25.04.2015, 03:58
Gary is now ready to tune the posi unit. Here is his explanation of the process.
"Here I started to tune the posi. While some think you just remove the springs and plates and bolt it together, there is much more to it. The process requires running in the new clutches to "seat" them. This will change the lash after about 50 rev's but I go at least 300 per side, CW & CCW. Then check it on the bench fixture and re-shim. The shims come in 005 increments so I grind them to within 001" to dial in the tune. The end result is a balance setup between both the Left & Right sides. The naysayers will tell you it will not work, yet Tom's has been building them like this for over 40 years for street, strip, and road race cars. You will have full posi action yet there won't be any hammering in the corners and there is less load on the clutches. All my vettes are setup like this and work great."
Video of process
Just click on picture for video
![[Bild: th_posi%20tuning_zpshcan3mch.mp4]](https://i633.photobucket.com/albums/uu57/jackfit87/Restoration%202015/Rear%20end/Posi%20Unit/tuning%20video/th_posi%20tuning_zpshcan3mch.mp4)
"Here I started to tune the posi. While some think you just remove the springs and plates and bolt it together, there is much more to it. The process requires running in the new clutches to "seat" them. This will change the lash after about 50 rev's but I go at least 300 per side, CW & CCW. Then check it on the bench fixture and re-shim. The shims come in 005 increments so I grind them to within 001" to dial in the tune. The end result is a balance setup between both the Left & Right sides. The naysayers will tell you it will not work, yet Tom's has been building them like this for over 40 years for street, strip, and road race cars. You will have full posi action yet there won't be any hammering in the corners and there is less load on the clutches. All my vettes are setup like this and work great."
Video of process
Just click on picture for video