I just finished reading a thread from 2005 regarding the posi carrier preload spring and plate assembly. Great input from Ken and Adam.
I'm rebuilding my diff right now (1975 code AA 3.55 gears). I'm replacing the clutch packs but reusing the original spiders and side gears which are in great condition. I purchased the master rebuild kit from Bair's but it does not contain shims for the side gears so I cleaned the original shims, 2 on each side which I measured to .045 (.025 + .020) on one side and .040 (.025 + .015) on the other. Is reusing the shims ok, a bad idea or an absolute no-no?
When I reassemble the carrier without the preload assembly, I can spin the unit on an axle with a moderate effort but once I install the preload assembly, spinning the unit on an axle by hand is impossible. Should I be able to spin the unit or does the preload assembly make that impossible without the assistance of tools?
to the best of my knowledge, the diff has never been worked on previously, but I could be wrong.
Also when I inspected the diff housing axle bearings I found one side to be relatively flat and the other to have a radius. Does the radius side face outward?
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
As long as the old shims are in good condition, you can re-use them. Be sure to put them back on the same side they came off of. With the spring pack installed, you will NOT be able to turn the axles by hand, independent of each other. If you can, the spring pack is not working, or you dint get enough clutches back in. As for the side axle bearings, I can't say that I have ever even paid any attention to the "flat/radius" on them....just banged them in. Assuming there is a flat side, then normally the flat side would be out. I really don't think it would matter, to tell the truth.
____________________________________ Joel Adams C3VR Lifetime Member #56 My Link
Vette(s): 1969 350 4 spd drop top
1972 350 auto coupe
There will be a difference between your new clutches and the originals. The originals have been seated and have slots in them for posi additive to work in. The new ones should be solid steels but some places have been pushing the fiber coated ones. The springs and plates are a band aid to support tolerance changes from one posi to the next, basically production build units vary a lot.
If you are using the springs again then you want to get the backlash to 002"s per side compressed. Then stick the plates and springs in there. It should take 40 ft/lbs of load to break them loose in this setup. There will be constant tension on the clutches and they will seat in, the springs will maintain the force on them. This will give you posi but depending on how you set them up will depend on just how much they may chatter in use.
When I build a posi I polish and tune them, never use the springs or plates again and have a better working setup.
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