How do I replace third member???

84convertablegt · Apr 25, 2005

How exactly do you pull the rear axles to install a new third member? I just got my 3.55 auburn posi 8" pumpkin today and just want to make sure i do everything correctly. so help me out here. this is what i know: jack up the car and put it on jackstands (rear end) take off back tires. remove driveshaft. ok, thats all i really know. im assuming all you do it pull the axles and unbolt the center section and it should come out. but how do you remove the rear axles??? i have rear drums all stock if that helps. i need specifics here. also, im assuming the old pumpkin wont just fall out after 40 years so should i beat on it with a mallet or what? help me out guys and gals who have done this!

84convertablegt · Apr 25, 2005

anyone?

geostang351 · Apr 25, 2005

I'm sitting here waiting for the important answer as well. Sorry

Loup-garou · Apr 25, 2005

There's not much more to it than that. Sometimes the axles don't want to slip out; if that happens just reverse the drum and retain it loosely with the wheel lugs. That way, you can use the weight of the drum like a "slide hammer". Be careful to support the weight of the drum as you do this. In fact, take care to support the outboard end of the axle as soon as the bearing slides free of the case. Otherwise, you risk buggering up the axle seal. The smell of hot 90-weight emanating from your rear brakes is definitely a bad thing.

Once the axles are free of the differential, the third member should unbolt easily enough. I've never had one "stick".

On the 8-inch rear axle, remove the four nuts that retain the axle behind the wheel flange (check out the bottom-most two pictures at http://www.mustangmonthly.com/howto/41618/), the retaining plate is easy to see.

84convertablegt · Apr 25, 2005

thanks, thats what i wanted to know oh yeah, 1 more thing, what weight and how much oil do i put in the rear end? i know ill also need a bottle of friction modifier.

geostang351 · Apr 25, 2005

How far out do you pull the axles>? All the way? Do you haev to disconnect the brakes in anyway to take out the axles?

slackr · Apr 25, 2005

No, you don't have to disconnect the brake lines. I would completely yank the axles so they aren't resting on the seals. If the diff has never been pulled before, look for copper washers behind the diff mounting nuts... make sure they are off or they might give you problems getting the diff out.

96 DOHC Cobra · Apr 25, 2005

Be sure you have a pan and plenty of rags around in case the old oil catches you offguard. I don't think you need friction modifyer with the Auburn. I could be wrong, but I thought it was for clutch-type diffs. Not sure how much oil you'll need, but it shouldn't be more than about three pints. I'm sure someone here will know.

Edbert · Apr 25, 2005

A couple of things to add...

Plan on replacing both outer axle bearings and oil seals when you do this.

You can only fill the rear-end with oil AFTER it is reassembled. You fill it to the bottom edge of the fill plug, kind of like adjusting the floats in your Holley.

If this is the first time your axles have been out I would recommend taking the housing to a steam cleaner. Not for the outward appearance, but have them clean out the INSIDE. You'd be amazed how much gunk and junk will have settled in there over the last 35-40 years!

gjz30075 · Apr 25, 2005

And, if the diff has never been pulled before, or a long time ago, use your floor jack from the front of the diff to jack it up to break the seal loose. It'll be a mess so have a pan ready. If you used your floor jack from the rear of the car, there'd be no room for the pan.

Clark · Apr 25, 2005

As for the quanity it will take about 1 1/2 quarts of gear lube and a I recommend 75w90 synthetic. Costs more but worth it and you will never need to change it.

krash kendall · Apr 25, 2005

Another not so messy option is to go to a marine hardware store and buy an oil change pump to remove the oil from the filler plug before dissassembly. Its easier if the oil is warm.

84convertablegt · Apr 25, 2005

yeah, i read on the oil. auburn recommends non-synthetic 75w90 with a bottle of ford or gm friction modifier. so dont u have to take the axles to a machine shop to press on new bearings?

taylor4g63 · Apr 25, 2005

Glad to see you got the pumpkin. Heres what i have found is the easiest way to replace the pumpkin.

Break lugs loose
Jack up car, put on stands
Take off tires
Pull off drums, take out 4 bolts through the lil hole in the axle (don't know what its really called, but u should see what im talking about)
Pull axle out 4-5 inches, just enough where its not in the pumpkin
Take out driveshaft
Take out all the nuts holding 3rd member on
Get a drain pan of some kind under it, and pry the 3rd member away from the housing. Gear oil will start coming out, and its gonna take like 30mins. to come out.
Then start prying it from every side. You can try getting a small jack and jacking it up a tad to get it off the studs and then sliding it off. Be careful though, might hurt if it landed on your head. Then I would try to clean all the old oil out of the housing. After its all clean, put a gasket with silicone on it on the housing and muscle the new differential up there. Torque all the bolts down, fill with fluid, wiggle the axles back into place, etc... Its a pretty simple procedure, shouldn't take more than a couple of hours.

Edbert · Apr 25, 2005

84convertablegt said:
so dont u have to take the axles to a machine shop to press on new bearings?

Yes, you're going to have more trouble getting the old ones off than putting new ones on though. So while they are the machine shop getting the old ones pressed off have them do both

geostang351 · Apr 25, 2005

Tayler, Perfect post. Thats what the do-it-yourselfer needs to see. Thx

84convertablegt · Apr 25, 2005

yes, thanks to taylor again. he's the one i bought the pumpkin from. it looks great although shipping a 68 pound chunk can do some interesting things to a cardboard box the differential is in great shape though. looks brand new!

Clark · Apr 25, 2005

I agree, Taylors instructions are simple and accurate. If you decide to change the rear axle bearings you will need to take it to someone to have them changed and if you don't know if they ever have been changed, change them!

Not familiar with the Auburn setup but they also recommend changing the fluid every 7500 miles! Sorry not me, I am a beliver in synthetic and see that they meet all specs compared to reg. oil.

taylor4g63 · Apr 26, 2005

84convertablegt said:
yes, thanks to taylor again. he's the one i bought the pumpkin from. it looks great although shipping a 68 pound chunk can do some interesting things to a cardboard box the differential is in great shape though. looks brand new!

Glad to see it got to you alright. Just wondering, what did the box look like when it got to you? What gear do you have in your car now? If you have a 2.79 open like i did and upgraded to the 3.55 posi, be ready for a whole new car...

84convertablegt · Apr 26, 2005

well, the box was open when i got it, it just looks like it burst open. you know it was probably tossed all around by the shipping company, they dont care whats in it. all they know is that its heavy. but i took it out and inspected it and turned the pinion and all, and everything looks great, no problems. i do currently have a 2.80 open rear, so the excitement is uncontrollable right now, problem is my car still is at the paint shop getting painted so i just have to wait a few days. im sure it will run like a whole new car, ive heard the rear gears is like one of the best seat of the pants mods there is

How do I replace third member???

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