I have a mild clunk when I depress the clutch pedal and engage first gear. After trying a few things I think I might have figured out what is going on.

So I sit at the stoplight with the car in neutral, clutch completely disengaged. At this point the engine is engaged with the transmission turning the main input shaft, of course the car goes nowhere because it isn't in gear. Then I press in the clutch and engage first gear, note that first gear is not moving because it is connected to the output shaft and the car is sitting still. I think the clunk is when first gear causes the main input shaft (which is still rotating even though the clutch has been engaged) to stop rotating. It's not the same feeling as a single gear synchro (like shifting without using the clutch at all) and I think it's the action of stopping the input shaft from free rotating.

So here is the test, please try this as see if you get the same results:
1) Sit stopped for 20 seconds with the car in neutral and the clutch disengaged (at this point you have one foot on one pedal, the brake), depress the clutch and quickly put the car in first gear - I get a clunk.
2) Sit stopped for 20 seconds with the car in neutral and the clutch fully engaged (at this point you have one foot pressing the clutch and the other pressing the break), put the car in gear (remember to wait 20 seconds) - I get no clunk.

So why doesn't everyone get "the clunk". Maybe the input shaft doesn't move as freely on some cars and it slows down by itself before the gear is engaged, maybe some people (without knowing it) actually sit on the clutch for several seconds before engaging first gear thus allowing time for the input shaft to slow down.

Thoughts?

 

Jay - that's an excellent analysis. I can't test because it's snowy in CO now, but the roads should be better next week. I agree that it doesn't feel like synchros, because you don't feel any grinding in the stick. Just the clunk in back.

Do you get a clunk through shifting from 1st to 2nd quickly?

 

Sometimes I think I can feel something when shifting from 1st to 2nd, but it's not easily repeatable.

You can run the two tests in your garage, never said anything about releasing the clutch and moving after you engage first gear. Be sure to open the garage door

 

Another thing I've noticed though is this:

1. Shift into 1st and get the clunk.
2. Don't move the car forward at all.
3. Shift back into neutral and let the clutch back out.
4. When you repeat and shift back into first, you won't get the clunk (at least I don't).

 

I do, I sat in a parking lot and it was very repeatable.

Leave it in neutral with the clutch out, wait 10 seconds, clutch in, engage first - clunk. Remove from first back to neutral, disengage clutch, let it sit like that for about 10 seconds, then try it all over again again - clunk. I'm pretty sure I could do that all day long.

And if I never disengage the clutch I can shift from neutral to first with no clunk.

I'll go play with some more in a few minutes.

 

I think it's normal. My '14 C2S did that all the time. The 7MT is kind of a strange gearbox, probably because it's adapted from the PDK.

I also noticed that it would grind a lot going from 2nd to 3rd, probably my fault though...

 

As for a gearbox I find it rather buttery smooth, in fact it shifts very good without using a clutch (nothing I recommend but that is a good way to test the synchros on the gears). However, trying to figure how that complex mechanism they have for the rods connected to the gearshift works gives me headaches. They seem to be very proud of it because it is written up in several places.

 

Same here with the cold and clunk but only if I go into second first.

 

I get the same clunk often on the GT4 if I make shifts right after depressing the pedal. But it can never be repeated unless the loading is reversed. It's almost as if the clutch release is delayed or incomplete.

 

Yes, as if an inner shaft is still turning.

Try this, coast to a stop in neutral, press the clutch and hold it for a good 20 to 30 seconds, then slip it into gear - do you feel the clunk then? I don't in my car.

It seems like there is enough inertia to keep something in the gearbox spinning for a good 10 to 20 seconds.

 

Heard the slight thunk in my 996, 997.2 and my 991 when pushing in clutch right before shifting into first after sitting at a light in neutral. I think it's normal.

 

991 gts 7MT here. Yes, I have the clunks as well. Never thought much of it.

 

I know this is an old thread but wanted to see if the OP or others ever found a resolution for this issue?

I have the same issue in my 05 C2S. Haven’t found too many people with the same issue, and no real divinities solutions.

Any updates are very welcome!