First off all this is in reference to my '97 Lariat 4x4 with 3.55 Open Diff. The truck has 206,000+ miles and the previous owner told me the rear Diff was replaced around 100,000. I haven't had any leaks or had any abnormal noises. Before or after the Oil change.

I recently changed the Gear Oil in my Rear Differential. What I saw was, to say the least, disturbing. I'm sure it can't be good, but since I didn't feel qualified to tear into it. I took the pictures below and closed it back up.




I'm assuming these are shims and though I normally feel very comfortable working on any vehicle and have done engine and manual trany rebuilds on automotive vehicles and heavy industrial equipment, I've never done more than remove the axels and replace the wheel bearing and seals on Diffs before. And from what I've heard some experience is best when tearing into the "guts" so to speak.

I'd appreciate any info or expertise that anyone could share. Is this something I could handle on my own or should I bring it to a professional?

 

More of a servant here, but it's an obvious problem. Your carrier shims are falling out due to inadequate carrier bearing preload. Driving them in wouldn't be likely to solve the problem. The total shim size will need to be increased. This requires some general adjustment tweaking. You can read about the basics here:
http://www.ring-pinion.com/downloads/yukoninstman.pdf

 

I was afraid it was something along those lines.

Doug

 

Someone wasn't sure what they were doing. The proper Ford shims are one piece. You could take one side apart at a time and use a micrometer to measure the total thickness of all the shims on that side, add about 0.003 inch to your measurement and go to the Ford dealer and see if there is a shim the thickness of your measurement and order one for that side. If you replace one at a time, you won't have to tear the whole thing out. Torque on the caps is about 77 foot pounds. The caps are machined for the side they are on. Good luck,

Robbie