OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers New to SB45's

Hello all,
great forum and oh so helpful. I have just got myself two 45's hopefully to replace my little rover thoroughbred that need some attention and a new catcher. The idea being that I either turn the two into one good mower or have one to restore and use the other for weekly mowing duties.

The first is an earlier model 07154 single rail with a kirby tecumseh hk25 spec k1055 serial 9204 9102. The motor runs but not very well. There are a few 'dings' on the blades and it has lost drive to the blades (my fault - need to work out how to adjust it) and the main clutch has a lot of slippage and needs new cork. It seems complete other than an air filter.

The second unit is a later twin rail mower. 66594 - 450423. This has been re-motored with a 3.5 hp b+s mode; 93312 type 01155 E1 code 060601YA. This runs better but not perfectly. The blades appear in better condition although it doesn't cut well. Drive and clutch are good. However the motor looks out of alignment (see clutch photo) and it shakes like crazy.

Attached are the usual photos.

I really like the simplicity of design and the quality of the components (really nice not to have a bolt head round off, or a nut strip etc) Love the fact that the forum is here to help. Love the fact that so many parts are still available!

So.... Which one would is worth putting more effort into?
Is there any way to align the motor ( It seems like the lower nuts for mounting the motor are captive)
Can someone please guide me to the section on the adjustment for the drive clutch (looked but I can't seem to find it)

I like the fact that the newer motor is more powerful and may be mor5e reliable. I also like the fact that I can get my teeth into restoring the older one. At this stage I am weighing up my options and resisting spending too much in the short term till I become more SB45 savvy

Thanks in advance. This really is a great forum!
















[img]https://www.outdoorking-forum.com.au/forum/uploads/usergals/2015/10/full-9664-24799-img_1840.jpg[/img]

Hi Mark1,

Welcome to the ODK Forum, we all love to tinker here so you'll be in good company.

Well you've certainly got yourself into a predicament there haven't you, comparing apples with apples.

I can see good and bad points on both machines so it's not really going to make much difference which one you start on.

Firstly you must ascertain the condition of the rails on the twin railer. 75% of them have fractures induced by the power plant radiating from the two mounting holes nearest the clutch body. Generally if these are advanced you can see them without removing the engine, just look for cracks in the paint around the base of the engine. If there are any there I would move on to the Solid deck machine as these don't fracture no where near as much as the twin railers do.

I duly note that there is a major Engine / clutch alignment issue with the series two machine.

The solid deck (series 1) machines are clearly the better designed unit, using a solid mounting deck for the engine, utilising a brass thrust pad opposed to a plastic one and also using a cast brass height adjuster knob opposed to a die cast unit, also all the early machines used a full cast iron clutch body which far out lasted the later rubbish die cast units that usually flogged out on the PTO shaft and thus induced extra vibration into the rails of the machine which then sped up the fracturing issue.

Your twin rail machine (early series 2) would've originally had a Kirby HK25 on it but as we can all see it's been replaced with a 6th of June 2001 model Briggs engine which clearly would be the better power plant to use when running correctly, proof of this is the odd looking modification to the petrol tank so that it clears the early style kirby fitted handlebars. This mower also has the better reel and near new bed knife on it, but that can be easily transferred over to the solid deck machine. I guess until you ascertain the condition of the twin rail chassis we won't delve into it much further.

I'll await your response.

Cheers,
BB

Thanks BB for the quick reply.
Yes it is a bit of a predicament. Create a great everyday mower or a something I'm scared to use. Actually it's not that bad. I can't see why I can't have both!

I hadn't noticed the bedknife on the twin rail. It measures 66mm vs 52mm on the single rail. Win 4 me! You mentioned the later reel was the better one. Is this because it is not damaged or was there different designs? The blades measures 22.5mm newer vs 23.5mm older. How much meat does a new blade have and how do you know when they are past their service life? (Sorry about the questions - I am only up to page ten on the topic list.....)

I just checked the twin rails. Without taking off the motor (which I will do tomorrow) they appear fine.
Cheers Mark

Hi Mark1,

Both reels are rather identical and have no advantages over each other. BTW the two hits that the one reel has suffered is repairable. Both have plenty of material left for a number of machinings. As mentioned the twin railer has a near new bed knife so no real money needs to be spent on that apart from a freshen up on a Foley grinder (brand name reel grinding machine)

I totally agree, there's no reason why both machines can't be restored etc. regardless of the situation of the chassis rails, as they can be repaired back to new if required.

Anyway take that engine off and have a really good look, even rub the paint back to bare steel around the area of the mounting holes as it's better to find out now of hair line fractures than later on after they've been painted and the fractures extend.

Cheers,
BB

Thanks BB
Was half way through taking the engine off When I realised I hadn't taken any photos.
I'll let you know how I go tomorrow.
Any ideas re the drive clutch behind the big sprocket and how to adjust same? I undid the bolt through the centre of it and now don't have any drive.
Also still have the issue with motor alignment on the twin rail. There seems to be no way to adjust the alignment.
Cheers mark

Hi Mark1,

The bolt you refer to is a bit of a adjust by feel set up. They use a nylock nut on the clutch pull fork end.

All you need to do do up the nut until the top of the fork can be pulled towards the engine with your fingers freely and create approximately a 1.5mm gap between the fork and the chassis side plate. The rest of the adjustment is then done by the cable adjusting sleeve nut and bolt assembly to take up any cable slack.

Remember that centre bolt must be slightly loose (that's why a nylock is used) so as that the clutch has the ability to grab and release.

Hope that this helps you out.

As far as engine alignment is concerned all you have is the amount of hole clearance in the engine block, but that is enough to manoeuvre it into the correct position. Again this has to be done carefully so as that the engines PTO shaft with the clutch half fitted does not move the clutch cone sideways in any manner. Also a good clutch half is essential as if you have a flogged out one on the shaft it will not sit straight (true) thus alignment is not possible. Once this has been achieved then all you have to do is carefully lock down the engine mounting bolts.

If you have any further issue with this please don't hesitate to ask.

Cheers,
BB

Thanks BB.

I had a muck around with the twin rail today. Removed the motor. The rails look perfect. I investigated the alignment issue. Couldn't seem to get the engine shaft pointing anywhere near the right direction (ok an exaggeration it was about 5 mm out). Realised the chain tensioner might have been stopping it pointing in the right direction if the chain was too tight. Slackenened this off and all seemed good. Checked the runout on the clutch body whilst still attached to the motor. Was about 6mm. ?????????

Took the clutch body off to find a stuffed woodfuff key and a cotterpin that does nothing (removed key put clutch back and and then tightened cotterpin - did nothing). Lots of slop on the crankshaft. I span the clutch body on the crank without the woodrff key nd it appears square. Looking at the engine parts list is shows two diameter cluch bodies. It seems my clutch body is the bigger size and the crank the smaller size. Does this sound right? is there a bush or similar available?
Any suggestions? BTW Iput my micrometer away somewhere really safe...........So safe even I can't find it

Hi Mark1,

Well the chain tensioner is an obvious one if you can't get the transfer shaft to sit correctly unloaded without even taking the engine into consideration.

It is most certain that you clutch body is flogged out as its an early die cast unit and with the way that piece of Key Steel is damaged it tells me that you clutch body hasn't been running true for quite some time.

You are really lucky with the chassis as a flogged clutch just invites stress fracturing into the rails and yours seem to have been spared and also your pocket for that matter, so that's a big plus towards rebuilding the twin railer.

Throw the clutch body straight into the scrap bin and organise another. There are two sizes as you correctly state, 5/8 and 3/4 with most being 5/8, the smaller size shaft diameter. BTW that key is not a Woodruff key as a Woodruff key is flat on one side with a half moon on the other. These are used on most of the sprockets and the clutch cone
/ transfer shaft joint.

Keep plodding on and don't forget to post up photos as you go as that's great for both myself to give you advise and also other members to learn from.

Cheers,
BB

Thanks BB.
Is the earlier clutch body the one with cotter pin that doesn't go through both sides?
The single mower's clutch body has a cotter pin that goes right through and the twin rail's doesn't - so now I am a little confused?

What would be the diameter of a b+s crank be on this later motor? Just want to make sure trhe clutch is the right one before I throw it away!

Thanks for the lesson on keys ad all your time and help!

Cheers

Mark

OK found the micrometer.
crank is 0.624 inch (close enough to 5/8) and clutch body is 0.634 inch. Amazing what a hundredth of an inch can do!
So the clutch body is flogged!
Still trying to work out which is the old and which is the new and the differences

Hi Mark,

The solid deck machine has the earlier cast iron clutch body and the twin railer has the later revised version being made out of die cast, this one has the hidden captive cotter pin. Neither unit is as good as the current spec that has two set screws that pin the clutch body to the PTO shaft in two places 90 degrees to each other and thus eliminate any ability for the body to move, thus less flogged out clutch bodies now. BTW if you have a correctly maintained first version cast iron bodied clutch then that is the very best unit made but as we all know that all companies try to trim the fat in production costs and the clutch was a major fat trimming area on the machines as they evolved.

Cheers,
BB