OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers scott bonnar 430 and 590 diplomat

hi there what a great site fantastic ive had my 430 for about 8 years now.can someone please tell me the diffrence between the 430 and the 590 models.and there always seem to be alot of mower shops out there that dont like working on the diplomats,what is the reason for this, and also are parts still avalaible for this model as my mower shop stated these mowers are no good,and if my clutch goes its time to get a new mower is this correct?as i have never had a proplem with my diplomat.i love the idea of the rear catcher i can get into tight spots.hope someone can help answer my questions.love my diplomat .also is there any way of getting a copy of the manual for this model cheers marc from adelaide

Hi Marc,

The clutch cork is available HERE and as to them not working on the 430 it is because they don't have the knowledge base these days to be able to repair them. If it requires thought then it is too hard so it is stuffed buy a new one.

This is happening more and more as the good old Technicians are leaving the industry. The problem is these days the young people coming into industry are not trained that if something is broken it can be fixed and you should buy a new one. It took me 6 months to get the same attitude out of a young person that I am training and believe me it is not easy to do, now nothing is stuffed unless I say it is and that only happens very rarely.

I will get off the soap box now because I don't think this page would be long enough if I keep going on with my thoughts.

The parts list for both machines are in the parts list and manuals area and you will see the difference which is one has the clutch and the other is drive by a belt tensioned leaver and the size of the cut.

Hope that this is of some help.

And as Bruce jumps off the sopa box I will jump back on.

The whole its stuffed buy a new one thing, is really starting to get under my skin, I am pulling4-8 perfect machines a week from scrap metal with the local shops customer tags on them, all they need is maybe a bit of fuel line maybe a spark plug, only simple stuff.


As to parts no longer being available, 9 times out of 10 something aftermarket is made and available in the catalogues if you look far enough. Hell I have seen carby kits for my 50 year old victas listed somewhere.

Seems like the mower dealer has made a business decision not to sell second-hand mowers beyond a certain age, and there is no other official dealer who feels differently, so Joe has become the 'other dealer' for that part of the world - getting mowers for nothing, and repairing them for not much. This should be a good deal for you, Joe. The dealer seems to feel that selling repaired old mowers in competition with new mowers is not the business he wants to be in, probably for marketing reasons (or maybe because he doesn't have competent mechanics). I can understand why he doesn't want to weld up failed steel Victa mower bases - if you costed the time it takes, you probably wouldn't do it yourself. However if you can pick up 5 mowers a week for nothing, repair them in less than an hour each of your spare time for less than $20 each out-of-pocket expense, and sell them on ebay for $100 each, then you are making $80 an hour and having fun doing it. If it takes 2 hours each (including ebay time), I can understand why the dealer doesn't want to do it.

hi guys thanks for the response.ive paid the 15 bucks for the access of the parts and manual section, but i cant find what actual parts are currently available for the 430 and what is the difference between the 430 and 580 cheers marc hopr yah can help

I will be uploading hopefully this week the complete book on Scott Bonnar mower history from 1925 on which includes pictures of the mowers.

If I can't get it done this week it will have to wait a few weeks as I have a lot on at present.

Hi all,
Being a young feller myself I see exactly what you are talking about first hand every day. My generation is a bunch of do-nothings to be totally honest. All they are interested in is buying a new mobile phone and texting each other. when I tell them I have spent my weekend under a ride on mower they look at me as if I�m an alien and tell me I�m a looser until I explain every mower I fix is another $100, then for some funny reason they want to come work with me. It worries me to think what will come of this world with them in control.
Anyway correct me if I am wrong but I believe that the difference between the 430 and 580 was width of cut.
Bruce if you do not have the manual for the 430 I think I have a copy floating around somewhere.
Regards Jay

Jay,

Both manuals are already in the parts list and manuals area at present and I am trying to scan the history of scott bonnar and upload it as well but it is not a small book and will take over an hour to scan and then upload.

As to the young guy's these days it is a totally new learning curve for us older people. It took me around six months of learning how to work around the way they think but if you have the patients then sometimes it works.

I have an apprentice which is proving a hard nut to crack as all he is interested in is money and not really knowledge, so I am assuming as soon as he finishes his trade he will jump ship. They don't really have any pride in what they are doing so it is a real problem for them.

Hi Marc, I have a S.B.Diplomat self drive mower just been given to me, it has the cork gasket hanging out between the flat clutch plate and the pulley, I have no idea how to remove the front plate, it has two holes but they are not threaded, my mower is belt driven and has a handle that puts tension on the belt when pulled back. It has a 2h.p. briggs and stratton engine. no model or serial number on this model (it is in the manual (which I dont have )
thanks for any help.

Hi Marc
If you are still after info on your mower (your post was almost 3 weeks ago)your model sounds like my Diplomat 430. I built mine out of 2 diplomats about 14 years ago so I can't quite recall about dissembling the clutch. I do have a part explosion if you need it, let me have an email address and I will send it to you as an attachment.

P.G. This topic was discussed under a different thread...see HERE

Hi all, Any tips for re setting reel and bed knife after sharpening? never had to do this before.
It is a diplomat 430.
Regards.

gravelman, our main guru on this is Deejay, who has been out of contact but is now back in action. BTW, can you stick to one thread for these questions please? It makes it easier in future for people who use the Outdoorking archives to solve their problems or read up on a a subject. (Yes, there is a reason I'm called grumpy).

Hi gravelman, Never having owned or worked on one of this model of Scott Bonnar, I am flying blind here, but I will try and give you some advice.

You see the main difference between the Model 45 and the Diplomat 430 is the cutting set-up and drive train.

In the Model 45, the cylinder reel adjusts to a fixed bottom blade; whereas in the Model 430, the cylinder reel is fixed and the bottom blade adjusts to it.

For this reason the cylinder reel must be ground perfectly parallel; for it to achieve a correct cutting action, along the entire length of the bedknife (bottom blade)

From looking at the illustrated parts list for this model, I suggest you re-intall your reel assembly, bottom blade assembly and then finely adjust the bedknife to the cylinder reel....Remember the reel has to almost contact the bedknife, and thus spin freely by hand....the front perpendicular edge of the bedknife and the helix spiral of the sharp reel, is where the cutting action occurs.
Let us know please how you get on.

Alignment went well, got it to a point where i was happy, but there was one tiny spot where the blades met ever so slightly.
I ended up leaving it there as any farther away and there was too much clearance at one end for my liking, plus it was only just just touching i figured it would wear nearly instantly. The cut was superb compared to how it was before, i am happy, although i did make one mistake - due to the reel being new i did not re adjust the height enough and ended up with a brown lawn.

Thanks for your help.

If you have bedknife adjustments at both ends, bear in mind that it is quite legitimate to adjust them separately so the knife is very slightly twisted. You should not end up with more clearance at one end of the knife than you have at the other.
You probably know that the ultimate test is to feed a sheet of newspaper through between reel and knife, then rotate the reel. Ideally you will cut the paper smoothly the whole way across the knife. Your tiny point of contact is not really an issue if the contact is very light. Any substantial contact will cause grooves in both the reel and the knife - if this happens you are up for a re-grind of both parts. Once you have some skill in adjusting the knife, you may want to mark the contact spot, and relieve the knife in that precise spot with an oilstone - but this is postgraduate stuff: more or less for bowling green-keepers only.
Glad to hear that it is mowing nicely now. Soon you'll be getting those striped cut-marks (each the width of the mower) that enthusiasts love to see.

Hi gravelman, Great to see she's up and running and you are happy with the result.
Grumpy had given good advice; there is a slight amount "give" that will achieve perfect alignment, but providing the contact is very slight, you will find it will bed itself in, fairly quickly.
Congrats on a good job.

Thanks guys, i just cut my grass for the second time since the grind tonight, and noticed it cutting deeper on the left side (had wondered why before), upon investigation i found the front roller was missing a bush/spacer thing where the left side roller assembly connects to the frame. This allowed the left side to drop about 3mm lower than the right.
I will have one made at work tomorrow which would fix the problem.
Question tho, are the two bolts that hold the roller assembly in place and allow it to rotate supposed to be loose fit or do you loosen then adjust roller and then re-tighten the bolts?
Also, can a front roller with bearings be found at all? or do i need to get the plastic end caps made new with bearings?

Thanks for all your help.

Gravelman,

Is this the plastic end cap you are talking about and if so you can get them HERE

Yeah the end cap is similar to mine. I want bearings tho!! That one is from a 45, mine is 430 - not sure if they are the same.
Got my bush made, now i just have to figure out how the adjusting should be done??
are the two bolts that hold the roller assembly in place and allow it to rotate supposed to be loose fit or do you loosen then adjust roller and then re-tighten the bolts?