Could someone walk me through changing out the Differential on my 8"

[jb1dsl]

I have got my hands on a complete differential with 3.55's. I need to know what to do to install in the car. What do I need to check before I install, backlash,bearings? Is there a good book or website to check out? I hope going from 3.00 to 3.55 in the 8" really wakes the car up.

thanks

 

[Edbert]

The factory shop manual has a fully detailed write-up on installing and meshing the gears. The tricky part is the mesh, and adjusting it is very time consuming although not too difficult if you have the right tools.

If the diff you have is the entire center chunk (pumpkin) then it is simply a bolt-in job and shouldn;t take more than a few hours. You will have to partially remove both axles though. I say partially since you risk damaging the bearings if you pull them all the way out. Of course now would be a good time to replace them anyhow.

 

[jb1dsl]

Yeah is is the complete chunk, don't I have to get the bearings pressed on and off the axles?

 

[1966conv]

You don't need to change bearings if they're good. If they're questionable I'd change them. It's going to take a press of sorts to get them off and on. Any machine shop can do it in about 10 minutes. Some autoparts store can do it for you also.

 

[Edbert]

Not the inner ones, the axles pretty much slip right into them, maybe a hammer just to make sure the splines are fully seated The outter bearings were the ones I was referring to and they should be pressed on. In my experience you'll need a press just to get the old ones off anyhow.

EDIT: Oh, and be sure to use the correct crush-washers on the housing studs, they help prevent leaks. Make sure either the housing or the carrier have a fill hole on them. Having two wont hurt but having neither will

 

[jb1dsl]

so what is the procedure for replacing the pumpkin?

 

[1966conv]

Loosen lugs on tires
Loosen nuts on driveshaft
Raise car, put on jack stands
Remove driveshaft, put plug in transmission to stop fluid leakage
Remove drum on brakes
Remove 4 bolts on the axle retainer on each side
replace drum backwards to use as slidehammer (this may be optional depending if axles come loose easily or not)
Tie up brake hardware
Pull axles out
remove all but 2 nuts from differential
loosen those 2, catch fluid (appx 3 qts) hold nose!
place jack under differential and remove last 2 bolts very carefully. Be ready to support differential and lower carefully watching fingers, toes, and other extemities.
Clean out differential case

Reverse order except put fluid in last. If track lock/posi be sure to add friction modifier. Check/replace bearings on axles. Check seals in end of tubes.

First time should take you a couple hours.

 

[krash kendall]

You may have to use a floor jack on the nose of the pumpkin to break the seal. I recently had to lift mine and leave it for ten minutes before it unseated. Also, there is a hole in the axle flange you align with each retainer nut to pass a deep socket through.

 

[my66coupe]

If youve never checked the condition of your outer axle bearings, I would now. If they are hard to spin, make weird noises when they spin....or any other abnormalities....I would replace them. Now is the time to check out the condition of the U joints as well, might as well freshen those up while your down there.

Mike

 

[jb1dsl]

I got new joints, but I will be checking the axle bearings