MOTOR TRAXX MOPAR TECHLINE
by Bob Doty
When change is necessary, you obviously need to look for an 8-3/4" A housing from an A-body vehicle. The A-body housing is approximately 2 inches narrower and places the wheels correctly in the wheelwell (side-to-side). If you must use a more common housing (B-body), consider calling on Greg Moser Engineering to narrow the housing. He does quality work, has a quick turn around, and is reasonably priced. For the pure performance addicts, if you are having a housing narrowed, have the pinion centered. This makes both axles the same length (you just need one spare).
If you have the rearend (8-3/4") and you are ready to change out the old one, follow these simple instructions for a minimum of labor.
1. Block and raise the rear of the car approximately 2-4 inches off the ground with jack stands in front of the rear wheels.
2. Place a floor jack under the center section and raise to take the pressure off the rear shackles.
3. Remove the driveshaft from the pinion shaft.
4. With the floor jack still in place, remove the thru-bolt from each rear spring eye and lower the floor jack until the rear wheels touch the ground.
5. Remove the U-bolts and literally roll the rearend out from under the car on the tires.
Reverse the process to install the new rearend.
With the matching drums, the rear brakes will interchange on any 8 3/4" rearend. The 7-1/4" brakes will not fit the 8-3/4" housing (different backing plate bolt pattern).
The 8 3/4" rear-end is a frequent source of confusion, and the Sure-grip, as installed in the various carriers. The 8 3/4" carrier was introduced way back in 1957 and was produced until 1974. There are three (3) basic types of ring and pinions that fit these carriers. The common identifier among Mopar addicts is the last three digits of the casting number on the center of the carrier on the left hand (or driver's side). You will see 741, 742, or 489 as the last three digit;. Note: there is also #657 used up until 1964, but it is rarely found. The digits identify the pinion size and configuration.
It is important to note that the ring and pinion configuration must match the carrier. Ring and pinions are not interchangeable from carrier to carrier.
Sure-Grip Units and Interchangeability
Now that that is out of the way .... we can clear up the Suregrip issue. There are two types of Sure-grip units found in the 8 3/4 center section. We commonly refer to these as the cone-type or the clutch-type. Both work very well and are interchangeable among each carrier, with the proper bearings. For the trivia buffs out there, the correct names are as follows: The DANA POWER LOCK was produced from 1962 until 1969. The Borg-Warner Spin Resistant was introduced in 1969 and was used until the end of the production run.
Thanks -Bob Doty.
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