06 Gt 3.73 Install Nightmare

Discussion in '2005 - 2009 Specific Tech' started by militarystang06, May 23, 2013.

  1. over the weekend me and my dad who are both mechanically inclined, decided to throw 3.73's in my stang. its an 06 gt auto. the tear down was easy and nothing was damaged. car has 86k on it. we have all the special tools and goodies to properly complete the task. our first problem was that the pinion with stock thirty thousandth shim on it, would sit too far in the pumpkin and hit the carrier. so we took it all out and used the stock bearing with the center grinded out to get an idea of how big of shim we needed. so we went with no shim on the pinion and therefore the fitment seemed perfect. with everything in and the gear shimmed right(or what we thought was right accorinding to three different books) everything seemed to be perfect. so we get it all back together and fluid in it, let it run at idle with it on jacks for about ten minutes, got it off jacks and took it for a test drive, literally around the block no faster than 20 mph and right away we heard the infamous whining, and when i let off the gas it was kind of a clunking sound like once i let off the gas and the pressure wasnt there :poo: was just rattling and loos inside the rear end. so we said screw it and took it to a reputable mechanic. at first he said without doing anything but taking the cover off, said my clutch pack went bad...after getting on him he finally tears it all down and says the "oil slinger" a washer behind the bearing on the pinion wasnt there when we put it in?? i am on military leave and already passing my allowed leave 500 miles away. really need my car fixed and not getting any good knowledge it seems like. very frustrated so please any help is appreciaited. sorry its such a long story
  2. Not sure what help you're looking for. I know you said you're both mechanically inclined, but if this is your first swap, being in a hurry isn't going to work out well for you. My first swap took me about 20 tries to get everything set up right, and I didn't have issues with the pinion.

    Best advise I have for you is find a good DRIVELINE shop that can fix it for you. They can do the whole swap from scratch in about 3 hours. If you need this car to get back to post, you're going to need it fixed reliably, and ASAP. Swallow your pride, pony up the cash, and find a guy with a lot of differential experience to fix it for you right, rather than continuing to figure it out yourself.

    And thanks for your service!
  3. What a frustrating situation. But I agree with Husky; I'd take the hit in the wallet and take it to a good driveline guy and let him fix it. Learning at the tail end of your leave, under pressure is bad all around.

    I really hope you get it resolved quickly. Let us know.
  4. Yeah man its sitting in a shop right now. To make matters worse its memorial weekend so what he ordered is taking even longer. I guess what I'm asking, is what's the clunk sound when I had let off the gas and it just felt like stuff was loose back there. From the book it seemed as if we shimmed it right and everything. Its just frustrating not getting a 100% diagnosis. And I don't see how the "oil slinger" would have been a huge issue since I've seen people have taken their pinions out with no slinger on them
  5. I certainly don't know. It's been many years since I've dug into a differential. And the last time it was a Chevy. I've since remedied my ways, but lack experience to offer input. I certainly hope the shop that's helping you now can provide a reasonable and sound diagnosis and repair.
  6. You should have measured the pinion head you took out and then the new head and with the difference and the original shim, you could have calculated what size shim you need. Just to say the fitment looked good isn't very exacting. Look up an article by James Adkins, http://www.superstallions.com/tech/gears/gears.html and use the MHD calculations for the pinion shim thickness. Then there are the side shims sizes and pinion bearing preload and backlash to consider. As well when everything is together mark the teeth and check the pattern. Do some searching there are a lot of good articles and instructions in the various Mustang sites. Site above doesn't work. Here's a good one http://mustangforums.com/forum/4-6l...o-4-10-install-and-differential-overhaul.html
    Good luck
    #6 lenko, Sep 17, 2013
    Last edited: Sep 17, 2013