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

Hi all
I got my self anather scott bonner .This time its the diplomat 430. Cost me $20 from a auction (bargain)lol. I got the motor running ok but the clutch seems to be castus. I subscibed to the Manuals secton and found the parts list but couldnt find an actual manual. The problem I have is how do you remove the clutch pulley?

Congratulations Jason, sounds as if you've got a bargain.

Dismantling the pulley clutch on the Diplomat involves a non-obvious process. Due to the ingenuity and persistence of Outdoorking members we now have a fairly detailed explanation of it in the archives:

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=22699&page=1

To rebuild the pulley and clutch you just need to remove it as an assembly, then work on it on the bench. You do not need to get into the complication of removing the roller, so only the first part of the explanation is relevant to your needs.

That thread is gold! Now I know where to start. If that plastic ring gear is stuffed I will take to work and cast one up out brass or ally. Sounds like it's just the gasket is glazed,worn.. I will update on my progress. Cheers

Made some more progress!
Remove the allen key bolt..

Then I slowly worked the pulley off with a couple off screwdrivers.. Its off!! Finally

Then remove these bolts either side of the mower..

Then the roller simply drops down..

Then work the cap off.

Just what I wanted to see! An aluminum gear.

Just got to figure out how to get this pulley apart now. Somehow clamp the gear I spose.

Jason, thanks for posting those pics, they are a valuable supplement to the other thread. It looks to me as if the pinion screws onto the pulley shaft - if your second-last picture went up a bit higher we could probably see the end of the shaft and be sure. My method for removing such things is simple but involves you making a tool. The tool spans the two holes in the clutch member that squeezes the clutch material against the pulley. It is apparent that the previous owners have not made a proper tool but have mangled the clutch member a bit with loose pins, probably with threads on them. If you make a tool by taking a piece of, say, 1.25 by 0.25" flat steel about 15" long, drilling a pair of holes the same diameter and distance apart as the holes in the clutch member, and welding two pieces of steel rod through those holes, it should be useful for removing one of the other pulleys on the mower as well, and will not harm the mower, even with repeated use. To hold the gear without damaging it, my method is to squeeze it between two blocks of soft wood, in a vice. The gear teeth will bite into the wood, preventing rotation without harming anything. Then apply your pin-wrench to the clutch member and it should screw out, and later back in, with no fuss. Be careful, because I believe it would require a left-hand thread. The pulley is driven anticlockwise by the belt to move the mower forward, and if it had a right-hand thread in the pinion, it would simply unscrew in service.

I think there is a good chance that the plastic gears usually failed because someone tried to use the gear train to resist the unscrewing of the clutch member, to service the clutch lining. There is only one way that could end, with a plastic ring gear restrained only by moulding it onto a knurled surface on the outside of the hub. However they could also have been broken by people trying to pull them off, instead of dismantling the whole central mechanism of the drum.

I got it apart. I put the gear in the vice. Bloody hell it was tight! I used the blow torch on the gear cause they must have used lock tight on it. The gasket clutch looks pretty glazed. I dont understand how the lever thing works? Guess I will get some more gasket and make a new clutch. I wont be using lock tight till I know the clutch works again.

I clamped the part that the allen key screws into in the vice then spun the lever. I know how it works now. obviously the gasket clutch slipping bad then. So where would you buy this gasket stuff from? Looks like the gasket they use on engine sumps,rocker covers..

Now I don't know how it works, Jason. Can we have another pic that shows the left end of the shaft, please, plus the center of the pulley, and a closer view of the right hand end of the drive bearing housing (that's the part the Allen screw is screwed into)? I don't know how the pulley is supported, and I don't know what supplies the clamping force for the clutch, or what disengages it.

Your clutch friction material is severely glazed, indicating it has been slipping, as you said. This was probably due to insufficient clamping force - either due to wear, or maladjustment. Since I don't yet know how the clamping force is supplied or adjusted, I can't tell which. The friction material is usually cork, which is indeed the usual material engine sump and rocker cover gaskets are made from. I think you can probably buy it from an automotive shop such as Repco.

a good old mower shop usually keep clutch corks for scott bonnar $10 tops cheers steve.

Hi Jason, what you require is the cork clutch lining as Steve (deviosi) has said; I have done some research and found that the Diplomat 430 cork lining is the same as the Scott Bonnar Model 45 drum clutch and is available from the OutdoorKing Online Store. Click HERE

Hoping this helps,

It turns out that one of my workmates has a very old scotty. He told me to go to this particalar mower shop where they will have the right cork lining i need. They had some thin gasket cork in a roll but i thought that wouldnt be much good to me. It was very thin unlike what the clutch lining is now. I tryed repco,autobarn no luck..

Thanks darryl I will buy that clutch lining. I will put up more pic's of that clutch assembly to "Grumpy"

I am also trying to find new Diplomat decals. Any idea what ebayer sells them? I have also been trying to find out what colour green the mower is. Once I get it running well I want to restore it. I spose the briggs&statton decals would be on ebay USA..

Hi Jason, if you could send a private message (PM) to willingworker; Click HERE He will be able to supply the correct decals for your machine.

For the Briggs and Stratton; Click HERE and then click on "Decals" and search for the particular decals you require for your engine.

As for the colour schemes, Chevy orange heat-proof engine enamel is very close and is available from most automotive spare parts outlets.
For your mower frame paint and engine colour discussion... check out the threads...Click HERE

Don't forget to let us know how you get on.

Thanks. I done up model 45 recently and couldn't find any hammertones similar. So just I painted like my newer one. Like a kermit green. Sold it off on eBay. I want to keep the diplomat I am sick of smashing the My 45 into stuff!

I found some Briggs 3hp decals on eBay US that seem ok. They don't offer freight to us but..
I will keep updating my progress. Just waiting on the clutch lining now.
Cheers

Here are some more pic's of the clutch assembly. Just to give anyone an idea of how it works.
Where the arrow is near the bearing. That slides when that lever is engaged..
It pushes the pulley into the outer plate.



The problem I have now is the model 45's Clutch lining I have now is a little bigger than my old one. So how should I modify it? I could trim the outside of it but then I would loose clutch face..mmm I could cut across it in four ways that might work.. Any idea before I chop away.

One of the machinests at work cleaned it all up for me. Done a brilliant job!


Old gasket clutch..


New gasket clutch used on the Model 45's

Jason, the cork can be cut easily with a box-cutter or even better, a scalpel. (The scalpel's narrow blade makes it easier to follow the curve.) If you do it that way, mark around the outside with a pen to show the exact amount you want to cut off, so it will end up round and concentric with the inside circle. I'd probably try to save work by just trimming it with the disk sander, but that's me - the disk sander probably gets more work than everything else in the workshop put together. Note, this is a 14", pedestal-mounted sander - don't try to do it with a hand tool.

I do not think cutting the lining into quadrants is a good idea. The lining is likely to come apart due to erosion of the clutch face, originating at each of the radial cuts. This is mainly because it is a soft lining - hard linings from car clutches can stand radial cut lines, but I don't believe cork can. At best, it would put a lot of strain on your glue at the leading edges of each segment,.

Thanks for that grumpy. I broke my scalpel's so used scissers instead. I cut the outside of the gasket then used the outside i trimed off on the inside.


I used araldite then let it sit with weight on for a few hours.


Yay it goes again! The clutch works good. The blade adjustment is different. You adjust the bottom plate to suit the reel. Its leaving lines on the lawn? But overall i am happy it goes again!

Thanks everyone for your help!

The motors govenor is cutting in and out. Any idea what the go is there?

The exhaust needs replacing. See all the black carbon crap behind the motor.

First, the "governor cutting in and out". Do you mean the engine speed is cycling up and down, maybe 2-5 seconds per cycle? That is called hunting, and is nearly always due to the mixture adjustment being set a bit lean. Turn the mixture screw an eighth of a turn anticlockwise and see if the cycling gets less intense or goes away. You may need a bit more than an eighth of a turn if it is severe. If it actually is hunting, the only cause other than lean mixture, is friction in the mechanism. The Briggs mechanism is only likely to be stiff or sticky if some accident has befallen it.

The black mark behind the muffler outlet may be due to the hunting problem. Each time the governor cycles, it slams the throttle wide open for a short time, and you'll get some black exhaust smoke (it may be too thin to see, but you'll be able to smell it). The muffler only needs replacing if it is rusted through or is wobbly.

A well-adjusted reel-type mower is supposed to leave stripes on the lawn, the width of the cut. Because the stripes show that you are using a reel mower, most people make a point of reversing the direction of mowing after each longitudinal cut. The rear roller is then rolling alternate cuts in opposite directions, giving you the stripes. Take a look at a bowling green or a championship football ground - no self-respecting groundsman would present the site without perfectly smooth, even stripes.

The motor is going good now. I found a spring under the air filter. It looked pretty loose so tightened it up now the motor runs well. The muffler is very rusted so I will replace that soon. I think the reel needs machining. The reels edges look rounded a bit.

Its a great mower for tight yards! Catcher is easy to remove and to refit. A lot smoother with less vibrations. I have read they have design fuilts. Probibly the plastic ring gear. I am very happy with it. Just hasnt got that look the model 45 has.

Where is the serial number? I wouldnt mind knowing how old this beast is..

That sounds as if the governor spring had been damaged (stretched), or the bent tin bracket that holds one end of it was bent out of position. If the spring is no longer close-coiled, it would be best to get a new one.

If the reel edges are rounded, it does sound as if it is very blunt. The bed knife (fixed blade) is probably blunt as well. How much meat is left on the reel, to allow future sharpening? Normally the reel and bed knife are both sharpened together, by someone with experience. Our reel mower guru, Deejay, recommends asking the local bowls club greenkeepers to tell you who sharpens their mowers.