News:

It appears that the upgrade forces a login and many, many of you have forgotten your passwords and didn't set up any reminders. Contact me directly through helpmelogin@dodgecharger.com and I'll help sort it out.

Main Menu

8 3/4 742 drop out with 4.10's I'm thinking of buying

Started by cougs, March 26, 2012, 06:39:22 PM

Previous topic - Next topic

cougs

Hi everybody,
There is a 8 3/4 742 case with 4.10 gears and a posi I'm thinking of buying. I would like to buy it but the seller can't confirm it's going to work perfectly becuase he's never run it before (He bought it used a decade ago).  Can you tell by these pics what kind of posi it has?  What is a good quick way to check if a posi is good or bad?  How about the backlash?  What would you say this is worth?

Thanks,
Brock
1968 Charger 383/727  Restored to Stock!

doctorpimp

The gears themselves look brand new - Motive Gear brand.
The "posi" suregrip is the clutch type - you can rebuild that one.  There are only 2 ways to check if it works:  Install it in the car and test, or strip it apart and look at the clutches...  They usually are good to go though.
For the backlash, you need a dial indicator.  You could check the wear pattern to see if it's set-up correctly.  Do a search on google for "mopar 8 3/4 wear pattern" and follow the instructions to check it.
How much does he want for it?
'73 Coupe, 470, Keisler 5spd, 3.55 SG; Petty Blue; Hideaway Headlights.

www.cardomain.com/ride/2119216

cougs

$500 bucks.  This gear ratio is way lower than what I was looking for but my car sees very little time on the freeway. 
1968 Charger 383/727  Restored to Stock!

Kern Dog

This differential case is a rare and desireable part. The unit can be rebuilt over and over almost forever. It is known as a Power Lock Sure Grip. "Posi" is a Chevrolet term.
The 4.10 gear isn't easy to live with. I have one in my Charger with 27" tires. It scrams out of the hole, but forget driving on the freeway over 60 mph. I added a GV overdrive to reduce freeway rpms.

cougs

My 68 charger has a 742 case now with a 3.23 open diff.  I'll probably pick this up and see how the 4.10's are.  If they drive me nuts I'll look into 3.55 or 3.73. This rear should go right, right?
1968 Charger 383/727  Restored to Stock!

cougs

Sorry, I meant this rear should go right IN, right?  I've changed the third memeber from a ford 9" several times and I'm assuming the 8 3/4 mopar is similar? 

Oh, and sorry or referring to this as a "posi".  I didn't realize this was a GM term.  I hate chevys and feel kinda dirty now!
1968 Charger 383/727  Restored to Stock!