OutdoorKing Repair Forum Forums Collectors Corner Cylinder Scott Bonnar 45 renovation

Thanks for the kind comments.

I have hit a bit of a problem with the drive shaft - when I disengage the cone clutch, it periodically "bites" - ie it can sit there and be disengaged, but then randomly engage. I also notice that the black plastic "guide" gets very hot - the fork is backed off so there is a bit of slack, so that doesn't appear to be the problem. The other thing I notice is that when it "bites" and engages although being in the disengaged position, the drive shaft vibrates.

My hypothesis is that the clutch body end of the drive shaft is potentially not sitting in the clutch body bearing - does this sound reasonable, or do people have other experiences with this problem?

If that is the issue, is the solution as simple as backing off the grub screws on the engine shaft and pushing it across so it is on the shaft properly?


Cheers

Hi Bob,

Your diagnosis is sort of correct, it will be the end of the transfer shaft having excessive wear on it where it slips inside the thrust bearing to keep straight line integrity of the powertrain and stop it oscillating. Moving the clutch body further outwards from the engine will not solve this issue and looking at your photos you have about a 3 mm clearance between the engine and the clutch body which is pretty much correct. Any more and it creates it's own new set of problems with the clutch fork adjustment.

The only way to rectify this issue is to replace the transfer shaft. This is why they have now become available as a replacement part as many have this wear factor and also sideways wobble of the Woodruff key inside the clutch cone.

You'll never get it to run true without the end shaft dimension being what it originally is meant to be.

Cheers,
BB.

Thanks BB - the shaft in there is brand new, as the old one was worn down (I think it might have been yourself who noticed it was worn down from one of my earlier photos on this thread, and suggested I replaced it?).

It may well be worn down again already with all the vibration though.......

Hi Bob,

Oh yes I recall that now. There's no way that it could've worn down that quickly. It will take years for that to happen again.

The shaft must be long enough to protrude inside the thrust bearing. I would disengage the clutch via the primary lever and then grab hold of the shaft and cone area and see if there is much sideways wiggle movement. Once we've ascertained what's going on there we can then proceed I guess.

Cheers,
BB.

Hi BB - last night I removed the engine and the clutch body to have a good look at what was happening. I couldn't see any signs of wear on the shaft, which we expected given it is only new.

What I found though is that the drive shaft wasn't in the thrust bearing - it was just shy of it. I backed the adjustment screw for the thrust pad right back as far as it can go, and now I can get the drive shaft rough half way in to the thrust bearing.

I gave it a quick run this morning (didn't think a test run at 9pm would please the neighbors....) and it ran fine - no vibration or random engagement.

I would have thought the shaft needs to be completely inserted in to the thrust bearing, however I don't have any adjustment left in the thrust pad screw. Any guidance is appreciated!


Cheers

Hi Bob,

The shaft merely has to only protrude in by about 3 mm. To achieve this you should have between 3 to 5mm of gap between the back of the clutch body and the oil seal / PTO surface exit of the engine.

Once you've achieve this the clutch fork should be adjusted so that it's pretty much perfectly vertical (perpendicular to the engine deck) when the drive is in the engaged position and leaning slightly towards the engine when the clutch has the drive disengaged.

Cheers,
BB.

Hi All,

This thread is invaluable. I have just recently purchased a SB45 which i intend to restore. I will post in my own thread some pictures etc and try and document my rebuild process as well.

I'm looking forward to the journey.

Calla