G9601 transmission issue

[6ta1]

Hi!

this is my first post here as I have owned my first Porsche for less than a week... and I already have an issue!

My transmission (std 6spd) is making a loud noise in first gear.

When I drive I can here the noise only if I accelerate, but as you can see in the video, it happens also at idle.

No noise in any other gear or if I press the clutch

Any idea on what this could be? And how to fix?

To be noted:

previous owner had the transmission rebuilt recently to fix the 2nd gear issue

however car was already making the noise before the rebuild

it is currently filled with non-synthetic 75W90 (not sure of brand) -> should I try to use a 75W140?

http://www.youtube.com/watch?v=ohHYATUCC3E&feature=youtu.be

Thanks for the feedback!

[RFM]

Could be a dual mass flywheel faillure if the car is still stock, you will need to know this in first place. Perhaps by the previous owner?

[6ta1]

Thanks for your reply. I had not thought about this. I am the 3rd owner so hard to tell if the FW is stock or not.

What would be the reasoning for the knocking to be only in first gear though?

[RFM]

Both dead centers of the engine during the combustion process cause vibrations which manifests itself in the gearbox as chatter, this phenomenon is reduced as the motor torque increases. To avoid this chatter a dual mass flywheel is mounted. It's all a bit more complicated, but this is the shortest and simplest explanation.

[6ta1]

well, I would like this for sure - means a less expensive fix and a good reason to go with a LWFW.

Shouldn't the noise disappear as I accelerate even in first gear?

Thanks for the feedback!

[RFM]

An LWFW can not solve the problem, in contrary it is solid and absorbs no vibration at all. Only a properly functioning dual mass flywheel does the job as it should.

[JFP in PA]

Just in passing, if you do not know what brand is in the trans, drain it and fill it with the factory gear oil. Many of the complaints we have heard about using aftermarket gear oils involved strange noises; it may not be the entire issue, but it could also be your cheapest solution to at least some of the problem.

You should also stay away from light weight flywheels unless you intend to rebalance the entire rotating assembly; lightweight flywheels do not dampen any of the rotating assembly’s harmonics, but a dual mass will.