I was leaving my house last night and had put the car in gear and was just taking off. Suddenly I heard a thump from underneath and lost the transmission. ie, the engine revved fine but no power was being transmitted to the wheels in any gear.

I could shift into the various gears smoothly with no grinding whether or not the clutch pedal was depressed. When the clutch was engaged, i could hear a faint whirring sound when I had it in gear and no sound when it wasn't in gear. With the clutch disengaged (ie clutch pedal pressed), there was also no whirring sound regardless of being in gear or not. Also, when in gear and clutch engaged (so I 'm hearing the whirring sound) the car would roll freely as if it was in neutral.

Since I can shift gears, I'm thinking that something is wrong with the input side of the clutch assembly. ie, I think the tranmission itself is fine, but something's broken in the clutch itself (input shaft?). Does this sound plausible? Any other ideas?

Thanks!

Andrew

 

sorry, the car model is 1999 A4 Avant, 2.8 liter, 5 speed manual, about 111K miles.

Andrew

 

It sounds like you broke one of your front CV axles, jack up the car and grab a hold of both front axles. If one of them flops around like a fish inside the cv boot its snapped.

 

If I understand correctly, you're saying that with one front axle broken, the diffs and transfer case are set up in such a way that all the power is being transmitted to that axle since it has the least resistance.

But why would that be different than if one of the front wheels was on ice? why would there be no power transmitted to the rear wheels through the transfer case with a broken front axle? or am I misunderstanding something?

Also, would a front axle just break like that? on a flat, smooth road at a normal level of acceleration?

 

sorry, I guess I forgot to mention that this car is a quattro as well.

 

Yep, if you break one of the front axles the car won't move anywhere. There has to be at least some resistance in order for the Torsen differential to work, and yes it can break on a flat smooth surface. They commonly break at the connection point between the outer joint and the axle, so you won't see it unless you grab it and try to move it. Another way to check it is jack the car up and have someone try to drive it, you will see that axle flop around.

 

Look at it as good news. It is a lot easier, and cheaper, to replace a front axle than a clutch or taking your transmission apart.