Sticking clutch disc
11-17-2008, 02:12 PM
#1
Instructor
Thread Starter
Sticking clutch disc
I have finally figured out what is going on with my sticking clutch disc. How to fix it is the question.
Most of the time the clutch disc will not fully disengage from the flywheel unless the engine is loading the transmission. If I let off the gas and let the weight of the car load the transmission, then try to shift out of gear, I will encounter resistance; the clutch is not completely disengaged from the flywheel. Under acceleration it shifts just fine. It will eventually disengage completely when I slow down enough or if I blip the throttle. The PO had the clutch changed but might have failed to lubricate the spline while they were in there.
It has to be lack of lubrication on the spline causing it. Is there any way to get some lubrication to the spline without complete removal of the transmission?
Or by my description, could it be anything else?
'91 964 C2 cab. 49K miles.
Most of the time the clutch disc will not fully disengage from the flywheel unless the engine is loading the transmission. If I let off the gas and let the weight of the car load the transmission, then try to shift out of gear, I will encounter resistance; the clutch is not completely disengaged from the flywheel. Under acceleration it shifts just fine. It will eventually disengage completely when I slow down enough or if I blip the throttle. The PO had the clutch changed but might have failed to lubricate the spline while they were in there.
It has to be lack of lubrication on the spline causing it. Is there any way to get some lubrication to the spline without complete removal of the transmission?
Or by my description, could it be anything else?
'91 964 C2 cab. 49K miles.
11-17-2008, 06:34 PM
#2
RL Technical Advisor
Sorry to tell you that the transmission must be removed to fix this.
One should polish the splines on the input shaft to get rid of surface rust and any small burrs as well as burnish the splines in the clutch disc. I put a thin coating of Optimoly inside the disc splines to prevent it from hanging on the input shaft.
One should polish the splines on the input shaft to get rid of surface rust and any small burrs as well as burnish the splines in the clutch disc. I put a thin coating of Optimoly inside the disc splines to prevent it from hanging on the input shaft.
11-18-2008, 09:25 AM
#3
Professor of Pending Projects
Rennlist Member
Rennlist Member
What if you push the pedal all the way to the bottom? Will it work then?
I would try the easy stuff first before you drop the tranny... This will take you less than three hours to do...
Replace the hose to the slave cylinder (and the slave cylinder while you are in there if it is old) and flush the system with new fluid. Replace the pin at the pedal cluster.
Test and see if that improves or eliminates the problem.
I would try the easy stuff first before you drop the tranny... This will take you less than three hours to do...
Replace the hose to the slave cylinder (and the slave cylinder while you are in there if it is old) and flush the system with new fluid. Replace the pin at the pedal cluster.
Test and see if that improves or eliminates the problem.
11-18-2008, 10:08 AM
#4
Do you need to remove the pedal ***'y to replace the pin?
Can you see if the pin is "bad", or is it crushed on the inside?
Mine looks fine without removing the ***'y, and the pedal seems tight. Though, there is a bit of travel before real resistance is felt. Not sloppy, but light for the first little bit (I've not measured this).
Note that I've had this same issue with the clutch not quite disengaging, but only when the car is cold. Once warm, no issue. At any rate, I measured my pedal travel and discovered that I had roughly 135mm of travel rather than the spec'd 145mm. I adjusted the rubber stop mounted to the floor board to enable 145mm of travel and thought I had fixed the problem. However, I've had difficulty pulling out of gear once or twice since. Pushing a little harder on the clutch pedal helps. Rev'ing the engine definitely helps.
Note, also, that I have a new clutch (Jan '07, 20k miles since) and expect that the spline was cleaned and lubed. Though, I can't say without looking at it with my own eyes.
Can you see if the pin is "bad", or is it crushed on the inside?
Mine looks fine without removing the ***'y, and the pedal seems tight. Though, there is a bit of travel before real resistance is felt. Not sloppy, but light for the first little bit (I've not measured this).
Note that I've had this same issue with the clutch not quite disengaging, but only when the car is cold. Once warm, no issue. At any rate, I measured my pedal travel and discovered that I had roughly 135mm of travel rather than the spec'd 145mm. I adjusted the rubber stop mounted to the floor board to enable 145mm of travel and thought I had fixed the problem. However, I've had difficulty pulling out of gear once or twice since. Pushing a little harder on the clutch pedal helps. Rev'ing the engine definitely helps.
Note, also, that I have a new clutch (Jan '07, 20k miles since) and expect that the spline was cleaned and lubed. Though, I can't say without looking at it with my own eyes.
11-18-2008, 10:13 AM
#5
Professor of Pending Projects
Rennlist Member
Rennlist Member
Do you need to remove the pedal ***'y to replace the pin?
Can you see if the pin is "bad", or is it crushed on the inside?
Mine looks fine without removing the ***'y, and the pedal seems tight. Though, there is a bit of travel before real resistance is felt. Not sloppy, but light for the first little bit (I've not measured this).
Note that I've had this same issue with the clutch not quite disengaging, but only when the car is cold. Once warm, no issue. At any rate, I measured my pedal travel and discovered that I had roughly 135mm of travel rather than the spec'd 145mm. I adjusted the rubber stop mounted to the floor board to enable 145mm of travel and thought I had fixed the problem. However, I've had difficulty pulling out of gear once or twice since. Pushing a little harder on the clutch pedal helps. Rev'ing the engine definitely helps.
Note, also, that I have a new clutch (Jan '07, 20k miles since) and expect that the spline was cleaned and lubed. Though, I can't say without looking at it with my own eyes.
Can you see if the pin is "bad", or is it crushed on the inside?
Mine looks fine without removing the ***'y, and the pedal seems tight. Though, there is a bit of travel before real resistance is felt. Not sloppy, but light for the first little bit (I've not measured this).
Note that I've had this same issue with the clutch not quite disengaging, but only when the car is cold. Once warm, no issue. At any rate, I measured my pedal travel and discovered that I had roughly 135mm of travel rather than the spec'd 145mm. I adjusted the rubber stop mounted to the floor board to enable 145mm of travel and thought I had fixed the problem. However, I've had difficulty pulling out of gear once or twice since. Pushing a little harder on the clutch pedal helps. Rev'ing the engine definitely helps.
Note, also, that I have a new clutch (Jan '07, 20k miles since) and expect that the spline was cleaned and lubed. Though, I can't say without looking at it with my own eyes.
Originally Posted by Eric Kessel
I'm sorry, I put it back together again. If you look at the p-car.com/diy section on the kinematic lever update, that is the part that is held on with the roll pin. (the 993 part will not work with our cars, since it uses a spline to hold the part on, while we have a rotten roll pin)
It was actually pretty easy to do, there are the three screws holding the wooden floor board (two on the bottom, and one right behind the accelerator pedal), then there are the four 13mm nuts on the floor holding the pedal assembly. There are two more 13mm nuts holding the clutch master cylinder on. After that, there are the two safety clips (one for the brake rod, and one for the clutch). Detach the accelerator cable (ball joint that just pops off), and unplug the cruise control wires, and the brake light connector. I was able to wiggle the pedal assembly out without breaking open the clutch hydraulic lines.
I found a 6mm bolt (about 35-40mm long) with a lock nut to use, although I'm not sure it a2-70 steel is strong enough for the long term.
The clutch feels great now, very smooth, and much easier to actuate, it improved the feel immensely.
I had a couple inches of clutch pedal travel without moving the master cylinder, and it felt very "crunchy".
What is next for our DIY adventures? (I don't have a garage, so I do all my work in the driveway. With snow coming any day now, I was anxious to get this fixed....... )
-Eric
90 C2
NER/PCA
It was actually pretty easy to do, there are the three screws holding the wooden floor board (two on the bottom, and one right behind the accelerator pedal), then there are the four 13mm nuts on the floor holding the pedal assembly. There are two more 13mm nuts holding the clutch master cylinder on. After that, there are the two safety clips (one for the brake rod, and one for the clutch). Detach the accelerator cable (ball joint that just pops off), and unplug the cruise control wires, and the brake light connector. I was able to wiggle the pedal assembly out without breaking open the clutch hydraulic lines.
I found a 6mm bolt (about 35-40mm long) with a lock nut to use, although I'm not sure it a2-70 steel is strong enough for the long term.
The clutch feels great now, very smooth, and much easier to actuate, it improved the feel immensely.
I had a couple inches of clutch pedal travel without moving the master cylinder, and it felt very "crunchy".
What is next for our DIY adventures? (I don't have a garage, so I do all my work in the driveway. With snow coming any day now, I was anxious to get this fixed....... )
-Eric
90 C2
NER/PCA
11-18-2008, 10:13 AM
#6
Three Wheelin'
What if you push the pedal all the way to the bottom? Will it work then?
I would try the easy stuff first before you drop the tranny... This will take you less than three hours to do...
Replace the hose to the slave cylinder (and the slave cylinder while you are in there if it is old) and flush the system with new fluid. Replace the pin at the pedal cluster.
Test and see if that improves or eliminates the problem.
I would try the easy stuff first before you drop the tranny... This will take you less than three hours to do...
Replace the hose to the slave cylinder (and the slave cylinder while you are in there if it is old) and flush the system with new fluid. Replace the pin at the pedal cluster.
Test and see if that improves or eliminates the problem.
I ran into a very similar problem for the first 2 years I had the car. Clutch was replaced right when I got the car(and I know the splines were cleaned and greased, was there when it was done.) I bled the clutch a few times. No difference. I replaced the slave and slave hose, and bled. No difference. I replaced the clutch master, and bled the system. Better, but not perfect. For some reason I bled it again about 3 weeks after I replaced the master. Clutch feels perfect, and has for the 4 months since. I am inclined to think the master was bad, but I can't say that for 100 %, as it didn't resolve it right away. Have always used a motive bleeder, never let fluid get low, etc. I have not replaced the clutch pin yet, and probably will do that this winter. The nice part about replacing the master, slave and line is that they are all pretty cheap, and at this point, probably need to be replaced anyway. Good luck.
11-18-2008, 01:07 PM
#7
Instructor
Thread Starter
What if you push the pedal all the way to the bottom? Will it work then?
I would try the easy stuff first before you drop the tranny... This will take you less than three hours to do...
Replace the hose to the slave cylinder (and the slave cylinder while you are in there if it is old) and flush the system with new fluid. Replace the pin at the pedal cluster.
Test and see if that improves or eliminates the problem.
I would try the easy stuff first before you drop the tranny... This will take you less than three hours to do...
Replace the hose to the slave cylinder (and the slave cylinder while you are in there if it is old) and flush the system with new fluid. Replace the pin at the pedal cluster.
Test and see if that improves or eliminates the problem.
Bled the system with the Motive Power Bleeder, replaced the slave hose.
I also changed the gear oil.
Have not looked closely at the pin; however the pedal easily comes back to the home position.
I think I may just have to do the blip the throttle thing every time I drive it. That works without fail, it will easily pull out of gear that way.
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11-18-2008, 04:15 PM
#8
Professor of Pending Projects
Rennlist Member
Rennlist Member
I just finished replacing the clutch pedal pin and bushings... Old pin looked fine. And one of the plastic bushings looked like it had been replaced in the past, but the other one really needed to be replaced.
So, in my case, after changing the hose and bleeding, it cured the problem. I am not sure that the clutch pin and bushing replacement did anything to it... oh well, at least I know those are new.
Clutch is back to being butter smooth.
So, in my case, after changing the hose and bleeding, it cured the problem. I am not sure that the clutch pin and bushing replacement did anything to it... oh well, at least I know those are new.
Clutch is back to being butter smooth.
