Changing out third member - Vintage Mustang Forums

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post #1 of 8 (permalink) Old 07-27-2004, 03:17 PM Thread Starter
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Is it necessary to drop the rear axle housing to change out the chunk? I want to switch to a "posi" unit in the future but I'm not sure how soon. I will be replacing the rear suspension in a month or so and plan on cleaning up the pumpkin but I don't really want to change out the third memeber at that time. So what do the experts say?

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post #2 of 8 (permalink) Old 07-27-2004, 03:27 PM
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Is it necessary to drop the rear axle housing to change out the chunk?

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post #3 of 8 (permalink) Old 07-27-2004, 03:28 PM
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No, it is not necessary to drop the rear axle housing to change out the rear pumpkin. Just be careful when removing the pumpkin, 'cause it's a heavy sucker! A good jack adapter is nice to have, if not a lot of heavy bodies! If you are going to change out the suspension anyhow, why not just drop out the whole thing, detail up the housing and the pumpkin and change your rear end all at the same time? A lot less hassle for you to do that out of the car!
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post #4 of 8 (permalink) Old 07-27-2004, 03:28 PM
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Its not necessary to drop the third member to change the rear gears (pumpkin or chunk) That one of the reasons Ford rear ends are so popular with Chevy guys You will have to pull the axles out to pull the pumpkin (Make sure you remove ALL of the copper crush washers or it won't come out)

If you are going to upgrade rear suspension I would do both of these jobs together to make this swap easier than lying on your back

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post #5 of 8 (permalink) Old 07-27-2004, 03:29 PM
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While not necessary it sure makes it easier. The third member is heavy, and does not fit well on the pad of the average floor jack. Why not replace it when you do the suspension replacement?
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post #6 of 8 (permalink) Old 07-27-2004, 03:36 PM
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If you're going to pull suspension anyway, you'll find all the work a lot easier if you drag the 3rd out from under the car. There isn't really much effort to save in leaving the axle in place, and replacing the center section in place is a huge PITA unless you have a lift. Get all your parts together, then spend the hour it takes to bust everything out at once.

I just did this. I'd replaced the springs earlier, so I left them attached and just walked the 3rd out over one of them on a roller jack. Here's my recommendations:
  • Set the car on jackstands just ahead of the rear spring mounts.
  • Disconnect the driveshaft and the flexible brake hose from the body line fitting.
  • Put a roller jack under the pumpkin and take the spring load off the shackles.
  • Bust out the shackles.
  • Bust out the front spring mounts.
  • Drop and drag the whole shebang out from under.
  • Bust off the springs and clean up the 3rd member.
  • Pull the axles and the center section.
  • Install the new center section.
  • RECOMMENDED: have the axle bearings replaced and get new axle seals. Cheap maintenance while you have it apart.
  • Reinstall the axles.
  • Install the new springs. RECOMMENDED: poly bushings.
  • Walk the completed 3rd over one spring (a roller jack is necessary, a friend very helpful).
  • Bolt it all back up.
This would be a good time to replace the rear brake lines (the flex line if not the hard lines) and put a new axle vent tube in place as well.

Hope that's useful...

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post #7 of 8 (permalink) Old 07-27-2004, 04:28 PM
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I did exactly what you saying. New springs and shocks one day and then a month later swapped out the 2.79 open for a trac-loc 3.25. The floor jack and my 10 year old helper made removal a breeze.

We try to keep the car driveable and off the stands as much as we can.

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post #8 of 8 (permalink) Old 07-28-2004, 12:26 AM
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I find it easier to separate the 3rd member from the housing while still installed under the car. when you pull the rear end out you have to muscle the third member out. While still under the car, pull the axles, remove all the nuts and driveshaft, then jack up just the third member. The weight of the car will break the tight seal. When in the junk yard, if you have the rear high enough and only want the 3rd member, just hit each stud through with a hammer and pull it out. Saves a lot of time.

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