When the car manufacturers build their cars they always try to save as much money as they can to make more of a profit. For example, if a car maker can save a dollar per unit by switching tires, we're talking about potentially millions of dollars in total savings for the company. This same mentality is used by most car makers when it comes time for their rearends. Why spend money on a posi-traction rearend when a limited slip would do pretty much the same job without incurring the expense?
Performance enthusiasts know, however, that a posi-traction rearend is positively the way to go, so we called up Sutton Engineering in La Puente, California, where they specialize in shortening rearend housings as well as building stock and race setup rearends. The Sutton Engineering team had just finished adding a posi-traction setup on a chrome rearend for a lowrider and they invited us to document the next one that they were working on as the steps are fairly the same on most GM third members. We packed our cameras and were on our way to document the pros at Sutton Engineering as they added posi-traction gears to a factory stock rearend for better handling and performance.
1. The car was secured with jackstands before the wheels were taken off.
2. The first step was to remove the oil in the rearend housing.
3. Ed showed us the new ring and pinion posi-traction setup before it was assembled.
4. Ed assembled the ring gear onto the posi unit. | 
5. The pinion bearing was pressed onto the pinion. |
6. The carrier bearing was also pressed onto the posi unit. | 
7. Here's an exploded view of the assembled posi unit. |
8. Mando had to disassemble the brakes to remove the axles. | 
9. Mando removed the C-clips from the axle shaft allowing the axles to come out. |
10. Here's the axle being removed. | 
11. The stock non-posi unit was removed from the rearend housing. |
12. The carrier was removed from the housing. | 
13. Mando proceeded to remove the pinion nut. |
14. The yolk was removed from the pinion. | 
15. Next, they cleaned out the housing, leaving it prepped to be reassembled. |
16. Here's a look at the broken pinion which kept the rearend from operating properly. | 
17. The rearend was ready to have the seals and bearings replaced. |
18. Nate removed the axle bearings. | 
19. The axle bearings were placed into position and taped into place. |
20. The seal was put on and lightly coated with a touch of white grease which allowed the axle to slip on without tearing the seal. | 
21. The pinion was installed on the rearend. |
22. The posi unit carrier was bolted into place. | 
23. Here's an exploded view of the posi unit when the rearend gears are assembled. |
24. Nate finished the job by pumping gear oil into the rearend. Once the rearend is broken in (at about 500 miles) the oil should be changed and then maintained normally. | 
25. While we were at Sutton Engineering, the guys showed us a rearend that had just received a posi-traction system. |
26. The pros at Sutton explained that most GM rearends are assembled the same way as the one featured in this article. From your project hauler to your lowrider, it's all the same for a pro builder. | |