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

I have no confidence in a pre-ground bedknife being anything like flat and straight after it has been clamped onto a random soleplate without even a clamping jig. Have you looked into the cost of getting the job done professionally? I have the impression that a raw bedknife tends to cost considerably less than $40, from the right workshop.

We generally recommend that people in your position contact a nearby bowls club and talk to the greenkeeper. Make his acquaintance and ask where he has his reels and bedknives sharpened. The greenkeeper is a valuable contact, who can help you in many ways. Whatever you do, don't use a mower repair shop as an intermediary. That doubles the cost while losing you the opportunity to choose the supplier.

Hi xhall,

No No No that's definitely not the correct method as the bed knife MUST be ground while attached to the sole plate. Many sole plates are not perfectly straight and as such you will only replicate that non straightness to the bed knife, thus it must be done together so that the final finish is a straight one. The reel and bed knife should be done by the same machinist.

Don't bother with bed knives off eBay, they'll give you more grief than you realise. Let your machinist do that side of things for you.

I think your biggest concern should be that rear rail, how did it ever get bent like that ???

You'll require the services of an experienced press operator and the sole plate will have to be firmly installed while the work is being done so as to maintain structural integrity of the chassis.

Cheers,
BB

I have no idea how it bent like that. My local mower shop has facilities to sharpen reel mowers. The last time it was taken there (3-4yrs ago and when it was still working) it cost about $120.

OK, i'll take both and get them to replace the bed knife and sharpen together as a set. They can have a go trying to get the rusted bed knife off.

Remember that mangled keyway on the crankshaft?



Somehow I managed to jag a black 3hp briggs engine (a freebie - in a very sad state) but with a crankshaft that is in great condition and a perfect replacement for my red engine. Just have to dump the oil and swap them over. It has a 3/4" shaft to boot! Can finally get that 3/4" bonnar clutch with set screws.

Won't end up restoring the black engine, it has too many problems and won't be much use with the damaged crankshaft. I will end up keeping it for parts, maybe cleanup the carb and fuel tank to keep as a backup. The previous owner even tried replacing the diaphragm, it looks newish and is still quite supple, not rigid like an old one. The valves, springs, retainers, camshaft, head, head gasket and flywheel are in good condition too.

It's done. Just have to wait for the silicone to cure and then I can fill the sump with oil. Going to secure it to the edger frame and test it out tomorrow afternoon. I will post a video, if all goes well.

Looks good thus far and looking forward to the end result.

Here it is. A video of the engine working with the new crankshaft. Had a tough time getting it to start for some reason. I needed to put some fuel in the spark plug hole and then it started first time. Afterwards it started easily. I didn't include any of that messing about in the video. Just a short clip of it running.

[video][/video]

Hello xhall,

As I predicted earlier, this has been a great instructional post
on the work you have done, with good photos and video.

I think you have been duly rewarded with the result, though.
I think that original quote for re-boring was over-the-top.

So what's next?
--------------------------------
JACK

Hi CyberJack,

Wish I could proceed, but since swapping over the crankshafts the engine has lost all of its compression. With the previous crank there was a lot of resistance. I don't know what I have done wrong, I may have accidentally switched the tappets and now the valve clearances are incorrect? It is too easy to crank and I need to put fuel into the spark plug hole for it to start. Would an air leak in the sump gasket or oil seals also cause a loss of compression? I am also so wondering if the journal offset is a different dimension and if I need to change over the connecting rod too.

Problem solved! I think the previous post can be disregarded. The poor starting was due to the temporary throttle control setup I was using. It really needs to be replaced as it's off the old Scott Bonnar and the plastic is crumbling to bits.

In the video you can see it has been taped to the handle. It wasn't adjusted properly and was only opening the choke about 1/3rd of the way. When I held it fully open with one hand and yanked the pull rope with the other, it started first time (cold start). The engine is good to go!

Hello xhall!

Well, that was a bit of a ...


So what's next?
--------------------------------
JACK

Ummm, before gettig the bed knife and cylinder sharpened, I was planning to repair the twin rails. Especially the one with the bend. Then I thought why not get some 1/8" or 1/4" steel plate cut, remove those thin/flimsy rails and then weld on the new plate? Seems as if those rails have too much flex and only the cast iron sole plate is holding everything together.

xhall, please do not remove those original rails. If you do, it will become very difficult to fit new rails that give you accurate alignment of the two side plates relative to each other and the soleplate. There is a recent thread showing an easy way to weld repair/reinforcement plates to the original rails, hopefully making them much stronger while restoring accurate alignment.

Hi xhall and Grumpy,

I think this is the thread Grumpy is referring to.

https://www.outdoorking.com.au/forum/ubbthreads.php?ubb=showflat&Number=64426#Post64426

Cheers,
BB

Hello again, it's been a while!! I have finally built up some courage to proceed with the overhaul of the SB Model 45. I didn't really have a clue where to start and was mulling over it for some time. Just disassembled everything and proceeded to remove rust and clean up any old grease/dirt.

Only things I haven't managed to remove is the two bearings either side of the cutter. Everything else came off with a little heat and some persuasion. I figure it is going to cost a fair bit of dough for some much needed replacement parts. Things such as engine drive shaft, clutch covers, bearings, cork, new bottom blade, screws, front roller end caps and shaft, throttle lever, handle grips etc. Lots of $$$$.

Managed to remove the bottom blade, so that I am able to paint that heavy cast iron sole plate. I'll have more photos as I progress. Already started to repair the sag in the rear rail using heat, clamps and a straight edge. Going to try strengthening the rails with some flat bar welded along the sides (underneath) so it can't bend again. Any cracks I find after sandblasting will be drilled out and welded.

I am looking for some opinions on what I should do regarding parts, as I have noticed wear etc. This is what my work bench looks like.




Now...

1. I used a bench grinder and wire wheel to clean off the rust from the front roller. For me, hot dipped galvanising would be the perfect choice to protect the steel roller and to stop it from rusting. Only might have to drill a hole in the side somewhere, so it can be hung by some wire.



2. Sprockets look really good, from the images does it look like any of them need replacing?







3. The shaft that goes through the front roller has been badly worn, as dirt has got in-between the end caps, causing abrasion and wear at both ends. These need replacing?




4. I already figured out that I need a new 3/4 inch clutch to match the PTO of my 3hp Briggs that has a 3/4" crankshaft installed. This is what the original 5/8" clutch and keyway looks like... I also need to replace bearings on the cutter, should the shield washers be a cone shape as show, think they need replacing too.





Lastly, I have been fortunate enough only to find only one prominent crack around a bolt hole on the front rail, as it is a lot thicker than the rear one, some small welds should suffice.





About to try ordering parts from this site. Any comments or observations will be much appreciated!

Pretty serious resto you are doing on this one, did you get the new sprockets made or were they an off the shelf part? The welds appear recent

Hi Norm,

Yea, there is no turning back now. About to get a complete set of new bearings and might even look at getting a new 8 blade reel or one that has thicker blades to stop them from bending when hitting debris. The sprockets are all original, just wanted to get some perspective from users here as to their condition and whether or not they need replacing. There is no welding yet, the blackness is from burnt paint; where the chassis was heated to bend back a dent in the rail.
I did manage to remove the bearings at either end of the reel using an old 3 jaw bearing puller I had in my possession.

Sprockets all look in good shape, no sign of wear on them