Weird Differential

Reply Subscribe

Thread Tools

Search this Thread

Oct 5, 2014 | 02:27 PM

rustbucket_78

Thread Starter

New User

Joined: Oct 2014

Posts: 8

Likes: 0

Weird Differential

Hi.

New guy here. Just recently bought a 78 f150 custom 4x4 4-speed (with bulldog) It's rusty and needs some work but nothing too major. I jacked up the rear the other day to replace the bake shoes and observed something I'd never seen before. With one wheel up I could rotate the wheel. It was ratcheting or something. It kind of clicked. The other side worked the same way. The drive shaft did not turn, but I could turn a wheel. What black sorcery is this? It is not open, it's not LSD..... Some kind of locker?

Possibly related is I hear a clicking sound when I turn sometimes.

Thanks!

Oct 5, 2014 | 03:48 PM

co425

Cargo Master

Joined: Oct 2010

Posts: 3,417

Likes: 32

It sounds like you have a detroit locker or the like in your rear end. Lift both wheels turn one forward and if the other does the same you have a locker.

Oct 6, 2014 | 08:35 AM

rustbucket_78

Thread Starter

New User

Joined: Oct 2014

Posts: 8

Likes: 0

Thanks, that is what I suspected. I confirmed that with both rear wheels in the air, it does as you describe... So that is a happy surprise. The guy I bought it from either didn't know or forgot to mention it.

Is there anything I should know about them? Do they require different fluids or modifiers or anything?

Thanks.

Oct 6, 2014 | 08:52 AM

co425

Cargo Master

Joined: Oct 2010

Posts: 3,417

Likes: 32

Quote:

Originally Posted by rustbucket_78

If it's a mechanical locker like a detroit, no. Posi, and the like with internal clutches require the friction modifiers. You'll have to pull the differential or the cover depending on if you have a 9" or not to find out what you have. Maybe call the guy he may know what's in there.

Oct 6, 2014 | 08:56 AM

rustbucket_78

Thread Starter

New User

Joined: Oct 2014

Posts: 8

Likes: 0

Thanks. I can't pull the cover since there is no cover. I'm trying to figure out which rear-end it is exactly. I'm at work right now and can't remember if it has a "hump" on one side making it a 9" or if it is just a round hemisphere... I do remember that there are no bolts or drain plugs on the back.