Can an LSD, posi, rearend lock up an axle??

[Bob Hoffmann CLC#96]

My 70 has one. Went to move it recently & LH wheel would barely turn. RH one is OK. There was some clanking when I first tried to move the car. It's not been moved for about 9 months. I'm gonna pull the drum maybe even today. Car stored in a dry garage. Never had any brake problems with the car. Any ideas appreciated.
Thanks, Bob

[Dave Shepherd]

Bob, never seen that series posi unit lock one side, sounds like a brake issue.

[Bob Hoffmann CLC#96]

Dave,
You're partially correct.
Pulled wheel  off. Could not move drum. Used hammer, lots of brake dust & very lite old brake fluid dust.  Finally got drum off by tapping & prying . Cleaned drum & brake shoes. Determined shoes were too expanded. Backed them off quite a bit. I'm not sure why that happened. Installed drum. Still no movement. Jacked up RH wheel.  Started car & carefully put in gear. Small clunking noise from diff. Both drums spinning as normal. I plan on test drive tomorrow.
Bob

[TJ Hopland]

Brake fluid dust?   Any fluid or oil can make a drum brake grabby.   If this has some miles on it also check the backing plate where the shoes ride.   With miles and use the steel part of the shoes will wear into the backing plate and sometimes the wear will end up making a groove that the shoe will catch in.  Wear int he backing plate will also prevent the auto adjuster from working correctly which generally accelerates backing plate wear because the shoes end up moving more than the should each time the brake is applied.

You said both drums spin normally now meaning with both wheels off the ground you spin one the other spins the opposite direction?   What sort of limited slip did Cadillac use in the 70?   I didn't think think any of the limited slips that were in use back then would allow you to do that especially by hand.    With those older and even most current designs you would have to put the trans in neutral to be able to spin either axle.   Or was Cadillac using something different back then?   

I know at some point in the late 70's or early 80's the trucks got something called the 'Gov lock' but I don't think it ever got used in cars.  The gov in gov lock was actually a mechanical governor with fly weights that was mounted to the carrier inside the diff.  It drove off small gears that were attached to each axle.   If there was a difference in speed between the 2 axles the gov would spin and engage clutches that would lock the axles to the carrier.   This meant that at very low speeds like a parking lot or you turning one wheel by hand it was pretty much an open differential and free to do its thing and let the wheels turn at different speeds but as soon as one wheel started to spin like mud ice or snow it would lock up.   These are pretty freaky to look at, seeing all those tiny fragile looking parts attached to these huge gears that you know are spinning really fast and smashing into thick oil.  Lots of people called them the grenade lockers because sometimes these little pieces would fly apart and even smallish metal bits mixing in with those big gears isn't a good thing.  Usual result is your whole diff goes boom and you are shopping for a new or used one.

The more classic and typical aftermarket limited slip has similar clutches but instead of controlled by the governor they have springs that pretty much create drag all the time and are hopefully tuned so when you do need them to slip like going around a corner they actually slip.