8 3/4 742 Center Section Rebuilding

[Dana67Dart]

Well the mechanic I was going to have rebuild my center section has ghosted me so dang it I'm going to do it myself! (first time!)

It is a 742 center with clutch type Powr-Lok, 1969 (IIRC), I will only be reusing the cast iron center section, caps, yoke and Powr-Lok carrier. All else will be new.

Before disassembly I will punch IDs into the caps and the carrier for reassembly

Questions...

1. I don't have a proper way to hold the yoke to remove / install the nut. I have seen plates that use the U-Joint Bolt holes to secure it to the yoke and add a breaker bar for leverage. I have seen a Miller 6719 type took that goes around the outside of the yoke. I could use a huge pipe wrench or vice. Any good or bad to the above options?

Once I get it apart I will remove the bearing races and have the cast parts cleaned.

Question...

1. Sand blasting, Media blasting, hot tank? issues with any option?

I plan to leave the external cast surfaces that are not currently painted natural and was thinking use a clear matt finish after cleaning.

Question...

1. Recommendations on product / manufacturer for rattle can paint?

As I get closer to pulling the trigger And during assy I will have MANY more questions

I had planned to follow the 67 FSM but with it being a 742 center with 69 gears Im thinking 69 would be better

Question...

1. would I be better to follow 69 FSM?
2. Can I press in the races without a press? should I have a machine shop do this part?
3. Dr Diff sells a spanner wrench for the bearing preload (out of stock), other options?
4. What other special tools will I need? Dial Indicator? Magnetic base? Feeler gauges?

Thanks guys.

 

[12many]

In no particular order: Autozone loans race/seal drivers. I bought the same tools from Harbor Freight, work great. Factory service manual is all you need for instructions, study it like preparing for finals. As for the factory tools mentioned in it, you can improvise. With a helper you can place the yoke in a vise, then torque it. Cumbersome, but if the vise is secured solidly it will work. A big *** pipe wrench with some protective inserts so the jaws don't dig in works also, or just fab a tool similar to the factory item. You don't need to buy a preload spanner. Improvised tool will do, or a brass punch and hammer even. Harbor Freight for the dial indicater with vise grip mount will work. All tools can be improvised. Good luck

 

[Dana67Dart]

All tools can be improvised.

that's what I have done my whole life!

 

[dano]

Use an impact gun, be it pneumatic or electric for the pinion nut. A big wrench to hold the yoke, I held mine by hand, but it had been apart before. Tank or brake clean the case. I wouldn't blast it unless its super rusty. Any automotive grade paint will work with proper prep and follow the directions for cleaning and a primer if called for. A 742 is a 742, use what manual you have.

Dr Diff is the way to go. Cass is awesome!

 

[RustyRatRod]

I knock races out and in with a hammer and punch. The number one biggest advice to me is, hone the old large pinion bearing so it is a slip fit on whatever pinion gear you are going to use. This enables you to change the shims out very easily finding the correct gear pattern. Once found, press the new pinion bearing on and assemble.

 

[SGBARRACUDA]

Do you own a large bench mounted vise? I place the yoke in the vice when I torque the yoke on a 742 to 250 ft lbs. You can remove the pinion bearing without a press but it's much harder. You can cut the race with a dremel almost all the way thru then smack the cut with a large chisel and a BFH. But then you won't be able to use it as a set up tool. Now would be a good time to buy a dial type inch pound torque wrench for pinion preload. Or rent one.

 

[Daves69]

Improv tools don't need to be pretty, just functional.
Spanner is easy, couple of bolts though some old tube or 1/4" flat....……..

For the yoke, mine is just welded 1/4" flat stock drilled for a 7290 yoke pattern on one end of and old "persuader". I can use a 2 jaw on the long outside of it to pull the yoke off once the nut is off.....

My holding fixture is 1/4" angle that bolts on the engine stand...……...

 

[toolmanmike]

Improv tools don't need to be pretty, just functional.
Spanner is easy, couple of bolts though some old tube or 1/4" flat....……..
View attachment 1715394355

For the yoke, mine is just welded 1/4" flat stock drilled for a 7290 yoke pattern on one end of and old "persuader". I can use a 2 jaw on the long outside of it to pull the yoke off once the nut is off.....
View attachment 1715394363

My holding fixture is 1/4" angle that bolts on the engine stand...……...
View attachment 1715394364

Thanks Dave. A buddy and I were just talking about those a couple days ago.

 

[Dana67Dart]

Thanks all for the input. Keep it coming! I'm absorbing it like a sponge.

 

[Dana67Dart]

Well I finally got the yoke off!

First I tried with my 50 year old 1/2 inch Craftsman breaker bar and two 24" cheater bars. When I saw the end of the breaker bar spread I decided to stop.

I got a 3/4 drive breaker bar and socket and with the two cheater bars, the nut came loose no problem. The yoke came off with no additional effort, no need for a puller.

Amazing what happens when you use the right tools for the job

Assuming the old pinion and the new pinion have dimension for depth is it safe to do the math with the old shims total thickness to determine the new shim thickness to use?

I plan on honing the old bearing to allow it to slip on and off for setup but wondered if you can trust the markings