OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Scott Bonnar cutting and clutch problems

Better photo of the rear rail without the grass, but still no ID plate

I reckon the frame at least is a Rover 45. It has the 4 holes in the rails where the black plastic cover fits over the clutch cone and screws to the frame. Im no expert but dont think the Scott Bonnars had the covers fitted. I could stand corrected though
cheers Ross

Hi Rossf,

I reckon you're on the money as those holes are a dead giveaway and as such then the motor may still be the original unit fitted. If Tim could get the code of the motor cowling then we'd get an even clearer picture to what this one may be. One way or the other the chassis ID has been removed as they were one of two designs either a riveted ally plate stating Rover Australia or a metalised sticker which was used on the very last Rover Reds as is the one pictured with the rearward facing clutch lever. They also had the 75db noise rating sticker at that point stuck on to the rear rail,

Cheers,
BB

Hi Tim, BB and Ross,,
I think we all agree that it is a Rover chassis. I believe it also to be a 'bitza'. To prove my point, no Rover red 45 had the cotter pin inner clutch half....you can even see the old Scotty green under the flaking black paint.
I don't believe the engine to be original to this chassis, Keith would have selected one from his reconditioned lot and bolted it on....

But for all of that....we have gone seriously off topic...this thread concerns cutting and clutch probs...We really should get back to that.

Thanks Deejay, great to see the enthusiastic responses but I want the mower to cut grass! You have already given me some advice on cutting adjustments, Gadge has given me some tips on the motor, and I had a question on what clutch parts do I need to replace the cotter pin set up

Regards Tim

Hi Tim, you will just need to purchase an inner clutch half and the 2 grub screws to suit. Just check the diameter of the engine PTO shaft before you order the part, as there are 2 clutch halves sizes available, to cater for different engine shafts.
Please see our video HERE for instructions on how to remove the engine and clutch.
Once you have it removed, please post some pics of the inside of the clutch, we will need to check the serviceability of the thrust bearing and the clutch cork on the outer clutch half.

I can't believe that we are going back to clutches as that was discussed in the first few posts that Tim and I exchanged regarding not using a clutch half that had a captive cotter that was coming out and that the body would be flogged out, thus requiring a new one to be purchased.

Hi BB, this is what sometimes happens when threads go seriously off topic....It is a good idea to check the subject of the thread occasionally to make sure that what we post is in the bounds of the subject matter.
We all got caught up in trying to sort out what this machine was, instead of helping Tim get his machine up and running.

As nobody has yet listed these, now that we have 'returned to our muttons', the bits that Tim62A will definitely need are:

5/8" crankshaft clutch body

OR

3/4" shaft clutch body

PLUS

Clutch body key
2 off 'clutch body set screw'
clutch cork lining

Possibles:
Clutch thrust bearing
clutch body screws

All good guys, thanks for your help. I will order the parts and tackle it after Christmas. I think I will stick with the existing motor for now

regards

Tim

Hi to all who have assisted so far.
The state of play now is that I have received the new clutch parts and painted them up. I have removed the engine and decided to buy a new Honda. I thought the engine shaft look damaged as it had a big gouge out of the side where the cotter pin must have slipped on it at some stage. I wasn't overly happy with the way the engine was performing anyway so decided to bite the bullet. I am in the process of backlapping the reel whilst I have the engine off. I have gained some practice on this on several old handmowers this week and very impressed with the results from what is a simple procedure.
Any tips on reassembling the clutch? I have gone with a grub screw version rather than a cotter pin version. I have a new bearing to install in it and I assume this just taps in with some encouragement?
regards Tim

Hi Tim,

As far as the thrust bearing is concerned just use a small block of wood and use it as a drift to knock the bearing in. Just make sure you keep it rather square when knocking it in. Make sure it is quite well lubed up with a good HTB grease before putting it back into the clutch body.

Also make sure you get the clutch body on the shaft towards the engine so that you have a fair bit of adjustment in the clutch fork adjusting bolt.

From there there's not much more to say but best of luck with it and hope all works well.

Cheers,
BB

Hi BB,
Yes all went pretty smoothly. A bit of fiddling to get the engine back on but the photo attached is the final product. Running and cutting well. Next step is to touch up the red paint on the chain guard plate
and a few other areas. Otherwise I am pretty chuffed that I was able to do this. Thanks for everyone's help!

regards

Tim

Hi,
I happened to read your forum as I was in the process of replacing the clutch thrust pad. I have removed the clutch body and while doing so, the clutch body key came off and did not have a chance to look at how it's fitted. I noticed the key has a slight bend on the other end and I thought this end should fit on the rod coming out of the engine. Any advice/comment on how assembling this ?
Also, I did not disassemble the clutch body as I don't see the need for. Any comments as well ? Photos below.

Hi Shannon,

Welcome to our wonderful Forum where we all learn something new everyday.

Well that is the sign of a well flogged out piece of key steel and as such you might have issues getting it back in where its supposed to be. As such I wouldn't reuse it and just replace it with a new piece which can be bought for around $5 to $6 through the online shop or if you have a mower shop near by you'll get one there. The Woodruf key (half moon shaped)is also showing signs of wear and I'd replace that one too while it's all apart. It's a small price to pay and not have bigger issues later on.

You might want to consider splitting the two clutch halves open and removing the thrust bearing inside and re-lubing it with new grease, as you might as well do it while you have the clutch assembly out, also inspect how much cork thickness is still there so as to avoid an issue that one of our other members had of no cork at all left. Greasing the bearing will quieten the machine down somewhat when it is running with the cutter clutch disengaged and all the pressure is on that thrust bearing. (same as having your foot on the clutch in a manual car)

Just before putting it all back together get a small file and chase out the keyway on the engines output shaft thus removing any of the proud burs that have been created by the key steel, this will ensure that it will all go together rather smoothly.
Also splitting the clutch apart and only installing the engine side first will allow you to adjust the key steel back and forth so that it's in exactly the correct position as it can slide in too far if it grabs onto the shaft when installing the clutch half. This is just a suggestion.

Let us know how you go and once again a huge welcome to the ODK

Cheers,
BB

Thanks BB for your advise and suggestions. I have opened the two clutch halves.
The cork appears to be ok and intact with the inner cone snugly sitting on it. I did not remove the inner cone anymore.
The thrust bearing appear to be so attached with the clutch body and not that easy to remove. I just left it as it is as I could damage it if I force to remove it. I cannot seem to see any signs of grease from the outside. Will it be ok if I just put engine oil around the gap on this bearing ? Also, if I have to use grease, is there a special type of grease I should be using ?
The spring looks ok as well.

Hi Shannon,

Yes there's plenty of cork in there that's for sure.
Normally one would use a slide hammer with an expandable shank that fits in through the hole and then you wind it out to expand, once that is done you just use the slide part to knock out the bearing without any damage. Can't see any other way of doing the job without screwing up the bearing which is quite an expensive little fella.

In your case I would use some fairly heavy oil (the heavier the better) and let it soak in through the opening that you can see between the inner and outer race. Just don't flood it as that creates it's own set of issues. Then after a while rotate it and see if the bearing has taken enough oil to reach the bearings inside and provide the lubrication it should have. You'll certainly feel the difference.

Have you managed to source any key steel yet ?

Cheers,
BB

Hi BB,

Thanks again. Not sure what you meant by heavy oil. Are you able to give me an example brand and type ? I will also try squeezing the grease in the gap and see if it gets thru.

I assume I can use just the standard grease.

One thing I for forgot to mention was the cutter keeps on spinning even if the clutch was disengaged and so I thought this was because of the worn out thrust pad. Will this be correct ?

I have not ordered the keys yet as I though I might need something else for the clutch body. Good that the body is ok so will order the keys thru the online shop.

Hi Shannon,

I'm starting to think that you have a slightly flogged out clutch half as that key steel is a bit of an indication that the clutch half is moving on the output shaft and as such is no longer running true, thus catching on the clutch cone ever so slightly and enough to keep the cutter spinning but without much force. Also a worn out or melted thrust washer is a sign of an untrue running clutch. I notice there is no captive cotter pin and nut in any of your photos, is it missing or just not in the shots ?

If I am to be correct in my observations then to over come this you'll have to purchase a new clutch body of either 5/8 shaft or 3/4 shaft size,( whichever yours is) an engine output shaft key, woodruf key and thrust washer. The newer designed clutch bodies no longer have the captive cotter and alternatively have two set screws that lock onto the shaft at 90 degrees to each other, this pretty much eliminates the problems with the die cast clutch bodies of old.

Slide the old clutch body onto the shaft without the key installed and if there's any play (wobble) whatsoever, there's your problem.

Cheers,
BB.

Hi BB,

I tried installing the clutch body on the shaft. Is it supposed to sit tightly on the shaft without being able to move it at all as I find there is a slight play ?

I'm not sure what the captive cotter pin, nut and thrust washer are. Are you able to refer to the parts diagram and let me know what number it is on the diagram.

I can only find 2 screws that lock the clutch body onto the shaft.

Cheers,
Shannon