991.1 PDK with knocking noise in rear CV?
11-04-2023, 03:19 AM
#1
Rennlist Member
Thread Starter
991.1 PDK with knocking noise in rear CV?
I had this noise seemingly coming from the right rear develop about a month ago and pulled the wheel after thinking a pebble in the brake or suspension but didn't find anything.
Next day I jacked up both sides and couldn't get any noise while spinning the wheels back and forth in neutral, so I figured maybe there was debris lodged somewhere I couldn't see or missed.
Since car was loaded on the way up the coast from RR7, I gave it an Italian tune-up and it went away....only to come back again last week.
The sound happens under accel/decel and you hear it fluctuate in relation to my right foot in the video, but is not heard when in neutral and doesn't change much at all if turning or pretending to heat up some F1 slicks.
So I jacked up both sides thinking CV was done and after noticing about twice as much in-and-out play on the passenger side, I thought I may have confirmed what is causing the knock.
Then I put car back down and drive it for a couple days with no noise, until this week when it comes back. So I have a new CV in hand but after pulling the inner bolts to trans output flange, the CV doesn't seem especially loose. Before I blow a nut and pull the axle to install a new CV joint, I thought I'd see if anyone's experienced a similar noise and what it was?
Additionally, there's a slight amount of rotational and lateral play in the output flange of the PDK but I'm hoping that's normal and figure I'll ask a dealer tech tomorrow if I can catch one for a sec.
Thanks to you all!
Next day I jacked up both sides and couldn't get any noise while spinning the wheels back and forth in neutral, so I figured maybe there was debris lodged somewhere I couldn't see or missed.
Since car was loaded on the way up the coast from RR7, I gave it an Italian tune-up and it went away....only to come back again last week.
The sound happens under accel/decel and you hear it fluctuate in relation to my right foot in the video, but is not heard when in neutral and doesn't change much at all if turning or pretending to heat up some F1 slicks.
So I jacked up both sides thinking CV was done and after noticing about twice as much in-and-out play on the passenger side, I thought I may have confirmed what is causing the knock.
Then I put car back down and drive it for a couple days with no noise, until this week when it comes back. So I have a new CV in hand but after pulling the inner bolts to trans output flange, the CV doesn't seem especially loose. Before I blow a nut and pull the axle to install a new CV joint, I thought I'd see if anyone's experienced a similar noise and what it was?
Additionally, there's a slight amount of rotational and lateral play in the output flange of the PDK but I'm hoping that's normal and figure I'll ask a dealer tech tomorrow if I can catch one for a sec.
Thanks to you all!
11-04-2023, 10:58 AM
#2
Rennlist Member
This might sound bizarre but please check all your fan and fan cover mountings above the engine.
See if any of those rubber grommets have gone missing.
See if any of those rubber grommets have gone missing.
11-05-2023, 04:14 PM
#3
Rennlist Member
Thread Starter
No missing grommets or loose connections with any of fan/shroud mountings.
I do have a broken engine lid release this reminded me of that could create a noise, however it's been that way for a year+ and I've never noticed a noise from it.
After removing the CV to output flange bolts, the CV joint didn't have excessive play, feel loose, or have any clicking or other indication it was bad, and the trans output flange play was normal, so I re-installed and checked for any noise while in the air in drive and reverse. No noises, so took it out for errand last night and a thorough beating early today and all's quiet and seemingly normal again...
Made an appointment with the dealer a week from now after a tech and svc writer had no guess as to what it may be. If it comes back, I'll drop it there to let them have a whack, but for now it seems the noise goes away after jacking up to see what it may be, so I guess I'll add the cheapo aluminum HF jack to the frunk if I go anywhere far from home, lol....
Best part of it all was I finally had the excuse to buy a couple more Ridgid 4&6 Ah batteries to get the free 1/2 brushless impact with 650 ft./lbs. of Breakaway Torque & 500 ft./lbs. of Fastening Torque to end a couple decades of axle nut drama!
I do have a broken engine lid release this reminded me of that could create a noise, however it's been that way for a year+ and I've never noticed a noise from it.
After removing the CV to output flange bolts, the CV joint didn't have excessive play, feel loose, or have any clicking or other indication it was bad, and the trans output flange play was normal, so I re-installed and checked for any noise while in the air in drive and reverse. No noises, so took it out for errand last night and a thorough beating early today and all's quiet and seemingly normal again...
Made an appointment with the dealer a week from now after a tech and svc writer had no guess as to what it may be. If it comes back, I'll drop it there to let them have a whack, but for now it seems the noise goes away after jacking up to see what it may be, so I guess I'll add the cheapo aluminum HF jack to the frunk if I go anywhere far from home, lol....
Best part of it all was I finally had the excuse to buy a couple more Ridgid 4&6 Ah batteries to get the free 1/2 brushless impact with 650 ft./lbs. of Breakaway Torque & 500 ft./lbs. of Fastening Torque to end a couple decades of axle nut drama!
05-16-2024, 07:26 PM
#5
Rennlist Member
Thread Starter
05-16-2024, 08:26 PM
#7
This sounds exactly like CV joints / bad rear axles on older Porsches I've had. Other than that, can't really help... but that does sound exactly like a worn CV joint / axle component.