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

Hi, stumbled on your site on the weekend and I am amazed at the support offered here. I went into my shed the other day with my camera with the aim to sell my Scott Bonnar on Gumtree; hoping to get $100 for it. I had it serviced about 5 years ago only to be told it will cost $850 because the cylinder needs replacing. I took it home without the service and used it a few more times before smoke came from the clutch so parked it up and never used it again.

I don't know why but I goggled Scott Bonnar and came across your site and have decided to fix the old girl.

Do I need to change the cork on the clutch and the cylinder as recommended?






Thanks

Craig

Welcome to the forum Craig!

Plenty of guys on here with a wealth of experience that can point in the right direction as to how to proceed from here.

Given the fact that you have been previously told that the reel needs to be replaced, it might pay to remove the reel and soleplate from the machine and have them inspected professionally by a machinist/engineer. Since a new reel is the most expensive ($350+) part on the machine, the engineers report of this component may ultimately decided the course of action you wish to take.

Hopefully a forum member from Perth can chime in and assist in pointing you in the right direction to find a suitable engineer for the inspection. Short of that you could speak to a greenskeeper from a local bowling club as to where their reels they have their machines serviced and reels ground.

Here is a link to show you how to remove these components.

Simon

Hi Qwerty8, welcome to Outdoorking.

Our main SB45 guru, Deejay, is away from home due to a serious family health issue and may not be able to reply for a while, so I'll give you an interim report on what you have said about your mower.

Usually the reel has to be replaced for one of three reasons: it has been reground so many times that there is no "meat" left on the blades before reaching the disks they mount on; or it has been damaged by some kind of mishap and the individual blades are badly bent; or the axle is damaged and the whole reel is running out of true. Your reel does not show signs of any of these things, as far as can be seen from the photograph. However you need to rotate it, and see if the blades move closer to, then further away from, the bedknife as it rotates. If they do, the axle is bent and you have a fairly serious problem.

We would need some more detailed pictures to assess what is going on with the machine. The cork clutch lining looks all right in your picture, though it may have run out of adjustment and consequently slipped. If that happened, most of the time it is due to the clutch half that mounts on the engine's crankshaft having slipped along the shaft toward the engine, so that spring pressure is lost. It is easily corrected by adjustment, subject to the captive cotter pin not having deteriorated. If it has deteriorated, you will need a new engine-side clutch-half. The primary chain is not fitted in your picture, and the first sprocket is not visible, but the second sprocket looks to be in terminal condition and may have been slipping. The third sprocket looks downright weird - I'd need close-up pictures to try to assess what is going on there. Essentially though, you need new chains and sprockets, as do most well-used, but not well-maintained, old SB45s.

There seems to be red primer on the front frame rail, pretty much in the locations where that rail is prone to cracking if the machine has been run for a long time with an excessive vibration condition. It may be that there has been an attempt at repairing rail cracks, or cracks are still present. This is fairly difficult to fix, but by no means impossible.

In summary, from what I can see so far, your SB45 is in a bit worse than average condition for an SB45, but is well within the range of machines that our members regularly repair and put back to work. Assuming the reel is not damaged and just needs sharpening, the most serious problems seem to be the fairly awful state of the chains and sprockets, and the possibility that the front rail is cracked. Both problems are rather routinely found in old SB45s.

Hi Guys,

Just wondering why Qwerty's photos are not showing up ?

Cheers,
BB.

Thanks for your help so far. I will take some more photos on the weekend and post them and hope someone can point me in the right direction from the photos.

I have owned this mower for 25 year now and it was previously used by my Grandfather so roughly how old is this mower?

I can see my photo's on this post so I am not sure why someone else wouldn't be able to see them.

Craig

I can see 5 photos you included with your first post, Craig, so please keep doing what you are doing. It sounds as if something may be wrong at BB's end.

Your mower is a Series 2, so I'd guess it was probably made later than 1973, but I can't tell how much later. However we should be able to tell you within a few months, if you post the Model, Type and Code of the Briggs engine. Those are stamped on its cooling air cowl, near the carburetor.

Our SB45 guru, Deejay, will be on line soon and will continue this thread. Please post the Model, Type and Code as soon as you can though, since he will need them.

Thanks Grumpy, I will need those numbers to be able to give the approximate date.

cant see pics either????

Well I can't see them either?

Hi to BB, newlifemowers and to Murray,
Re the pics (which are in the first post of this thread).....can you see the links to the photos?

Today I have removed the cylinder reel as suggested and I have posted some more photos below. The Briggs numbers are 80102 0233-01 74071803. I acknowledge I need a new cutter drive sprocket; I am hoping I can get away with the rest. While it would be wise to replace the chain it doesn't seem that worn. Using 1973 as an estimate I know it is over 40 years old. Given how much I used it back when it was working it has done a great job. Don't think any of today's mowers could do that.

I have also listed below what I think I need so far. The big question will be the cylinder reel. I would like to give the mower a paint job so it would be good to know the colour code if there is one. The mower did have some welding repairs done by yours truly. It had developed a large crack so this is how I fixed it.
As mentioned in my earlier post I was going to just get rid of the mower, but the more I think of it, it is really an heirloom of which this is the only item I have from my grandfather.

Thanks again for everyone's help. I hope there isn't too many photos












Thanks

Craig

Hi Deejay,
All I see is 5 small white boxes where the pics should be.
If you right click on them and select properties, there is no link.

The latest pics are no problem, I can see all of them.
Murray

That Briggs engine was made on 18 July, 1974. The mower may have been made about 6 months later, but this could vary according to how many mowers were being sold and how many engines SB held in stock. Here is the Illustrated Parts List for the engine:
http://bsintek.basco.com/BriggsDocumentDisplay/Z6jmvGVJ1DajI.pdf

Here is the Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/lrvvA-wU7eL7hAxB91ObQ.pdf

I'll leave the remaining points to Deejay.

Hi Deejay,

Can't see any links at all

Cheers,
BB

Man that is the worst cutter sprocket I've ever seen. I'd say that there would be some severe marking on the inside of the chain case with the amount of slop that's been created.

Also is just my observation but the rear rail is bowed downwards and as such the motor will never run true with the clutch and flog out the plastic thrust pad and also it will induce more vibration again which inturn will again cause more rail cracking. The rails must be totally running true or it's basically a waste of time what you are going through.

Sorry if that sounds harsh but that's just the reality of it all.

Cheers,
BB
BTW I'm seeing all the other photos just not the 5 in the first posting.

Hi to All,
I have re-posted the first 5 pics using our Inline Uploader and changed the Markup to "Using HTML and UBB Code" so all members should be able to see them now.
Please let me know guys.

Hi Deejay,

You've done a superb job, as the song goes, "I can see clearly now the Rain has gone" especially here in Adelaide where we've just copped heaps of the wet stuff.

Cheers,
BB

Hi Deejay,
I can see the first 5 pics now, thanks.

Thanks all for your replies, this is a good exercise in showing that the use of our forum inline uploader is the way to go. For new members that are not familiar with it...the instructions for its use can be found HERE

Hi Qwerty8, and a warm welcome to the forum. It's always nice to welcome another Scott Bonnar model 45 aboard.

Here are some of my observations regarding your machine.
This old girl has had a hard life and I agree with BB's observations....but I realise that it is an heirloom and belonged to your grandfather, and so you would like it to be restored. To get it to a good serviceable condition will take time and some expense...but the reward will be a machine that will give you hours of mowing pleasure and if carefully maintained will last a lifetime.

As grumpy has stated, this machine would have most likely been erected in late 1974 or early 1975, so she is an early Series 2 twin rail machine.

The bent and cracked rail issue has be be addressed and repaired to an accurate standard....if it is not, you would be just wasting your time and money.
You may care to read the thread HERE as this addresses that very issue.

If the cylinder reel runs true, you will need to get it sand or bead blasted, re-paint it to your colour of choice...you may choose powder coating which is my personal choice as it is very durable.
You then take it with the soleplate with the bottom blade still attached, to the engineer/machinist for grinding. He will also supply and fit a new bottom blade if necessary.

You will need a new double cutter sprocket and also a new primary chain and I'd almost bet that the upper engine driven (small) top sprocket will be pointy and knackered as well. It is no use using a new chain on worn sprockets, as it will flog out the chain on no time....Conversely, using an old chain on new sprockets will ruin the new sprocket in no time flat!

As you would have read in other threads, there is, unfortunately no colour formula available for SB machines, but the hammertone can be colour matched by an automotive paint shop, using the cleaned inside of the handle or chain-case cover.

We will address the cutter clutch issues (if any) when we get to that stage.