gday folks, been reading a lot of posts, but aren't quite sure about my greenfield clutch setup,
I've got it all apart because it was jamming in forward, usually when you were heading straight towards a tree or ditch, how does it know?
see photos, but I'm guessing the two internal plates on the drive shaft should be held together by some small pins, but mine is not. Looking closely I can see where they may once have been, but I'd say it's been this way since before I got it - I bought it secondhand about 5 years ago.
my question is therefore, what do I do about the old pins, & where can I source some new replacements so I can get the grass cut? I really should have attacked this a couple of months ago when the lawn was dead, but you know how these things go...
The 4 ‘dots’ in the second photo are simply stake marks. These are to secure the insert into the bearing.
Jamming issues such as yours can be caused by the darndest things.
Start with the basics.
The clutch plates sticking on the shaft is a logical assumption and it can be the problem but start right at the beginning. Check the entire drive system from the pedal back for sticking and seizing. I’ve had a recent first hand experience where the pedal was sticking on its pivot shaft. I had to physically knock the pedal off the shaft, clean it up and lubricate it with anti-seize. Lubricate and check the entire linkage from the pedal to the clutch.
Also check for belt damage or tensioner issues.
Have a look at how much clutch material is on the clutch discs. They start out 1/8” thick. 1/6” thick is minimum. If you have a lot of pedal free-play this can be an indication of wear. If your metal-to -metal then sticking could be a problem.
Did the plates seem free on the shaft when you took it apart?
A few more details and photos might help us to better understand your issues.
Well that's good to know, thanks. I'd see s few photos that looked like there were pins joining the two discs & thought it'd make sense to have them like that.
I've resurfaced the discs with new corks now & I'll clean all the old grease off the shaft cause it's pretty grotty & gone a bit hard, so that may well be a cause.
What grease would you recommend lubricating the shaft with?
Next thing then is to check the pedal & linkages for wear, I've also got a new belt to fit so that may help as well.
also, how much wobble is acceptable on the drive pulleys (the outer ones without the cork clutches), the bearings are nice & free but ther's a bit of sideways movement there, probably a few mm at the outer rims of each. Looks like the bearings are a pain to replace too..
Hi Tim, just to make it easier for you to change the belts etc, remove the battery, drain the oil from the motor and fuel from the petrol tank and tip the mower up on its side, so much easier for you to see what you are doing
Yup, if the shaft and the square bores in the plates were gummy then it’s a fair bet that was at least a good part of the problem. Also check for burrs on the shaft before it all goes together-check that the plates slide freely on the shaft and carefully file any burrs if needed. You don’t want to remove any material from the square drive, just the burr itself.
A bit of lateral ‘wobble’ in the pulleys is normal and acceptable. Even with new bearings there is often a bit of play. I guess bearing quality has a fair bit to do with it and it’s a big diameter pulley. Once the belt is on and tensioned they run quite true and the clutch plate loads the play out anyway. 3mm is probably what I’d call normal ‘wobble’. At 5mm I’d change the bearing.
Bearings are easy to change if a little care is used. I warm them with a hot air gun first to ease the process and then drive or press them out evenly BUT please support the pulley AT the bearing while doing this and not on the outside diameter. If not supported properly it’ll crack for sure! Restake the new bearing once it’s in. I used to always replace the bearings when I had them apart but these days tend towards an ‘on condition’ philosophy. I.e. If it ain’t broke, don’t fix it
Lubrication of the shaft is one that’s been discussed a few times. Gadge and others recommend silicone spray lube only on the square drive. Nath uses the thinnest smear of antisieze. I tend toward silicone spray but have put a few together recently with a little antisieze- mainly because I didn’t have any silicone spray.
Key points to consider with lubricating the shaft is that excess lubricant or any oily substance will attract muck and gum up the works. You’ve worked that out with the help or the previous owner Also, any wet lubricant or excess lubricant will be thrown by centrifugal force to the corks which is also undesirable.
ok, got it all back together, fitted the new belt, got the tension nice & tight, ready to test... won't bloody start now..
it was working up until I pulled it apart, but before I did I gave it a good going over with the compressor to get all the crap out. got spark, got fuel, won't start. grr.
turns out the valve seat on the intake valve had come loose & was jamming the valve open. that's a new one for me. tapped it back into place carefully & away she went. I'll be able to test the drive tomorrow, that'll be interesting
Bit of a heads up on the valve seat, we always went around it with a center punch to hold them back in, otherwise with heat cycling it will come out again.
