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I have a difference of between .008 to.016 of ring gear backlash depending on which point of the ring I am checking it at. What would cause such a large variation? I am assuming it is worn teeth on the ring gear? Am I correct?
Thanks
I would disassemble the entire rear to inspect the bearings, pinion, and ring gear. Then I would reinstall the carrier back into the case without the ring gear installed and check for runout along the ring gear seating area.
Shoot a couple of pics of your dial indicator setup, one where you are observing the 0.008” and another where you are observing 0.016”. Be sure to capture how your indicator holder is secured.
Thanks Fly Skids Up,
My entire rear has been apart. I just rebuilt the posi case with new clutches, shims, and center pin. The pinion gear and ring gear look OK, no damaged or heavily worn teeth. The bearings appear to be OK, but I am just replacing the carrier bearings but haven't yet. I have put all new seals in the case. The carrier has a couple of gouges where it previously broke a ring gear bolt before I owned it, but doesn't look serious. I will take your advice and remove the ring gear and reinstall the carrier and check the runout on the carrier face to determine if it is the carrier or the ring gear that may be warped?
69L88,
I did not change the mounting of the dial indicator on the case. It was still in the same spot when measuring both the .008 and the .016 I was just rotating the position of the ring gear and remeasuring..
Have you measured the lash at each tooth? You have 30 some odd teeth on the ring, depending of course on the ratio. I’d check each one and see if the data will tell something. What brand of gear?
I'm guessing that broken ring gear bolt area has a raised spot and ring gear isn't flush or all were loose and the case needs to be machined flat or ring gear trued.
Thanks 427Hotrod,
The ring gear bolt was replaced previously when it was broken, and I checked the torque on all bolts before reinstalling the carrier. How do you re-true the ring gear if it is warped? I guess I am going to remove the ring gear and put the carrier back in without it and check the face for runout where the ring gear seats. If the carrier face is good, I will need to replace the ring gear, and also the pinion as well, as I understand you cant do one without the other..
69L88,
Not sure what checking at each tooth will prove? Right now I am showing .0035 - .004 of runout on the ring gear. The ring gear obviously is not sitting flat or is warped? I'm not sure how an extra .003 of runout would give me a difference of .008 of backlash?
That does seem like too much variation in backlash.
It would assume you have either a burr or a piece of dirt under the ring gear somewhere (or) the posi gear flange is warped from the previous bolt that broke.
#1 is easy to check but I vote for #2. Pull the ring gear off the posi unit and chuck up the posi case and put a dial indicator on the flange to check it for trueness.
It happened to me on a posi that had also broken a ring gear bolt. It would be pretty easy for a broken bolt or tooth to get jammed in there somewhere while rotating and exert enough force to put a slight bend in this unit. My flange was over .010" out and had to be trued on a lathe. The B/L was fine after that. You can see where the lathe was only touching the flange on one side of my posi.
Last edited by leigh1322; Jun 26, 2022 at 12:35 PM.
Thanks Leigh322,
Gonna do that. Woll pull the ring gear off and mount the carrier back in the case and check the runout on the carrier flange. If it is good I guess I need a new ring and pinion. When I tool it apart, all was running fine. No noise in the rear end. I originally took it apart to tighten up end play on my stub axles. I rebuilt the posi with new clutchs and shims and center pin and now when putting back together I am finding this backlash and runout issue...
69L88,
Not sure what checking at each tooth will prove? Right now I am showing .0035 - .004 of runout on the ring gear. The ring gear obviously is not sitting flat or is warped? I'm not sure how an extra .003 of runout would give me a difference of .008 of backlash?
I am the type who likes to have data for analysis before I dive into attempting to address a problem. Has saved me many time from thinking my problem was X when all along it was Y or, worse, was not a problem at all. Knowing where your lash is the greatest and where it is the least can give you some insight as to where your issue might be. I agree with the other posters that an improperly seated ring gear could be the source or it could be a case flange that is not parallel but knowing where (example flange bolt 3 or 6) will make it easier for you to home in it.
The relationship to your 0.003” vs 0.008” dimensions is in the geometry of the measuring planes.
Jim,
I measured the runout on my ring gear and it is basically .002 - .0025 Is that too much? I do seem to have a pretty good variance in backlash and am wondering if it has to do with too much runout?
Thanks
Ring Gear Backlash
