I have a 3.73 gm Trutrac 8.5 10 bolt posi rear end in my 82. New 700r4 and driveshaft. When I pull out on the street slow turn it always kinda chatters like was mentioned by the op. I have always thought it was the inside tire doing that because the outside tire has to travel faster than the inside tire but, with posi they spin the same speed. Am I missing something? I don't think it's the clutches since it's brand new.
No, you're thinking of a locker where the axles *always* spin the same. A locker keeps the two wheels locked together at all times and chirps the inside tire on tight turns. A posi should lock and unlock as needed, so it should typically operate like an open diff around turns.
A posi works by using a combination of wheel speed differences and torque being applied by the engine/driveshaft/pinion to lock up. Your TruTrac is a gear-type posi, not a clutch-type. I have no experience with them, but I have heard for years how smooth and seamless their operation is.
I have a clutch type posi unit (Yukon Duragrip) in my C10, with the automatic, it was almost seamless in operation. It would only lock if I really romped on the gas and usually that would induce a slide because I was on the gas pretty hard. Now that I have a stick, it's locking more often/chirping the inside tire because there's more torque being applied to it during acceleration than with the auto (torque converter "softens" the blow), so I'm constantly chirping/chattering the inside tire.
If yours is chattering all the time, regardless of speed/amount of throttle, first go to a parking lot and do several slow speed u-turns in both directions to try to unlock the posi. If it continues to do it, I'd take it somewhere to be checked out just to make sure. You don't wanna grenade that thing if something is wrong.
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