NTMD8R

I had a 2007 Z51 convertible, bought in 2008.
In 2010, with less than 10,000 miles and still under warranty, the clutch
slave cylinder failed. It cost me $2800 for GM to fix it (not under warranty). Yes, we do serious autocrossing.
I now have a 2008 Z06 with 40,000 miles bought last September.
Last weekend the clutch slave cylinder failed.
This will cost me $3000.
Yes, we do serious autocrossing.

There are many threads/posts about clutch failures for C6 Corvettes.
There is quite an after-market business in offering non-OEM parts, and replacing clutches and components.

So I thought I'd ask people if they have had a clutch failure (likely slave cylinder) or not, and what mileage and kind of driving they do.
I am trying to keep the number of poll options to a not too large number, so please bear with me in the choices I have offered.

Thanks

Unfortunately it took more than 5 minutes to come up with all the 24 poll choices, and so this system won't let me post the poll questions.

So, answer here I guess.....

1. Clutch Failed with less than 25K miles, street and/or spirited driving
2. Clutch Failed with 25K to 50K miles, street and/or spirited driving
3. Clutch Failed with 50K to 75K miles, street and/or spirited driving
4. Clutch Failed with more than 75K miles, street and/or spirited driving
5. Clutch Failed with less than 25K miles, street/autocross/some track driving
6. Clutch Failed with 25K to 50K miles, street/autocross/some track driving
7. Clutch Failed with 50K to 75K miles, street/autocross/some track driving
8. Clutch Failed with more than 75K miles, street/autocross/some track driving
9. Clutch Failed with less than 25K miles, track/drag racing
10. Clutch Failed with 25K to 50K miles, track/drag racing
11. Clutch Failed with 50K to 75K miles, track/drag racing
12. Clutch Failed with more than 75K miles, track/drag racing

13. Clutch NOT Failed with less than 25K miles, street and/or spirited driving
14. Clutch NOT Failed with 25K to 50K miles, street and/or spirited driving
15. Clutch NOT Failed with 50K to 75K miles, street and/or spirited driving
16. Clutch NOT Failed with more than 75K miles, street and/or spirited driving
17. Clutch NOT Failed with less than 25K miles, street/autocross/some track driving
18. Clutch NOT Failed with 25K to 50K miles, street/autocross/some track driving
19. Clutch NOT Failed with 50K to 75K miles, street/autocross/some track driving
20. Clutch NOT Failed with more than 75K miles, street/autocross/some track driving
21. Clutch NOT Failed with less than 25K miles, track/drag racing
22. Clutch NOT Failed with 25K to 50K miles, track/drag racing
23. Clutch NOT Failed with 50K to 75K miles, track/drag racing
24. Clutch NOT Failed with more than 75K miles, track/drag racing

Barndog Buddha

No. 13 no clutch failure w/22,500 miles street and spirited mix

CMY SIX

20 20 20

Amric

36k miles at 550hp on stock clutch with no failures

Dano523

Be specific!!!!

Bank that is was not the slave that failed, but the slave's plastic threw out bearing pivot race sleeve that failed instead.

So banking that this happened,


And had you changed out the plastic race with a metal race, would have not had the problem isntead.


Plastic on the left, metal on the right.


And how it installs,



Lastly, before you install the slave with torque tube, be dam sure that the TB has .125" free play (TB spring compressed all the way in) before engagement to the fingers. Too many times the clutch is installed without checking the free play between the TB and the clutch fingers and if there is not enough free play, the TB will be under constant load to not only burn the TB out, but cause the burnt plastic TB pilot sleeve melting as well.
With the metal pilot, you won;t burn it up, but the TB is still going to burn if you don't have at least the .125" free play to begin with (correct range should be between .125" to .150", but some after market clutches are different, and may have a wider range instead) .


As for the Oem Sachs clutch, it's normal to burn them up if you are abusing the clutch/shifting at high revs with too much over gassing. It was designed to slip to save the drive line since it was the part that GM does not warranty instead.

As for burning the clutch up auto crossing, the Motor has more than enough torque, so there is no reason to slip the clutch every gear change like your on a 125 two stroke motor cross bike. Hence get the thing in gear and off the clutch before you get deep into the throttle, instead of trying to run too high of a gear and play the grunt clutch slip game to control the back end instead.

Also, if you get the throttle mapping re-tuned, you can play rev ranger with the motor and control the back end just like as you did coming up from Kart. With OEM stock throttle mapping, there is too much of a delay between pedal to motor response (GM did this to get better gas mileage and to prevent gas pedal bucking) for rev ranging the motor out of a corner to be able to control the rear end predicable isntead (why so many people try to grunt out of the corner using the clutch with too high of a gear, and end up burning the works up instead).

To prove if you are slipping the clutch too much, data log the AC kick out switch (top of clutch pedal switch) with your data logs for runs. It should be just like your time between gas to brake and back, with less than a half second at any given time for auto cross (longer for high speed track work where you are on the clutch and brake with heal/toe as you are dropping down a few gears to get ready for the hard drive out of the corner from a High speed section after the apex isntead).

HC Mechanic

Where do you get the metal race?

Does the ZR1 have a better slave cyl. we can use?

69 L46 4 Speed

18...

Dano523

Sorry and forget to post the link that the photo's came from to order the metal race.
https://www.corvetteforum.com/forums...-cylinder.html

http://monsterclutches.com/c6-corvet...earing-support

The install directions,
http://monsterclutches.com/billet-bearing-install

Or
http://www.quartermasterusa.com/qm/b...cylindershtml/

As for the OEM race on the ZR1, it's plastic as well.

To add, the harder you are on the clutch (more clutch dust in the housing), the more you need to Ranger power flush the fluid.
The Slave lacks a front side scrapper on the U seal, so over time clutch dust gets on the main sleeve to end up getting into to the fluid as the U seal is pushed out wards to drive the clutch inwards.

https://www.corvetteforum.com/forums...-and-cure.html

So this is the normal conditions inside the bell housing.


Here is where it going to pack,


And since the U seal does not have a forward swiper edge to push the abrasive clutch dust fouling forward on the sleeve,

it end ups riding over some of the fouling to trap it back in the fluid isntead. The more clutch dust in the fluid, the faster is going to wear the U seal to cause it (slave cylinder) to leak instead).

How to ranger flush,


As for the first time you do the ranger flush and your fluid was dirty to begin with, it may take a few times over several weeks until the fluid stays clean for a while. From here, it just a mater of changing out the fluid without having to do the pumps as the fluid starts to turn a light amber again (maybe every few months for normal street use, or after every autocross or high speed track use; depending on how badly you are abusing the clutch each event).


To bottom line it, your slave, the TB and even the pilot bearing, should long outlive your pressure plate[s]. If you are wearing these out faster than the pressure plate(s), then you have problem on hand that need to be resolved, even if they are being self induced.

HC Mechanic

Really appreciate it Dano

Unreal

Never seen a plastic race melt if clutch it working properly. Once it slips, or isn't disengaging properly they can be damaged, but on a proper functioning clutch, zero issues.

Stock clutch wouldn't hold 700rwhp
Put LS9 clutch in it, it wouldn't hold 900rwhp
Put Mantic twin, did 24k miles at 1100-1200 miles before it started slipping under full power
Put a Mantic Triple in it, 3k miles now and no issues.

Stock GM slave the whole time. Same with all the other corvette clutches I've installed.

Now maybe its worth it since its cheap insurance, but the shops I deal with do 100s of clutches, and never once had that issue unless it was a bad clutch take it out.

Joe_G

Dano523, GREAT post as usual.

I have 80,000+ daily driving miles, 497 track passes and a few HPDE's on my original equipment clutch.

I've been following the Ranger clutch fluid procedure since new, and I removed the pedal spring 10 years ago when I installed a cam and the clutch started sticking to the floor on the drag strip.

I think that qualifies me to 24 on your list.

BSPC608

Master cylinder failed covered under GM extended warranty. Happened this year 1 - 2 shift clutch went to floor and would not return driving on street no drag racing but plenty of track days less than 8,000 miles.
5 or 9

cdngolfer

I had clutch pedal to floor issues

Put in a Katech billet slave as the Ls9X slave melted. No problems with slave. Have Tick master too.

Pedal goes to floor every time I am over 5000 rpm. Maybe I have a bleeder leak....

Tick and Kaytech had no sure answers

Using Motul 600 fluid

hippy

Currently 14 and 15. On 15 I've been doing The Ranger method for 2 years. On 14 I started this year.

NTMD8R

Well, thanks to all who responded.
I was obviously mistaken in thinking that the clutch (slave) failure was
a large issue. I guess my 2 experiences with 2 C6 Corvettes was unusual.

Of course, I do/did use the Ranger method... but now, with the remote bleeder,
I'll be flushing the fluid completely several times a year.

HC Mechanic

In my experience in road race the Motul fluid was some excellent stuff, but in my C6 that's another story. The cheap fluid works WAY better.

I'm now in the habit of soaking the fluid out of the tiny GM clutch fluid bottle and replacing with fresh dot 4 fluid. I'll post a picture of what I've found to work best. Believe it is Prestone..

Clutch slave has functioned great ever since. And I did destroy one btw. Not sure of the exact cause, only spirited street driving; what our cars were designed for.

HC Mechanic

Come to think of it, the slave died shortly after switching to Motul. Clutch functioned the same on that stuff, routinely sticking to the clutch pedal floor under spirited street driving conditions.

Curt D

#10 for a buddy with 08 base. Pedal stuck on floor. Not under warranty but he mentioned the TSB 14717 and everything was covered 100%

meanjoe

#14

NTMD8R

Well, DAMMIT !!!!!!!
It has just happened again !!!!

So, last May 26 (2017) I go my GM dealer to replace clutch assembly, flywheel, master
cylinder, slave cylinder, and install a Tick remote bleeder. This was because my pedal was stuck on the floor.
So I figured, let's do EVERYTHING. So $3500 CDN later it is all done.

We did 4 autocross events in June, and 3 in July.
At the July events, we noticed that the clutch pedal would not always come back up fully.
But we could just put our foot behind it, and pull up... up it came.
This went on for the last 2 events in July.

2 weeks ago, I decided to replace the clutch fluid.
Open the master cylinder reservoir, and it is empty.
What ????? (the car is up on a hoist) Look all over, under, around, etc., etc.,
no sign of fluid leaking anywhere. Nothing on my garage floor,
nothing on the bell housing, nothing on the driver carpet... where is it going ?

So we replaced the fluid (power bleeder), and made sure it was full.
I drove it home from the shop. Pedal usually comes up fully, but not always.
Sat in the garage until today for our latest autocross.
I checked the fluid level last night, and it was down a bit, so I topped it up.

Drove to the race site this morning (25 miles highway and city driving). Pedal worked OK.
We started our runs (2nd group) at 10:50. I went first, pedal worked OK
until run was over, then went back into only partially up. Bring it back up.
My wife was next... get up to start line, pedal was fully down, and wouldn't
come up at all. I manipulated it for her.... up/down a few times, and it seemed to be OK.
She made her run, and then the same thing happened as for me... pedal would only come up partially.
So we played with this back and forth for the next 2 runs each... intermittent pedal.
It would engage the clutch OK if it had enough travel.
Now I am ready for my 4th run. Clutch pedal is now only working on bottom 10% of stroke. So it is really hard to shift with hardly any travel. And after my first shift to 2nd,
that's it... fully on the floor. So I limp back to the pit area in 1st gear.
I can't shift in or out of gear because it just wont engage now.
Guys push me into our pit spot.

I check the clutch reservoir... EMPTY !!!!
Again, where is the fluid going ???????

I got a ride to a parts place and bought some Dot4 fluid.
Another guy loaned me a couple of wrenches, and we did a slow bleed and fill
(manually pressing and releasing the pedal). I aimed the remote bleeder back into the
reservoir to catch any fluid that did come out.
So we were able to get the clutch to work again, after we bled and filled the reservoir.

We did not want to take another chance on losing fluid so quickly, and being stranded
on the highway, so we decided to NOT drive it home.

So, again, flat deck it to dealer to check things out.

Dealer can't look at it until Tuesday... I'll keep you posted.