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Why does the C6 have such a weak clutch hydraulic system?
Also the slave cylinder has a bad design where clutch dust accumulates and makes its way into the hydraulic system.
I see there is even a TSB for the MC. (TSB #14717) Where GM replaces it if your clutch pedal starts getting stuck to the floor. Shouldn't ALL the factory ones that are not revised be replaced under warranty no matter what? Is it even a true fix?
Also read this about the factory CM cylinder from Tick:
GM did not want to replace transmission and driveline parts under warranty, so they designed a very weak, anemic clutch master cylinder barely capable of moving enough fluid to fully disengage the stock clutch in perfect working order. With years of wear (and/or an aftermarket clutch that requires more fluid to disengage), the inadequacy of the GM Master Cylinder becomes even more apparent.
I just hope my factory CM Cylinder will not cause expensive drivetrain problems in the future.
Just wanted to vent. I love the car, I am just upset with the shifting. I also had a 02 C5Z where the clutch pedal would stick to the floor, so getting a 2010 with potential shifting problems isn't cool.
GM designed the clutch fluid line with 3 orifice restrictors in it (to slow the fluid returning back to the master cylinder).
Worst yet, the clutch pedal has an assist spring on it, which makes it easier to hold the clutch to the floor, but slows the fluid returning to master cylinder as well.
The reason for the above, if you try to dump the clutch at high rpms, it will cause the clutch to slip and burn up; to save the drive line.
Hence GM does not warranty the clutch (friction plate), so it becomes the sacrificial part you have to pay to have replaced, to save the drive line that they do warranty instead.
So if your car is under warranty still, keep all the above in mind, and what mods you are going to do that may void the warranty.
Sounds like you're not having problems yet so this is just my 2 cents.
My 07 Z wasn't having problems other than I hated the high clutch engagement point. Removing the assist spring helped with the feel, but still too high for my taste. Last winter I installed the TICK MC I bought 18 months earlier, even though I was still within the 10 yr coverage of the TSB. I also fabricated a pedal stop and used a C5 assist spring. With the adjustability of the TICK along with a MGW shiftier, it's damn near perfect for my (not real aggressive) style of driving.
Even with the Tick master cylinder, if you do not install the solid one piece braided line from master to slave, you are still leaving in a orifice restrictor at the hose connector to the slave cylinder via the OEM slave cylinder line.
As for with the improved OEM master cylinder, it did solve some of the problems, and it easy enough to drill out the 3 line orifice restrictor's instead. When done this way, you can swap out to the C5 assist spring/still solve the handing clutch pedal problem, and will be hard for GM to tell that you did anything to void the warranty on the car instead.
Here is a write up on the orifice restrictors and how to drill them out, being one at the line coupler to the master, one at the middle connector coupler on the master side, then the third at the connector conenctor for the slave.
They are at the bottom inside of the coupler fitting, and piece of drill rod is the easy way to feel them; and you just need to drill out the coupler ID channel to remove it, then blow/clean the hoses out to remove the drilling shavings.
Why does the C6 have such a weak clutch hydraulic system?
Also the slave cylinder has a bad design where clutch dust accumulates and makes its way into the hydraulic system.
I see there is even a TSB for the MC. (TSB #14717) Where GM replaces it if your clutch pedal starts getting stuck to the floor. Shouldn't ALL the factory ones that are not revised be replaced under warranty no matter what? Is it even a true fix?
Also read this about the factory CM cylinder from Tick:
I just hope my factory CM Cylinder will not cause expensive drivetrain problems in the future.
Just wanted to vent. I love the car, I am just upset with the shifting. I also had a 02 C5Z where the clutch pedal would stick to the floor, so getting a 2010 with potential shifting problems isn't cool.
There is a dust cover that surrounds the slave cylinder now, which C5's did not have
Mine had no trouble making it to 130K miles... so it's not something to worry about unless you're having issues.
Could it be better? Of course.
Remove the pedal "assist" spring if you haven't already
It appears that some Corvette owners are removing or disconnecting the clutch over center spring on their vehicles.
This is not a recommended practice and customers should be advised of the implications of such an action.
Recommendation/Instructions:
The clutch master cylinder has a compensation port that is positioned within 1 MM of the top of the stroke. The compensation port allows internal pressure in the clutch hydraulic system to be exhausted into the master cylinder and also provides for system refill as the clutch disc wears.
One purpose of the over center spring is to return the clutch pedal to the very top of the stroke to expose the compensation port. The second purpose of the spring is to provide for the designed clutch pedal feel.
Removing or disconnecting the spring may allow the clutch pedal to hang in an at rest position with the piston short of the compensation port. If the internal pressure is not exhausted the CSC may get stroked too far and a clutch hydraulic system failure may result. The C5 clutch hydraulic systems were built by AP. The C6 systems were manufactured by FTE. Also, the pedal must be in the full up position, with the compensation port exposed, to bleed properly.
Anytime a dealer gets a hydraulic system complaint, the tech should inspect to insure that the spring is in place and properly connected. Related customer complaints might include poor shift performance, improper clutch release or transmission synchronizer damage.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
Where having the assist spring in play (be it the smaller coil one out of the C5), is it hold the clutch pedal tight up against the top clutch pedal button, and prevents the cruse control from kicking out if you hit a small bump to dance the clutch pedal without spring off the button instead,
So the assist spring does two thing, with the most importation one being that is holds the pedal all the way against the top switch.
The second, it a good or bad thing, depending on how you look at it. when the spring cams over when the pedal about half way down, it is helping you to get the pedal to the floor and hold it there instead. The downside to this, is it more pressure for the fluid returning to the master cylinder that has to push the clutch pedal up off the floor to over comes the spring tension until it gets about half way up isntead.
So if you not a granny that need the help to hold the clutch pedal to the floor, there there is no need for a assist spring to help you get and hold the pedal down, but instead just a linear return spring to hold the pedal all the way up against the top switch isntead.
So we yank on the on play of these out (C6 assist spring on the left, smaller C5 assist spring on the right),
And install a clutch return spring like this isntead.
to add to this and maybe Dano would know, Does any supplier sell a full braided line (2 parts) that goes from the master to the slave and rid you of the restrictions?
I had a tick (still do) but just replaced it with a new oem unit. I grew tired of the adjustment and never felt like I had it just right. But since the removal of the tick unit, my clutch has stuck to the floor a couple times......it may just be coincidence it's hard to say
Short of drilling out the restictor in the stock lines, the only line that has no restrictors in it, is the Tick one piece solid hose isntead (the one that does not have the middle connector fittings, and that you have to remove the line off the slave to connect it directly from the master to the slave instead).
The glitch here, it has the tick master cylinder connector end piece on it, and will not work for the stock master cylinder.
If you are using the tick master cylinder with it two piece line (one that uses the center connection point connector off the oem slave line), then half the battle is done, and all you need to do it remove the line OEM line off the slave via the cross pin that hold it on, and drill out the restrictor there at that fitting, flush of the swaft out of the line, the reconnect it back onto the slave via the cross pin.
I had the pedal stick to the floor once and when I put the twin disk clutch in, I put a Tick with the one piece line and it has been trouble free for 5 years or so.
As started, the Tick two piece line removes two of the restrictors, and better yet, it eliminates the assist spring holding the pedal down to the floor as well.
So the magic of the Tick master Cylinder kit helping to solve the problem, in not in the Tick cylinder to begin with.
Hence just drilling out the 3 restrictors in the stock lines, and changing out from the C6 to C5 assist spring, or just going to a linear return spring will solve the problem as well.
Hence under high spin, the clutch has a lot of inertia holding it out, and this means that the return spring pressure on the pressure plate is less than stellar to get the clutch locked back up at high spinning forced . Now add in the restrictors that are slowing down the fluid back to the master, and the added spring tension of the assists spring holding the pedal to the floor that the slowed returning fluid has to over come, and this is what causes the floor stuck for a second clutch pedal problem of the clutch pedal not immediately returning up instead.
Note, notice how the clutch pedal will come back up one the revs drop back down isntead.
And Yes, GM designed the clutch this way to save the drive line. Hence they warranty the drive line parts, but not the pressure plate; so when you do try to abuse the car, your going to burn up a part that they don't warranty instead.
I have an old master laying around and can't find any restrictions. So I'm guessing in stock form, the 3 restrictions are on the slave side of the lines? The article from super chevy "camaro" was great but had some different parts than out c6's
The restrictors are in the hose lines, at the bottom of the fitting.
Take a rod the size of the fitting opening, and press it into the fitting deep enough and you will find them at the bottom of the fitting channels.
So one is on the fitting on the hose where it's roll pinned connected to the master, the second on that line at the other end for the quick connector, and the third is on the hose fitting for the slave cylinder.
And again, they are not at the end opening side of the fitting, but deep at the bottom of the fitting channel where the hose is gromit clamps on instead.
What would be the threaded end sides of these fittings,
yes I follow that Dano but the C6Z line on the master is just a quick S-bend small metal fitting at both ends and then that plastic adapter for the to slave quick connect. I used a cotter pin and didn't see or feel a restriction on the master side of things at least 1.5inch deep. Looking at the photo above it looks nothing like mine. No braided line just a 3/16 line with an s-bend
yes I follow that Dano but the C6Z line on the master is just a quick S-bend small metal fitting at both ends and then that plastic adapter for the to slave quick connect. I used a cotter pin and didn't see or feel a restriction on the master side of things at least 1.5inch deep. Looking at the photo above it looks nothing like mine. No braided line just a 3/16 line with an s-bend
I had the new GM clutch master cylinder installed on my 2008 and the clutch pedal feels smoother and slightly less effort. I am also running a Mantic 9000 dual disc clutch and I can now say it really feels like the stock LS3/7 clutch.
Sorry It took a bit to respond. I really wanted to take a picture in order to explain myself a bit better. I may not be the original owner of the car but I did swap the master twice, both purchased through the dealer and this is one of them. What I don't see is restrictions on the master side. I have pushed a good size tie rap through the entire s bend of the master to demonstrate what I mean. Therefore as I was saying..... The restrictions must only be on the slave side. If so, swaping out the master for an aftermarket one does little if the slave as restrictions..... Exactly what dano523 said earlier. But still scratching my head about non present restrictions when everyone says there is. I have a spare slave that I will dig into soon and get to the bottom of this first hand. If there is a way to help flow with stock parts I want to do so.
06-22-2016, 12:54 PM
C6 Clutch Master Cylinder WOES
