OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Reel-Type Mowers Scott Bonnar 45 Rebuild

Hi,
Just thought I would show progress of my rebuild of an early 70s model Scotty.
When I bought it, the clutch would not work and when I tried to adjust it, it just slid along the shaft. I pulled it apart and the cotter pin looks cactus along with the woodruff key. The engine shaft looks a little damaged at the tip, I will let the experts decide though.
Here are a few pics.
Cheers

The thrust bearing is also buggered I think, as it sounds quite rattly.
Thoughts on the clutch housing and engine shaft?

Hi Boeing,

Well I can say categorically that the cotter is shagged and also that PTO shaft is rather suspect.

Can you confirm if that's a definite crack adjacent to the key way ? if it is I would say it's curtains for that crankshaft and replacing the whole engine would probably be the easiest option, depending on your mechanical ability I guess.

The clutch body will most definitely be flogged out and require replacing especially with it running with a shot captive cotter like it was.

The thrust bearing would probably be ok even though it sounds rattly I would clean it out in clean petrol and dry it out then soak it in oil and allow it to thoroughly drain and after that you'll find it should be ok for another battle.
Remember that the bearing will run smooth when the centre race is pushed in and rotated and not the opposite direction as many people evaluate.

I'd like to see some really good close up photos around the engine mounting points on the two rails.

For now,
Cheers,
BB

Thanks BB, there is no crack on the PTO shaft, that was just a grease mark. The key way has some slight marking on one side and the woodruff key is most certainly U/S. The frame rails also seem good. They have been repaint at some stage. When I put the clutch body back on the shaft with the key there is no movement but without the key there is very slight movement. How much movement is too much?

I'll grab some more photos.

Boeing

Actually on further investigation it appears that the crankshaft may have been repair at some stage. That mark looks like it might have been welded up maybe..

That is very clearly a major weld repair to the PTO. It may not break again, but it may not run true due to heat distortion. If you are doing a repair, you might as well run it and see how it goes, but if this is a restoration, the crankshaft is below standard in my opinion.

From your pictures of the rails, I'm not convinced that they are not cracked, welded, or both. You need pictures from above, front, back, and underneath, and from a lot closer up. Remember, that mower trashed its crankshaft, keyway, key and engine side clutch half from running out of balance. If the rails survived that, it would be remarkable. That is a pretty badly damaged mower.

Hi Grumpy and Boeing,

Well I'd consider that engine as scrap. The crank looks as if it's been silver soldered to hold the broken piece in place while the clutch is placed over the shaft.
I totally agree with Grumpy regarding the the damage that such a situation would inflict upon the chassis rails. I'm pretty sure I can see signs of fractures in the rear rail, but it would be best to using some very coarse sand paper and remove the paint to reveal any damage that's lurking underneath.

I must admit that I picked up a 20 inch machine yesterday that has had both rails totally fail and this will be my first donor chassis to try out the gusset repair method and get it all back together again.

Cheers,
BB

I gave it a sand, and there are a few small fractures on the rails. This would have been the second engine this mower has seen so maybe it wasn't on that long after the failure.
Will post some photos soon...

Is the best way to fix this by grooving and gig welding?

We need to see the rails from underneath, and front and back, to see what is going on. There is a vertical line on the vertical flange in the lower picture which looks rather like it has been cut and joined.

Hi Grumpy,

I'm not sure I'm seeing what you are ? all I can see is the split in the drive roller and nothing on the rear rail flange at all.
As Pauline said, please explain LOL !

I feel that this is the perfect example where the gusset repair method would be the best and then groove out the existing fractures and zap them up with a TIG. Again this really is a job for a qualified tradesman and not a back yard operator.

Cheers,
BB

Quite right, BB I was far too casual in my inspection. It was the separation of the drive roller halves I was looking at.

From the appearance of the area around the cracks, I suspect there has been a repair to the underside of the rail. I'd like to see what has been done there before discussing the next step.

Roger, I will get some photos from back and underneath. Do you think these surface cracks are severe? Going by some of the ones I have seen on here they don't look that bad.

Hi Boeing,

I will categorically say that those fractures are all the way through from top to bottom.

It is at the lower end of the scale compared to what I've seen. I currently have a 20 inch machine that has two totally failed rails and that's going to take a bit of effort to restore back to, one, a fully working and aligned correctly machine and secondly, cosmetically in perfect shape showing no signs of surgery.

Honestly I feel that the photo below (gusset Repair method) is a good representation of a solid remedy, after that has been done then the fractures in the rail itself can be ground out and TIG welded to double the strength. Note how the engine mounting nuts are tied in to the gusset so as to share the load onto both pieces of metal.




A really good job in my humble opinion.





Cheers,
BB

Thanks I agree, thats looks pretty good.

I'm not so confident, BB. It is nicely done of course, but you've got the reinforcement ending near the middle of the span of the rail. There will be a considerable stress concentration at that point, so with the long rail span on the 20" model, there still seems to be some potential for cracking. Time will tell, though it will probably take years to do so.

FWIW, I'd have preferred to see the reinforcement continue to the mid-point of the clutch mechanism platform.

That's the back rail. Grumpy do you mean extend the gusset to under the clutch?