i am confused, not sure i understand what you are trying to say, you mean that having a front diff or not shouldn't change the sound of the transmission bearing? If so, that would mean noise is not from the transmission?

thinking about it, i don't know if i did hear it with the car in neutral, i do hear it with the clutch pressed in, just unsure if i did the test in neutral or not.

 

i am often unclear. sorry.

what i am saying ( or did ) is that you would hear the whine of bad trans bearing whether your front driveshaft were connected or not...

and if you do not hear it in neutral ( and i realize it takes a minute to isolate both the source of the noise as well as the conditions in which it is present..) then i am going back to suspecting it is in fact worn pinion/thrust bearings in the box as the cause of your issue. but again, you shouldn't hear it with clutch engaged or in neutral. only while the trans is under ( any ) load.

when i had this issue, it took me a minute to self diagnose that it was indeed the trans ( and not a wheel bearing ) but it was a gut feeling, and a few drives testing the conditions in which it occurred. it turned out i was right, and the box had to be opened to replace the bearings. but all else was fine.

they are sealed and enough ( serious ) heat cycles simply dry out the grease in which they are encased. it's really that simple. though a pita to deal with.

 

ok well i certainly do hear it with the clutch engaged, in fact, i think it's even a little louder.

The fact that i don't hear it at all with the driveshaft not connected, does that point more towards the front diff? So much that i tried it two times to take it off and put it back on and i really don't have the noise anymore with the driveshaft unhooked.

 

yeah, i would think so. it may be emanating from the front differential for all we know. there is oil in it and oil stops oiling over time. if you are certain you don't hear it whenever the driveshaft is disconnected? then that would definitely point to that as being the cause. again, it is filled with trans oil. or should be!

while i've never heard of the front diff drying up? it has to be possible.

 

i changed the diff fluid like 3 years ago so i know there is oil in there.

I'll try to see if i can borrow a front diff and do a quick swap to see if it solves it.

thanks for the help

 

thats what i would do. good luck

 

If you are running factory size tires or tires without the same roll out the front and rear axles are spinning at different speeds, loading/warming up the viscous coupling. I would think it is the front drive.

 

i have been carefull in my tire choice, i am using 305-30-19 and 255-35-19 front which is pretty close to the stock ratio and i have been running this setup for like 3-4 years.

I have done a lot of track days which might have been hard on the diff though

 

My front diff output shaft bearing let go a few years ago. I never disconnected the drive shaft, just let my mechanic diagnose it.

The noise was a high pitched whine that started around 30-40 mph and could sometimes be heard up to 60-70 mph. It was generally constant when decelerating/accelerating/cruising, but would would go away for a brief moment (1-2 seconds maybe) when the drive train was unloaded - like cresting a hill during when you transition between throttle to deceleration.

Not really apples to apples with your symptoms, but maybe a data point for comparison sake.

This isn't the power steering pump reservoir noise, is it?

 

dude, this is exactly the symptoms that i have and at the same speed also and i also get that 1-2 seconds where i don't hear it until i use the throttle again.

So which bearing was it, those that go to the axles or the one connecting the driveshaft to the transmission?

 

i think we have a winner.

 

Would be nice to know wich bearing you had to replace Rich! They are not shown in the parts cat??? Any part numbers?

 

And there is a very good thread about the front differential and many parts numbers from Adam 699 here: https://www.6speedonline.com/forums/...ferential.html

 

The bad bearing was the passenger side output shaft bearing. My mechanic said there was a minor leak at the seal and some play in the output shaft. From what I understood, some mechanics will service these, although the procedure is undocumented from Porsche. The seals can be readily obtained, the bearings aren't available from Porsche but were manufactured by *** and could be sourced.

From what I understand, there is a bearing near the half shaft entry. My mechanic did not think that one was serviceable. I assume the viscous coupling has associated bearings, but they were never mentioned. Perhaps they are built-in with the VC?

I was able to source a front diff from another 6spd member. It was more economical than any other option.

I know there was a DIY on this forum from a few years back that detailed the rebuild really well.

 

pumalex! if in doubt? and no replacement part is within reach? just rip that sucker out! lol