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

Hey everyone, just a quick questions, whats some tell tale signs that the bearings need to be replaced? I'm currently stripping down my 45 for a rebuild, and am going through it all. I plan to replace the bearing that goes on engine clutch, at at least the bearings on the blade cutter for that perfect finish! To me the rest of them seem in pretty good condition, no play, spin freely etc! Thanks for your help in advance!

Hi, Ride to Live, the golden rule of cylinder mowers is this: Reel mowers are expensive to run and maintain....bearings are cheap (by comparison) so, if in doubt replace the bearings.

By this, I mean , if you don't know the history of your SB, and you don't know what bearings have been replaced and (more importantly when)....replace them. they are cheap by comparison of the heartache you will (and dollars) feel if they fail...usually at the most inconvenient time.

To assess them is a matter of experience and feel...it is hard to explain...unless they are really shot...therefore my recommendation to replace if in doubt....that way you can't go wrong.

Thanks DeeJay, I didn't think they were to bad of nick but as you said there a small cost for piece of mind.

Would it be worth buying sealed bearings instead of the stock ones? I'm sure you would be able to get them but whether they would work as well is another story. Let me know your thoughts. Cheers Daniel

Deejay and I fitted sealed bearings to the reel of his scott bonnar with no ill effect, if nothing else the seals will prevent the grease leaking out or dirt and contaminant getting in.

The bearing for the clutch shaft must be an exact replacement, somone on here a while ago fitted a cheaper variant and it ended up with an ill result.

The bearing on the sprocket end of the clutch shaft must be a self-aligning type. If I recall correctly SB originally used a double-row one and Rover changed to a single-row one, but I haven't heard of that causing a problem. Deejay will set me straight if my memory is wrong about both those points.

Do not attempt to use a deep groove ball bearing instead of a self-aligning bearing. The engine and sprocket will not line up well enough for this to work. Yes, given enough time you could shim up the four corners of the engine, and set it up with a dial indicator to precise alignment horizontally and vertically, then dowel it into place on the mower frame and all might be well with a deep groove ballrace at the sprocket end. However we both know you aren't going to do all that, so a self-aligning bearing is the only practical solution.

Long ago, veteran cars used to have their engines and gearboxes shimmed and doweled to the chassis. More recently they have been machined much more accurately in the factory to eliminate the shims, but the gearbox is still doweled to the engine's cylinder block. Lawnmowers are not built with car-like precision, and their frames are not especially rigid either. The result is to rely on self-aligning bearings, which will work well enough for their relatively short lives (measured by hours run, of course).

Hi Daniel, expanding on what grumpy has said, he is correct, the engine clutch shaft bearing changed to single row when Rover started manufacture of the Model 45 as a Rover 45.
However, the good news is that the self aligning double row engine clutch shaft bearing, as used in the original Scott Bonnar models, is still available and can be sourced.
I will send you a PM with the details.

Thanks alot for your help guys greatly appreciated. Ive managed to get a set from a local thanks to deejay. Cheers!

As you have sorted it out and this thread is complete I will lock it, if anyone has anything to add please PM a moderator.