OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Reel-Type Mowers Christian: Another SB45 restoration.

Hi everyone,

I'm new to the forum after having recently purchased a 20" Scott Bonnar 45.

I'm looking to get it back into reliable working order and was hoping to get some advice.

My thoughts so far are for the frame to be repainted, reel sharpened, new engine (probably Honda GX120 but happy to take suggestions) and a new catcher.

After inspection today, it looks like the reel has taken a hit as a blade is bent. Can this be repaired or does it mean a new blade reel?

I've attached a few pics so could you please advise on the sprockets, frame, blade reel, etc to give me a bit of an idea of what I'm getting myself in to.

Also, is the conversion from the current B&S 3HP to the Honda GX120 a simple conversion?












[/b]Moderator comment: Note only 10 images can be included in one post.[b]


Thanks,
Christian

Hi Christian, welcome to Outdoorking.

Note that only ten images can be included in one post. I've localised the 11 images, because external storage sites delete them after a time, and we need our archives to be permanent.

Final image from your post:

Hello Christian!

Welcome from me too!
Thanks to Glo Mod Grumpy for embedding the photos.

This machine is the less common 20" Model 45.
This machine presents as being in sound condition in terms of the sprockets.
I don't think it's had a hard life at all.

Yes, the reel can be straightened. That is not a big issue.

Advice for sharpening:-
[1] Do your homework first.
[2] Ensure the repairer is not an agent, but has the specialised grinding machine
for the reel and bottom blade on site.
[3] Specify new, sealed bearings for the reel
[4] Take the reel and bottom block complete to the repairer - meaning, do not
remove the bottom blade from the sole plate. Take the bottom block complete.
[5] Ensure both the reel and bottom blade (or new replacement) are both ground.

Advice for painting:-
Other folks on this site should be able to assist with colour.
Whatever you do, do not use the powder coat process.

Preliminary Advice:-
Before you do anything, you must assess the condition of the top rails,
the two rails the engine is bolted to.

To do this, remove the engine and primary clutch complete.
[1] sand the frame rails and inspect for any cracking of the rail.
[2] a straight edge across the top will help assess warping (if any).

At this time remove the clutch from the engine by loosening the cotter pin nut.
The clutch housing should be a firm fit on the crankshaft. At this time, measure
the crankshaft OD or clutch housing ID. This will determine the replacement
engine. Replacement engine fitting is straightforward.

Advice on Engines:-
Some folks here have strong Briggs or Honda preferences. [I'm sure they will tell you ]
Either OHV Honda or OHV Intek Briggs will be fine in my book.

There are many helpful topics on this site to assist you.
The main thing, now, is to disassemble and check the frame for damage.
Please report back with your findings.

Yours presents as a good candidate for restoration and should give
many further decades of reliable service.

Hope this helps.
--------------------------------
JACK

Thanks very much for the comprehensive advice CyberJack.

I've commenced the stripping of the frame so will post a few pics of the rails tomorrow hopefully, if I get a chance to remove the clutch.

I'm relieved about the straightening of the reel blade. A replacement reel wasn't in my plans.

Also, thanks to Grumpy for embedding the pics in my post. I was all at sea trying to do that.

Cheers,
Christian

Hi Christian,

Just a quick word on Honda engines, they are probably the best power plants available and certainly surpass the old Briggs and Rattlers especially when it comes to the vibration factor, something which is really crucial to the 20 inch Series II model (which is what you have) so as to avoid rail fatigue and eventual failure. The only thing is that most Honda's have and I stand corrected here is they use a 3/4 inch size PTO shaft size and as such you'll probably have to source a new clutch half as the Briggs units are mostly 5/8 inch bore units.

Cheers,
BB

Thanks bonnar_bloke for your advice RE the Honda conversion. I measured the ID of the clutch and can confirm it is a 5/8 inch bore. Do you know where I can get a 3/4 clutch half from? Will this half bolt on to the original other half?

I've pulled the mower down, given the frame a bit of a sand and the rails look pretty good to me. There aren't any cracks in the areas which I've sanded.

CyberJack and others, what are your thoughts? Is this a sufficient inspection?

I put a straight edge across the rails and they are fine.

At the bottom of this post is a few pics of the frame.

In relation to the reel and the bent blade, I'm guessing this should be straightened before powder coating, and after these two steps, the reel and bed knife should be sharpened??

Are you able to make suggestions in this forum for a good sharpening service in Melbourne's west-northern suburbs? If not, no problems.

Only early days on getting this SB45 into working order, but quite enjoyable so far.

The Scott Bonnar videos on YouTube have also been very helpful. I'd hazard a guess and say the star of these videos is also on this forum, so thanks.

Here are the pics:

Hello Christian,

That's a good frame, as most 45s frames still are.

Yes, the reel should be straightened and painted first.
But remember, NO powder coating. Conventional painting is the best.

I can't personally recommend a sharpening service in Melbourne.
I know ADE use Foley grinders at Cheltenham.

Administrator Deejay is the star of the videos.
Hopefully, now that he's back, he will want to say something here.

As to the 3/4 clutch inner half, I'll leave that to member Bonnar Bloke.

Hope this helps.
----------------------------------
JACK

Hi Christian,

As far as 3/4 clutch halves are concerned they are readily available through our online store or other outlets which ever is easier for you.

I must admit I'd really like to see much closer shots around the engine mount holes as I'm somewhat concerned that there are a few fine fatigue fractures showing, but as your shots are not close enough I can't confirm positively.

Could you take some extra shots for me so as to evaluate and then I'll get back to you with a solution to remedy the situation if it's what I think.

As far as Jacks advice on reel damage correction and refinishing I couldn't agree more with his solid advice, especially when it comes to powder coating.

Cheers,
BB

Hi Christian,

Gotta say I agree with Bonnar Bloke. There are some v suspicious marks from the lower holes in the photo. I'd be paint stripping the area rather than sanding as sanding can mask fine cracks. Then a good look with a 10x glass.
Reel mowers are not my area of expertise but finding and repairing fatigue cracking in structure is something do a fair bit of.
Hope you enjoy your project.

Hello Christian and members,

I downloaded the photos and viewed them at your original size:

I read these as outlines of the engine base. I guess some surface pitting caused by
the close contact of an alloy base with the steel rails over 3 or 4 decades.
There is also some pitting from surface rust. I do not see any cracks on this 20" frame.



Christian, could you also take a close look at the underside of the rails
to confirm you see no cracks. If you do not see any, but would still like a
second (or third) opinion, then please supply photographs as suggested.

Clutch:
The 5/8 DIA clutch half is HERE.

The 3/4 DIA clutch half is HERE.

The Thrust Bearing is HERE.

Either the Briggs OHV or the Honda OHV are smooth, reliable engines.
Either would be suitable to re-power your application.

Your old side-valve Briggs - by its design - produced more vibrations than
an equivalent OHV. They were very good engines but no match for the new OHV
designs offered today. The main thing is that you re-power with an OHV design.

If your 5/8 clutch is sound, the Briggs would be entirely suitable (and economical).
If you would prefer a Honda, make enquiries as to whether a 5/8 shaft is available
in AUS. The Briggs, as a full-line engine manufacturer, will offer both sizes.

Hope this helps.
---------------------------------
JACK

Hi Christian, CJ and prd,

I have to agree with Jack (he has tools at his disposal that us mere mortals don't) that these marks are very consistent with the underside casting profile of the Briggs engine, also with the enlargements of the shots they now show that the marks are very straight lines on both front and rear rails and thus won't be fracture lines as fatigue will normally not create straight line fractures, they will radiate in all different directions away from the mount points.

Personally I think you are one very lucky chappy having a twin rail 20 inch chassis that requires none if any work in this area. Normally most 20 inch machines will have had a flogged out clutch at some point in time which will exaggerate the vibrations from a Briggs engine and thus induce much stress and flex into the longer 20 inch rails around the engine mounting points. I currently have a 20 inch machine the same as yours and it has had two massive rail failures. I will take some shots of it tomorrow and post them up onto this thread just showing what can happen due to lack of maintenance.

I will say that you've got a fairly good canvas (so to speak) to work with as a basis and it would be lovely to see that 3 HP Briggs fully restored and powering that machine again for another 40 odd years.

Cheers,
BB

Hi all,

Thanks again for the responses to date. They've been helpful.

I've stripped the rails further this weekend using paint stripper, where you can see some photos below. The rails look good and I can't see any stress cracks or other deformations. Let me know your thoughts on the rails.

I've taken the blade reel to get straightened before painting, so I should get that back later next week, where all parts getting painted will then head off to get sandblasted.

Bonnar_bloke, you raise an interesting point about rebuilding the B&S 3HP. Part of me would like to keep the mower in it's original condition, however the mower will be used regularly so I'd like a reliable engine, hence why I was leaning towards a new Honda GX120. If rebuilt, will the B&S make for a reliable engine?

Hello Christian

The rails look fine to me.

I think prd's idea of using paint stripper (rather than sanding) for inspection
of Model 45 rails is a good idea. Perhaps that should be the recommendation
in future cases. Perhaps Mod BB might have something to add there.

FRAME:-
Christian, you've said this machine will get regular use. I made a recommendation for
an OHV engine, not on the basis of reliability, but on the basis of preserving the frame.

I do not believe there is any dispute on these forums that some high work hour machines
of 17" and 20" sizes have in recent times experienced rail failure. We have no reliable data
as to how wide-spread that issue is, or the exact causal factors. Anecdotal evidence is important -
that's all we have at the moment - but the years ahead will give us a better idea.

It is, I believe, a vibration problem, as our Engineer Grumpy has identified. The combination
of rail thickness specification, combined with the vibrations characteristic of single cylinder side-
valve engines is probably the main contributing factor - plus the hours of operation of the
particular frame. This is a new issue, only emerging in the last few years.

It would be easy to argue that the 20" frame is more susceptible to failure, given the longer rails.
The problem is, though, the 17" machine was, by far, the biggest seller. The 20" machines catered
for a niche market of larger residential lawns and lawn mowing contractors. The best advice I
can give is to play safe, and opt for a new OHV engine, that has reduced vibration levels.

ENGINE:-
The old Briggs engines were super reliable. The new Briggs engines are super reliable,
as are the equivalent Hondas. It is really a personal choice here.

The desire to keep the machine in original condition is a good one; but what is in
your favour here is the fact that re-powering requires no modification. Returning
the machine to original spec. could be done at any time. Again, whether you decide
to recondition the side valve Briggs, or re-power is a personal choice.

Hope this helps.
------------------------------
JACK.

p.s. Christian, your excellent photo record of the frame, and the discussion here, will be most
helpful to members and moderators alike.

A big thank you to Mod BB and prd for their contributions.

Hi Christian , CyberJack and prd,

I really like the idea of using paint stripper for removing paint without disturbing the substrate underneath, but its a bit of a messy procedure for some as I could imagine.

I generally use a 4 inch grinder with a flap disc on it and that rips everything off and gives a great finish, admittedly not everyone has 5 x 4 inch, 3 x 5 inch and 3 x 9 units all with differing wheels on each at their disposal as I have so using what is convenient to each person will differ. Oh and while I remember I forgot the 7 inch machine in that lot, man too many grinders in my power tool cabinets.

As far as choice of power plants is concerned I totally agree with Jacks idea of of the OHV units opposed to the side valve units. My main concern is that you've gotten an "out of jail free card" so far with those rails and you don't want to start something that requires a whole lot of rework so a newer breed OHV unit such as a Honda would really be a bit of preventative maintenance in the long term I'd say.

I really think that a nice restore job on this unit will have your mower coming into the $1600~$1800 bracket and that's nothing to sneeze at. As Jack has already suggested, it would be easy enough to substitute power plants without having to do any structural changes whatsoever and if you so desire you could return it to original factory specs without a worry in the world.

We'd love to see progress photos of what you are doing as it all helps others and instills huge confidence in new Scott Bonnar restorers that view our forum before tackling any type of work themselves.

Cheers,
BB

Thanks to CyberJack, bonnar_bloke and prd for your comments and assistance thus far. It has been really helpful.

I've decided to go with the Honda powerplant for the reasons provided by you guys.

An update on the restoration. The reel has been sent off for repairing the bent blades. It's ready to be picked up, which I will this week. I'll then be taking everything that is getting painted off to get sandblasted.

I'll probably order the motor this week. I know i'm probably over-keen on this front, but it will make a beautiful centre-piece at the dinner table for a few weeks before going to work.

I'll post some pics up shortly when I run into some inevitable barriers.

Cheers.

Hello Christian

That's good news!
Yes. there's nothing like a new engine as centre-piece on the dinner table...
A conversation starter ... do that trick with the whipped cream

Thanks for the update.
-------------------------------------
JACK

Hi all,

I thought i'd post an update of how the SB45 restoration is going, since I last posted.

It hasn't progressed a great deal unfortunately due to work commitments, however I have got the blade reel back from having the blade straightened.

Now the reel, frame and other bits will go off next week to get sandblasted, before painting.

I've been having a read on this forum about the best hammer tone paint colour to replicate the original Scott Bonnar green. Galmet Jade Green was suggested. Are there any others?

Also, the disassembly of the mower has gone well to date with the exception of the rear rollers. I was hoping to disassemble the rear rollers completely to enable me to sandblast them and then re-paint, however I have been unable to remove the internal wheel/hub from each roller. There is rust inside the rollers which may be a reason for this, if they are even able to be removed. I will post some photos tomorrow of what I mean as they will provide a much better explanation than my words.

Thanks again for everyone's help.

Hello Christian,

Okay, we'll wait for the photographs.
Generally, the rollers should come apart relatively easily.

--------------------------
JACK

Hi all,

As far as paint colour is concerned there is absolutely no commercially made paint that comes close to the colour that Scott Bonnar used on your machine. The Galmet colour chip is nothing like the actual colour so please disregard the colour chip you've seen. The only way you'll be able to replicate it is to get a can of "Silver" Hammertone and have it colour matched from the inside of your chain case before you have it sand blasted and that will give you the best result.

Have a look at the machine that member "mikeo" has restored and that's about the best match I've seen on this forum. At this stage we are still hopeful that mikeo can get the actual formula from his paint supplier and share it with us as this will make life really easy for all the new members that come to the ODK forum. BTW there are no records of any of the colours used by Scott Bonnar on file with any of the Australian paint manufacturers and no records from SB have survived after Rover took over in 1980.

Cheers,
BB

Hi all,

Here are some pics of the rear rollers. A bit hard to see inside them, but rust and other rubbish is present.

Should the internal hubs/wheels be able to removed by hand? Ie. without much force?