OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Reel-Type Mowers Scott Bonnar 45 Questions

Hey all,

Long time lurker on the forums but first time posting, i have recently jumped into the world of reel mowing and purchased what I believe to be a scott bonnar 45 twin rail, however the serial badge has long since disappeared from the rail to be able to confirm. I do need to get some more photos of her to upload but will get to that this evening after work. I intend to fully restore the old girl to her former glory but was hoping to wait until winter to do this, as after adjusting the reel the mower is still cutting very well, in saying this looking at the bottom blade i believe i will have to replace this when i pull her apart.

First question would be is there any way to identify the model of mower seeings how the serial badge has been removed?

Second question is, currently it has a briggs and stratton engine on it, somewhat newer than the mower i believe, the previous owner has been servicing her regularly and has provided receipts to back this up, the motor runs fine but is insanely noisy, i am currently under the impression the muffler baffles may have collapsed, i have been told by my local mower shop that it is quite common when undoing the muffler that the casing on these engines will crack, is there any way to avoid this or a recommended way to remove the muffler?

If i was to crack or damage the casing i have already priced a new motor, either a honda GP160 or briggs and stratton 550, any thoughts on these two would be appreciated.

Will upload more photos later on.

Looking forward to your feedback.

Hi Paulie,

Firstly welcome to the ODK Forums.

Your machine is not missing it's ID plate and that is because it was never fitted with one originally.

You'll see that it has the white serial sticker on it which states nothing more than the Model: 45 and a Serial number given.

The variant number is no longer given as by this stage of production there were not a number of different variants available like there was in earlier times. Simply all that was available was the 17 and 20 inch machines, both Briggs powered.

Am I correct that yours is the 20 inch machine as it looks somewhat wider than the 17 in your included photo. I'd also say that yours was built around 1979 to1980 during the Challenge Banks time of Scott Bonnar ownership.

Cheers,
BB.

Hey BB,

THank you for the information, that makes a lot more sense and is a relief to know that there isn't a piece missing from my machine no matter how small.

The machine is a 17 but it would seem that my photography skills are not very good. A 20 inch model would be more than overkill for my yard at this stage i'm afraid.

In relation to the Briggs attached, do you know if they were a 3/4 or 5/8 keyway, not particularly wanting to go and buy a set of callipers just to measure this?

I should have some more photos up this evening.

So finally got home and tried to loosen the retaining ring on the muffler, (penatrant oil soaked since last night) with no joy. I'm worried that any more force may damage the casing on the mower. Is there an easier way to remove the muffler?

Photos uploaded, had to be a little quiet so no photo of the chains or gearing yet as bub was asleep on the other side of the back wall, any tips on what i may need to get sorted as a priority during my restoration?

Am hoping to get to this during winter as the machine is cutting pretty well at the moment and would like to see the growing season out with it before pulling her apart.

Cheers,

Paul

Hi Paulie,

Firstly, Sorry but I didn't address your issue on the muffler in your previous post.

Honestly I've never had any sort of issue removing these and as such have never cracked an engine block in the process.

How I do it is to simply use a long series pin punch (8 to 10mm) and place it against one of the teeth of the lock ring and give it a sharp blow and it generally comes undone on the first strike. Giving it an overnight soaking of penetrene etc. is a good practice.

Now that you've put up a full series of photos we can see that this chassis has either suffered from a catastrophic rail failure due to a non maintained clutch half which incidentally has already been replaced or it was well on the way and someone has simply tacked on some strengthening steel so that it doesn't get any worse, regardless it's currently looking rather ugly and will require someone with good skills to unpick it all and restore it back to original appearance with no scars left behind as evidence, also keeping in mind that all this will cost a fair bit over and beyond a normal restoration if employing someone to do this procedure.

Alternatively you could just tidy it up mechanically and just keep using it, they don't all have to be spotless show-pieces I guess and as such keep a look out for another that has a much better chassis to do a full resto on.

Cheers,
BB.

Thanks BB,

I will have another shot at loosening the ring this evening after work, there is the possibility that i didn't hit the punch hard enough after being told the casings tended to crack if not careful.

The guy i got the mower from had some photos left from during his fix of the rails that showed a very small crack on the rear rail near the right hand bolt hole, maybe 3mm long, i'm pretty confident i can get the welded steel off and tidy up his handy work without to much drama, benefits of growing up with a boilermaker welder father i spent weekends in the workshop with i guess.

We will see how i go i guess, i do intend to have a go at repairing the damage he has caused to the rails, before doing this i will take the paint off around the bolt holes just to make sure it isn't worse than the photos showed, if they are too far gone i may be forced to seek out a different mower to restore (i need a winter project this year, car restoration last year). If nothing else this mower will work well to keep the grass in check until i can find a suitable replacement.

What would be your recommendation for repairing damage around the bolt holes in the rails typically be?

Hi Paulie,

Have a good look through the following thread as the specimen mower is of the worst case scenario.

We here on ODK call it the "Mr.Jones Gusset repair method".



https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=64696

If you have these skills as you suggest at your disposal then nothing should be too much of a problem for you and you won't have to look for another mower.

In saying that, many people will have to pay for these services and then with all spare parts and sundries required on top it then becomes an over capitalised project that rapidly has interest lost in it, therefore it then ends up in the for sale listings, if you get where I'm coming from.


Cheers,
BB.

Thanks Bonnar Bloke,

I appreciate all the assistance, that seems like a very simple yet clever way to strengthen the rails, it certainly beats the plate i was intending to use under the engine, alot cleaner finish, i should have a nice bit of steel laying around that i can cut down to match Mr.Jones fix.

Again thank you for your help and will get some photos up once i can complete the repair of the rails.

Paul

Hi Paulie,

It's quite difficult to judge from a glance. It will take removing the engine from the chassis and separating the clutch assembly from it, and then measuring.

Although - I had the exact same engine on my 20 inch Model 45, and it was 5/8.

All of the (x number of) Model 45's I've owned and worked on with past generation B&S or Kirby/TM have all had 5/8 keyway shaft motors.

I personally don't know the older Briggs models that well to determine if this particular variant was offered with the 3/4 option. But the main thing that makes it more of a question mark is, the clutch half currently fitted with the 2x grub type set screws do come in the 3/4 shaft size option. So the possibility is there.

If it was a clutch half sporting the old captive cotter setup, I'd say it was 99% certainty of being 5/8.

The usual culprits for 3/4 shaft sizing I've come across on Model 45's are Honda powered.

Thank you GTX,

I was looking at the engine replacement as a way to reduce vibration through the twin rails.

Any thoughts on the Honda GP160 at all? It is ohv so was hoping I may be able to get away with instead of forking out the extra cash for a GX120.

Honda would be my preference but the Briggs and Stratton 550 will be the go to if I end up having a 5/8 setup.

Paul

Hi GTX and Paulie,

I'd bet London to a brick that the current power plant is a 5/8 shaft unit and the only reason there is a new clutch half fitted is because the original cotter equipped unit had been allowed to run loose for quite some period of time and thus became flogged out, in turn this destroyed the rails and why they have had the repairs done as we see them currently.

I'll be the first to say that the older style Briggs and Rattler engines were the most unbalanced units around and thus this was the start of all SB Twin Rail fatigue problems on the 45. The newer style engines are far more vibration friendly on the Series 2 Chassis and thus I'd strongly recommend that if you were considering a replacement that you would choose one of the newer style sloper designed engines.

The current 3.5Hp Briggs units are pretty good but if you can afford a Honda then go for it.

The current Briggs units are now being sold for around $250, whilist Chonda's (Chinese Hondas) can be had for around the $125 mark delivered to your door.

Horses for courses I guess. Choose your Horse wisely.

Cheers,
BB.

I haven't owned either, but hear many good things. Honda's usually come with the higher price tag, which you can expect from the brand badge.

The GP160 equivalent (or close to) power wise in the late Briggs range is the 750, and I don't believe it is available here with the 5/8 keyway shaft option. Only 3/4 (keyway), or 5/8 (threaded / pump) - which is no good for us in these applications anyway.

I do highly recommend (and own) the B&S 550 range. They're well priced, efficient, quiet, smooth, easy to work on and in my opinion the perfect power match for the Model 45. Pretty certain there is a 3/4 keyway shaft option available with this model also.

The engine replacement can certainly assist with chassis vibration. Although it's equally (if not more) important to inspect the engine side clutch half, the clutch cone, and main/PTO shaft keyways, and even all of the individual keys. If they are looking pretty worse for wear and key fitment is loose and sloppy, do away with them and replace them. The most expensive parts out of the whole PTO assembly are going to be the main clutch cone and the engine side half. The PTO shaft is pretty cheap, and usually come supplied with keys.

Edit - BB has beat me to it!

Thanks guys,

The local briggs dealer i spoke to wants to charge around $300 for a b&s 550. If i can get a new one for $250 i may well just put a B&S on, the only reason i looked at the Honda was it was only an extra $15 from what i was quoted for the B&S.

Will get the motor off this weekend and see what the clutch and keyway conditions are at the very least. I still need to see if i can that muffler off at this stage but i dare say at $250 for a new motor that will reduce vibration i wont be able to get that idea out of my head.

Thank you again for all the info.

Pays to shop around, that's for sure.

If you can't get a better price than $300, I'd almost be happy to get the Honda at the extra $15. But don't forget you'll need the 3/4 clutch half, so expect another $80-100 on top for that. Potentially the clutch bearing as well if you can't salvage the one out of the existing half- $25 - 40 there.

If and when you do buy a B&S, unless you already have some - don't forget to buy the oil for it - hey BB
Wonder if the Honda's come supplied with oil...

I haven't looked at these clutch halves but can't you get somebody to just mill it out to suit the 3/4 shaft, you are only taking 1/16th of an inch out of the wall thickness

Hi Norm,

I'm not sure if you've had work done at a machine shop as of late, but their prices have outstretched their usefulness. If you had your own mill and also had the expertise then I'd say go for it. I had a Series One 20 inch Model 45 bearing carrier TIG welded as it was cracked when I got the machine and then had the bearing size re-milled out afterwards to perfection and that was $60 at mates rates.

I would most definitely stay with the Briggs replacement as you won't have to mess around with changing any drive train gear and the extra cost involved. The Briggs engines are available in both 5/8 and 3/4 size PTO shafts and are the same costing for either.

Now as far as oil goes, Briggs have organised me a replacement motor as they can see the issue of what's happened.

All they really need to do now is actually clearly label either the packing carton or the engine itself that it requires oil as they've had a few issues as of late with some engines having a full crankcase while others only have around 150ml of assembly oil inside. They admit that a standard of some sort should be sorted out, thus why I got caught out like I did.

I will say that most manufacturers that sell new engines place predominant labels on their product stating "REQUIRES OIL". They do this so as to avoid having to ship engines as DG cargo (Dangerous Goods), so isn't a truckfull of engines all with 150ml of oil inside each one considered DG ???


So in the future "I ain't fallin for no banana in my tailpipe"

BB if you go to a bearing place and ask if they know anybody with a mill that does odd jobs at home, they usually know somebody in the area

Hi Norm,

You're absolutely correct on that score, but I've never asked or needed to as I know someone with a mill, but in saying that you are correct that it's perfectly possible to mill out a 5/8 to a 3/4 size requirement. Now lets see someone do the reverse eh ??

Cheers,
BB.

To be honest with the price of a new Briggs at $250, if I can find a dealer that will sell me one around that price point i am going to follow BB�s advice as I am happy with getting a new Briggs.

I really am hoping to do the restoration mainly at home with the exception of using a mates workshop for sand blasting the old paint off. I�m sure I could get it Milled but defeats the purpose for me at least if I can get a engine that bolts straight in.

Paul

So finally got the muffler to release tonight, installed the new one with no visible damage to the motor thankfully, now I�m having trouble with the motor and getting it running. Painful as she was running well enough over the last month to cut the grass with, bad fuel perhaps. Will not get up to operating rpm and is blowing a little smoke, next task on the weekend seems to be to drain the fuel clean the car I and see if I can get her running again.

Pretty regular occurrence with these old motors hey Paulie. Definitely focus attention on the fuel system. Give it a good clean up.

These old motors can really give the patience a workout. Purring one day, spluttering and choking the next. Not to mention the stench of spent unleaded all over you after use. This is why mine end up on the shelf to collect dust in the shed. With a very 'laid back' intention of tearing down and attempting a refresh... some day.

When you're pretty time poor and just want to put these machines to work on the spot, new motor is the way to go (obviously budget permitting). Do it Paulie, you will love it.

Old motor syndrome hey GTX,

I have some carby cleaner to run through on the weekend, was up late last night cleaning the old fuel out and only got the motor 90% back together after that. Will get it fully reassembled after work tomorrow and run the cleaner through. I really am trying to keep the old motor if possible but will be buying a cheap set of calipers today to make sure on drive shaft size before refitting the motor to the mower. Being as impatient as i am, i want to be in a position to get a new motor on the weekend if the clean up of fuel system doesn't get the old girl firing properly.

Can't wait for the growing season to be over so i can strip her down completely as at the moment i need to mow twice a week, i had to pull out the rotary mower on tuesday and managed to near scalp half of the back lawn so currently really wanting to get the reel back up and running.

As a side note i did have a quick look around the engine mount bolt holes while motor is off, i cant really see much in the way of damage but need to get the rest of the old paint off too make sure. Of course i did forget to get some photos.

Yep! Precisely. I get a small window of time to get all three patches done at my place. 40 year old motor misbehaviour - I just can't accommodate the time for at the moment.

Don't worry too much about the calipers (unless you really want them). Do you have 5/8 and 3/4 open ended spanners? Stick them over the engine shaft, that should give you a pretty clear indication of what you have. Or you could measure the hole on the engine side clutch half, and do your conversion - close to 16mm is 5/8.

and 19mm is 3/4

Well I bit the bullet and bought a brand new briggs and stratton today,

After looking inside the carby and the condition of it, it became an easy decision to get a new motor. Guys i brought it from oiled it up and ran it up for a few mins for me as well so shouldn't have any issues, low/no oil or otherwise.

The new Briggs may be a little fun to set up with the old thumb throttle cable.

Happy learnt how to putt ! LOL


These new engines are such an improvement to the old L engine.

Cheers,
BB.

Very, very nice Paulie. Did you give it a run today? What do you think? Anticipate it runs beautifully.

Very easy to add the throttle cable. I can take a photo of one of mine set up if you need?

Cheers

Hey GTX,

Did get a quick cut in today. Cutting very nice. New engine definitely highlighted how poorly the clutch was set up though as well as the fact the reel definitely needs to be sharpened, ordered a new bottom blade today as well so once that arrives I will send both to be sharpened together.

New engine was a good call though. After stripping the old engine down today the old one is in really bad shape. Thinking I may rebuild one day however. Maybe someone else could get some use out of her once complete

Hi all,

It's amazing what a difference a new engine will make, especially a smoother running one without the thump in it like many of the earlier power plants had, thus why most bowling clubs where it is far more critical had electric powered machines opposed to petrol driven.

Electric machines just don't have that downward thump that effectively will make the surface uneven to a rolling ball.

Cheers,
BB.

Hey BB,

I actually only spoke to the local lawn bowls club yesterday about where they have their fees sharpened, their grounds keeper was very reluctant to share any info with me to begin with.

He did however let me have a look at his mower, very impressive machine, although I have no idea what brand/mode it was.

He did say they post their blades for sharpening, couldn�t tell me to whom though.

I have ordered a new bottom blade as I need to get the reel sharpened, I figure with such little life left in the bottom blade now was as good a time as any to get a new one honned with the reel. Also have a feeling the bearings need changed out so will be ordering new reel bearings this week also.

I am enjoying the project so far although it is insanely addictive so far.

Will get some progress shot once new reel bottom blade and bearings arrive.

Paul

Hi Paul,

Most of the good clubs send their reels off to the same sharpening service location that all the others do as good recommendations travel fast, while the bad ones travel even faster.

Here is Adelaide you'll find that Steve Rose at "Australian Saw Blades and Sharpening" gets most of SA's larger reels from all over the state, thus he's never really (pardon\the pun) out of work.

I'm constantly referring work on to him and to date have never had a bad word come back to me.

Cheers,
BB.