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

Hi all,

I'm new today - I managed to come across a Diplomat 430 yesterday. It's working really well, in exceptional condition, but I've read all of the threads regarding the dreaded nylon gear which I'm now worried about. I did, however, note that most of the threads were quite old, and often when people had sought to fix the problem, they were unfinished.

So, before I go and spend a bit of money getting the blades sharpened and a new belt which is needed, I'm wondering if anyone has any insight into this problem or a workaround? I'm no worried about having to modify this machine - not wanting it for collectors/originality sake, but just to get a nice cut on my new turf going in soon!

Thanks in advance for any insights.

Hi heady,

Firstly welcome to the ODK Forums.

Sorry that I can't be the bearer of any good news but some years ago there was a batch of around 150 metal replacement units made and they sold out within weeks. There were never any more made.

Sadly it's just a matter of time until yours lets go and thus why these have developed such a poor reputation through out the Lawnmower industry.

When it goes bang it will revert to a push mower, or even better a donor engine for a Model 45 with a crook power plant.

As previously said, sorry to be the bearer of bad news.


Cheers,
BB.

PS. Hope you didn't pay any more than $50 as basically you've bought an engine. Sorry that this sounds brutal but that's how it is.

Thanks so much for the quick reply, BB. Notwithstanding your bad news, it's still good to know where it sits. Unfortunately I did pay a bit more than $50 but not too much - and as I said, it does work for now so I might get some use out of it.

Can I please just confirm with you - and please excuse my ignorance here - but when you say it will revert to a push mower, does that mean that the blades would spin independent of the drum? If so, this might not be too disasterous for me, given that the area for me to cut is only going to be about 25m2 and so, whilst heavy, it would be do-able until I could get a decent 45.

Thanks again for your help!

Hi heady,

As a push mower they ain't that flash.

I have a friend who had an identical mower and the drive was suspect on it and we spoke about the actual mower and how he used to push it all around his back yard and he wasn't aware that it was meant to actually drive itself until I told him that it should, but when he bought it he was sold a pup as the seller showed him how to operate it and how you push it. DOH !

I bet that seller was doing cart wheels one second after George wheeled it out and put it in his ute.

After my words of wisdom session it quickly went to SB heaven without an engine, that item is in my shed now awaiting to power another Model 45.


Cheers,
BB.

Hi Guys,
I recently purchased a 2nd hand Diplomat 430 before hearing about the notorious plastic drive gear. As I am on leave at present, I thought I might give her a once over to check the bearings etc, also that drive gear. Much to my surprise my drive gear is actually aluminium. I suspected that the previous owner must have already had an issue with the plastic drive gear and had a replacement manufactured. I posted this in my local Facebook site and someone stated that the last one made had this drive gear fitted. Anyone else come across one like this?

Hi Greg,

I think you'll find that this one is one of those low volume replacements that were made and released on to the market briefly.

Cheers,
BB.

G'day folks,
IIRC we did find out some time ago, that SB supplied these aluminium gears as replacement parts, at some time before the Rover takeover.

Greg f, you've really struck it lucky! These gears are long unavailable new, and very rare.