Hi folks, this is my first post and I am not usually a mechanical guy so excuse my terminoligy please. My Scott Bonnar Model No. is 450589, Serial No.01499 I think the problem is the clutch, (I will call it that until you tell me different), the motor is fine but when I move the lever across it doesn't turn the rod that turns the blades. I can turn the rod and blades by hand so they are free and not siezed. In the past I have had almost no trouble with this machine, but, it has occasionally gives me a problem engaging the clutch. Some times this is caused by the adjusting bolt on the lever working a bit loose, on other times the bolt needed a little tighten. I feel the adjustment bolt is at its maximum now but when I push the lever across the shaft doesn't turn, hence the blades do not turn either. I have not touched anything fearing I may do more harm than good, I badly need some advice or I might have to abandon the machine, which I am reluctant to do. If I took it to a local professional I know I will be told parts are not available and the cost would be high. I look forward to any assistance, Thank You, Wally Pat
CyberJack, Thank You, you have been a great help. I followed Deejay's clip and dismantled the machine as instructed. I did not know what I was looking at but after cleaning and reassembling everything the lever returned to almost upright and the machine works fine. I do not do a lot of work with it,(a small putting green)I expect it to last a while. I would like to know the correct type of spark plug I should be using, I think the motor is original. My next project will be to study the backlapping procedure, would we have a similar clip on that? I find it a bit difficult to follow instructions when I do not know the terminology of the items described. Thanks again, very happy with the result, we have saved the machine. Looking forward to your next advice, Regards, Wally Pat.
Spark Plug Your 450589 should have a Briggs 80202 Motor. To confirm this, please tells us the Model, Type and Code numbers located on the metal air cover. Similar to this:-
Backlapping Remember, backlapping is not a substitute for grinding, but an edge maintenance procedure, meaning: the reel and bottom blade must be in relatively good condition. A couple of photos would help, if you would like us to comment. [Photos looking from above and below the front roller are helpful]
I attach instructions for backlapping from Richard Jones of the UK's Old Lawnmower Club's Grassbox Magazine 85 of 2013. It's a good, no nonsense, practical guide to the method.
We do not have a video for backlapping Model 45s. Here is a short video of a professional unit being backlapped:
Sorry not to have came back to you earlier, I've been busy lately. Details you have asked for are; Model No. 80202 Type; 0607-02 Code; 36070903
I can follow the back lapping procedure re. chains, drill backwards and rinsing etc, what I am not comfortable with yet is which bolts or screws adjust the blades to the plate.
I have used the machine a couple of times since we corrected the clutch adjustment, it's working really well, am I pleased about that. Cheers, Wally Pat
Thanks for that Grumpy, I suspect that first code digit should be a '7', making this a 1976 machine.
The sparking plug will be a Champion CJ-8 or equivalent.
Wallypat, it's great to hear the machine is working really well. They certainly 'hold their own' to any residential machine offered today.
For instructions as to 'set' adjustment, I have remastered a 45 Operator's Manual that would have accompanied this lawnmower. See the History Forum record HERE.
Please let us know how you get on with this. ---------------------------------------------------------- JACK
You are right the number is most likely a 7. Some of the numbers are difficult to read because they are stamped, it would help if they were on the outside too. Originally I read the dash in the type as a 4 until I went back to your pic. It seems I need a CJ8, which I suspected. When I bought the machine it had a plug with a longer base, I always doubted it's authenticity. I will fit a new CJ8 pronto. Just printed the manual, that will be a great help. I will get to the back lapping soon, at the moment I'm strapped for time. Thanks to all, WallyPat
I've printed the manual, it plainly describes how to adjust the blades to the cutting plate. I am sure I can follow the instructions easily enough. It also answers another problem I had, I will explain; Not too long ago I had the machine professionally sharpened by machine, just as your pic describes. It came back to me set right but after a short period the blades did not cut properly. I took it back and the guy re set it and the same thing happened again. I took the chain cover off and found most nuts to be loose including the one that fixes the cutting adjustment, I tightened them. It still lays some grass down and cuts the rest. I do a double cut to overcome the deficiency. I will adjust the blades now that I know how, hopefully it doesn't need backlapping at this time. I have changed the spark plug to a CJ8 equivalent. Thank You WallyPat
I am in need of more help. While I was adjusting the blades I removed the Chain cover, I identified the need for 2 new chains. Firstly; the main chain, I counted 59 links, Secondly; the chain at the bottom behind the big cog. I counted 39 links in that chain. I hope you can identify the chains from this description, I cannot post a pic until one of my grand daughters turn up to help. You might tell me if I have counted correctly, also, what information I need to take to the chain shop. I saw a post from Deejay that seems to tell me I need a 3/8in. pitch for the 59 link chain and 1/2in. pitch for the other. I am not sure this is enough to go to a shop with. I am hopeful CyberJack, Bonnar_Bloke or Dejay can assist. Doesn't seem to be a lot of room to fit the smaller chain. Is there something I should be aware of here? I seem to have adjusted the cutting OK, left hand locking nut was a bit tricky though. Thanks again, Cheers, WallyPat
I don't know what the specification is. Expert BB will undoubtedly know. Deejay is away.
Why not take the chains along to the chain shop? That way, you're assured to get the right ones, and even if the originals are stretched! Alternatively, they may be purchased HERE.
Fitting is straightforward. Remember that all chains have adjusters. Two are adjusted via the one adjuster - (G) nuts.
When fitting, chains should have slight visual deflection (not tight). If you have any problems just post us.
Hope this helps. ---------------------------- JACK
I have dismantled the two chains we think need replacing, they are marginal, it is probably prudent to replace them though. They are; the one going to the clutch plate, and the one behind which seems to be a driving sprocket. The chains are the same pitch (I think). Tomorrow I will go to the local supplier, with the chains, to have them replaced quickly, if they are not available tomorrow I will get them from our shop. The good news is; 1. The sprockets are all in good order 2. The clutch plate is good too. I was surprised to find the clutch plate here, couldn't work out in my head where it was, thought it was up on the shaft. My other problem is, how do I properly tighten the two 3/4in. nuts? They seem to tighten to a point but without securing the back I am not too sure how tight they should be. Cheers, WallyPat
Remember that both of these chains will be adjusted together. Loosening the "G" nuts enables the whole clutch plate assembly to be moved in any direction, up, down, or sideways.
These are conventional nuts and bolts. Check that the threads are okay. They should be secured tightly using a ring or open end spanner. The chains should have a small amount of slack when tensioned.
Hope this helps. ------------------------------- JACK
Hello Forum, I have just successfully completed my project. I wish to thank you all for your input, Deejay, Bonnar bloke, Grumpy and especially Cyberjack, who has been a tower of information. For the benifit of the forum I will list my actions. Firstly we had a machine whose motor was OK but the blades would not turn. I thought this was a clutch problem and listed this to the forum as such. Cyberjack directed me to a video from Deejay which was simple to follow, so I dismantled the motor, did not know what I was looking at, re assembled the machine which re adjusted the clutch lever, and away it went, I still don't know what I did. With the machine in working order I asked about the correct spark plug to use, I had always been suspicious of the one in use when I bought the machine, but always replaced it with the same type plug. From this I learnt where the ID numbers were and reading them a couple of times you people identified the machine, and suggested a CJ8. Having paid good money not too long ago to sharpen the blades I was not happy with the result so the machine went back a couple of times for adjustments. I later unscrewed the chain cover to look and found all nuts and bolts were loose. I tightened them but was never truly happy with the cut. With this in mind I thought I might get a little more adventurous and do a backlapping. On inspection I found the chain E could not be adjusted any more because of the blade adjustment. The other two chains were a bit slack, even after maximum adjustment, so I thought I would replace them, later deciding to add a half link to the E chain. While I was doing this I would backlap. Traps I fell into; 1. On reassembling the two new chains I found the mower would not pull backwards, Cyberjack says, loosen the main bolt, I mistakenly thought all bolts should be tight, loosened off all was well. 2. Having bought two new chains I asked for a half link, forgetting at the time it was a different size, I had to eat humble pie and correct my order, all is well now. 3. After backlapping To re adjust the blades I was loosening the lock nut and when I re tightened them the adjustment moved, I now know the proped sequence for these adjustments. For a guy with no experience in these machines we have done well, till the next time, Thank you all again, Cheers, WallyPat.
Well that appears to have ended with a positive resolution. It is a worry, though, that you found all nuts and bolts loose after a service...
Note: the "main bolt" Wally refers to is the one through the landroll clutch. It's set to just allow clearance between the clutch plates, done prior to and clutch cable adjustments.
All very resolved. ------------------------------ JACK
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