Drivetrain Rear end rebuild

Discussion in 'Fox 5.0 Mustang Tech' started by 88vertgeetee, Feb 21, 2013.


  1. 88vertgeetee

    88vertgeetee Member

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    Hi I am looking to rebuild my rear end. Have a bad pinion bearing. I got a quote for 250 labor plus bearings and fluid. That's if the gears are still good. My rear has been vibrating for the last two weeks. Is there a way to tell if the gears are bad or am I just gonna be surprised when the mechanic pops the over?
  2. 2000xp8

    2000xp8 Mustang Master

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    I'd buy new gears. If the pinion bearing is that bad the angle the pinion meets the ring if off.


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  3. ratio411

    ratio411 Founding Member

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    Sounds like a pinion bearing to me.
    I have had them go out several times on my business trucks/vans, and have yet to have anything else damaged.
    Hopefully you'll have the same thing.
    The price sounds reasonable.
    If you have been wanting a ratio change, now is the time.

    It's not terribly hard to swap a pinion bearing. You would just have to put everything back exactly as it was.
    If you are not changing the gear it's pretty straight forward.

    Another option I have used when the pinion bearing goes out and I don't have time to mess with it: Get a used rear, and put the other aside for a high quality buildup. Stang 8.8" rears with the limited slip still inside only run $100-200 around here, and way cheaper if you luck up on one at the u-pull.
  4. ratio411

    ratio411 Founding Member

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    Did your mechanic put it on the rack and tell you the pinion bearing was bad?
    A bad rear u-joint has the same symtoms, and is far more likely on a car.
    My trucks go through the pinion bearings because they are Powerstrokes that tow day in, day out.

    If I was a mechanic looking to scam a quick 200 bux, I'd find someone with a bad u-joint and tell them that it was the rear. Then charge the $250 after replacing a $15 u-joint. Just sayin'...

    If your pinion bearing is bad, the companion flange will move up and down inside the front of the rear end.
  5. 7991LXnSHO

    7991LXnSHO Active Member

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    The price seems quite reasonable if you can just get the bearings and seal done. I do not know how you can tell if the gear is scored in the bearing area without popping the cover. Sorry. The good news is new bearings and seals can last a long time.
  6. 88LX5.Oh

    88LX5.Oh Advanced Member

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    I'm with Rate, it could be a U-joint. Definitely check that out unless you know for sure that the mechanic got it up in the air and pinpointed it to the pinion bearing.
  7. ratio411

    ratio411 Founding Member

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    You aren't anywhere near Pensacola, are you?
    Long shot, I know...
    There are 2 GTs in the local u-pulls at this moment in time, and both had rears still in them a few days ago.

    I have a spare 8.8" out of a GT, but it's a 2.73 gear.
  8. 1200gt

    1200gt Member

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    Personally, based on the info i'm hearing, I'd pop-in a set of u-joints myself to see if that fixes it. Those are real easy for anyone with basic tools to knock-out and inexpensive parts -besides, they would probably need changing anyway if the rear is suffering. If that doesn't fix it, then I'd consider the other options.

    Dwayne

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