T3C

Trying to troubleshoot a really odd issue I encountered while pulling into my driveway. Short story is that the clutch pedal won't fully depress and allow me to select a gear.

Car is an '03 manual. Relevant mods include an RS 4.0 clutch pack and LWFW that has about 35-40k miles on it and a numeric shifter. Stock slave cylinder was replaced about 35-40k miles ago and the clutch master was replaced about 1k miles ago. I had just finished a little test drive after doing a brake upgrade/full system flush (i.e. accelerating and getting on the brakes hard) when I went to pull back into my garage. I was idling in neutral in my driveway, which is on a slight incline, for a minute or two before putting the car in 1st gear and must have let out the clutch a little bit too slowly causing the car to stall. No weird sounds, just the engine cutting out. I turned the car back on (I have the clutch switch bypassed so I can start the car without depressing the clutch), but I could only depress the clutch pedal about 50-75% of it's travel before meeting A LOT of resistance. Not the kind of resistance you feel when the accumulator fails, but this felt like if I pressed the clucth all the way to the floor that it would result in me breaking something. It feels completely normal for that first 50-75% pedal travel. With A LOT of effort, I can get the clutch all the way to the floor, but I can't select any gears. However, if I turned the car off I was able to select all gears as long as I didn't press the clutch pedal.

I pushed the car into the garage and tried troubleshooting things right away. Admittedly, I've stalled my fair share of manual cars in my life, but never had a clutch pack itself up afterwards...

- no obstruction impeding the travel of the clutch pedal
- no fluid dripping from the clutch master
- no fluid coming from the clutch reservoir (in fact the fluid level is exactly where it always is)
- no fluid leaking from the slave cylinder
- cracking the bleeder on the slave results in the clutch pedal going to the floor
- flushing the clutch/slave did not change the feeling of the clutch pedal
- I stuck a borescope in the transmission window and could see the pilot bearing seated in its normal position; I could see that the slave rod was seated in the pocket of the clutch fork (can see it move a bit if you depress the clutch, but definitely isn't exhibiting full travel); I couldn't see the entire pressure plate, but didn't see any broken bits

After I flushed the whole system I kept the rear of the car in the air. I turned the car on, pushed the clutch with a lot of effort all the way to the floor and was able to select 1st gear. I could see the wheels spinning. Wasn't able to select any other gear, though. Turned the car off and on again, but wasn't able to select any gears again.

Any ideas as to what may have gone wrong? I want to rule out everything I can before I commit myself to dropping the trans.

theprf

The only thing that comes to mind is something internal with the clutch, perhaps a piece of friction disk came off the clutch.

my04996tt

Since the m/c was recently replaced that would be my first thought.

T3C

There's a weird story about the MC replacement, unfortunately. The MC was replaced by the PO right before I bought the car. The PO told me that the shop flushed the system with DOT4 fluid rather than pentosin. Immediate red flags started raising in my head b/c there was nothing in the car's very well documented history about a GT2 slave conversion. Getting under the car after delivery I was able to confirm that the car indeed still had the stock slave cylinder, accumulator, and lines running to/from the PS pump. So I totally drained the PS system and clutch slave of all the fluid. Then I put pentosin back into the clutch reservoir and the PS reservoir. I've run the car for approx 2k miles since then, and it seemed to have been fine with regards to clutch feel, operation etc.

Is there a way to bench test the MC? I don't want to just throw unnecessary parts at a problem.

Also, somewhat relevant, is that I had noticed the last couple times I ran the car that the clutch may have started showing early signs of slipping at full boost in 3rd and 4th gear. Again, the clutch has almost 40k miles since it was last replaced so I wasn't too surprised. Maybe a piece wore too much and sheared off..?

Using the borescope and having a buddy operate the clutch I can see the slave rod and clutch fork operate somewhat. Depressing the clutch only as far as it will go until meeting resistance, you can see the rod and fork moving, but only to a certain point until it stops short of full actuation. I will try to upload a video if it would be helpful.

QwikKotaTX

In Clint Hightower's video he uses an adapter and a section of clear tubing to bleed the master on the outlet. That would be about as close to bench testing that I could think of.


Edit: that fitting is kind of expensive. Might be cheaper to replace the reservoir line and use the old one as a bleeder fitting: 996-423-147-01

Lazurus

Only data point I can add is that I recently had a brand new OEM out of the box clutch master cylinder fail, and unbelievably so. A second "new" one sorted my clutch master issues out but I also installed a new clutch at nearly the same time frame. Your issues suggest something more internal than any master cylinder failures though. Good luck with sorting it out.