Howdy

I've fallen hard for these old mopars lately- I was looking for a beater to drive while I swap the rear on my 73 swinger, and ended up buying a '72 demon instead!

The demon came with 8 3/4 rear, with 4.10 gears in it and a four speed close ratio. It is really fun on twisties in third gear but it runs a little high in the rpms on the highway, like around 3500-4200...

I have a 3.55 posi center chunk and a 2.9? open chunk, ready to swap in. I am psyched that the swap looks so easy, and I want to try the 3.55 gears, but I haven't done this swap before and I have a few questions:

1- Do people usually use a gasket or liquid gasket? The previous owner (bought it as a project from his son) supposedly would put in the open diff and drive to the track, then put in the 4.10's. I would think that liquid gasket maker would need time to set up before the diff oil could be poured back in, right?

2- It looks like once the brakes are off you can just unbolt the axle retainers and pull the axles out enough to free the chunk. I am wondering how hard it is to pop them back in once the new chunk is bolted in. It seems like there wouldn't be good leverage working from the wheel side of the axle. (of course I have no idea, never did it before!)

3- are there any other issues I should be aware of, or things I should look out for? I am pretty sure that the diff is setup for my axles (did some reading on the early vs. late center spacer setup) but I don't want to run into unexpected trouble.

I got real lucky with this car so far- all four brake bleeders opened uneventfully after fifteen years in storage, engine started right up, etc. I want to keep my winning streak rolling!

Thanks

Kevin

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madam im adam

Do you know what type of posi (Sure-Grip) is in the 3.55? Is it a Auburn "cone" (you will see some springs thru a big "window") or is it a clutch type unit. (no big window & 4 "V" cuts on the center carrier).
If it is a clutch type unit, it needs to have a center thrust buttons, these sometimes fall-out, you need to check to be sure they are there.

Get a new gasket and glue it onto the axle housing, then put a light film of oil or grease on the center section side of the gasket. Doing this will allow for many gear swaps with-out having to use a new gasket each time. Don't use "goop".

Jack the car up as high as possible & support with jack stands
Remove the wheels and brake drums.
Remove the axle retaining plate nuts. (5 per side)
Pull-out the axle shafts, take them out of the housing so they don't lie on the seals.
Remove the driveshaft.
Remove the center section nuts, have a clean oil drain pan ready.
"Crack" the c. section from the gasket by pushing it up, oil drains into the pan.
Clean and prep housing with new gasket.
** Important **
Inspect the new center section for the thrust button and for double axle spline alignment. (clutch type SG units) Use an axle to check the alignment.

Install new c. section & reassemble.
Force some axle grease into the axle bearings.
Be sure axle shafts go into the c. section's mating splines, all the way.
Adjust the bearing end play to .010 (see FSM)
Refill with GL-5 oil (limited slip type lub.)
Change the speedo drive gear if you want to avoid speeding tickets.
DD

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madam im adam

What a pro me or Bagel could not have done a half a job as Doc.Thanks Ron Parker












Jaggers Fabrication Slanted Attitude Dart

Don't over simplify this if he hasn't done it before.
There are Park Brake equalizer bars across from one shoe to the other.
Before you start to YANK on the axles, make sure you at least remove the leading (forward) shoe so this flat bar can be removed.
They just get into the way of the axle retainer flange during removal AND re-instal.
Don't forget to readjust the end play as most spider center spacers are not identical.
Good Luck,
Terry

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Terry Bogusz
From Super 6 Left turns to Straight again.

I'd a left the 4.10's in there.

If your axles have the green (sealed) bearings you need to make sure the thrust button Doug mentioned is out. The axles will not seat properly with it in there.

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Official Cookie and Mater Tormentor.