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

Hello. I have just purchased a Scott Bonnar 45 17" with a 3HP B&S engine. All appears fairly original.
I noted a missing bolt in the clutch housing and some slop in the clutch so followed DeeJay's excellent video and pulled it apart.
The captive cotter is damaged as is the key on the engine side and there is slop in the engine side clutch half.

I am concerned about the damage to the shaft. There is wear where the captive cotter contacts and in the keyway. Obviously I would rather not have to replace the shaft :-(


Your thoughts would be most welcome.

Hello waverider

So, let's sort the image issue.
Right click on the image (below) and save it to your computer.
See if you can then upload it...



Hope this helps.
-----------------------
Jack

Thanks Cyber.Jack - all fixed :-)

Hello waverider

That's good news, and great photos for assessment.

I do not want to preempt what members might say on this, but I
believe the crankshaft should be serviceable, provided a new cotter,
key and clutch half are installed. The clutch halves come in two
sizes, so please confirm the size before ordering [5/8" or 3/4"].

Moderator BB is on holidays in Melbourne but may be able to offer
a response by tomorrow.

Hope this helps.
-------------------------
Jack

Thanks CyberJack I'll wait for others to respond

Thought I'd just add the engine details.

Hello waverider

A big thank you for that information.
It is very helpful to match up model with engine code.

The engine was made in November of 1981, meaning that this
is one of the last Scott Bonnars made in Adelaide, before
production was moved to Rover's Eagle Farm factory.

Hope this helps.
----------------------
Jack

Hi waverider, and a warm welcome to the forum. I'ts great to have you aboard and always nice to have another Scotty owner with us on ODK


Here's how I would tackle your problem:
Purchase a new engine shaft key
After ascertaining the size of the shaft as Cyber Jack has explained, purchase a new model clutch half plus the 2 grub screws to suit....this will guarantee correct alignment and fixation to the shaft.
Put the machine back together and after adjustment (which we can help you with....Happy mowing!

Hi Waverider,

As both Mod CyberJack and DeeJay have eluded to that your engines output PTO shaft is quite serviceable and no need to worry about the wear factor on the key way. This is because the new design of clutch half is designed some what different to the earlier units that used the sliding cotter pin to clamp against the shaft while the new ones use two set screws to actually pin the the clutch to the shaft at 90 degrees to each other thus there will be no clutch movement on the shaft and the key steel is also pinned to the shaft, again no movement.

In the end all will be better than original.

Cheers,
BB

Thanks Deejay and BB for the replies. I have already ordered the parts from ODK not realizing I should use set screws instead of the cotter.
Does the clutch half comes pre-drilled and tapped for the set screws? If so I may be able to pick up a couple of set screws here rather than having to pay more postage ordering them online?

Hi Waverider,

The newly designed clutch half comes with the holes pre-drilled and threaded, so set screws are easily obtained and inserted. There is no provision for the cotter pin any more.

Cheers,
BB

Thanks BB - all I have to do is wait for delivery :-)
I thought I would add a few more images and get views on my rather uninformed opinions in relation to the condition of the machine.

It would seem to me that the reel and bottom blade need sharpening (along with a bit of straightening on two blades on the reel which have hit something hard) but it is still OK generally.

Chains and sprockets seem to be generally in good condition?

If anyone can see any faults I have missed i would greatly appreciate advice.







Thanks for the help.

Hi Waverider,

Well it seems that all your sprockets and chains are in good order so there's nothing more than adjustment and lubrication required.

Now as far as the reel and bed knife are concerned they most definitely require attention.

If you watch the following video you'll get this part done easily,

https://www.outdoorking.com.au/forum/ubbthreads.php?ubb=showflat&Number=31688#Post31688

As far as repairs are concerned to the bed knife you'll have to get your engineer to do that. There still seems to be a reasonable amount of material on it for future machining but until you give it to your engineer for final assessment you won't really know. Most engineers will suggest a new bed knife opposed to straightening as it may well be the cheaper option.(cost of item versus hourly rate)

Do not attempt to remove the the bed knife from the sole plate yourself as whoever you get to do the machining work will do that if required.

The reel will automatically require 2 new RLS5 bearings to be fitted as this is pretty much standard procedure when machining reels as the previous bearings will have x amount of wear in them which restricts the tolerances used in the machining process.

Also I would let your engineer straighten the bends in the reel as he would have the best techniques in doing that. This is a job for only experienced players to tackle.

I hope I've answered your questions at this point of the project.

Cheers,
BB

Thanks for the advice BB. It's much appreciated. I'll ask at he Golf Club and see who does theirs