OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Model 33 clutch

Hello everyone I apologise if this has already been answered. Please tell me which direction does the brass nut holding the clutch rotate to remove it i am in the process of replacing the old Kirby engine that has died with a replacement engine. Please also tell me what the shaft size and length of the drive shaft is as i have read that it should be 5/8 or 3/4 inch. Which is the right size. Thankyou for listening to me.

G'day Hermosil
I'm hoping a member will know this.

But - best guess - it should be a normal RH thread.
There is no engineering reason it should be otherwise.

The engineering specs for cranks are below.
I'm not sure which crank it will be.

Extension 2 is 5/8"
Extension 3 is 3/4"
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Jack

Thanks for the reply cyber jack so to be sure i shoud be turning the nut anticlock wise as in the picture then. I just want to be sure because its going to take a while of soaking it in wd40 then using a gear puller on it Once the nut is undone. Thanks for the pictures they explain how the bits all work together

G'day Hermosil
No, opposite to your wrench set-up.

Looking from the chaincase side, the nut needs to rotate clockwise -
that is, towards the rear of the machine - away from the fuel tank.

In your picture, turning the adj spanner anti-clockwise would tighten the nut.
Put the adj shifter on the other side and push downwards.

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Jack

Thanks for clearing that up i must be suffering a bit of brain fog i will have another go tomorrow the correct way

Hello all i have had a set back with my clutch removal a piece has broken off it so my question is now 1 can it be welded back on if so mig or oxy ? 2if not where can i get a replacement one from thanks

Welding cast iron is a specialists job and believe me you're not the first to Pioneer this act so don't feel too bad. Model 33 clutches can be replaced with a Model 45 set up as the 33's are not available anywhere. Matter of fact Model 45 units are currently not available either as there has been a manufacturing issue with the bore size being out of whack as they come out of a mould and are not bored to size. All the current clutch halves out there are faulty and anyone thinking of purchasing one needs to be totally aware of the suspect units that are as bad as an old flogged out one. The nominal bore size should be 15.87mm, but these current units can be anywhere between 16mm and 16.5 and also slightly oval as well ranging between the two figures quoted above.

This observation is current at 20/06/2019 and will change at a later date, thus why I've documented the date here so when this is viewed in the future it'll probably no longer be relevant.

At this point in time the only way out is if you are buying a new engine is to buy a 3/4 sized PTO output shaft unit and then the respective clutch half to suit as those are originally made in 5/8 size and then bored out to 3/4 and as such are no issue at all.

Anyway in regards to your issue Hermosil, I'd wait until new 5/8 clutch halves are again of a satisfactory standard and then convert over to the 45 Model set up.

Cheers,
BB.

Thanks for your reply Bonnar Bloke I didn't think that welding it would be an option for me. So a 45 model clutch will work with the modell 33 drive line. It makes sense as the shaft on the mower end is 3/4 . Ahh well i will have to wait for one of these clutches to become available. Just as well i haven't bought the engine yet.

Hi Hermosil,

If I recall correctly you'll just require a packing spacer to be placed inline within the clutch fork area, but that's nothing uncommon to do.

Cheers,
BB.

Thanks for that there is always a way of getting things done ie using a 45 clutch replacement ill get this old girl going again eventually. Thanks very much for your advice.

Hello every one an up date on my model 33 clutch situation. Success! I have replaced the engine with a new b/s engine with a 3/4 shaft and a 3/4 model 45 clutch as bonnar bloke suggested and i t all works quiet well. I bought the engine half of the clutch locally and had to source the other half from a bout 3 or 4 different sources and put it together myself it works quiet well thanks for all the advice as it has been a great help to me . My only question is should i repaint it and get new decals or not?