|
|
|
|
| Author |
|
|
Registered
|
G50 Clutch Autopsy
Pelicanites - my clutch failed and I'm trying to understand what happened, so I'd like to check my theory with with wisdom of the group.
The car is an 88 911 with the G50 gearbox. I noticed it started getting a bit rattly at idle and then all of a sudden the clutch wouldn't disengage the transmission and things were a lot noisier. My first clue was finding a metal shaving that was thrown from the bell housing...  After I pulled the engine and split the gearbox, the gearbox face looks good. The flywheel might need a cleanup, but nothing horrible.   Clutch disc also seems relatively trauma-free.  So I think the problem is with my throwout bearing. I found this ring of shaved off metal inside the pressure plate and there were little bits of Porsche stuck to my crank position sensor. Also, the TO bearing has quite a bit of play sitting in the pressure plate and will flop back and forth over a quarter of an inch.   So my theory is this.... There is bearing material on the throwout bearing that failed. This caused the rattly noise at idle. The clutch still worked, until it didn't. The TO fully failed allowing too much play, metal to be shaved off, and the TO bearing had too much play to disengage the transmission. Does that sound plausible? Is this a common failure mode? I've not found this by searching the archives. What causes a throwout bearing to fail? Thanks all, Lawrence |
||
09-01-2021, 07:09 PM
|
|
|
Diss Member
Join Date: Jul 2002
Location: SC - (Aiken in the 'other' SC)
Posts: 5,020
|
I'd want to see some close ups of the throwout bearing because the metal had to come from somewhere. The 'c-channel' cross section of the chunk makes me wonder if the bearing had a swaged ring around it outside to hold it together. Been a lot of years since I had to look at one.
All throwout bearings in the last 40+ years are "angular contact bearings". If you even lightly load the bearing along its axis this will take all the play out of the bearing and there won't be any slop in it. If there is any slop the bearing is toast. The one thing I would check is if the tips of the fingers on the pressure plate's diaphragm are worn. A failed throwout could grind them down.
__________________
- "Speed kills! How fast do you want to go?" - anon. - "If More is better then Too Much is just right!!!" - Mad Mac Durgeloh -- Wayne - 87 Carrera coupe -> The pooch. |
||
|
09-02-2021, 03:33 AM
|
|
|
Registered
Join Date: Nov 2017
Location: Houston, TX
Posts: 870
|
Nose bearing in the flywheel looks a little beat up too.
Sent from my Nokia 7.1 using Tapatalk |
||
|
09-02-2021, 04:42 AM
|
|
|
Registered
Join Date: Feb 2009
Posts: 1,006
|
Looks worn out. TO bearing failed causing it to destroy spacer between TOB and diaphragm of pressure plate. Time to clean up and renew.
|
||
|
09-02-2021, 07:01 AM
|
|
|
Registered
Join Date: Mar 2001
Location: Marysville Wa.
Posts: 22,449
|
Do you sit at stops with the pedal to the floor? Takes a toll on T/O bearings.
__________________
https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
||
|
09-02-2021, 07:13 AM
|
|
|
porsher
|
Your shrapnel could be the release bearing mounting components
 993 G50 shown
__________________
86 911 Race Car, with a few 993 bits in the boiler room 79 928 Race Car 88 928 Becoming a Race Car |
||
|
09-02-2021, 10:59 AM
|
|
|
|
Registered
|
Thanks everyone for your inputs. I don't think I ride the clutch at lights, but I may need to pay more attention...
I'll get an order in for a full clutch kit from our host and probably hit a few other things while I've got it all torn apart! Lawrence |
||
|
09-02-2021, 06:22 PM
|
|
