MrEracer

I have struggled with this problem trying to understand what is going on. I now believe I have identified the major contributor to this problem. This is very similar to fading brakes on track day... It's caused by boiling the fluid in the line. I discovered that my clutch hydraulic line ran very close to my left side header. Under sustained high power operation a lot of heat is radiated from the header to the line.

I have never experienced the clutch on the floor problem while driving normally on the street. At the track I usually didn't have the clutch problem until the second track session. This is B/C the system and the day were cool in the early session but as the heat accumulated in the line with subsequent sessions it would finally boil the fluid... This creates a pressurized bubble which forces fluid back into the M/C leaving a compressible bubble/void in the line... The next time the peddle is depressed, the delivered slug of fluid only compresses the bubble and there is not enough fluid in the line to expand the slave cylinder and disengage the clutch. The result is a clutch that is not disengaged and the peddle stays on the floor...

In my case, with the clutch peddle on the floor I still could not shift into the next gear which indicates that the clutch was not properly dissengaged (even though the peddle was down). This caused me to destroy my third gear syncro's trying to shove it into gear while the clutch was still engaged.

To solve this problem I have replaced the clutch fluid with high boiling point brake fluid (Motul 600) and I have wrapped my clutch line with an insulating blanket where it passes near the header. I have not been back to the track with these mods, but it is the only explination that is consistant with all the symptoms... I will let you know how things work at my next track event in two weeks. Any comments?
Shirl
SDRE

Mean Green

I for really appreciate the thoughts and investigative work, I've had similar thoughts regarding temps and have considered swithing fluids as well. Will be extremely interested in what you find out :cheers:

allanlaw

My experience with sticking clutch pedal at the track is the same as yours. It always seemed to happen when the internals would be at their hottest. After the first stick, I would cut the remaining sessions short (20 minutes instead of 30, etc.) and the pedal wouldn't stick, because it wasn't getting as hot (?). I was looking at a heat shield that is like the coverings for spark plug wires, but instead of being a complete sleeve, the seam is open and has velcro closures, so you can slip it over the line and then close it up. Now I have to figure out what catalog is was in :)

Z11409

Barrister--Any hydraulic hose store--Hosemart Etc. Orange Thermal Sleve,$3-4 a foot.If you want I will bring some to next Pahrump Exploration Day.Use also on exposed brake lines below the master brake cylinder and stainless flex gas line leading to fuel rails.

allanlaw

Hey, Zman, I'll take you up on that offer. Does this mean you're not doing WS on 5/19?

Z11409

Not 5-19 but will be there this Monday for the OTR Race,If you want I will bring the White Whale with needed tools,jacks and first aid kit if YOU want to install it there.Or better yet we could meet at DALTON'S in near future.

allanlaw

See you there Monday at OTR festivities - but don't bother with the tools, I'm going to work on this in conjuction with some other secret DCB projects :reddevil

Z11409

YOU WILL be the first to transplant a Viper engine into a Tupperware car

allanlaw

If 8's good, then 10's better . . . .

allanlaw

The heat shield I was thinking of is in the Eastwood catalog. It's called heat shroud sleeving (hook and loop), so I would guess you can put it around the clutch line without disconnecting it.

Tony @ MPH

Interesting thoughts MrEracer. I too noticed clutch pedal sticking syndrome only after the car was good and hot. It seems to have gone away though at this point now that I've swapped fluids, M/C, and the clutch altogether.

If the symptoms come back though, your work will go a long way towards making me sane again, as I find the sticking clutch pedal to be the most obnoxious C5 bug other than the column lock.

Avanti

BINGO! :yesnod: All the other fixes mentioned here over the years struck me as so much wishful thinking.

Thanks. I suspect you'll find your experience is different next time.

LoneStarFRC

Try http://www.thermotec.com. They have a pretty good lineup including some that can be used with lines still installed in the car. HTH

Robert

allanlaw

Good stuff - Summit Racing seems to have most of the Thermotec line (doesn't look like Thermotec sells direct).


[Modified by allanlaw, 11:19 AM 4/22/2004]

Bink

Any reason not to run Motul 600 fulltime on the street?? Thanks to all for the info. Thermotec's link isn't working for me??

LoneStarFRC

If the link isn't working, try doing a Google search using Thermotec's web address. HTH

Robert

Dugmole

I also had the dreaded stuck pedal.

I replaced the stock clutch with a Ram setup, performed the drill mod.

I still just use dot 3/4 and my lines are not insulated, and they are close to the headers.

I have 10k miles with many spirited passes with no stuck pedal.

tcmc5

I definitely think you're on the right track, Shirl. Two weeks ago at VIR I experienced clutch pedal fade for the first time near the end of my last session. Replaced fluid today with Motul and will shield lines before VIR next weekend. I bet it works.

chuckster

Shirl, It can be aggrivated by a number of things...But I am certain of one thing...
I replaced the Master 2 times
Did the Drill out Line Mod
Replaced the fluid with Superblue Racing Fluid
Still did it..
the dealer replaced EVERYTHING this time and so far so good.. I am sure it will come back soon though...Especially the way I drive.. ;)

It's the CRAPPY SLAVE Cylinder design.. Think about it.. Everything in the clutch assembly can be replaced be aftermarket parts including the Master....

But Not that $h1tty Slave... You can MAKE A FORTUNE if you design, build and market a heavy duty slave for the C5.. :cheers: :smash:


[Modified by chuckster, 6:48 PM 4/24/2004]

LoneStarFRC

:iagree: You're probably exactly right. As a matter of fact I surprised no one has done it yet. :lol: