Z.06

My 2008 Z06 is tracked on a roadcourse. I have done this occasionally in past years, and have had it on track 14 times since April of this year. I don't race the car at all, nor do I beat on the car; the rev range in 3rd gear is so flexible, that it matches the track, so no shifting and no depressing of the clutch is necessary while I am on track. I do use the clutch for starts and gear changes on the pit road. A couple of weeks ago, while on track I found that my clutch pedal had sunk at least 2", such that disengagement of the clutch was occurring with the pedal nearly on the floor. I found that I could pick up the clutch pedal with the edge of my foot and it would come back to stock height and feel completely normal afterward.

At this point, I should state that I have owned the car since new, and have maintained the clutch fluid via the Ranger method. The clutch slave cylinder has never needed fluid and the master cylinder fluid has never been low except when I have sucked it out with a turkey baster. And then it is immediately filled with DOT 4 brake fluid.

Not feeling like bleeding the slave cylinder or changing the master cylinder myself, I took the car to my local Chevy dealer. I remembered the voluntary program for replacement of the master cylinders on my car. The dealer said that the program was only for cars that are less than 10 years old and my car was 7 months past that birthday, although it only has 31.000 miles on the clock. Anyway, he offered me a deal I could not resist, so I let the dealership replace the master cylinder. Everything seem fine afterwards, but I knew that the significant test could only be had at the track. So I went back to the roadcourse yesterday for a test. The repair did not work, and my pedal sank over two inches three times. Each time I discovered it, I would pick the clutch pedal up with the side of my shoe during the cooldown lap, and it would work perfectly.

Since the pedal is going partway down without me even pushing it down, I cannot think of any factor at play here except the heat from the engine and exhaust. My car has the OEM cast headers on it, no longtubes. And yet after I pick the pedal up, the heat, which is still there does not cause the pedal to sink again. It takes another track session, say 10 laps on a 1.8 mile track, to do that. Could it be water vapor in the slave cylinder? I have no remote bleeder, so installing this will be a real job as well.

Please advise if you have had similar experience and how it was finally resolved.

Z.06

BTW, I realize that a possible solution to my problem is the Tick clutch MC, but am not sure it is the solution. Why has GM's solution failed so completely? I still suspect that the problem on my car is with water vapor in the slave cylinder, but GM does not seem to want to look there. Perhaps this is because the recent generation corvettes have no suitable and convenient provision for bleeding the clutch motive fluid from the slave cylinder, despite GM's recommendation to bleed the clutch master cylinder fluid every 24 months.

JimsCorvettes

I had the same issue with my 2006 and after the master cylinder replacement, this band aid fix worked:

https://www.lingenfelter.com/PROD.ht...ode=L360080197

Not the best solution as not getting to the root cause.... But it worked.

ttx350z

Z.06

Still not getting what I need, so here are all of my Z's symptoms for consideration:
1. Pedal will go halfway down without any action or pressure on it. Disengagement point goes down as well, being just off the floor.
2. The only time it has ever happened is on track, and as you are aware I am not using the clutch at all. I believe heat from the engine/exhaust is probably a factor.
3. Without the car cooling off, I can pick the pedal up with the edge of my shoe and the height of the clutch pedal and the disengagement point are immediately back to normal.
4. After #3, I let the car cool and then go out to do 10 more laps, and the clutch pedal has dropped again.
5. If I do not pick up the clutch and let the car cool off, the pedal height does not come back to normal. I can drive the car all the way home and not pick up the pedal until the next morning. On the drive home, if I am not careful to push the pedal completely to the floor, the transmission will not want to shift, or it may grind the gears very slightly.
6. One I pick up the pedal, whether the engine is hot or cold, completely normal clutch action is back.

I get no clutch slippage and my car/engine/clutch only has 31,600 miles on it. The car is one owner(me) and I have never abused the clutch. I'm just trying to find out what needs fixing so I can take care of it.

I appreciate your responses.

0Tampa Tuning

Have you changed to a different DOT 4 Fluid.

My video isn't the greatest, but your get the point =
Camaro Corvette Truck Tuner in Tampa

Tuning@TampaTuning.com

double06

So basically they installed the black master cylinder in the car and the put new GM DOT4 fluid in it at the dealership?
If they did - that part is now taken out of the equation. Do you know what clutch is in the car - is it stock. I am wondering if the seals are going in the slave - your comment number 5 above would suggest that. What most people here do is get rid of the factory clutch. I had the same issues (I call it the "ghost pedal" - because a ghost must be pushing on the clutch pedal because it is not me) as you - though in my case the new factory black reservoir was not out yet. I went to a Mantic Twin still have the stock slave and new black reservoir and that was it. Maybe not what you wanted to hear from a cost stand point but you can read for days about clutch issues on this Forum and what seems to be a true 100% fix was to get rid of the factory clutch. You have the full stock exhaust or headers makes no difference it is still really hot in there and maybe more so with the cats tucked next to the bellhousing there in the factory set up. The dual disk aftermarket clutches seem to dissapate heat better and have a different clutch spring design. Of course GM changed the clutch design in the C7 and I don't think you here much about clutch issues over there. The Monster clutch uses this design if I remember correctly.

Z.06

The first time it happened it had Motul 600 in the clutch fluid reservoir (Ranger Method). Last time it happened was after the dealer had installed a new slave cylinder with the black reservoir. I presume the tech put GM's DOT 4 fluid in the reservoir. I also presume, but cannot confirm that he completely bled the air out of the connection.

Thanks for the video. Where do you get tubing small enough to go down the clutch hydraulic line to the bottom of the slave cylinder? Do you know that this length is 20" for a C6Z06, or does it vary from the C6 to the Camaros, etc? Does the line go all the way into the slave cylinder? If I understand correctly, the tube OD is sufficiently smaller than the clutch hydraulic line that the injected brake fluid will sweep any contaminants and all of the old brake fluid up into the reservoir, where the second catheter syringe is used to remove the old fluids and contaminants. One may be lucky enough to get some of the old fluid and contaminants from the slave cylinder as well. Do you do this more than once? I want to try this. I have some fresh Motul 600 on the shelf. Do you think this is OK, or should I go out and buy some fresh Castrol SRF?

Z.06

Yes to the black reservoir master cylinder. Tech confirmed using DOT 4 fluid and bleeding the air out at the connector. Clutch is stock. Car has 31,600 miles on it and I put all of the miles on it myself. No standing starts, no abuse, no riding the clutch. I normally get over 100,000 miles out of a clutch on a manual transmission car. I do have the stock exhaust headers and pipes, although my cats were gutted before I started having this sinking clutch issue. That should be less heat rather than more though, right?

I recently finished major work on my engine, so the idea of pulling out the driveline to change the clutch is really unappealing right now. I will try the idea above to reverse flush my clutch line first. If that doesn't work.....probably do a clutch next spring. Currently, my clutch pedal has never gone to the floor, and is manageable. How long have you been running your Mantic Twin? Any issues? If you were doing the job today, would you go with a Mantic Twin or a Monster or ?

double06

If you had the Motul 600 that is good stuff not sure if castrol is going to change it much. You can try the motul with the new master you got see if it works. The hole system takes like 6-7 ounces. The spring might be an idea. I can only speak about the Mantic Twin it works great. I with the heavy flywheel option as I live in a dense area and has lots of hills with stop lights. Drives like stock good clutch. You will see lots of good reviews on Monster or Mantic on the site here.

AHP

Remove the over-center (helper) spring, keep fluid clean. Problem solved.

Mr. Gizmo

Z.06

Thanks AHP. I will definitely give this a try as soon as I can figure out how to do it (and also how to wiggle into and out of my Corvette footwell. I am interested in trying out Tampa Tuning's backflush trick as well as soon as I can acquire a couple of syringes and some suitable catheter tubing. Better to try these easy things before yanking out the entire driveline to replace the clutch. Saving that for last resort.

Thanks Mr. Gizmo. My service date and 10 year anniversary passed last April. Nonetheless, I asked my dealer if they would give me a goodwill extension. They did this with me sharing $136 of the cost of the replacement (black) clutch master cylinder/reservoir. Unfortunately the new clutch master cylinder assembly did not help out things.

0Tampa Tuning

I also had the black master recall done to my ZR1 after I was stuck on the side of the road. The dealership added GM fluid and the fluid was black again within 100 miles. My first though was the dealership didnt bleed the system well enough. For the next 2-3 months ( changed the fluid 7 times), I used an off the shelf DOT4 and again 100 miles the fluid was black. Its mainly a waxer for cars and coffee. No It wasn't because the master is black. The fluid was black when I drained it.
I picked up all the supplies through Ebay. I used JB weld to seal the black tube to the syringe. In the back of my head, I was thinking that I didn't want for the tube to separate. I dont think that would happen once the weld dried, but over time Ive given it a tug to make sure the brake fluid didn't deteriorate the "weld".
I bought the 1/8' OD tube in a 5' or 6' length. The black tube was coiled up when it was sent to me, and as I drove it down the slave to measure how far down I could go, I met slight resistance at about the 20" mark and said to myself that's good enough. I could have pushed it in a little further to see if the resistance was me or a curve in the hose and could have snaked passed it to get deeper, but I figured what im doing was better than just cleaning out the reserve.

The first syringe I made, I slid the black tube about an inch into the needle end of the syringe. I found that left to much fluid in the syringe. The next one I made and use was the 20" line and "welded" it about a 1/4" in the snout of the syringe.

Process
1) Have the snake system ready with fluid in the syringe. Make sure you turn it upward and pretend your a doctor to cycle air out in the tube and syringe. I waste a good amount of fluid, but it beats inserting a air pocket.
2) I drain the master of existing fluid with a non modified 60cc syringe and shoot that fluid into a Gatorade bottle in the engine bay. Then close the cap on the bottle.
3) Clean out the master with a rag.
4) I use my 2nd syringe and I snake down my syringe 20 inches and introduce 2oz of clean SRF fluid, and pull the snake system out. This will fill up the master again to reduce introducing air. When you remove, make sure your following it up with a paper towel so it doesn't bounce out like a door stopper and splash fluid.
5) I drain that fluid out of the reserve and clean it with a rag again.
6) I refill the snake system, and I snake down my syringe with new fluid to 20 inches and add the final 2-3ozs of SRF.
Make sure you protect your paint from the brake fluid because it will eat it up quickly.
7) In hindsight when I was done, I hung the leftover tube from a cabinet with clamps at both ends in the garage to straighten out the plastic and I may have been able to fit a longer length down the master with the next syringe I "JB weld" up
I have a better video on my phone and go pro, but I haven't had a chance to edit it down.

When I went with the Snake and syringe method with SRF fluid that has a higher wet boiling point, now the fluid doesn't get black as quickly. Im a little ****, so I started to change the fluid every 3 months with the SRF. At best the fluid gets yellow/gold, and while im changing it, I say to myself it doesn't need it this often now with the SRF and snake method, I can change it at the 6 month mark...........which maybe is 1000 miles spirited fun driving for me.

Maybe the Snake and Syringe method is overkill. It cost me about $15 bucks, but was easy enough for a little more exchange of fluid and I like the idea of it. My thought was if I have to pump the clutch pedal to cycle fluid, let me try and snake down the hose to get more fluid in the first place.
I also use the SRF DOT 4 for the brakes. That hasnt never discolored but I figured WTF I might as well use the same fluid.

Hope it helps,
Phil
www.TampaTuning.com

Z.06

removed the clutch pedal spring and Rangered my black clutch reservoir with fresh Mogul 600 yesterday. Without the spring it feels like a real clutch instead of a light switch. Glad I don't drive it in bumper-to-bumper traffic anymore.

Z.06

Still trying to find a source for the tubing. My daughter is a nurse in a cardiac unit and all of the stuff they use is either 18 or 22 gauge, which is much smaller diameter. Do you have a place I can order it from? Also, the picture in your video makes the tubing look much same than .125" OD. Will 50 ml syringes work?

Apocolipse

Why dont you just install a remote bleed line instead if this mickey mouse stuff

0Tampa Tuning

I went back an checked my history, and I picked these both up from Fleabay not Amazon.

item sold by safecomponentsPressure Hose Nylon 1/8" OD Tubing .096"ID .125"OD Black Semi-Flex 5-ft R52 $5.27



sold by lbchiroandmed5-Pack 60cc 2oz CATHETER TIP Easy Glide SYRINGES 60mL NEW SYRINGE ONLY NO NEEDLE $6.85

Z.06

It's called not wanting to remove and reinstall the entire driveline until I am sure it is necessary. A better question is where Chevrolet gets off requiring that owners replace our clutch fluid every 24 months without providing either a remote bleed line of reasonable access to the slave cylinder bleed valve.

double06

You will still have to some type of ranger flush as this will only get about 40-50% of the fluid. The whole system is like 7 ounces 2 of which are in the reservoir. you will probably get another ounce with the hose here but the rest will be in the master cylinder slave cylinder and the lines going to it. I was able to measure it once with my bleed line and see how much it took to get the fluid clear again.