OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Output Shaft Briggs & Stratton replacement engine

Hi everyone, thanks to all people on here for your help. I'm sure my question has been covered 1000 times but I can't find it, sorry.
Current shaft size on my Scott Bonnar 45 is 5/8, I can get a cheap 3hp Briggs and Stratton with with a 3/4 shaft, can I. Make it fit? Is it worth the stuffing around? What's required? Or should I just get another exact replacement?
Thanks in advance

Hi Calvin74, my understanding is that you will need to match the inner clutch half to the output shaft of the engine. So if you're current output shaft is 5/8" and you switch to a 3/4" shaft, you'll need to buy a 3/4" clutch half to suit. If the new 3/4" shaft engine and clutch half is cheaper than a 5/8" shaft engine on it's own, it'll be a good way to go. There's no extra labour involved as the clutch has to be removed from the engine either way. Hope this helps.

Cheers, Michael

I agree with Michael, and I'll offer a couple more details. If your current 5/8" engine-side clutch half has a captive cotter pin, there's a likelihood that you'd have to replace it at some point with the later type which had two set-screws at right angles instead of the cotter. The cotter type has reliability problems, the underlying cause of which is uncertain at this stage. However it is known that with the cotter, the key that drives the clutch from the crankshaft gradually slides along the keyway until it fouls on the thrust bearing in the middle of the clutch. The set-screw type of clutch half has one of its set-screws directly over the key, ensuring it does not move.

So, it is possible that you will eventually need to replace the engine-side clutch half anyway, and doing it now will not cost any more than doing it later. I'm told the clutch half costs about $80.

Hi to All,
I also agree with Michael and grumpy, the set screw clutch half is the way to go, can save a few hassles in future......

Thanks heaps guys 3/4 it is, ill let you know how i go and post some pics