A friend is bringing over a late model A for me to check out. It has a loud knock every time it fires. I have done the pry bar to the ear listening and can't figure out where the knock is coming from. I have listened on both sides of the crankcase, block and governor. No matter where I check, the knock sounds the same. I checked the clutch driver and it is tight on the crankshaft. They said they checked the flywheel and it's tight. I had them put it in gear with the clutch released and that changed nothing so I know its not in gearing. Any ideas before I start tearing things apart? Thanks.
- Thread starter KL in Wi
- Start date
coonie minnie
Well-known Member
Recheck the flywheel. That is the place to start before going inside. The bolts can be tight, but if splines are worn it will still rock on the crankshaft.
rick deere
Well-known Member
Take rod cover off and take flywheel cover off, take spark plugs out. Than carefully hold one rod at a time and barely move flywheel back and forth just a little, if you feel any play in the rod its your rest pins, if you can pull up and down on rod at crank it the rod bearings. and the nut on the rods could be loose. that's my thought. may not be right.
jd man wis
Member
Take one spark plug wire off as its running will help tell what side is bad if it gos some what quiet. Do this to both sides one at a time. Also open if it has pet cocks one at a time this will help make them run with less pressure on the compression making less noise If it a really bad knock I would not run it much I would take the top off and see what is going on in there.
620 John
Member
All good suggestions. Once you pull the flywheel cover off to check the flywheel, you can lift up on the crank and see if there's any play in the left main bearing. Engage the clutch and lift up on the pulley and see if there's any play in the right main. While you're at it check for excessive crank end play. Pull the crankcase cover off and feel around in there. While you're in there check the camshaft gear to see if it's loose. I had a loose camshaft gear on one of the 620's. I think they're supposed to be grade 8 bolts holding those gears on but someone must have replaced them with grade 5 and didn't use thread locker.
Thanks for all your replies. Really appreciated. I just came in from checking it out. Took the top cover off. Rods had no play in any direction yet if I rocked the crank I could hear a clunk like a loose rod bearing or wrist pin. Took the clutch apart, all good. I didn't check the flywheel then yet because they said they had checked it and it was tight. Well, I decided to check it. Dang it! They said it was tight. I can rock it a little over half the width of a tooth on the flywheel and it rocks a good eigth of an inch sideways. Any hope of tightening it without a different crank and flywheel? Thanks again
rick deere
Well-known Member
It sounds like you got a very big job ahead of you.
coonie minnie
Well-known Member
you need a taper lock flywheel. Call Allen Machine works, Jonesboro, TN. They are the manufacturer of them.
620 John
Member
It might be cheaper to go with another flywheel and crank vs a taper lock. Make sure you use new bolts for the flywheel and clutch driver. I believe these bolts stretch which allows things to come loose. I think it's always good to replace these bolts whenever they're taken apart.
620 John
Member
Forgot to mention I'm in the same boat with a loose flywheel on a late B. My flywheel was cracked but I bought a good one for $100. Since the crank journals and clutch splines are in good shape I might try to weld up the splines on the flywheel end and machine it back down (if I can find a big enough lathe). This could be another option for you if you can find a good flywheel.
fixerupper
Well-known Member
I welded up and ground down by hand the clutch driver splines on a 51 A 25 years ago or so. I took the right rear wheel off so I had lots of room, found a comfortable stool to sit on and ground and measured, ground and measured till I got it right. It took lots and lots of time and a few ‘walk away for a cup of coffee’ sessions to get it done. When I got done there was a slight flutter in the clutch for awhile, then it smoothed out. I’m still using the tractor and so far, so good. If I remember right I rigged up a piece of angle iron to measure from to get it right. These splines weren’t worn terribly bad but I couldn’t get the driver tight anymore befor I built it up. I don’t think I would tackle buggered flywheel splines though.
620 John
Member
The flywheel splines aren't worn too much on mine (a few thousandths on the worst splines). They're not chipped out or anything. Biggest problem would be finding another crank that doesn't already have wrecked splines and/or out of round journals. Then having to regrind journals, refit bearings, etc. I might end up taking it to a machine who has the right tools to weld up and re cut the splines.
This might be time to ask your friend what his budget is for repairing the tractor. He can probably sell this one to a salvage yard and buy a nice replacement or a 60 in better condition for a net cost of between $500 to $1,000. That could be less than the cost to repair this one. That would be better than putting a lot of your time and money into the repair and then owning the tractor through a mechanics lien.
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