I'm in the process of tearing down the engine on my '37 F-20, and at this point it's just the block and crank that's left. (and a couple of valve tappets that there doesn't seem to be any way to get out of the block, but that's another matter.) I've got a service manual that specifies tolerances for the connecting rod bearings, but it doesn't give any info for allowed play in the main bearings. There's no longitudinal (front-to-rear) play in the crankshaft, and the rear bearing has no lateral play in it, but the front bearing does have some. My question is: How much is too much? I want to rebuild the engine properly, but at the same time, I don't want to go through a lot of extra work and expense replacing a front main bearing that's ok as-is.
- Thread starter Mike Dau
- Start date
Nebraska Kirk
Well-known Member
These old low rpm engines are pretty forgiving, a little play in the main bearing won't hurt anything. You can buy new main bearings off ebay very cheap, they won't be the max fill bearing like the originals, but since you won't be working the tractor all day for days on end like when it was new, it will be just fine.
Just search for "6313 bearing" on ebay and you will find plenty of choices ranging from $5 to $135.
Just search for "6313 bearing" on ebay and you will find plenty of choices ranging from $5 to $135.
cole in mo.
Well-known Member
The mains are ball bearings, so any up and down-sidways play could mean its time for replacement. THey are pricy, but lots cheaper doing it now.
Tom Fleming
Well-known Member
quoting from one of my old shop manuals,
Using a piece of wood, with the inspection covers off, apply pressure to the crank shaft with the piece of wood, wedging it against the block. If there is lateral or longitudenal movement, the main bearings need to be serviced.
I agree, depending upon the amount of "slop", would help me make my decision on what to do. If it is slight to non-existant, use what you have. If it is very obvious, replace them.
All depends upon what you have in mind for this tractor. Think about how many of these old girls ran and ran and ran with worn bearings. I am a bit proponent of doing things right the first time AND when you have things apart. However, the depth of your wallet can influence your decision at a given time.
Using a piece of wood, with the inspection covers off, apply pressure to the crank shaft with the piece of wood, wedging it against the block. If there is lateral or longitudenal movement, the main bearings need to be serviced.
I agree, depending upon the amount of "slop", would help me make my decision on what to do. If it is slight to non-existant, use what you have. If it is very obvious, replace them.
All depends upon what you have in mind for this tractor. Think about how many of these old girls ran and ran and ran with worn bearings. I am a bit proponent of doing things right the first time AND when you have things apart. However, the depth of your wallet can influence your decision at a given time.
Anonymous-0
Well-known Member
I agree with Tom Fleming. However, IMHO, any slop is too much. Since you have the the engine torn down, and presmumably?? have it out of the frame, I would certainly replace both of them. You will be much more satisfied in the long run. Both my F20's have new mains and now run like Swiss watches.
The original mains have 11 balls in them. There are aftermarkets available (so I'm told) but they only have 7. Remember that the rear main is the only part holding up the crankshaft, flywheel and clutch. I would try to find new originals if possible. Just my .02.
The original mains have 11 balls in them. There are aftermarkets available (so I'm told) but they only have 7. Remember that the rear main is the only part holding up the crankshaft, flywheel and clutch. I would try to find new originals if possible. Just my .02.
they do make new ones with the same bearing count as the originals, however i highly doubt anyone is gonna want to pay for them. they are serriously pricey.
unless your building a 100+ horse puller, the standard aftermarket bearings will do just fine. ive built plenty of these pre 39 engines and use the 7 bearing standards available now with ZERO issues, even in pullers
Careful study of how this engine is built shows the rear bearing positions the crank and controls longitudinal movement, the front bearing can float front to rear in its cage while the rear is captured. If the front bearing rolls quietly it should be good for limited use. If its noisy of really loose, replace it.
I bought fully loaded bearings for my 30, and yes, they will make you pucker when you price them. Its what I wanted for that tractor. Other tractors I have will get the cheaper ones.
I bought fully loaded bearings for my 30, and yes, they will make you pucker when you price them. Its what I wanted for that tractor. Other tractors I have will get the cheaper ones.
OK, I've decided to pull the crank and replace the front bearing. Unless somebody knows where I can get my hands on an F20 crankshaft puller, I'm going to fabricate my own. (Hopefully it won't need to be as heavy duty as the flywheel puller I made.) I've checked the threads on the flywheel nut and they seem to be regular pipe thread, but none of the hardware stores I've been to so far have pipe fittings that big. Does anybody know if the rear threaded portion of the crankshaft just happens to be the same diameter as a standard pipe fitting, or do I need to get ahold of another flywheel nut to make my puller with?
Nebraska Kirk
Well-known Member
The crankshaft threads are not the same as pipe threads. I have several extra flywheel nuts, I would be more than happy to mail you one.
Tom Fleming
Well-known Member
Well, not sure you need a great big puller to get the crank out. I just "pushed" the crank out of mine using a large puller cross piece and some all thread. I actually pushed the crank out, and it did not take a lot of effort.
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