OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Phase 2 of SB45 Overhaul

The Scott Bonnar has been going well, and thankyou for the help and assistance I have gained.

As you can see from the photos I have a Scott Bonnar, That has been painted rover red to match a late model catcher and handle bar trim. This mower was a miss match of parts to begin with and I have re-furbished it in the later Rover Red. I now realise that SB units are more desirable, but in the end I will have a good al be it non original Scott Bonnar.

The clutch was starting to show some signs of slippage. And I know from the original tear down the cork was in not good condition. So for the sake of $9 for a new cluch I figured I would have a go at replacing the clutch.

Looks good. I noticed mine is starting to slow down on up hill climbs.

Hi Jarrad, on getting your machine all ship-shape....It looks good in red, and of course, you could always change back to Scotty green at any time down the track. Thanks for putting up the pics of the roller clutch internals...good for the archives mate.

Picked up a 2nd hand sole plate last week. The bed knife is stuffed but the soloe plate is in better condition than mine.

Also grabbed a good 2nd hand clutch cable as a spare.

Some parts arrived in the mail from TMS, including handle bar decal and some new red plastic caps.

Things change quickly in 5 minutes. Have just won this SB / Rover 45 on Ebay, so hopefully I can pick it up this week.

Will then work out if it's best to swap the good bits off this one onto my Red SB or sell of the Red SB as is and do another restoration on this new one.

The red one presents well, has been sharpened and serviced, so dont think it will be too hard to sell.

Because good, well-presented SB45s seem to sell at relatively high prices in Perth, there may be a business opportunity for you Jarrad. Against a background of high selling prices, doing simple clean-up, repaint, adjust, replace worn parts, resharpen, and offer the mower on ebay with a warranty, might be a viable way to spend some time. I seem to recall you were in Pinjarra, though. Unless the road system has improved a lot since I lived in Perth long, long ago (which I'm sure it has) that might be a barrier to getting buyers to pick up their new machines. About 100 km from the city, as I recall?

Your right Grumpy, I am about 100km south of Perth in Pinjarra. We have a Freeway that runs from Perth to Bunbury now. But eastern states people would call it a two lane road.

Yeah SB45 seem to sell for good money, but the fully retored ones that people ask $700-800 for done seem to sell very quickly. Most people are after a good one for $500 ish or nothing.

You'd have to work out the numbers Jarrad, but I'd have thought a mechanical tidy-up and a basic repaint to make it look nice, would take a fraction of the time a restoration would. The art would be in picking the machine to work on. There's no way you'd make money out of taking on a basket case and selling that for $500 in good condition.

If you could find a way to get them to Perth, there seem to be plenty of easily fixable SB45s in the eastern states for around $150.

Too many projects Grumpy. Just need to get a really good unit for myself and I will be happy. Learnt the hard way about buying a basket case (ie) the red one I have now.

The latest purchase cost me $400. Has been sitting in shed for last 3 yrs as lady's husband was ill and recently passed away. She said they brought it about 2 yrs before he got sick from a mower shop and paid over $1000 for it.

Anyway will see how good it is next week when I go and pick it up, but from the photo's I could sell it locally and get my money back. The deciding factor was that the reel was in good nick and given a new reel for the Red SB was going to cost me $400 anyway. I should come out even.

I do keep an eye out for the odd bargan in WA, but they go so quick. Plus need to finish project car, motorbike, camper trailer and the jobs to keep the wife happy

Yes Jarrad, we mower hobbyists have to keep the little lady happy or we suffer the consequences...

When you finally get the new SB home and give it a thorough look over, it will be easier to decide what to do.
You may well decide to swap not only the cylinder reel, but the sprockets and chains as well....This later Rover manufactured machine would have a newer model Briggs, but your red one may have a stronger chassis...

Picked up the new mower today.

It has not done a huge amount of work in it's life, but here are my initial observations:
*Engine needs a freshen up but runs sweet
*Handle bars have surface rust
*Main chain way to long and cant tension any more, Max on tensioner now
*Bearings all feel good
*Catcher dented up more than the red one :-(
*Paint all flaking off chassis and catcher

So in 2 minds of what to do:
Swap reel, engine, sprockets onto the red beast.

Strip green one, sand blast chassis, re-paint chassis, shorten chain and get new tensioner block also. Then knock as many dents as possible out of catcher and put up with it. Or source a new catcher. There is a local company that sells aftermarket ones for $150. I would assume that a Rover one would be expensive

Any thoughts?

Also whats the best way to clean up the rusty handle bars?

Thanks

Jarrad, it is unlikely the chain was too long when it was fitted: it has probably stretched. If it has, it will quickly ruin the sprockets if it has not already done so. You can check whether the chain is out of pitch by removing it, and holding it straight, edge-on. The slack in the pivot pins (and that is what chain stretch is) will result in it drooping over its length. If it droops substantially it is garbage, and you should post pictures of the sprockets so we can see if they are worth keeping.

It is not impossible of course that someone replaced a worn chain with one a couple of links too long. If that is the case, you will find out when you do the wear check. You can fairly easily shorten the chain. You can also buy a half-link if necessary to get it to fit.

Hi Jarrad, We need pics of the machine from different angles so as to make some observations.....
From what you have said, the main chain may have stretched over time....sprockets could be worn as well; we need a pic of the chain case and in particular the sprockets where their not covered by the chain.

Regarding the surface rust on the handles, try soapy steel wool (it won't scratch the chrome...do not use a 3M scouring pad; it will damage the chrome) and finish off with a good quality auto polish that you would use on your car.;)

We may be able to tell you more when we see the pics, mate.

Hi Grumpy, great minds think alike mate...you were quick off the mark....

Will get some pix up later, goin to give machine a wash first as its pretty grotty.

Thanks Jarrad, looking forward to seeing them.

Hope this helps, to me the sprockets and chain look OK. I think the chain would benefit from removing 1 link.

Need to get new seal or complete fuel cap as this leaks. Dont know why Briggs went away from the old fashioned screw type cap.

Will get new clutch cork and chain tensioner on way home. Goin to keep this one and keep all original. So will start strip down this weekend.

The two small sprockets are fairly badly worn, Jarrad, and the damage to them is characteristic of being run with an out of pitch chain. I suggest you do the wear check on both of those chains. If they are as bad as I expect, what you should do depends on how bad the other sprockets are. The large one wears more slowly due to spreading the damage over more teeth, so it might be savable now if you fit a new front chain right away. The problem is that the worn out small sprockets will damage the new chain fairly quickly.

If you post a good, square-on picture of the large sprocket we can talk about whether it is worn out too. It is only if it is already ruined, that it makes sense to drive the whole setup into the ground by continuing to run it.

Bit of a progress shot

Chassis and Chain cover have been paint stripped, sand blasted and coated in grey etch ready for a coat of bright green.

Havnt taken a pix of engine, but it's been rubbed back and had a coat of black engine enamel.

Hi Jarrad, she's going to look like a bought one when she is finished mate....well done thus far.
BTW, I agree with Grumpy on the condition of the cutter sprocket...the chain will be stretched as well, and will require replacing.

Just went out to the shed and had a look at the two chains, that run on the cutter sprocket. If you hold them on edge, they look like there smiling at you. Guess that is not so good.

As for the sprocket, yes it is worn but I didnt think it was too bad. The larger sprocked on the cutter sprocket assy is visably worn from a loose chain, but the teeth I thought were still usable.

The top little sprocket I thought was quite good.

Deejay or Grumpy can you please explain for me what you are looking for to determine that a sprocket is worn.

For $55 for 2 new chains from mower shop, dont really want to destroy them. However 415 and 06B type chain is quite common, has anyone tried to source it elsewhere?

Ohh and cheers for the tip for soapy water and steel wool for the handle bars. Look a lot better after that and a polish with some Autosol. Only some minor pitting.

Here is a pair of teeth from your larger reel sprocket:


You can see that on the left side of the recess between teeth there is a very steep slope, but the other side has a much gentler angle, due to the tip being worn or broken away. This happens because the rollers in the chain are further apart than the teeth on the sprocket, so they wear away the sprocket to match the pitch of the chain. As wear proceeds further the steeper side will become undercut, then the tip of the tooth will fall off. When the tips are gone most of the way around the sprocket, it will start slipping.

Here is a pair of teeth from your smaller reel sprocket:


This time you can see that the teeth have splayed out on both sides, resulting in the height of teeth being reduced. On the left side of the left tooth you can see some secondary angling of the tip of the tooth. This reduces the height even faster.

Some better pix, So it wears the same as a motorbike chain and sprocket. Just harder to see without my glasses.

So regular checking and replacement of the chains would save in the long run

The problem is that if you keep running the worn chain, you'll ruin the large sprockets as well as the small ones. They are likely to be expensive. If the large ones are worn already, you might as well run the whole thing as it is until the sprockets go bald, since you'll have to replace them all anyway. The aim of the game is to keep from ruining the large sprockets, if possible.

Of course if the previous tenant had replaced the chains in a timely manner, the damage to the small sprockets would have been delayed a long time.

Hi Jarrad, owning a Scotty 45 is owning a piece of complex machinery that needs a routine maintenance schedule to keep it running sweetly and prevent wear to the moving parts.
Lubrication is also very important for the sprockets and chains and will lengthen their life greatly if applied on a regular basis.
For my routine maintenance schedule....Click HERE
This guide also includes changing the engine oil which is most important on a regular basis....as a very wise old man told me once..." Oil is cheap....Engines are expensive!"

Jarrad, I'll make a specific suggestion with regard to the chains. There are two ways chains wear out: lack of lubrication, or dirt sticking to the lubricant and making a form of lapping paste. The latter is usually slightly more disastrous than the former.

The easy and effective way to look after the chains is to have a regular service schedule that includes washing the chains and sprockets with solvent, drying them, then oiling them. In the old days this was done by taking off the chains, washing them in a kerosene bath, blowing off the kero with compressed air, and oiling them up before putting them back on the sprockets. These days it is probably more common to leave them on the machine, blast off the oil and crud with a degreaser spray, dry off the degreaser with air blast, then spray on new lubricant. Both systems can work well or badly, depending on the operator.

Hi Jarrad and grumpy, I have found over the many years of operation of my Scotty, a good quality grease is the way to go with the sprockets and chains....rather than oil...In fact all mine are original and have never been replaced. I will however have to replace the small engine sprocket some time in the future, as it is showing signs of wear...but it has done its job for 30 odd years....
The design of the chain case cover prevents dirt and crud getting in there and with regular maintenance should not pose a problem.

Thanks for the advice

Big sprocket looks quite good. The excessive amount of grease in this machine may have done some good.

Just ordered small and cutter sprocket from Outdoor King store. Cheaper than these parts were avail locally. My best price in WA was $53 for the little one and $92 for the cutter sprocket, plus $20 p&h

Goin to order chain locally as can get 3 meter lengths for $25. Just need to cut to length. Even considered making own sprockets, but not worth it given the two were only $100. That wouldnt cover the time it would take me to machine them.

Hopefully will get the chassis, chain cover and grass deflector into green paint before end of weekend.

Few more progress shots

Got the chassis painted green before work on Friday, so spent some time putting it back together over the weekend. I still need to paint the handle bar trim and grass deflector. The colour came up pretty close to the original as I got the paint shop to match it.

Waiting on sprockets, chains and I need to freshen up cutter assambley. But all going well it should be back together for the weekend.

Will give the catcher a freshen up next, so it all looks like a new mower.

I havnt worried about re-painting the rollers as this mower will be used.