8 3/4 Rear Center Section 741 case

[DY31970]

Hi, There is a guy selling an 8 3/4 center section, 741case, 3.23 gears, non sire-grip for a fair price. It's the gear ratio I want. Can I convert it to a sure-grip? If so, is it relatively easy? Or would it better getting a sure grip right off the bat?

 

[pschlosser]

It can be done.

Thread over on FEBO

Changes to clearances and shimming is often involved, and it's tricky and not easily DIY. Some must take their pumpkins and/or axles to a shop for proper fitment.

That said, I hear good things about using a Detroit TrueTrac unit, instead.

 

[heminut]

Changing out the peg leg for a sure-grip is pretty straight forward, no shims involved. Since you're using the same gears you don't even need to mess with the pinion gear the only part that uses shims. Pull the carrier and swap the ring gear onto the sure grip carrier and put it back in. The carrier adjustment is done with the threaded collars on each side, no shims involved.

You'll want to check your engagement pattern on the gear teeth using white grease before removing the carrier and when you put the new carrier back in you want to adjust it to get the same tooth engagement pattern. The FSM explains how to do it. If you're not comfortable doing it, you can pull the carrier out and take it to a shop and have them do it pretty reasonably.

Be advised, the ring gear bolts are left hand thread.

 

[DY31970]

Thanks pschlosser and heminut. What is the FSM?

 

[Chryco Psycho]

Factory service manual
You need to measure the backlash with a dial gauge before disassembly , the side adjusters are threaded so you need to have the measurement to reset the back lash after removal of the center carrier to install the sure grip

 

[Xcudame]

Rockauto sales copies of the Factory Service Manual. Both paper and disc for all e-bodies. I get one of each. Paper copy for the garage and electronic copy for the laptop. If you don't have a dial indicator, get one with a magnetic base. It gets used for so many things on our Mopars.

 

[pschlosser]

the service manuals are all over epay.

some sites will provide the PDF versions for free, though.

Service Manuals
* 1970 Dodge Service Manual (Challenger)

* 1970 Plymouth Service Manual (Barracuda)

* 1971 Dodge Service Manual CHASSIS (Challenger)

* 1971 Dodge Service Manual BODY (Challenger)


Parts Catalogs
* 1970 Mopar Parts Catalog


* 1971 Mopar Parts Catalog

 

[challeng61]

One thing you should consider is the size of the pinion shaft for a 741 case is only 1-3/8". A 742 case is 1-3/4" and a 489 case has a 1-7/8". Just things to consider depending on use.