Ring and Pinion backlash on Farmall M

Schultz · Mar 7, 2012

Do you guys ever check this? I see in the book it's listed as 0.008"-0.012" I took mine apart to restore but didn't check it before hand. I kept all the shims in the right place and after re-assembly I decided to check it and it's more like 0.040" It never made any noise or anything before. Is this a problem, I am being too fussy?

Thanks,

rustred · Mar 7, 2012

it should be in the .008-.012 range. .040 is way tooo much. its not just backlash , but you must get the crown and pinion tooth contact correct also. to do this you need prusion blue or the yellow stuff to check the pattern.if you found the backlash in the book then follow the book for setup.

rustred · Mar 7, 2012

also it is important to check it beforehand so it can be set the same, as you will get gear howl if contacting in a diff. spot. providing all is within spec from the start.

pete 23 · Mar 7, 2012

Leave it the way it was or it will be noisy no matter how you try to check tooth contact.

Schultz · Mar 7, 2012

So if I leave it where it was it will be quieter but not to "spec" What are the downfalls of leaving it at 0.040" and quieter.

Super-H-Mike · Mar 7, 2012

I agree with pete23, leave it as it was. Those gears dont turn very fast at all anyway and are more than beefy enough to handle the job they are asked to do IMO, not like a car or truck differential which are kinda light and turn super fast,shock loads,lotsa heat ,etc . As long as its not "tight" ,which it isnt, I wouldn t sweat it. The gears have wear patterns already set into them from use, if they were new, I would go for the spec.

rustred · Mar 7, 2012

well with .040 clearance you will have a real noticeable clunk going from reverse to forward. there sure must be a lot of wear on them gears. or other thing is how did you measure that clearance? did you use a dial indicator? or more- less it? thats a lot of clearance, thats more than the sparkplug gap! i totally agree with keeping it the same but something seems wierd here. if it was mine i would reduse backlash reguardless if it was that high , which makes me wonder if it really is.

Schultz · Mar 7, 2012

I used a dial indicator on the ring gear. I'm definitely not a machinist but did the best I know how to. Might not be a full 0.040" but close.

rustred · Mar 7, 2012

ok, was just wondering. i know what i would do but its your call. good luck.

CenTex Farmall · Mar 7, 2012

Since you put all shims back as they were I would leave it alone. If you exam the gear teeth very closely you will find they've "worn together" over the years and trying to tighten them up will offset the pattern and then you will have noise.

You can check the pattern using heavy grease and a bright light. If you have even contact across the teeth then don't worry about it.

Where the backlash gets you is when you have a lot of loading and unloading such as in a car where you go up and down hill and lots of start stop forward and backward. Typical tractor work involves steady loads. An easy foot on the clutch will keep things happy.

Ring and Pinion backlash on Farmall M

Schultz

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rustred

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rustred

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pete 23

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Schultz

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Super-H-Mike

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rustred

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Schultz

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rustred

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CenTex Farmall

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