JD B flywheel questions

620 John

Member
I'm getting ready to put the flywheel back on my late model JD B and I have a couple questions:

1. The first flywheel had a crack in it (the bolts were really tight). I cleaned up the splines to the crankshaft and new flywheel. WITHOUT tightening the bolts I can move the flywheel back and forth (pushing and pulling parallel with the crankshaft) about a 1/16" measuring at the ring gear. Does this seem like too much wear?

2. I plan on using new grade 5 5/8x4" bolts and the ones I got from Ace Hardware are hex bolts and not square headed like the original ones. The nuts are not like the original oversized shoulder ones either. The old ones use a 1-1/16" socket and the new ones use a 15/16" socket. I'll be using lock washers under these, but is this going to be a problem?
 
if you push the flywheel up as far as it can go without using a hammer it has ware also , now that its up as far as you can push it try turning it forward and backwards or left and right if you can do this its worn out too. should not go left and right any. good luck ,if it was a very good flywheel you would have to tap with a hammer to get it up closer. your bolts should be the correct ones for best results. And your crank could also be worn .
 
I'd use the original john deere bolts and yes the flywheel would be loose back and forth with out any tension....Use the adjuster nut...tighten up thight then back it off about 1/2 turn...tighten to factory specs.
 
Id ask Kent Peterson he is the best of the best John deere man his whole life. No one any better than Kent.
 
(quoted from post at 19:35:21 11/08/17) if you push the flywheel up as far as it can go without using a hammer it has ware also , now that its up as far as you can push it try turning it forward and backwards or left and right if you can do this its worn out too. should not go left and right any. good luck ,if it was a very good flywheel you would have to tap with a hammer to get it up closer. your bolts should be the correct ones for best results. And your crank could also be worn .

I can slide the flywheel all the way on without using a hammer, which to me seems too loose. When I said I could move the flywheel back and forth 1/16" at the ring gear that's NOT rotational movement but side to side with the flywheel all the way on. Just for fun I was able to put the flywheel on and slide .002" shims a little ways under the flywheel on top of the male splines of the crankshaft. That took a lot of wobble out of the flywheel. Even if I get the shims to sit all the way under there I'm afraid I'm still asking for trouble.

I'll see if I can upload pics of the crank.
 
Here's the crank

This is one of the sides where most of the clamping force is produced form the flywheel.

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your new flywheel is worn out too. I'm guessing , it should not wobble I replaced one and had to hammer it on, you should never have left to right movement once it is up to tractor all the way. and crankshaft can be issue.
 
In that case the crank is worn too much. I know the new flywheel has excellent splines. Here's pics of the crank:
a177618.jpg

a177619.jpg

a177620.jpg
 
Thanks guys for your comments, I'll see what I can do.

For future reference do you guys think I could put flat washers under the bolt heads for the flywheel? The square headed bolts are NLA from Deere and I don't wanna reuse the old ones. The original ones had lock washers under the nuts so I don't think the nut shoulder size difference is gonna matter much.

Thanks again
 
Use hardened flat washers under the nuts so the nut doesn't gall the flywheel.
 
(quoted from post at 10:06:06 11/10/17) Use hardened flat washers under the nuts so the nut doesn't gall the flywheel.

Thanks ET, I'll see if I can find some washers that will fit because there isn't much room between the bolt and the flywheel boss. There's even less room on the bolt head side.
 
This has been beat to death, but let's go back to an (IMHO) essential point--why was the original flywheel cracked to begin with? The answer is: It became loose, probably wore a bit on itself and the crank.
Owner noticed it was loose and tightened it up. But, with the slight amount of wear on the crank, there was not enough "spring" in the cast steel flywheel for it to tighten up on the crankshaft without
cracking. So it cracked; maybe not right when he/she did it, but it cracked for this reason. The only viable-but expensive-solution is the taper lock. Been there, done that, got the bruised bank account.
 
(quoted from post at 16:27:30 11/10/17) This has been beat to death, but let's go back to an (IMHO) essential point--why was the original flywheel cracked to begin with? The answer is: It became loose, probably wore a bit on itself and the crank.
Owner noticed it was loose and tightened it up. But, with the slight amount of wear on the crank, there was not enough "spring" in the cast steel flywheel for it to tighten up on the crankshaft without
cracking. So it cracked; maybe not right when he/she did it, but it cracked for this reason. The only viable-but expensive-solution is the taper lock. Been there, done that, got the bruised bank account.

Yea I understand that. My theory is the bolts stretch and the flywheel works loose. Since there's no way (that I can think of) to keep the bolts from stretching in this case, the flywheel is almost guaranteed to come loose if never tightened.

Just randomly thinking out loud I think JD should have come out with a service bulletin to tighten or replace flywheel and clutch driver bolts after every so often. Then we probably wouldn't have as many wrecked crankshafts, flywheels, and clutch drivers.

The previous owners to this B are not mechanically inclined, so they have JD mechanics do all engine work. If a flywheel is to come loose they're most likely not going to notice any problem until it's too late. I'm sure this is often the sad case for most of these old tractors.
 

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