the only other is pull the ring gear and then clamp the true-trac back in and spin it and check its run out . if good its the gear . if not in the true-trac .
OK - I am a little fed up at this time.
Got the NEW Eaton TrueTrac and checked it for runout. It is maybe 0005-0001 but I am gonna bet it is true.
Installed the ring gear, torqued bolts and replaced in axle. SAME FKIN PROBLEM.
I contacted Yukon Gear and they sent these messages (My Message to them is in BOLD):
Yukon
Last year I purchased a 4.11 Ring and Pinon gear set from Amazon. I went about installing it this week and ran into issues. Installed ring gear on an new Eaton TrueTrac differential in a GM 14 Bolt FF axle. Preload is set and tight. The backlash runout was really bad. The difference between low and high readings was at least 005. .005 on low readings and 010 on the high end. I removed the gear and checked the differential gear mating surface on the TrueTrac and it had a runout of 002. Contacted Eaton and they sent me a new unit which I received today. I used 1200 grit sand paper to smooth out any burrs and wiped mounting surface clean with brake cleaner and lint free rags. I Put the ring gear back on and the same difference between high and low readings exists. I had previously used 600grit sand paper to remove any burrs on the ring gear but that didn't change/affect anything. I am using ARP Bolts and they are torqued to 120 ft lbs. Bearing caps are torqued when readings were taken. Do I need to take the ring gear to a machine shop??
Chris
Yukon responded:
For every 0.001” of run out on the carrier face it works out to roughly 0.003” worth of back lash variation . So if you are measuring 0.002” of carrier run out, then yes, 0.005-6” worth of back lash variation would be expected. Fwiw – GM’s warranty allowance is 0.003 for run out – this translates to 0.009” of back lash variation.While not “ ideal “ it is within a acceptable range and would meet OEM tolerances.
As far as de burring, a flat file , or a long flat stone is the recommended tool for deburring, not sand paper. When working with these tolerances, large flat surfaces will remove hi points that you wont feel with sand paper.
Gus Pyeatt
I informed Yukon I got a new Eaton diff and got this reply:
This was used If you had 0.002 run out previously and had 0.005 back lash variation And now have zero run out, but still have a back lash variation, then the ring gear is not sitting flat on the carrier .
As stated, sand paper is not typically used for gear prep. Mating surfaces should be dressed with a large flat file to remove hi spots.
The following is an img (SEE ATTACHJED) of a gear set that I flat filed to show high spots after an installer used the ring gear bolts to pull it onto the carrier. You can clearly see the high spots around almost every bolt . as well as several small spots randomly around the face. This was done in about 30 seconds with a simple Dimond stone like you would sharpen a pocket knife with in the solvent tank.
I would highly recommend proper gear prep to minimize these types of issues.
But as stated, even with out performing additional steps, the back lash variation you are experiencing is considered acceptable by GM’s standards and with in there allowance.
The image Yukon sent shows the scuff marks where he used a diamond stone to get rid of any high spots. I can see using a file to get rid of burrs but how in the hell can an average home mechanic accurately remove high spots along edges and bolt holes.
What is my next move? Machine shop to lathe off the high spots and true the ring gear mounting surface?
I have a buddy that has a Yukon Gear 4.11 ring gear sitting in a box. DOES the ring gear HAVE TO BE MATCHED to the ring gear?
IDEAS or Solutions anyone? What am I missing?
