What exactly is this? Is it synonymous with differential? Or does it apply to something more, like the term differential is limited to a specific mechanism while '3rd member' refers to the whole thing with the housing and everything?

Also, why is it called this? Is there a 2nd member somewhere?

 

Think porn. Like Goldmember, except this would be more like a threesome.

No it's the differential. Front or rear. Honestly, and someone will certainly speak up, I'm not positive where the term comes from, but it's the gear set in the front & rear axle.

 

Actually quite the opposite. The differential would be the whole thing with the housing & the 3rd member would be the removable center section.

 

Its the idea of a differential AND housing that is separate from the axle housing. WIth domestics (Ford 9" aside), the differential housing is part of the axle housing so you have to work on the diff in axle housing. Toyotas and most other imports have a differential housing that bolts into the axle housing:

third member


bolts into axle housing


domestic axle/ diff




Here is a third member that has been taken apart from the diff.

 

thanks Matt16 that is most helpful with the pictures and all-

thanks wilshire for not being afraid to ask. I never understood myself until now.