Clutch service
11-15-2022, 11:45 AM
#1
Racer
Thread Starter
Clutch service
Just finishing up changing out my clutch, pressure plate, release bearing, flywheel, and rear crankshaft oil seal on my 991.1
It’s a BIG job for a DIY’er, especially when working solo. Did it laying on my back with the car up on quickjacks.
FSM has some omissions. Found an extra electrical connector on my trans thats not mentioned in the manual and extra vacuum lines. Also some sequences are illogical. Just study the FSM and understand why they might be doing if that way before doing your own thing.
The dreaded #4 bolt on top of the trans isn’t really that bad. Remove a ground strap between engine and body and I could get fit my arm up there and get fingers on the bolt. 2ft extension and you can ratchet it off from the back of the trans. Remove that heat sink looking aluminum thing off the back of the trans for more room.
Ratcheting swivel head wrenches will be your savior. Unfortunately I can’t find them in E18 for the trans bolts, Luckily a 15mm wrench fit adequately.
Trans is probably about 150 lbs. You ain’t gonna just wrestle this pig.
The torque on the flywheel bolts is insane. Have a creative plan for a cheater bar to get that extra 120 degrees of rotation. Torque one down and lay under the car resting for a bit while you muster the motivation to tackle the next one. Do that 10x.
Mating the trans back up is the only point I said, “oh s?!t…this might be impossible and I’m over my head”. Literally took me 10 hours of struggling/improvisation. Key was to mount the trans on the jack with a good pivot point to easily tip it. Strap on jack kept shifting trans in gear. Perilously omitted the strap on the winning attempt.
Once trans bolts are started you need to draw the trans in as the fork/pressure plate/slave cylinder compress. I put a bottle jack on the very back of the trans. Lift the back, cinch up bolts, lower trans and cinch up again. Repeat until it’s closed up. You will get good at accessing those 6 trans bolts.
Oh, and remember to open your windows slightly before pulling the battery if you want access to the cars interior. You can still open a door but the weatherstripping will prevent you from closing it again.
It’s a BIG job for a DIY’er, especially when working solo. Did it laying on my back with the car up on quickjacks.
FSM has some omissions. Found an extra electrical connector on my trans thats not mentioned in the manual and extra vacuum lines. Also some sequences are illogical. Just study the FSM and understand why they might be doing if that way before doing your own thing.
The dreaded #4 bolt on top of the trans isn’t really that bad. Remove a ground strap between engine and body and I could get fit my arm up there and get fingers on the bolt. 2ft extension and you can ratchet it off from the back of the trans. Remove that heat sink looking aluminum thing off the back of the trans for more room.
Ratcheting swivel head wrenches will be your savior. Unfortunately I can’t find them in E18 for the trans bolts, Luckily a 15mm wrench fit adequately.
Trans is probably about 150 lbs. You ain’t gonna just wrestle this pig.
The torque on the flywheel bolts is insane. Have a creative plan for a cheater bar to get that extra 120 degrees of rotation. Torque one down and lay under the car resting for a bit while you muster the motivation to tackle the next one. Do that 10x.
Mating the trans back up is the only point I said, “oh s?!t…this might be impossible and I’m over my head”. Literally took me 10 hours of struggling/improvisation. Key was to mount the trans on the jack with a good pivot point to easily tip it. Strap on jack kept shifting trans in gear. Perilously omitted the strap on the winning attempt.
Once trans bolts are started you need to draw the trans in as the fork/pressure plate/slave cylinder compress. I put a bottle jack on the very back of the trans. Lift the back, cinch up bolts, lower trans and cinch up again. Repeat until it’s closed up. You will get good at accessing those 6 trans bolts.
Oh, and remember to open your windows slightly before pulling the battery if you want access to the cars interior. You can still open a door but the weatherstripping will prevent you from closing it again.
The following 2 users liked this post by JimEb:
AdamSanta85 (11-15-2022),
koala (11-16-2022)
11-15-2022, 03:57 PM
#4
Rennlist Member
What year is your 991.1 and how many miles are on it.
Finally, some serious wrenching going on here which is not the norm in this folder but understandable since 991s are not that old. There was much more of this going on in the 993 folder.
As for the flywheel bolts, were all ten torqued in stages or did you do one at a time?
As far as the transmission goes and as heavy as it is making it difficult to have the feel, getting the input shaft into the spline of the disc can be tough considering the near zero play between the two mating joints. Did you use an alignment tool for the disc?
Finally, some serious wrenching going on here which is not the norm in this folder but understandable since 991s are not that old. There was much more of this going on in the 993 folder.
As for the flywheel bolts, were all ten torqued in stages or did you do one at a time?
As far as the transmission goes and as heavy as it is making it difficult to have the feel, getting the input shaft into the spline of the disc can be tough considering the near zero play between the two mating joints. Did you use an alignment tool for the disc?
11-15-2022, 04:33 PM
#5
Racer
Thread Starter
2014 with 93k. Previous owner average 17k/yr with this car.
FSM calls for 25Nm initial torque and then 120 degree final. Doesn’t specify the final torque being in stages and indicates it being done in one stage. I torqued all down to the initial torque in star pattern then went through the procedure again for 120 degrees in a star pattern marking each bolt with a paint pen.
Not sure how you’d install a clutch without an alignment tool. My Sachs clutch kit came with two (guess I got a bonus one), which was good because they didn’t say it would when I order it.
The old clutch surprisingly had some life in it. The flywheel was toast. Deeply grooved and lots of play. The release bearing was sloppy and rough. Surprised I didn’t hear that chattering.
Oil seal looked good, but replaced it due to mileage and I was already in there. To insert the new seal I machined out a cup from Acetal plastic cut to the OD and ID of the ring (with some clearance). Cup was cut 7mm deep so I could tap the seal evenly to the spec’d depth as it bottomed out on the face of the crankshaft. Cheaper than the tool Porsche sells.
FSM calls for 25Nm initial torque and then 120 degree final. Doesn’t specify the final torque being in stages and indicates it being done in one stage. I torqued all down to the initial torque in star pattern then went through the procedure again for 120 degrees in a star pattern marking each bolt with a paint pen.
Not sure how you’d install a clutch without an alignment tool. My Sachs clutch kit came with two (guess I got a bonus one), which was good because they didn’t say it would when I order it.
The old clutch surprisingly had some life in it. The flywheel was toast. Deeply grooved and lots of play. The release bearing was sloppy and rough. Surprised I didn’t hear that chattering.
Oil seal looked good, but replaced it due to mileage and I was already in there. To insert the new seal I machined out a cup from Acetal plastic cut to the OD and ID of the ring (with some clearance). Cup was cut 7mm deep so I could tap the seal evenly to the spec’d depth as it bottomed out on the face of the crankshaft. Cheaper than the tool Porsche sells.
11-15-2022, 04:49 PM
#6
Rennlist Member
Flywheel bolts, makes sense. Same on my BMW motorcycle head bolts, inital torque and then 90°.
11-16-2022, 12:36 AM
#7
Rennlist Member
Fantastic. Please report back after your 1st drive. 
For comparison how much were you quoted by a dealer or independent vs DIY'ing?
For comparison how much were you quoted by a dealer or independent vs DIY'ing?
Last edited by CSK 911 C4S; 11-16-2022 at 12:38 AM.
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11-16-2022, 07:58 AM
#8
Racer
Thread Starter
I grab my $30 Amazon borescope that Bluetooth’s to my phone. I fish the scope up into the opening on the top of the trans that lets you peek into the bell housing. I couldn’t see the slave cylinder end but could see parts of the fork and diaphragm fingers. I actuate the clutch again while watching the video feed and much to my relief I see the fork moving and fingers flexing as they should. Clutch pedal finally feels like it should. Suspect the old one got heat tempered and the springs got stiff. Will not be going for a long, proper drive anytime soon as our roads are covered in wet, sloppy snow at the moment.
Cost for DIY was around to $2k. It was like $600 for the clutch kit, $1200 just for the flywheel, $50 in new bolts, $15 for the oil seal and $80 for new transmission oil.
Also spent $150 for a harbor freight transmission jack for this project.
Would have been a perfect time to install a Numeric shifter and cables but was hard to justify an extra $1200. That will be next years project.
Last edited by JimEb; 11-16-2022 at 01:54 PM.
The following users liked this post:
polobai (11-20-2022)
11-16-2022, 11:12 AM
#9
Rennlist Member
Almost always the case with an old pressure plate as I have seen it before. It is always a day and night difference.
On my 993 when activating the clutch, you'd hear a "grawk" sound...very typical when they get old. Not the slave cylinder as many claimed it would be, but the old pressure plate. I think it is the spring steel diaphram at the edge of the clutch as the clutch is activated that makes the sound, sort of like a noisy door hinge. Plus the added friction makes the clutch feel heavy.
On my 993 when activating the clutch, you'd hear a "grawk" sound...very typical when they get old. Not the slave cylinder as many claimed it would be, but the old pressure plate. I think it is the spring steel diaphram at the edge of the clutch as the clutch is activated that makes the sound, sort of like a noisy door hinge. Plus the added friction makes the clutch feel heavy.
11-16-2022, 01:01 PM
#10
Rennlist Member
Since I got this car a year ago I always complained about the heavy clutch. Was like driving a truck. So once I got the trans mounts back in so it was mostly all back together I had to try the clutch pedal. I was somewhat concerned the slave cylinder wasn’t properly engaged in the fork. Its a difficult reinstall where you have to work blind in tight quarters. I crawl in the car on the passenger side and push the clutch pedal with my hand…and it goes down real easy. That felt too easy, then worried that I just pushed the plunger out if the slave cylinder and should be expecting a puddle of brake fluid dripping out the bottom of the bell housing shortly.
I grab my $30 Amazon borescope that Bluetooth’s to my phone. I fish the scope up into the opening on the top of the trans that lets you peek into the bell housing. I couldn’t see the slave cylinder end but could see parts of the fork and diaphragm fingers. I actuate the clutch again while watching the video feed and much to my relief I see the fork moving and fingers flexing as they should. Clutch pedal finally feels like it should. Suspect the old one got heat tempered and the springs got stiff. Will not be going for a long, proper drive anytime soon as our roads are covered in wet, sloppy snow at the moment.
Cost for DIY was around to $2k. It was like $600 for the clutch kit, $1200 just for the flywheel, $50 in new bolts, $15 for the oil seal and $80 for new transmission oil.
Also spent $150 for a harbor freight transmission jack for this project.
Would have been a perfect time to install a Numatic shifter and cables but was hard to justify an extra $1200. That will be next years project.
I grab my $30 Amazon borescope that Bluetooth’s to my phone. I fish the scope up into the opening on the top of the trans that lets you peek into the bell housing. I couldn’t see the slave cylinder end but could see parts of the fork and diaphragm fingers. I actuate the clutch again while watching the video feed and much to my relief I see the fork moving and fingers flexing as they should. Clutch pedal finally feels like it should. Suspect the old one got heat tempered and the springs got stiff. Will not be going for a long, proper drive anytime soon as our roads are covered in wet, sloppy snow at the moment.
Cost for DIY was around to $2k. It was like $600 for the clutch kit, $1200 just for the flywheel, $50 in new bolts, $15 for the oil seal and $80 for new transmission oil.
Also spent $150 for a harbor freight transmission jack for this project.
Would have been a perfect time to install a Numatic shifter and cables but was hard to justify an extra $1200. That will be next years project.
https://www.ebay.com/itm/26440577550...Bk9SR9TOjpaQYQ
11-16-2022, 01:56 PM
#11
Three Wheelin'
Wow, that is quite the job. Well done!
I lucked out and had a new clutch and flywheel installed when my defective transmission was replaced so my labour cost ended up being nearly $0. The previous owner(s) definitely didn't have good manual driving habits as I had a lot of grinding going into 2nd on the original transmission, and some clutch slippage as well.
I lucked out and had a new clutch and flywheel installed when my defective transmission was replaced so my labour cost ended up being nearly $0. The previous owner(s) definitely didn't have good manual driving habits as I had a lot of grinding going into 2nd on the original transmission, and some clutch slippage as well.
11-16-2022, 02:12 PM
#12
Racer
Thread Starter
I bought this high mileage car with the expectation it would need some maintaining. Not only did I want a 911 but I also wanted a project car I could wrench on. Therefore I never actually got this project quoted.
Considering parts alone were $2k, book time is 8hr (maybe if you got a 2-post lift and done a few of these that time would be feasible). Figure $150/hr labor rate and 30% markup on parts I’d guestimate a shop would charge around $4000.
Considering parts alone were $2k, book time is 8hr (maybe if you got a 2-post lift and done a few of these that time would be feasible). Figure $150/hr labor rate and 30% markup on parts I’d guestimate a shop would charge around $4000.
Last edited by JimEb; 11-16-2022 at 03:01 PM.
11-20-2022, 04:39 PM
#13
Racer
Thread Starter
Update: Finally got an opportunity to take car for test drive. Clutch felt great. Smooth, predicable power delivery. No weird noises coming from the car, shifting felt ok. Was concerned because I changed the trans fluid. Couldn’t find the exact stuff specified in the FSM so I ended up going with Liqui-Moly 75W-90. Not sure how finicky these MT transmission are with oil.
Things were going well until I kicked it down on an highway on-ramp. Went to grab 5th and shift lever went floppy. Shifted into 6th fine. Took the next exit and I only had 2nd, 4th and 6th gear. Shift lever was floppy when attempting the forward gears (1st, 3rd, 5th, etc) so I was 99% sure a shift cable popped off.
Luckily the car has enough grunt and clutch is awesome so I could start from a stop in 2nd gear. I get it home and in my garage. Just as expected the black cable came off it’s anchor point. The ball pivot was still attached but without anchoring the cable sheath it wasn’t doing anything. Those nylon clips never gave me confidence as they didn’t give a positive click or anything to indicate they are retained when reinstalling. Maybe these are compromised now since I had them off. I zip tied the cables to the bracket so they cant just fall off now. Figured this is my temporary insurance policy until I upgrade the cables and shifter.
Things were going well until I kicked it down on an highway on-ramp. Went to grab 5th and shift lever went floppy. Shifted into 6th fine. Took the next exit and I only had 2nd, 4th and 6th gear. Shift lever was floppy when attempting the forward gears (1st, 3rd, 5th, etc) so I was 99% sure a shift cable popped off.
Luckily the car has enough grunt and clutch is awesome so I could start from a stop in 2nd gear. I get it home and in my garage. Just as expected the black cable came off it’s anchor point. The ball pivot was still attached but without anchoring the cable sheath it wasn’t doing anything. Those nylon clips never gave me confidence as they didn’t give a positive click or anything to indicate they are retained when reinstalling. Maybe these are compromised now since I had them off. I zip tied the cables to the bracket so they cant just fall off now. Figured this is my temporary insurance policy until I upgrade the cables and shifter.
04-19-2023, 04:43 PM
#14
Former Vendor
"I cut the bolt holes or "ears" off the front output as they were touching or almost touching hoses and cables.
Cutting these off gave be comfortable clearances"
That "spinner" can be just removed by loosing that big nut and then retightening it with a proper spacer.
Cutting these off gave be comfortable clearances"
That "spinner" can be just removed by loosing that big nut and then retightening it with a proper spacer.
04-19-2023, 04:53 PM
#15
Has any of you had their clutch replaced by a Porsche dealer? Mine has never replaced a clutch in a 991.1 since the car was launched (most 991 are sold with PDKs)