2001 GT New Gears Problems? Maybe?

[Beaux]

I recently had a major problem with the entire rear end in my mustang. I changed the entire differential carrier, wheel bearings, ring and pinion, EVERYTHING. I even installed prothane bushings all the way around and did my ball-joints, inner and outer tie rods, new shocks and struts, the works. I even put in a new gas tank while I was under there farting around. Here's my problem. I shimmed the diff and got the backlash at right at .12. And simultaneously shimmed the pinion gear and eventually got the wear pattern right in the center of the ring gear and backlash still at .12. This is where everything became wacky. I used a new crush sleeve when doing the install and measurements and had no problem torquing everything down to spec and once it was all perfect after assembling, disassembling, and reassembling a few times to get everything right, I did the final install with a second new crush sleeve. With the new crush sleeve it felt like the sleeve didn't compress at all and was a royal pain to get the pre-load right (involving destroying at least one pinion yoke tool). Install was like night and day between the two. Now after I finally have rubber back on the road i'm getting a loud whine under deceleration only which suggests that the pinion is too far in on the ring gear. Also, maybe it's my imagination but i'm noticing a very slight clunk when a let the clutch out (super slight and barely qualifying as a clunk). I'm thinking this is all the fault of that new crush sleeve I put in for final install. Any Advice?

 

[UndercoverGT]

You have a 8.8? Did you use oem parts or change the ratio? Most everyone I know In my area that did a gear swap have a little whine but nothing excessive

 

[Beaux]

Figured I might as well upgrade a little since I was gonna be in there anyway... But yes. 8.8 and 3.73s.

 

[wmburns]

I think you may be on the right track IF you didn't feel the crush sleeve compress. I suspect that if you rechecked the pinion preload it's not correct now that the car has been driven.

 

[rancorkeeper]

The FRPP 3.73 in my '01 Bullitt "whines" considerably on rapid decel, but it was installed by a knowledgeable shop & has over 5,000 miles in the last three years, so I chalked it up to different ring/pinion connection point or contact surfaces, which makes the metal sound different. I'm not suggesting to ignore it necessarily, but in my case it seems to be fine after all this time & I just got used to it.