928 dual-disk clutch binding
10-19-2017, 04:11 AM
#1
7th Gear
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928 dual-disk clutch binding
Hi guys,
Have installed new clutch plates, pressure plate, release bearing, spigot bearing, new bearings in torque tube. Machined the main flywheel and had the intermediate plate checked and confirmed as flat. They sandblasted the surfaces.
We cannot engage first gear with engine running. When running all other gears are great and no vibration.
Looking for ideas for adjustment possibly?
Cheers
Have installed new clutch plates, pressure plate, release bearing, spigot bearing, new bearings in torque tube. Machined the main flywheel and had the intermediate plate checked and confirmed as flat. They sandblasted the surfaces.
We cannot engage first gear with engine running. When running all other gears are great and no vibration.
Looking for ideas for adjustment possibly?
Cheers
10-20-2017, 08:30 AM
#2
RL Community Team
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Is this a 928 question? Why is it posted in the Cayenne DIY forum?
But, with the car off, if it goes into gear, but not with it running, it's because the clutch isn't disengaging. I've seen new intermediate plates crack which could do that, among other things. If it won't go in when off or running, then it's probably a linkage issue.
But, with the car off, if it goes into gear, but not with it running, it's because the clutch isn't disengaging. I've seen new intermediate plates crack which could do that, among other things. If it won't go in when off or running, then it's probably a linkage issue.
Last edited by Petza914; 10-20-2017 at 08:48 AM.
10-21-2017, 01:36 AM
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928 clutch binding
Hello Geo55
Yes the gears were fine. Reason for job was vibration in driveline.
This is no longer a problem. It appears to be an adjustment issue and am now checking for the finer detailed steps to complete the job properly.
Yes the gears were fine. Reason for job was vibration in driveline.
This is no longer a problem. It appears to be an adjustment issue and am now checking for the finer detailed steps to complete the job properly.
10-21-2017, 02:38 PM
#6
Chronic Tool Dropper
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Hi Tim --
First of all, welcome to Rennlist and the 928 Forum. There's a wealth of knowledge and experience here at your mouse's little fingertips.
Please take some time to read the sticky New Vistors thread at the top. Lots of info on common problems, plus some posting tips including a request that you include the year of your car in every post.
That said, from your description you have an earlier 5-speed car with the dual-disk clutch. And the clutch seems to be dragging or not releasing completely after work was done on it. The Common Causes that I'm aware of:
-- Worn or seized pilot bearing (stated as replaced with new)
-- Worn or failed release bearing (stated as replaced with new)
-- Worn/failed pivot ball or bushing.
-- Poorly adjusted intermediate plate.
-- Worn splined clutch shaft
-- Incorrect or poor lubrication on clutch shaft.
-- Hydraulic problems:
. -- Master cylinder failing
. -- Slave cylinder failing
. -- "Blue Hose" failing or failed
. -- Air trapped in the system
Solutions to most of these are pretty straightforward, except...
-- Bleeding the clutch hydraulics is best done from the bottom to top rather than the conventional method of pressing the pedal and bleeding at the slave cylinder port. Often the easiest way to do this is to connect a front wheel caliper bleed screw to the clutch slave bleed screw, open both, and gently pump the brake pedal to push fluid and air back uphill to the shared reservoir. Best to compress the slave cylinder before bleeding.
-- Adjusting the intermediate plate is best done per the workshop manual instructions. There are small ribbon springs that work to keep that plate centered between the cover and the flywheel, essential for full clutch release. You can test for this by removing the bottom bellhousing cover. With the pedal depressed, there should be pretty even clearance on both sides of both clutch disks. Use a feeler gauge to confirm.
-- A worn splined shaft or disk hub will keep the disks from sliding to their released positions when the pedal is depressed. This will show up in the measurement above, where the disks end up in their forward positions while released. A good visual inspection of the stub shaft will tell you a lot, but that includes removing the clutch assembly again. Greg Brown (GregBBRD screen name) offers a significantly improved replacement shaft.
First of all, welcome to Rennlist and the 928 Forum. There's a wealth of knowledge and experience here at your mouse's little fingertips.
Please take some time to read the sticky New Vistors thread at the top. Lots of info on common problems, plus some posting tips including a request that you include the year of your car in every post.
That said, from your description you have an earlier 5-speed car with the dual-disk clutch. And the clutch seems to be dragging or not releasing completely after work was done on it. The Common Causes that I'm aware of:
-- Worn or seized pilot bearing (stated as replaced with new)
-- Worn or failed release bearing (stated as replaced with new)
-- Worn/failed pivot ball or bushing.
-- Poorly adjusted intermediate plate.
-- Worn splined clutch shaft
-- Incorrect or poor lubrication on clutch shaft.
-- Hydraulic problems:
. -- Master cylinder failing
. -- Slave cylinder failing
. -- "Blue Hose" failing or failed
. -- Air trapped in the system
Solutions to most of these are pretty straightforward, except...
-- Bleeding the clutch hydraulics is best done from the bottom to top rather than the conventional method of pressing the pedal and bleeding at the slave cylinder port. Often the easiest way to do this is to connect a front wheel caliper bleed screw to the clutch slave bleed screw, open both, and gently pump the brake pedal to push fluid and air back uphill to the shared reservoir. Best to compress the slave cylinder before bleeding.
-- Adjusting the intermediate plate is best done per the workshop manual instructions. There are small ribbon springs that work to keep that plate centered between the cover and the flywheel, essential for full clutch release. You can test for this by removing the bottom bellhousing cover. With the pedal depressed, there should be pretty even clearance on both sides of both clutch disks. Use a feeler gauge to confirm.
-- A worn splined shaft or disk hub will keep the disks from sliding to their released positions when the pedal is depressed. This will show up in the measurement above, where the disks end up in their forward positions while released. A good visual inspection of the stub shaft will tell you a lot, but that includes removing the clutch assembly again. Greg Brown (GregBBRD screen name) offers a significantly improved replacement shaft.
10-21-2017, 09:14 PM
#7
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1979 928 clutch binding in first and reverse
Thank you Dr Bob for your very informative post and kind welcome.
The direction to new users and proper posting etiquette has been read and duly noted and I will follow accordingly in future posts.
Dave928s has been wonderful in his generous advise and appreciate your detailed reply also. I have begun reading some posts that you recommended and they look like excellent resources.
Cheers
Tim
The direction to new users and proper posting etiquette has been read and duly noted and I will follow accordingly in future posts.
Dave928s has been wonderful in his generous advise and appreciate your detailed reply also. I have begun reading some posts that you recommended and they look like excellent resources.
Cheers
Tim