bureau13

Most of the time, my clutch pedal feels fine. It's a bit different than before I changed the clutch, but only in minor ways. It still feels like it "should."

Sometimes, it feels...different. Everything works, no grinding, no slipping, etc, but when I release lift off the pedal, it's like it's slow to return, or maybe it just slows down near the end, and then my foot is already leaving it and it sort of thunks into place. I'm describing this terribly. It's actually a fairly minor difference, but when you're used to something pretty much always behaving a certain way, you notice minor differences pretty easily. And it can't be right.

Generally speaking I would be suspicious of the hydraulics. I have never actually bled the clutch. It's always worked so I've never done it. I could very well be developing a problem there.

On the other hand, I did just change out the clutch itself. The short shaft splines were good and the whole thing is greased with the proper stuff and slides smoothly. But I'm suspicious since I was just in there.

Any thoughts? I know it's tough to know exactly what I'm describing from that description...

PorKen

Won't hurt regardless to slap a Motive bleeder on there and replace the fluid in the line.

Counter-intuitively if there is any sponginess in the system the clutch pedal helper-spring will not have a force acting against it so the pedal return may be slow until it hits the helper-spring crossover point. If there is a lot of air the pedal may not return at all.






(Did a lot of troubleshooting on this here)

Petza914

You think you're describing this terribly, except your not to anyone who has experience the exact same sensation, as I have. When my clutch would get hot, the release of the pedal would hang up and then let go quickly and do this right at the engagement point of the friction discs to the flywheel and intermediate plate so the car would jerk when this happened, but it wouldn't happen all the time. I can't tell you for sure which of the 2 things I changed at the same time resolved it, but it was one or the other when I did my engine swap/update last year about this time.

I installed a new clutch slave and of course installed it with a GB line, but also removed the clutch assembly, cleaned the splined shaft really well and reinstalled it with a very light coating of the special super sticky Porsche clutch grease that I got from Roger and I no longer have that problem. All the other clutch parts are the same. My gut tells me my slave was also fine and what was happening is that he clutch assembly was hanging up on the splined shaft it needs to smoothly slide back and forth on.

Here's the grease you need.


Use it very sparingly on the section of the splined shaft that is inserted into the clutch assembly or it will sling off onto the friction discs and then guess what happens.

bureau13

I think I should change that fluid and bleed the system regardless. I do have a Motive bleeder but I've been paranoid about using it because of all the nightmare stories about clutch bleeding. Time to suck it up and do it.

I did use that grease when I assembled the clutch, and everything seemed to be moving freely.

One other possible data point...I went to a PCA breakfast yesterday morning, and on the way the brake fluid light came on and the "!" light started blinking. This was alarming, but when I checked, it wasn't particularly low (it wasn't at max either, so I fixed that) and nothing in the brakes or clutch pedal felt odd. On restart and subsequent drives, everything was fine, and indeed I have not had a resurgence of the pedal feel issue.

I think I will replace the fluid and bleed it, and then keep an eye on it. Crossing my fingers and hoping I don't need to pull the clutch out again! Although I feel like I'm getting pretty good at that...

Petza914

If you get the front inner drivers side fender wet, you'll get a brake warning as those sensors under the master cylinder mount upside down and will get water in them.

bureau13

Hmm...that's interesting. I am not sure how that could have got wet yesterday. I did wash the car but drove it afterwards. I'll have to think about that...

Petza914

Usually only happens if you wash the engine, not just wash the car, and if that's the cause of the error light it also usually requires a battery disconnect and reconnect to clear. If yours went away on its own, it may be a different brake warning like low fluid in the reservoir or a pad wear sensor.

Wisconsin Joe

You think you have a problem nobody else has seen? Ha!
The 'pedal hesitates on the way up, just enough that it throws off the engagement and makes launching the car smoothly difficult' is not new. It's been discussed on here before.

And I've dealt with it myself.

One thing I haven't seen mentioned:

The pedal pivot.
When I decided to finally try and address this in my car, I did a bit of searching (there are a few threads on it, but not a lot).

The idea of dropping the clutch pack to lube the pivot points wasn't appealing (I had gone through my clutch, lubed up all that stuff with no change). The idea of bleeding it wasn't either (I had flushed out the fluid previously, again with no change).

So I decided to start simple. The mechanical pivot point on the pedal.

Crawled under the dash & hit it with some spray lube.
I was amazed at the improvement.

It wasn't a permanent fix, the pedal stickiness came back after a couple months.
This year, the plan is to remove the pivot pin and put some of the clutch grease on it. Being the super sticky stuff, I think it will last longer. Pulling the pin and applying it properly will likely help some too.

It's a very easy thing to try (getting back out from under the dash was the hardest part of the whole project )

bureau13

Sounds like a reasonable thing to try!

bureau13

OK, so a few weeks have passed, the clutch pedal has acted completely normal over that time. I never did get around to bleeding it as I had other priorities, etc. Of course, with all the self-quarantining, etc I haven't drive it a lot. Today however, I drove to pick up some food, and when I started the car up to come home, the issue was back. Only this time, it got progressively worse until I couldn't the only movement of the pedal that seemed to do anything was a couple inches at the bottom, and that wasn't enough to get the car into gear.

With the car off, the clutch just goes to the floor. I can pull it back up, but if I push it in it goes right to the floor again. With the car running, there's an inch or two of pedal travel that's "working," it just isn't enough to disengage the clutch.

Pretty sure I have a bad master or slave cylinder, or something in between. I'll try and spot any leaks tomorrow, but I'm not sure how best to diagnose this if I find anything. Coincidentally, I have a very similar problem on the 931, and I just decided to replace all of it...but getting to those parts is not a huge challenge. Isn't the master cylinder on the 928 supposed to be a real bear?

Also...I'm very suspicious that I just replaced the mechanical portion of the clutch, and almost immediately after, I have an issue with the hydraulics. However I can't think of anything I might have done during that job that should have impacted any of the hydraulics. They're separate systems, really. Although, I did have to disconnect the slave, and so I did move it around on it's clutch line a bit, etc etc. Old parts...perhaps I hastened something to its inevitable demise? That would point to the slave or the line attached to it. I hear a lot of people discuss a Greg Brown clutch line that is highly recommended. Which part is that, exactly? Maybe this is the time to get that...

Petza914

The GB line is great. It's a flex line which makes removing the slave in the future after it's installed much easier as you don't have a hard metal line to deal with. I probably took mine off 3 or 4 times after the initial install to sort out a clutch issue.

It's this flexible grey covered line that goes to the slave cylinder. The grey covering protects the line itself from heat and external wear.

Sounds like your slave is bad or you have air trapped in there somewhere.

olmann

I had that exact same issue with mine that showed up on a road trip and would come and go. When I got back I bled the clutch with a Motive power bleeder along with pulling the slave and pushing the rod in and out. That seemed to get the last of the air out and cured my issue.

bureau13

Sounds like a good plan to start with. Hopefully that takes care of it. I might just replace the slave and flex line anyway, as if there is air in there it had to come from somewhere, and from the looks of it, replacing those parts is not really any harder than removing the slave and pushing the rod in and out a few times.

In related news, Petza914 the underside of your car is ridiculously clean. Wow...

bureau13

I hooked up the Motive power bleeder, opened the bleed screw and pumped it up to about 5-6 psi. Fluid started coming out of the slave, so I tried to see if I could find any other leaks. I noticed fluid dripping down from up in the driver's side fender area. Well, that's not good, that's master cylinder, right? Well, not so fast. Looking up from the bottom, it appeared to be coming from the BRAKE master cylinder area. Honestly, I'm pretty sure it was seeping out from around the cap. I put silicone tape around the threads and tried again, same thing. Given that I can't see the clutch master cylinder at all, how does one diagnose a master cylinder problem? Or do I just replace the slave and flex line and see if it's fixed?

If there is a leak, it is more about sucking in air than losing fluid, I think. I didn't really seem to be low on fluid.

Mrmerlin

If you follow these suggestions your clutch will work forever till its time to replace the hydraulics again say in 20 years?

NOTE If the brake MC has rusty collars around the tank feed grommets buy
a new ATE brake master cylinder,
and 4 new SS brake lines.
If your booster has ever seemed suspect buy
a new ATE booster,
1 liter of Gold ATE brake fluid.
Buy a
new clutch Master cylinder
new slave cylinder,
new blue hose/black now,
new Greg Brown flex line from the sway bar to slave,
new release arm bushing.

Remove the tank then the brake MC then the booster.

NOTE to remove the booster make a cover for the where the MC sits so you dont scratch the surface ,
I like to use an old coolant bottle as a cover for the booster,
then clamp the pushrod while the pedal is being pushed full down
NOTE this must be done as this will make the booster threaded rod easy to remove past the fender and cam cover otherwise it will get stuck.
NOTE unscrew the threaded clevis off the booster input shaft before removal.
Once the booster is out of the way then you will have clear access to the clutch M/C

NOTE if you have a dual disc then the piston tip of the new clutch MC should be cut down about 4.5MM and 2 winds off the spring at the base.
The new M/C pistons are 80MM so your looking for 75mm or a hair more.


bleeding the slave is as easy as opening the slave bleeder with a rag under the bleeder ,
and waiting for solid fluid to come out.
once this is done then remove the slave from the bell housing.
let the slave dangle,
while holding the bleeder so it at its highest point while dangling the slave,
open the bleeder again to expel any more air.
Close the bleeder,
then hold the slave with the line port facing up,
and with a folded rag over the pushrod,
push the rod slowly into the slave all the way.
Hold this position for about 30 seconds, then release the pushrod. it will extend . wait for about 30 seconds then repeat .
do this procedure 3 times then install the slave into the bell housing.
NOTE put some grease on the pushrod and release arm.