differential without oil?

So what did you do exactly?

(cheesy grin)

How many miles did you or your customer drive it

diffs are just like anything else. They need lubrication to cool, clean, and protect the gears inside.

If it were a transaxle, there would most likely be noise, slipping, and a burning smell coming from the car.

If its a diff only, like a rear diff on a 4X4, you would most likely notice a clunking sound coming from the diff and the burnt smell as well.

Someone reported something like this not long ago. Somehow there was an internal leak between the differential and the transmission such that the differential ran low on oil. Took a couple thousand miles before requiring expensive replacement of the differntial (gears?) The load on those gears is less than in rear wheel drive, but run dry they will exhibit typical wear patterns. You'll wind up with overheated metal and instead of properly formed gears little piles of metal will start to grow in the bottom of the case. I imagine if you ran it completely dry, this would occur sooner. It is possilbe, you would notice some noise if you were listening for it, prior to outright failure.

A diff without oil,..will fail in a matter of a few miles. The damage will be proportional to the length of the drive. If you stop when you start hearing noises from the diff,..it *may* still function if refilled, but it will be noisy. Eventually the diff simply siezes causing the car to stop, if you just keep driving.

The ball-bearings will survive relatively well in those few miles.

Gear teeth rely on a film of oil to stop metal on metal contact. Without oil, the friction will be great and heat will be generated to the extent the teeth start to shed their surfaces. This metal then collects around the teeth causing an eventual lock-up, or the teeth get so thin they snap off. Its not a pretty picture by any means.

Jason

54 miles until the differential froze up on the freeway after an automatic transmission overhaul where the repair shop forgot to refill the differential on a mid 80s Camry. Heard no noise up to that point. The newer ones may be different.

I know of one accasion where a rear-drive car which admittedly has hypoid gears which have a sliding contact, blew the diff in a few miles. So you are probably right. Straight drive gears will last longer.

Jason

Ermeyised (Mailcall): As long as the crown-wheel paddles in the little pond of the good stuff left,.there ain't no pain :-)

Jason

We got 175 miles on an empty diff in a late '80's corolla. Then it turned into a blob of metal in a matter of seconds at

60 MPH. Quite an experience! Zekers!