has anyone out there done enough 9.75 re-builds to tell me what the factory (or an average) thickness of pinion brg shim is? this is a 3.73 , 2005 yr. scab. I have lost mine from 3-4 yrs ago, and cant find where I may have wrote down the actual number. I do remember changing it out but not sure if I went a hair thicker or thinner. Got to crawl back in there and get the factory one in place and see if that fixes the infamous coast whine. backlash @ bottom of spec, all new brgs. Gets worse as oil tends to get good and hot.(like on a long trip). thanks in advance.....................rossford

 

I forgot to mention that the drive side of the ring gear teeth have a sharp edge on top. This really concerns me. Not razor-sharp but doesn't look right. Would this be more a BL issue or pinion needs to come out a tad or inward? Gears were broke in correctly and am using correct spec oil. These are yukons, thinking about going with the Ford racing R & P., if I have to swap out. The 373's & 355's are fairly cheap these days. thanks............rossford

 

Some aftermarket gears are marked for a measured distance from center. When you install the gears, you need to measure the exact axle center and determine what shim is needed. I bought a video from Richmond gear that explains all this. about $15 The old way is to check the wear pattern with Prussian Blue and keep changing shims until you get the pattern right. That can be time consuming and you might need a press. I have changed gears in one diff years ago and the original shim was the correct one so I was lucky. I've been told that once the whining starts, it can't be adjusted out. I disassembled another diff that had a bad pinion bearing and reassembled it so I didn't have to change the pinion shim. The most difficult thing was compressing the pinion spacer. That took about 400 ft. lbs.

 

thanks for reply,,,,,yes, Yukon puts that depth on the pinion head. but, of course , if I could borrow or rent this measuring set up, would be nice. if I had some parallel blocks, I could do this probably. That's the only thing I don't have. I'm getting more concerned about the sharpe edge on the drive side of the teeth. I still think BL is too tight. Anywho,,,, I've been googlin this and haven't really found any thing that covers my situation. Was hoping that someone has done a 975 tear down recently , and could tell me what the shim thickness was, if they removed the big brg. thanks!!!!!!!!!!!!!!!rossford