One more differential question

Zachary Hoyt

Well-known Member
I have had the transmission open a couple of times more and still have not been able to get rid of the noise. I ended up by removing two of the original shims from the pinion and either the noise is a little less or I am getting used to it. In first gear the noise is not audible over the engine, and in second and reverse it is just barely. With two shims out the pattern in the prussian blue finally looks like the picture in the book, so I was hopeful that this time it might be quiet. I did get a dial indicator but have not yet obtained a magnetic base so I made a hole in a 1x1x24" piece of wood and used clamps to get it where I needed it. I tried the new pinion position with two backlash settings, one was around .014 which was close to the .015 that D Slater told me was the measurement when he removed them. When that didn't work I swapped a thin shim for a thick one and made the backlash around .030 and it still sounded just the same. I am wondering if I will do any harm to any other part of the tractor by running it for a couple of months with the loud gears. I would like to just put it back together and put the loader back on till spring comes so I can use it to plow snow and move logs around the yard. I am not worried about damaging the ring and pinion since I have a spare set that I got from Marty on ebay a couple of weeks ago for $9.99 plus $26 shipping. They had had no bids and I figured another set might be worth having as a backup. Any advice on whether to run the tractor or not will be much appreciated.
Zach
 
The best of my research into straight cut bevel gears is that there are only two adjustments. Pinion depth, and backlash. (ring gear depth in the pinion)
In all my gear work, I have never seen straight bevel gears with more than about .006" backlash when new.
The machining of the differential housing by IH when it was manufactured pretty much guarantees the planar relationship between the two axis of rotation (ring gear and pinion)
If it were mine I would set it up to have about .008" backlash and run it. It will make some noise, but it will probably wear in and be less distracting.
The only thing that can make the issue be weak and easily damaged is to have the pinion shaft (trans output shaft) either bent, or out of alignment. The intermediate (pilot bearing between shafts, and the front trans bearing all play in the same orchestra toward that alignment.
If those are good, set it and run it. Jim
 
I worked as a diesel engine mechanic for over 10 years and my experience on semi-tractor rear ends is limited. Most shops I worked at there was one and I mean only one gear man that overhauled them. Even at that they were using new matched rings & pinions and still would sometimes have one that would just howl !!!
Since any NOS ring & pinion set would be hard at best to find, let alone a matched pair, and I am sure you could buy another complete tractor for what they would cost, you have to settle for a bit of a comprimise.
I would set it back to the .015 backlash setting where the prussian blue impression looked good and let it " wear in". It will quiet down eventually.
I seriously doubt you would do much damage either way, but IMOP those gears are very hard, and running in 85-140 gear oil it will take a week or two of plowing hard ground to get them to wear much at all.
 
You won't hurt it. I would suggest making sure the differential does not have over a few thousands run out on back of gear. Some times you have to loosen and retorque the bolts or shift the ring gear to a different position on the differential. Also, I never saw one of them set up with any less that about .010 and most closer to .012 when new in the 4 and 560 tractors. Better loose than tight within reason of course. Flush pinion or slightly protruding pinion, never less than flush into ring gear. Like I said before, they can drive you crazy or you can get lucky. There are humps on both sides of them gears now and they will take a long time to wear off.
 
Specs for backlash with new gears was .006 to .015. Can't remember finding any used ones under .010 and consider it lucky if I find them .015 or under.
On used try for contact center from halfway of the pinion tooth toward the rear of the pinion at hand load. From the undercut part of the ring gear toward the edge of the tooth, get pattern center a little over half way toward the tooth edge.
Pattern will get rear close to the tooth edge on some at hand pressure. Some will have a wide pattern and are hard to figure. This is just in the ballpark for used parts.
Like someone else posted, new is not a option for most. If you can still get them a main shaft was over $400 or $500 the last I knew.
Zach I bought some items from Marty before knowing they probably wasn't described real accurate. Lucked out until the last time I bought a ring and pinion for a 340. When they arrived my wife could tell they were junk. Looked worse than the ones you removed. Didn't get mad because I was dumb enough to chance it knowing all his descriptions for all items couldn't be accurate. Saw some items he has since that I would bid on if he wasn't the seller.
 
Thank you for the advice, I will swap the shims back so that the back lash is less. I will open it back up again when it gets warmer and either check the pattern again or swap in the other set. I figure it is a gamble with any used set so I will just hope for the best. Keeping on tearing it down in the cold was starting to feel like a recurring nightmare of some kind. I have bought a few parts from Marty, knowing his reputation and have done okay so far but I know I am on thin ice. I just bought a spare starter along with the differential parts and it is in good shape but the relay got crushed in shipping since it was rattling around with the transmission shaft. I figured I would rather have a spare gear set in case I ended up needing it than have it get scrapped, but if anyone else had bid they would have won.
Zach
 
I don't have experience with straight cut bevel gears, but I do have experience with the curved ones in my Mustang. I would agree, set it to where the Prussian Blue pattern looks like what the book says it should be, and then just run it. If the pattern is good, it should "run in", even if the gears are old and worn. It won't ever likely be silent, but you sure won't hurt anything if the pattern looks good. The only exception to that would be if the pinion, or the ring gear, is bent, and if it were, a dial indicator would tell you that in a matter of minutes. It would have to be several thousandths off, like .002 to .003 of runout, to make much difference on a carrier that big. If less than that with a good pattern, run it!
 
I did check on the runout (if that is the correct word) of the gear end of the shaft as best I could when I had it open and it seemed straight but without a proper magnetic base for the dial indicator it was hard to get it down in there. Thank you for all of the advice, I am hoping that what you said will come true about it getting quieter over time, and if not I can always try the other set.
Zach
 

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