget Bruce's warning that the clutch thread is left-hand.

Thanks Deejay, Bruce, and Grumpy, will give this a try, I will make up a tool as Grumpy suggested, before I start.Jray

Jray, sooner or later you will need to remove the reel for sharpening, and that requires removing its drive pulley. To hold the pulley while you undo the retaining screw, you will need to drill a hole exactly at the midpoint between the two pins in the tool. The size of the hole must match the diameter of the socket you will use for undoing the screw. This should make the job easy.

thanks Grumpy for the advise on removing the reel for sharpening, I am still getting the tool ready for removing the clutch plate, but it turns by hand, as if its not engaged in a thread, I tried hitting the centre of the clutch plate with a hammer (as Bruce suggested to releave the thread) so hoped it might work in reverse, any more ideas?.
thanks -jray

Does it turn freely both ways, or only one way? It may have a sprag clutch in the roller. Otherwise I don't see how it could drive the mower forward.
I suspect you are supposed to dismantle the clutch with the belt installed. You could then pull the belt clutch to lock the cylinder pulley, allowing you to unscrew the clutch center.

thanks Grumpy, it turns freely both ways, so I will put the belt back on over the weekend and give your suggestion a go.

I used a piece of flat bar and drilled 2 holes to match the pulley holes, in which i put matching bolts with a nut either side. Nice tool for the job.

Hi grumpy, the rollers on this model don't have a sprag clutch...it has a ring gear and pinion. The ring gear is made of plastic and often break, whereas the pinion is made of metal.There is an after-market ring gear now available in metal, tho expensive.

I'm also struggling to remove the centre plate with the 2 holes because it spins freely in both directions.
I quickly made a tool like you describe for removal, but if it spins how can you unscrew it?? and it spins independantly of the pulley so using the belt to hold the pulley wont work.
I tried to "shock" it off by belting the centre with a hammer then belting the end of the tool, hoping it would release, but nope.
I'm working on the theory it's a left hand thread therefore it would unscrew in a clockwise direction.
Can anyone tell me what the Allen screw does on the inside of the clutch housing?

We need a report from someone who has dismantled one. By the way, bear in mind that the clutch drives the drum (roller) via a plastic gear, so rough treatment is not a good idea.

Two disassembly methods occur to me, from looking at the parts list without any better information. The first is to dismantle the drum and find a safe way to hold the plastic gear that drives the internal ring gear in the left half of the drum. The second is to hold the left side of the drum from rotating, and turn the clutch clockwise with the special spanner, using a steady, gentle force to unscrew the clutch shaft from the inside of the plastic gear. However the second method can only work if my interpretation of the parts list is right, and the clutch shaft is screwed into the gear. The parts list is not intended to be an assembly instruction, it is just a bunch of extremely blurred pictures.

As this thread is over 12 months old I will now close it for the archival value....If any member has anything to add, please send me a PM.