[Alexander_992]

Good evening guys. I need your help.

With the clutch pressed down and shifting into reverse(or first gear, anything from a standstill), Ill hear a thud that sounds to be coming from either the center or rear of the car. Once I put it into gear with the clutch still pressed down I can move it into gear countless times and I wont hear the thud again. If I let off the clutch and repeat, the thud will be there the first time the gear is engaged and as long as the clutch stays down the thud won't happen again.

In the gif it shows the driveshaft play when I feel the thud, the grafts that come after remain immobile.

[Theodore2]

There might be more than one component contributing to the thud in your case, but as an inexpensive and easy first step I would suggest replacing the differential fluid with new fluid. I had a thud sound when first engaging the gas to move the car forwards or reverse (DCT) that took me a very long time to track down and the final fix was a simple differential fluid change. You also might want to post your question in this sub-forum here for the best chance at getting an answer from someone very knowledgeable with your model.

[jjFender]

I hear the same thud on my E82 when shifting into first. I'm sorry I don't have a fix but can offer my observations and some guesses:

For me, the thud happens when I shift "too quickly." As I clutch in, I move the shifter to the left, as soon as the clutch is all the way down, I push into first gear. I put "too quickly" in quotes because, to me, that's the normal process. But maybe I'm rushing it a bit? When I slow it way down: clutch-in all the way, wait a beat, then move the shifter, I can avoid the thud. But that takes an excruciatingly long time and really dampens the driving experience.

Great detective work filming the driveshaft movement. My first guess is that the clutch disengages too slowly. I.e. There is a delay between the clutch pedal being all the way down and the clutch itself fully disengaging. I removed my clutch delay valve but there is still some inherent delay in the system. It takes some time for the pedal action to move through the hydraulic system to the clutch in all manual cars but that delay really shouldn't be perceptible. Maybe for some reason, the delay in our cars is on the high side, even without the clutch delay valve. Maybe the old rubber clutch lines stretch too much? I wonder if steel braided clutch line would help.

Second guess is that the layshaft is big, bulky, and carries too much inertia. So even if the clutch is fully disengaged, the layshaft stays spinning and upon putting into gear, the first gear synchro brakes the layshaft against the driveshaft, taking up the backlash in the diff and causing the thud. I haven't seen the inside of our transmissions so this is just a total guess. As for possible fixes? Maybe thicker transmission fluid??

Anyway, subscribing to this thread to hopefully hear others' experiecnes and/or fixes.

[Redd]

On my DCT it happens randomly and only rarely. Sometimes shifting from automatic to manual mode while car is stationary it will thud. Sometimes it thuds shifting into first. But always while the car is not moving. I've learned to ignore it.