OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers 14" SB45, use for parts or fix?

Hi,

Picked this one up off gumtree for 100 bucks. Previous young owner said that he did not have enough time to undertake repairs. Apparently it was working prior to a lawnmowing accident; even the engine oil had been changed. When I got it home, I managed to start the engine (with the reel removed) but the clutch squealed like crazy and the pull rope kept jamming up. Luckily I had a spare starter clutch (clean and free of dirt/grease). After swapping out the dirty clutch the engine started nicely and ran without any issues (the engine is 2.5hp B&S).

In my mind I though it would be a good way to gather spare parts etc. But then I thought...maybe it could be repaired. I could do a tandem 14" and 17" rebuild. My main worry is that the dodgy coat of green pain is hiding some defects; still not sure about that yet, except for the catcher - that has been repaired using fibreglass/epoxy. My guess is that the paint job was a way to try and flog off the machine to an unwary buyer by hiding its true condition.

Anyway, I already knew that the cylinder reel was wrecked - I noticed that straight away. But found some additional issues. Wobbly clutch drive shaft; the result of a flogged clutch drive shaft bearing. Massive hole where the clutch woodruff key was. Flogged PTO keyway. Old cotter pin clutch with worn cotter pin but pretty good keyway. Noticed a kyoto bearing in one of the spockets, meaning some bearings may have been replaced (good thing). Question, shall I repair or keep for spares? Photos....












Bearings and shield washers installed like this?

Hi xhall,

Being that it is the rare 450511 model I would repair it. Hands down.

Which twit put the reel bearing shield on backwards !! Everything's there all it needs is for someone to take a step backwards and say to themselves, hey this isn't all that hard.

Once all the crappy paintwork is stripped off and all the components are reworked it will be a great mower again.

If you were in Adelaide I'd take it off your hands.

Cheers,
BB

BTW I'd say it is the original engine being made on the 18 of July 1974, thus making the mower around November 1974 which is towards the very last of the 14 inch model.

Hi BB,

I thought it was a good find. Definitely a keeper. Surprising that the engine has lasted so long without modification. It all seems to be in relatively good nick.

That bearing shield...I knew it wasn't right!
Got if off ok, phew!
Just needed a 3/8 socket and...bingo!
Shield washer on the other side was facing the correct way. It and the bearing slid off easily by hand. Although, I thought they were meant to be a press fit...




Really got my hands full now!

Hi xhall,

Yes they are meant to be a light press fit, but 9 times out of 10 they end up becoming loose on the shaft and the reel floats around inside the bearing.

There are two ways of fixing this and that is lightly knurl the shaft, but if that's not available to you then use a centre punch and carefully knock centre pop marks around the shaft at equal distances from each other as you rotate the shaft. That will achieve the same desired effect.


Cheers,
BB

Hi BB,

Re: Punch marks - might give it go as I have a set of pr!ck punches. Got lucky with my recent 14" SB45 purchase. I think all the bearings have been replaced on the machine (except the rear roller, haven't checked those yet), they are all smooth as silk and run freely with no play (once I degreased and removed dirt and debris).

Reel Bearing.


Clutch drive shaft bearing - self aligning.





Roller sprocket bearing.


Drive sprocket bearing



Something interesting I noticed, is that the bearing housings on the 14" have what look like oiling points/nipples. I don't think these are meant for grease at all (but the unsealed bearings did have black/grey grease packed inside and everywhere else too). All the bearings on the 17" are sealed, same with the clutch drive bearing (which is not self aligning). Bearings on the 17" have never been replaced of course. I feel bearings run smoother with just a few drops of oil and don't collect as much dirt.






One last thing...how is the condition of the bottom blade? Looks really good ey? Nice and square with no dings. I do believe someone has tried to take care of this machine. Thank god!



Cheers,

xhall

Looking inside the chain covers of the model 45's, I noticed that the colours they used between machines are quite dissimilar. The 17" seems to be a lot more turquoise than the 14" and the hammertone effect is quite reduced.

17" cover shown on the left.



Another discovery...I used a heat gun and chisel to scrape off the old paint and found this...



The old paint came off easy and so did the bog a previous owner attempted to use to fill in any dings. Unfortunately, none of the rust was removed first.


I have ground off the nuts from underneath the chassis rails to complete a gusset repair; shown on another thread. My choice is to use 6mm steel angle bar to strengthen the chassis, tack weld in place, grind out cracks and weld back in. These chassis are extremely flexible once the sole plate and rollers are removed. It seems as if the shape of the chassis can be affected by simply adjusting the position of the sole plate before securing in place (due to the play between the bolts and bolt holes).




Lasty, cracks are only showing around the holes on the engine side of the chassis; this includes the 14" model. The cracks in the 17" model are less severe, probably because it is a later model and wasn't used as often.

Hi xhall,

You shouldn't have removed the nuts at all !

In the gusset you should make holes so that they go around the nuts, then when welding in the gusset the existing nuts should be tied into the gusset. This way the engine alignment will always stay as per original.

Cheers,
BB.

PS. There were numerous different greens used over the production life of the Model 45.

You're probably right BB. But I don't see anyway around having to grind the metal to remove the cracks that wont end up interfering with them. The cracks go right through the bolt holes!

Hi xhall,

Honestly you don't have to weld the underside of the cracks, as if you grind out the traces from the top and then weld that will be strong enough especially with the gusset underneath taking most of the load. Now if we were talking metal that was 5 mm thick then I could justify what you have done but this chassis metal is only around 1.8 thick and the penetration from the top would be quite enough.

Anyway you've done it now, so you'll have to work it backwards I guess.

Cheers,
BB.