Differential tooth pattern-not sure what to do

Zachary Hoyt

Well-known Member
I tried to take a picture but I don't know if it is clear enough to help. The pattern seems to be more toward the base of the tooth and I am wondering if I should do as the I&T manual says and remove a shim from the pinion shaft or if that would be more likely to make it whine by tightening it up too close to new gear specs. Any advice will be much appreciated. I used long bolts as dowel pins and put a rubber band on the pilot bearing, both seemed to help and it went together smoothly. The band was pushed off by the input shaft as it went on and is now wrapped around the shaft just behind the bearing.
Zach
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you need to get a picture of the pattern on the crown gear. the crown side of gear, thats forward rotation.
 
is that the original crown and pinion? or are you putting a different one in?
should have checked the backlash and noted it before disassembly if thats what you did? also keep shims in order from side to side. once a used diff is worn in it should be kept as same spec. changing the pattern will result in gear howling.
 
Replacements, his were obtained from D Slater, I believe with the orignial shims which is the only way to do it. Yes, what you just posted is mostly what I said in the previous thread. My Super A adjustments were simple compared to his tractor. I took mine apart while on the bench, and got tired of several changes, none of which worked. And if I had have gotten the correct backlash, due to the new pattern it wouldn't have worked anyway, I didn't realize that until a similar thread came up on this site.
 
ok, i see. they sure are a pain to get used ones set up.
best to get the picture of crown pattern posted and go from there.
 
I tried checking the pattern with the prussian blue on the ring gear teeth and they were meshing on the outer half of the teeth. My book said to put the prussian blue on the pinion teeth, which is why I had done it that way the first time.
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setting up a used ring and pinion can be and is a ral pain in the drain due to differences in machining of the castings , And getting it dead on only happens about 1 in 10,000 times . You may have a high or low drive and a dead on coast pattern or the other way around . Study the OLD pattern and stop and think of what ya need to do to get the pinion set as close as you can to the org. ware pattern and this will take some playen since you do not have the set up tools that were used to get the pinion depth set to start . And with years of shell we say extencive field testing you have ware on all parts . Then here you come and oh these bearings are getting bad so i will just replace the bearing and i will reset backlash well when you did this you changed everything . and you can NOT go by the book here this is where experience comes into play with setting up a rear end . I(F the book calls for .008-.012 backlash that is for a new gear set on new bearings, so you put new bearings on everything but not a new gear set then you should be happy with .016-.025 back lash . better loose then nice and tight .008-.012 as now you pressed the ring gear deeper into the pinion and the tips will be riding on a new surface and only the tips are making tight contact . Be more concerned with a good drive patter or close then a perfect set on both coast and drive Also just because you have the org. shims this does not guaranty a perfect set due to machining of the housings, that is WHY they make shims..
 
Thank you. I do not know what coast means in a gear set, and I do not have a dial indicator so I have to guess about the back lash. The best that I can currently tell from what I have done is that the lower half of the tooth on the pinion is driving the upper half of the tooth on the ring gear. This would seem to me that it could indicate that I should take out a shim and put the pinion further into the rear end case. I am also wondering if moving it further in there would be likely to make it whine or be too tight. I have only done this sort of thing once before and that time I put a used SH pinion with its shims on a used H ring gear and it seemed to work fine, although I did not check anything other than visually and by feel and did not check the mesh. I am not sure whether to just put this together the way it is and see if it works or try to adjust things and maybe get myself into a worse mess.
Zach
 
Sent Zach a ring and pinion and what the backlash was when removed. It had the rear bearing and shims on the pinion shaft that was there when removed. Like TV said the housings could be machined a little different, even the housings that support the differential. Engine was freeze cracked, so I never drove it.
Ever since I put a ring and pinion in my first car out of the army and got it wrong I always worry when I do it. After a lot of success and a couple of failures (noise) its still not my farvorite job.
 
Things ya need as far as tools ya need , (1) dial indicator with a magnetic base -, (2) a set of Mic.'s 0-3 inches to start with (3) a set of depth mic.'s . And all can be had vfor not a ton of money as you do not need Starrets . And (4) a dial caliper . And since you are not sure what your doing then see if you can find someone to come over and help. If you were close i would do that.
 
kinda looks like your not that far out.
i would wipe the pinion clean from blueing and just coat the crown gear lightly and try it again. rock the crown gear back and forth , where the blueing is removed that would be the contact point. should invest in a dial indicator, would be handy. it is hard to guage thousandth's by feel but after a while you get in the ball park. you want the pattern centred towards the toe of gear ( narrow end) as under load it want to move towards the heel(wider end).
may as well have a better look at things.
 
Zack, There are two patterns, the "coast" and "drive" pattern. The drive pattern is the pattern on the one side of the gears when the tractor is accelerating. The coast pattern is the pattern on the other side of the gears when the tractor is decelerating, or engine braking.
Best Regards,
Charlie
 
Thanks, I tried it again and then decided I would just put the tractor together and see if it makes noise. I figured that I would be just as likely to mess it up worse by trying to fix it and end up having to tear it down again anyway so I might as well try it this way first.
Zach
 
No matter how you slice it, setting up a used R&P is a pain in the rear. What TV said is all true.

Going by the bottom set of pictures, I don't think you are far off. Hard to get the camera to focus, but it looks like the contact is a little high on the ring gear teeth. I would move the pinion toward the front of the tractor and then take one shim from the non gear side of the differential and put it on the gear side and then run it again. The book calls for the pattern to be showing on the "toe" end of the teeth which is the end closest to the differential. When the teeth deflect under load the pattern spreads across the whole tooth. That's for a brand new set and as TV pointed out, you have wear on a used set. I think the contact you have is ok where it is, just needs to be a little deeper.

The "drive" side of the ring gear teeth is what you have pictured on the bottom two that you added. "Coast" is the other side. More important to check in a road vehicle as tractors don't spend much time coasting.
 
You are right, I do need to get those things some day soon. I do have a dial caliper but none of the others.
Zach
 
I like what I see. If the pattern is high on one and low on the other it means at least the middle of that wipe is in the middle of the tooth flank.
Backlash can be tested with a piece of solder. Place a chunk of solder where you would hate to put your finger and run it through the gears. When out the other side it will be smashed thin in one spot.
cut that through with scissors, and use a micrometer on it to measure the thickness.
(or just compare it by feel to a feeler gauge. If even close all is well, run it. Jim
 
I like what I see. If the pattern is high on one and low on the other it means at least the middle of that wipe is in the middle of the tooth flank.
Backlash can be tested with a piece of solder. Place a chunk of solder where you would hate to put your finger and run it through the gears. When out the other side it will be smashed thin in one spot.
cut that through with scissors, and use a micrometer on it to measure the thickness.
(or just compare it by feel to a feeler gauge. If even close all is well, run it. Jim
 
Thank you, that is encouraging. I will remember the solder idea, it is a very elegant method. The tractor has now reached the critical mass where it looks more like a tractor than a pile of parts. I am hoping to get it all together tomorrow and try it out.
Zach
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