Troubleshooting Clutch/Shifting issue?
 

So... I was driving back from the coast today, nice drive at 80+/-, never had a problem shifting before, coming to my exit I tried to shift from 5th to 3rd, except the gear would not disengage. Engine died at the light, I shoved the shifter into 2nd and started the car and drove it to the parking lot...

So basically, I can force the gear box into gear and drive the car but I am unable to shift, the pedal is not soft or spongy, it depresses and releases as it always had, only I cannot place the shifter into any gear with the engine running. So... I'm thinking the clutch is fine and the problem is somewhere in the hydraulics which isn't allowing the clutch to disengage. Fluid level is full, no leaks anywhere. Since I do not have a service or Bentley manual, and my friendly Google search is not helping in troubleshooting this issue, I was hoping for some input from the best.

2001 Boxster, 86,400 miles

Does the clutch work? From your description I'm unsure.
When you push the clutch in does the trans disengage?

Wild guess...clutch throw out arm/bearing.

Check the shifter cables at the tranny. It's common for them to break.

I had a similar situation in my 996. Pressing the clutch, the trans would not disengage. At a stop, I could smell the clutch burning and would have to shut it off. I could then put the car in 1st, start it, and drive. Shifting took considerable effort, even with the clutch on the floor. I tried bleeding the clutch, but there was no change. I ended up replacing the clutch and pressure plate and it solved the problem. The disc was well worn, but not down to the rivets. The flywheel and pressure plate had some heat marking, but I was able to reuse the FW.

The clutch does not work. I have full pedal motion, no sticking and it even feels like it has normal pressure, I just can't engage any gear. Like I said, I was able to drive it when I put in second and started it.

Cables... ? I wasn't aware there were any cables? This sounds interesting, can I do a visual to verify? Diagram? Never mind, I just found a great write-up over at rennlist.

I'm trying to rule out the clutch/pressure plate for now since the vehicle drives fine when in gear.

Wait... If I had a broken cable, I would not be able to place the tranny in any gear with the engine off right?

my guess would be a broken pressure plate...

If I had a bad pressure plate, the car would not move at all due to the loss of clamping friction between the clutch and the flywheel, unless the fingers that the bearing press against have all failed, which while possible seems unlikely.

So I did some troubleshooting this morning, pulled the console and lower body panel covers to have access to everything. I Made sure the master fluid reservoir was full before anything.

Checked the cables and linkages for loose or obvious broken parts both at the console and at the tranny, had a helper go through the gears for me while I inspected, nothing was obviously inoperative or damaged, all gears worked smoothly and without effort with the engine off.

Thinking "what do I have to lose", I did a quick bleed test by having my helper hold the clutch pedal to the floor while I cracked the bleed screw on the slave cylinder, first indication that something was wrong was that the bleeder screw was just barely over finger tight but opening the valve fully produced only a small trickling of fluid, but no air. Closed the fitting and had my helper push the clutch a couple times and then held it down, again I cracked the bleeder screw almost a full turn, no air, but again, only a trickle of fluid, more like drops really. However, once we did a mini bleed of the slave, with the vehicle on jacks I was able to go through the gears with the engine running, although it did require a bit more effort to get into gears, possibly due to there being no rolling resistance on the vehicle since it is still on jack stands. Pedal seemed a bit firmer too.

So... Either my hydraulic system is clogged, or the master and slave are not moving fluid at the required pressure. A clogged system again doesn't sound possible since everything was fine prior to the issue. If one of the internal seals of either the master or slave has gone bad, would this be a cause of my issue, again, there are no obvious leaks anywhere in the system. I wish there was a way to fully test the master/slave system prior to replacing...

These clutch systems are notoriously difficult to bleed completely. It sounds like air may be getting sucked in somewhere, perhaps the masterhas worn internal seals . If it's a hydraulic problem than your getting off easy compared to a mechanical one....

And about 7 hours of labor... Parts on order, crossing fingers.

shifting problems
 

For some time Ive had a problem from shifting from 1st to 2nd when I start in the morning. After going to the dealer and being given the run around I found out the solution to the problem. The engine has to be warmed to 180 degrees at least. For some reason at that temperature the 1s-2nd works. Shifting has never been silky as the BMW 328 my son in law has.

Well, it looks like I am going to be pulling the transmission... Replaced the master and slave cylinder, bled the system completely and the problem still exists.

But before I order any parts, I want to see exactly where the problem is. As for ordering parts, I have heard that I can use the 987 S clutch and pressure plate which is suppose to provide a greater clamping force, since I have a 5 speed. Can anyone comment on this?

I believe you are right. Just make sure that order a 5speed setup if that is what you have or a 6speed setup. I have a 987 5speed plate and disc in my car now. I have for years. Good luck with the project and please fill us in on the results. Please take pictures too.

So I pulled the tranny today, actually went easier than I expected. Learned a few things along the way which I will share later. As for what I found, the clutch is gone, down to the rivets on the pressure plate side, which created a nice little groove in the plate. The throwout bearing is bad, nice groove from where the pressure plate had been riding. When inspecting the flywheel, it has a good amount of heat marks on it, no cracks or grooves, and it has about 15mm of play which I am told is acceptable. Still considering if I should change it or not, perhaps just a good cleanup...

I'm ordering a new 987 5 speed plate, disk and bearing, which I hope is here before next weekend, here are some pics.

Pressure plate
http://i59.tinypic.com/suxesl.jpg

Clutch disk
http://i59.tinypic.com/mj42q.jpg

Flywheel
http://i60.tinypic.com/1z1h8v7.jpg

Flywheel
http://i57.tinypic.com/15gpn4w.jpg

If you are here in the OC pm me, I have a guy who suppose to be able to resurface a dual mass for me for less than $100

Hit the flywheel with 80 grit paper on a rotary sander/polisher. Then inspect for cracks, grooves, etc. if its clean, then you can reuse. Just be sure it passes the rotation test.

Common wisdom is you cannot cut the flywheel, only clean it up.

Well with hot spots such as those shown if one were to reuse, it would be best to grind it. Hot spots are pretty hard, a cutting bit would have a hard time cutting threw a hot (harden) spot. A good fly wheel resurfacer can tell you if it is even recommended to try to reuse it at all.

Please note not many machine shops can grind a Dual mass flywheel please asked.


If I saw hot spots such as these on a brake rotor I would toss it.


If you are the type that believes brake rotors can or should be resurfaced for new brake pads you should consider resurfacing a flywheel when a new clutch is installed.

A flywheel with a bad surface can make it hard to launch a car smoothly in stop and go traffic.

"Rotation test"? Since a new flywheel runs about a thousand bucks, chances are I will just be doing a clean-up once I verify that it has no cracks... Though I might be looking for a good machine shop here in town to see about doing a resurface.

This is on a V10 BMW M5 with a SMG transmission I just did...

Its a dual friction clutch with a dual mass flywheel and I'm showing the amount movement in the dual mass flywheel. I believe the Porsche flywheel is tighter though.

https://lh3.googleusercontent.com/-L...407_180855.mp4

This happens to be with the clutch assembly bolted down to the flywheel (not required) but all the movement you see is in the dual mass flywheel.