Case DC ring and pinion help

[Lee_K]

I'm in the process of restoring a late DC with live power including rebuilding the entire transmission due to pitted bearings and missing gear teeth. I've installed the new used ring and pinion with new bearings. I set the ring and pinion per the numbers on the pinion using the procedure in the book. I was advised to check the mesh with Prussian blue which is where I am currently at. However I've now got some wear patterns but really don't know what I'm looking at. It appears the pressure or wear is concentrated toward the middle of the ring gear or end of the pinion but spread across the height of the teeth. Any advice on the pictures below is appreciated.

Thanks,
Lee

 

[mEl]

Do u have the service manual with the instructions on how to set the pinion depth. It has been years since I have done one but there is a gauge that the pinion sits against the mainshaft. Maybe someone has the thickness of that gauge piece, I'm thinking it is .500 square stock but easily could be corrected on that. Are their numbers etched on the face of the input pinion? if so they are used in conjunction with the gauge. Also, there may be enough wear that getting a factory footprint on the tooth face may be difficult. I am assuming that you have the backlash properly set so I would check the pinion depth, if that is correct as well, I would be comfortable running it.

 

[JOCCO]

I am on my phone so can't tell to much from pictures. Follow the book. Most ring pinion you do not want to much toe or heal or high (top of teeth) low will bind it. You should have checked the old one before dismantle. If your that unsure get a mechanic to look. I know finding one who will do rear-end is nigh impossible. I did my DC when I restored it. No trouble but done lots of differentials. Also on shims or bearing caps try the same number as you took out.

 

[rustred]

I'm in the process of restoring a late DC with live power including rebuilding the entire transmission due to pitted bearings and missing gear teeth. I've installed the new used ring and pinion with new bearings. I set the ring and pinion per the numbers on the pinion using the procedure in the book. I was advised to check the mesh with Prussian blue which is where I am currently at. However I've now got some wear patterns but really don't know what I'm looking at. It appears the pressure or wear is concentrated toward the middle of the ring gear or end of the pinion but spread across the height of the teeth. Any advice on the pictures below is appreciated.

Thanks,
Lee

what is your backlash ? it is important to have it set at the same as this used gears were before. its still not quite right yet. a person has to know the backlash so post that and then can further continue. you need the back lash set as before so the used gears run in the same mesh and dont howl.

 

[Lee_K]

The backlash is set to 5 thousandths which is what is indicated on the pinion. I will never know what the backlash was before since this is a used set of gears from a different tractor.

 

[rustred]

i dont think that is the backlash on the pinion, it has never been marked pinion. and for a tractor .005 is too minimal,{ too tight, } from experience i would think its more around .008 -.009 , maybe up to .0012. backlash is not a set number. that .005 number is for pinion depth. any how it needs ore adjustment. post a pic of that diff i have not been into a case diff, but i have some of these tractors. dont a pill of diff's in vehicles and trucks. the end result is the same , need the proper pattern. need the pattern towards the toe so when under load it is higher up towards the heel. to move the pattern face or flank that's the "in" or "out" pinion adjustment. if you want to get a good pattern use high gear and turn the engine oover with the starter even hold the brakes helps. on a second note your .005 might be correct as i was looking at the pic's and that's a small crown and pinion.

 

[rustred]

I found u some info regarding procedures. These are the small model farmalls. Don’t matter a diff is a diff.

 

[ShakerPrairie]

Actually that backlash of 0.005" sounds correct.
The pinion on my 1944 DC3 is marked 5BL.
And the pinion on my 1951 DC3 is marked 6BL.
In this case I would work with it a little.
You could for example add a 0.003" to the pinion bearing carrier and see what kind of a pattern you get in the blue.
There are three different thickness' of shims for the pinion bearing carrier.
30 gauge.
0.005"
0.003"
Then check the backlash and the wear pattern.
With worn gears you are shooting the dark, so to speak.
Looking at your last picture, the one of the pinion, there is heavy contact on the ends of the pinion gear teeth, and then a faint line deeper in the pinion gear teeth where the top edges of the ring teeth are contacting as the teeth roll apart/separate.

 

[Lee_K]

A little update here. I have done a lot of research since my initial post and talked to several people. As of right now I think I will keep it where it's at but I will explain why. I do not and cannot know how this gear sets was setup before since it was shipped to me in the mail. More than likely it was set per the numbers on the pinion because it was installed from the factory that way. This differential is now set again to the procedure in the manual. I am confident in my ability to use a feeler gauge and dial indicator. These Case gear sets have numbers scribed in the pinion (see picture)for backlash and pinion depth, using a special gauge which I have (homemade). What I am less confident in is reading the markings in the blue although I've learned a lot. It is my understanding that a perfect pattern would be a football shape dead center on the tooth. My pattern is roughly a football shape but toward the toe of the tooth. Through research and by testing that pattern will move toward the heel as load increases. I was able to verify this by using no load and having a little contact on the toe then adding load by hand to get what you see in the pictures. I can only assume a real load will move that pattern even farther toward the center. In the photo below you can see where the gears touched circled in red and where they got very close in green. My assumption is that under a real load the green section will become part of the contact patch. Also the coast side or the side that contacts when the engine is breaking looks perfect. The contact patch is basically the whole tooth. See picture
One last piece of advice I received from a respected Case man was to use a piece of news paper. Running that piece of news paper through the gears should result in a creased but not cut paper see final picture. I appreciate all the advice. It will be a little while yet before I close this transmission so I can still make adjustments if the consensus is it's needed. If I am still way off let me know that too and I will adjust accordingly.

Thanks,
Lee

 

[JOCCO]

Lee I would not get to shook up looks like you did your homework. A tractor runs at very low speed, so you do not have all the issues of say a racecar rearend. Once in a while like anything you will have a rear end that just won't set up well and will drive you crazy.

 

[rustred]

i agree with you , under load it will move towards the heal of the tooth. it dont look that terribly bad in your picture , yes i would leave it as is. much better picture this time.

 

[rustred]

and that number on the pinion, i cant figure out what is means with that scribbling. as i was saying before i have never saw a backlash number posted on a pinion, cause its a variable number. its not gonna matter anyhow, as its going into a different tractor. it when you pull a diff apart , you measure the backlash so it gets installed with the same backlash.