Take Care of Your Clutch--Preventing or Curing Pedal Issues
 

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Clutch pedal issues have bedeviled Corvette owners since the advent of the C5. I got on the case after buying my first Z06 in August 2000 and pedal woes bit my new car. Since then, I’ve learned a lot about the maintenance a clutch needs to keep performing normally under aggressive driving. And I’ve shared those insights in many threads, emails, private messages and phone calls over the years.

To get the word out more effectively, I’ve distilled that knowledge into a seven-minute video that lays out the symptoms and root cause, and demonstrate a protocol for prevention and cure of clutch pedal issues.

I particularly want to thank George Westby, Director of the Advanced Process Laboratory of Unovis Solutions and his lead engineer Martin Anselm. They collaborated in the analysis of clutch fluid and clutch dust samples, which I sent them from 2006 Z06s.

Click here to download a copy of the Unovis lab report

That report forms an important basis for concluding that clutch dust is infusing the clutch fluid of aggressively driven cars. And it is clutch dust that, if allowed to accumulate, constitutes an abrasive that damages integrity of seals in the hydraulics.

For clarity sake, driven “aggressively” means cars that are launched or see high-rpm up-shifts or down-shifts. And consequential clutch problems affect many brands of car besides GM and motorcycles too.

The good news is that we have figured out the root cause. That means the preventative maintenance (frequent swaps of the fluid via the master cylinder reservoir) definitely works. It also explains why, if the seals are already damaged by clutch dust, no amount of clean fluid will heal them. The crucial element is prevention, never allowing the clutch dust to accumulate in the fluid. The tell of its presence is murkiness or cloudiness. So don’t allow the fluid to stay murky.

I think water entering the fluid via heat-and-cool cycles plays a roll in clutch pedal issues. So frequent changes of the clutch fluid ought to be part of routine maintenance for owners who don’t do aggressive launch or shifts. Suspect there are a few owners like that around.

Hope the video helps more owners avoid the trouble and expense of clutch pedal issues…and helps GM further reduce warranty claims for clutch issues easily avoided by preventative maintenance. The routine I personally follow costs about $20 and two hours of my time per year. That’s a small investment with a big return in reliability and driving pleasure.

Best to all,

Ranger

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Comparison of various brake fluids
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How the Clutch Hydraulics Work
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It’s always a good idea to go to the source document for a definitive description of the operation of the clutch hydraulics. In this case the Corvette Service Manual 2006, Volume 3, page 7-360, and I quote:

The clutch hydraulic system consists of a master cylinder and an actuator cylinder.

When pressure is applied to the clutch pedal (pedal depressed), the pushrod contacts the plunger and pushes it down the bore of the master cylinder.

In the first 0.8 mm (0.031 in) of movement, the recuperation seal closes the port to the fluid reservoir tank, and as the plunger continues to move down the bore of the cylinder, the fluid is forced through the outlet line to the actuator cylinder mounted to the driveline support assembly.

As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the actuator cylinder outward.

As the actuator cylinder moves forward, it forces the release bearing to disengage the clutch pressure plate from the clutch disc.

On the return stroke (pedal released), the plunger moves back as a result of the return pressure of the clutch.

Fluid returns to the master cylinder and the final movement of the plunger opens the port to the fluid reservoir, allowing an unrestricted flow between system and reservoir….

Close Quote. There you have if from the source.

Summary: Clutch fluid circulates between the master and actuator (slave).

Note: The volume of fluid in the entire system is a very few ounces. One ounce is in the master cylinder reservoir until diminished as you depress the pedal and create the flow described above.

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How Clutch Dust Enter the Fluid
Update February 17, 2009
---------------------------------------
Today I spent time at the workbench with two Chevy master technicians (one who’s worked on Corvettes since the C3 was first released). We examined the operation of the Corvette clutch actuator and concluded following:

1. The bell housing is fouled with blown clutch dust during aggressive driving.
2. Clutch dust is penetrating the accordion shield on the actuator main shaft. That is obvious from visual inspection.
3. The piston slides along the shaft sealed by an O-ring. The shaft has a film of lubricant or clutch fluid on it. During aggressive driving, this film gets coated on each stroke with a fine layer of blow clutch dust. That is obvious from visual inspection.
4. The O-ring slides along the shaft and squeegees some of the clutch dust down the shaft where it contacts the clutch fluid and is infused.
5. The conclusions were unanimous and seemed obvious from a physical exam of the surfaces involved.

Plus, keep in mind that it is confirmed that clutch dust is getting into the fluid. The question is how. We believe the answer to that is in points 1-5 above.

http://www.rangeracceleration.com/ho...lutch_dust.jpg

[The following two photos are courtesy of Chuckster; they are of a C5 actuator, which is very similar to the C6 version]

http://www.rangeracceleration.com/ho...or_exposed.jpg

http://www.rangeracceleration.com/ho...-ring-seal.jpg


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Minimizing Water Infiltration to the Clutch Fluid
Update February 23, 2009
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I've been following the protocol for eight years now and never had shift-related pedal issues. That's includes a lot of burnouts, launches, and red-line shifts. So what I'm doing is definitely effective.

Brake fluid is indeed hygroscopic. By my approach the cap is off the reservoir for very brief periods and, while that occurs, each time you are swapping about 35-50 percent of the used fluid with new. Do that one-to-three times and the impact of water absorption from the atmosphere is essentially nil. In fact the more times you make the swap in succession, the less the impact of transitory water infusion.

The industry standard for "wet" boiling point is the fluid containing 3% water. That's amount of water infusion is not going to happen in fluid that's kept clear and fresh via the reservoir. I suppose water infusion can be an issue if you remove the cap from the reservoir outdoors on a very humid day (or in the rain) and then take a lunch break. But few of us would do that. And a couple flushes by the protocol and the water is gone anyway.

Another aspect of risk is using brake/clutch fluid from a can that's been open for months or left with the cap off for an extended period. That's ill-advised. But I routinely keep a can going for 30-60 days by....
(1) cutting a slot in the membrane at the neck vice removing the entire seal
(2) replacing the cap when not pouring from it
(3) keeping the can in double layer of double-seal zip-lock bags between uses

Those steps minimize moisture infiltration to a can that's been opened.

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Details on Remote Bleeder
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Glazing the Clutch by Driver Error
Update June 4, 2009
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On Launch
A driver can easily glaze the clutch on launch by inducing too much slip from too high a launch rpm or riding the pedal to keep the rpm up. Either way, the friction surfaces overheat and the clutch’s clamping power decreases dramatically. Once the friction surfaces cool down again (30-60 minutes), the clamping force is fully restored without lasting damage.

Here are some other ways to glaze the clutch.

During a Burnout
Overheating the clutch during a burnout can happen when:
(1) you don't have enough water on the tire tread surface
(2) you position the rear wheels too far forward in the tacky rubber and then start the burnout. In this situation the rear tires have too much grip to spin at the hit of the clutch; so the clutch slips instead. This quickly glazes the clutch.
(3) you do everything correctly except continue the burnout too long, allowing the engine speed to be drawn down by the growing traction at the rear tires. A crossing point is reached and the clutch begins to slip. That produces a spike in heat in the rotating surfaces and the pedal reacts negatively.

During High-rpm Shifts and Power-Shifting
On a high-rpm shift (using the LS7 as an example) the flywheel spins at say 7K (pre-shift) and 200-300 milliseconds later the post-shift rpm is drawn down to 4700 (1-2 shift), 5100 (2-3 shift), 5400 (3-4 shift). Those rpm deltas produce significant heat that must be dissipated from the rotating friction surface. A power-shift makes for an even higher pre-shift rpm and yields even more heat. That's one of at least three reasons that power-shifting is risky and can have unintended consequences.

Cumulative Heat Leads to Malfunction
The LS7 clutch disc friction material has strands of raw copper interwoven to help dissipate heat from the surface. And there's substantial air-flow within the bell housing to provide cooling and evacuate clutch dust. But these design features can't deal adequately with the accumulated heat from
(1) Improper burnout technique
(2) Too high a launch rpm or too slow a clutch release
(3) Power-shifting or improperly timed high-rpm shifts
(4) Any combination of (1), (2), (3)

Once the cumulative heat reaches a break-point, the clutch either glazes entirely, losing clamping force after the launch attempt, or no longer disengages properly during high-rpm shifts.

Here's what I do to keep within the limits of the my clutch:
(1) Keep the clutch fluid clean including changes between passes at the track (usually after 3-5 passes with my driving style).
(2) Keep the launch rpm at no more than 3600-3700 and make a fast, one-piece clutch engagement
(3) Refrain from power-shifting
(4) After every pass, I lift the hood and sniff the driver's-side firewall. If I smell even a slight "eau de clutch" aroma, I know I'm not getting the clutch pedal out fast enough. That rarely happens to me because I observe rules (1) (2) and (3) just above. The alternative is an aftermarket clutch with a different personality than the stocker.

A pointed warning to owners is to recognize the limits of your clutch. That means not adopting the all-out racing launches and power-shifting advocated by some drivers with stronger and more heat-tolerant after-market clutches. Such approaches give a dramatically truncated clutch life. My approach should give at least 200 drag strip passes at stock power-levels, before the clutch requires replacement.

For All To Read!! :cheers::thumbs::thumbs:

Great instructional video.

Thanks for posting.

The Ranger Method is an absolute must if you want to keep your clutch operating smooth!

Thanks for the great video and information!

:cheers: Ben

Where the hell have you been?:toetap:

Great read and video, thanks Ranger. Something to do today for sure.

Thanks for sharing this with us Ranger. :thumbs:

:iagree: without the toe tap...

I would like to add that even if you do not shift that aggressively that the clutch fluid will go murky in no time at all. My guess at a good interval would be every 1K miles for mild use.
Thanks Ranger :thumbs:

This is why this is the BEST Corvette site in the world....Great Job and thanks for sharing....:thumbs:

Thank you...We were just thinking about changing ours. The video is perfect. Thanks again..:thumbs:

COOL! Where can I find one of those jumbo reverse hypodermic thingies that was used to suck out the dirty fluid? Last time I did mine I used a turkey baster. It worked but not as good as the one in the video.

I can attest to Rangers advice and thank him every day. Since my first "event" I have followed his advice religiously and change the fluid frequently. This problem doesn't sneak up on you, it happens abruptly when you least expect it, so prevention is the operative word. Check that juice every week and/or after every time you "wring her out"!

Thanks, Ranger!!!

Hi Vette junkie,

The MixMizer can be found at Walmart, typically on a pegboard near the gas cans in automotive. Costs about $3. I've used the same one for 8 years.

Ranger

Mods, this is a stickie-worthy. May be better in tech section, if Ranger is OK with that?

Any M6 owner needs to implement Ranger's clutch fluid regiment as part of routine care and maintenance of their vehicles.

Just Do It!!!!!

:thumbs: :thumbs: :thumbs:

:cheers:

Very nicely done..:thumbs::thumbs:

I do not do hard launches (yet) but have followed your advice since picking up my 2006 coupe at the NCM. I have seen dark fluid every time and crud on the inside cap once. I do the process at every oil change. Your new video is great, nice work.
Mike

Thanks again Ranger :thumbs:

I first read about clutch maintenance on your website & my 08 w/ less than 4000 miles has had its fluid changed twice since May 08. Both times the fluid was dark only after a month or two.

BTW: for those that don't want to go to a WallyWorld, I purchased a 60cc irrigation syringe on amazon dot com for $8.23 including shipping from KCK Medical & it was medically sterile :yesnod:. Turkey baster FTL :nono:

Excellent! Very informative and great advice! I've been following this procedure ever since Ranger explained this situation quiet awhile ago.... Thanks again!! :thumbs::thumbs:

Terrific video!

Now if only someone could make a video on paddle shifter maintenance for us A6 owners... :lol:

Ranger,

Good to hear from you and appreciate your efforts. I have been using this procedure ever since you first posted and have had no problems for over three years. Few would investigate the root cause as you have and then so unselfishly share the results for all to see. Great job and thanks again.:thumbs::cheers:

Thanks much. I'm off to Wally World to pick one up. Great job on the video by the way. There's not a time that I log on and don't come away smarter. :cheers:

Appreciate the testimonials to the protocol and the all generous words sent my way.:flag:

Hi Marina Blue.

I tried to stay on the case until the root cause was identified. We were fortunate the the lab director at Unovis, a C6Z owner BTW, took a personal interest in the issue. Once the electron microscope was brought to bear, iron and copper in their elemental forms turned up in clutch fluid that had just a few miles of very aggressive launch and shift driving. Analysis matched them exactly to the samples of dust from the same vehicle's clutch disc. A second sample from a different car produced identical results. Mystery solved.

We can hope that GM will over time do some redesign work on the clutch hydraulics to reduce or eliminate the infusion of clutch dust into the fluid. But given GM's financial situation, we may be waiting a while. In the meantime, we have a preventative protocol that works and it's not much bother.

Best regards,

Ranger

Thanks Ranger.. I've been doing this ever since I saw your post a long time back... Great video... Appreciate the effort... :thumbs:

Thanks again Ranger, did mine yesterday as it continues to sit in the garage for winter:ack: It took me longer to run and get the GM Clutch fluid than it did to fill and flush the reservoir three times. Fluid was pretty dark and low at first, now nice and clear.

I just watched the video again (can't get the sound to work, but that's probably my problem) and I notice that you are also a role model for safety by not futzing with the Nav while driving!

Anyway, one more time, thanks, and as posted above, special thanks for sharing so freely and unselfishly. Amazing what results from passion.

Any recommendations on which fluid to buy ? (prefer something available at Wally World or local auto parts).

Prestone DOT4, shown in the video at 3:22, is available at most Walmart stores for about $2.60 per 12 ounce cans. If your clutch fluid is very dark, buy two cans. Otherwise one will do. I've used that fluid interchangeably with the GM-brand. No issues with mixing them.

Ranger

p.s. I have a question:

I do not doubt Ranger's theory because the consensus seems to be unanimous. But I am curious - I assume the hydraulic clutch circuit is a sealed system with a piston actuating components on the south end - all sealed.

How does clutch dust get into the fluid ?

Thanks Ranger :cheers: Next time I'll RTFM :lol:

I was planning on watching that video tonight while "kicking back" with a cold one. I'm on my way to Wally's now for other stuff and will pick up the components.

edit: holy sh!t !! I just looked at mine

bought the car new and it only has 4800 miles

:eek:

I'll be buying TWO cans ........

You must be in the population of vette owners that run theirs at the limit more often than they should. :D :cheers:

Mine was just as bad just as early.

Think of it this way. Let's say you have a pet door on the deck. It's for the cat. The cat passes comfortably thru that door.

You have a collie too. But it can't get through that door.

Not trying to over-simplify, just make the core issue understandable.

A seal on a moving part such as the main shaft in the actuator can have the effect of squeegeeing in small particles of clutch dust, while not permitting passage outward of the larger and more complex molecules of the clutch fluid.

Once in the fluid the particles migrate with the normal flow. They tend to precipitate out when not agitated. It seems clear the dust particles are causing nicks, abrasions, wear points on the seals, leading to failure over time.

Ranger

:D: :cheers:

While I don't abuse my baby, I do believe in "letting the horses run free (and often)"

Thanks Ranger. That does make sense. Dust gets on the shaft and the seals wipe the shaft.

Thank-you RANGER.

It's always nice obtaining information like this and appreciate the amount of work that went into your instructional video.

Nice to see you back and hope all is well.

Red Cell.:cool:

Most excellent, Ranger! Thanks for sharing! Don't be a stranger, Ranger!:cheers:

I have mastered the "Ranger" art of clutch fluid maintenance, now it's time to master his gear change technique.
Excellent article, very well made video, I have downloaded the HD version from Youtube.

THANKS !!

Great video
 

Dear Ranger,

I used your method two years ago and it worked great. I commented at the time, that based on the volume of the resovoir it would take three cans of new fluid to get the majority of old fluid replaced with new fluid by gradual mixing. You commented that this was about right. I used all three cans over a couple of weeks and the fluid has stayed clear for two years.

Thanks,

Rich

Thank you Roger for this very informative post w/video!

07' MN6 coupe with 23K on the ticker. Last week, while having my oil changed, I had my cluth fluid checked. It was completely black! They poured in new fluid. Just today, I checked on it again, and it's already solid black. I do NOT shift or drive aggresively!

Questions:

1.) Does this mean that it's too late for me? In other words, do I already have a case of "Clutch Fluid" syndrome, which will require the car to be sent to the shop?

2.) If so, is this something covered by Warranty

Now that I've watched your vid, I will make sure to stay on top of this much more frequently.

I suspect you just need to clean up your fluid following the protocol in my video. Should be fine.

Ranger

Great info, thanks for posting Ranger.

Since mine is completely black, how often should I do this until the color is clear? Daily, weekly, monthly?

Also, I noticed in your video that there was a bottle of GM clutch fluid and a bottle of prestone, yet I noticed that you only used the clutch fluid. What was the prestone for?

Video at 6:07 states to repeat as many times as necessary until the fluid remains clear after the pedal pumps. In extreme cases, 10-20 swaps are needed to clean it up.

The Prestone shown is a viable alternative, if the GM-brand shown isn't available conveniently.

Ranger

I hate doing this so I've only been doing it every few months or so. It's never been black, but it does get darker.

This is only my second stick shift car. Do they all have this problem?

Some of my own notes -
1. I tried using a turkey baster, but the residual dot4 eventually melted the plastic! So I went back to the mixer syringe.

2. I keep a dot4 can inside a plastic ziplock in my trunk, stowed amongst a bunch of towels and things. I've noticed that it can seep out from under the cap. Where it's touched the label of the can, the paint has dissolved. The ziplock hasn't dissolved though.

3. My dad (vetterodder) warned that when you use the syringe, be careful not to suck it out of that straw-sized opening at the bottom, because you might introduce an air bubble in there when you pour the clean fluid in. So I always leave a tiny bit in the bottom of the reservoir.

4. The person who invents a mod or something that eliminates this problem could sell it for a good profit.

Thanks for info. I'd been concerned about this almost since I took delivery in July. I changed it yesterday (first time) at 7 months/4300 miles. It was completely black, and had been for a long time.

A bunch of changes knocked it down to a brownish color, after which it took the the rest of the 12 oz Prestone bottle and half of another one until it finally stayed clear after pumping the pedal.

I had tried on Sat. to get the GM fluid, but oddly enough it was ridiculously hard to find and list price was about 3 times as much as the Prestone DOT 4.

Thanks to the video, I finally understood how the presure relief insert inside the cap was supposed to be folded up. When I got the car, it was unfolded and crumped up inside the clutch fluid reservoir.

I've done this a few times. The 1st time the fluid was NASTY and crud on the underside of the cap. I didn't know about this on our C5. That had to be extremely dark fluid when traded at 33K miles.

Fluid Flow between Master and Actuator (Slave) Documentation
 

Brought over from a the Autocross/Roadracing board from a parallel thread on the topic.

Hi Rob.

It’s always a good idea to go to the source document for a definitive description of the operation of the clutch hydraulics. In this case the Corvette Service Manual 2006, Volume 3, page 7-360, and I quote:

The clutch hydraulic system consists of a master cylinder and an actuator cylinder.

When pressure is applied to the clutch pedal (pedal depressed), the pushrod contacts the plunger and pushes it down the bore of the master cylinder.

In the first 0.8 mm (0.031 in) of movement, the recuperation seal closes the port to the fluid reservoir tank, and as the plunger continues to move down the bore of the cylinder, the fluid is forced through the outlet line to the actuator cylinder mounted to the driveline support assembly.

As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the actuator cylinder outward.

As the actuator cylinder moves forward, it forces the release bearing to disengage the clutch pressure plate from the clutch disc.

On the return stroke (pedal released), the plunger moves back as a result of the return pressure of the clutch.

Fluid returns to the master cylinder and the final movement of the plunger opens the port to the fluid reservoir, allowing an unrestricted flow between system and reservoir….

There you have if from the source.

Summary: Clutch fluid circulates between the master and actuator (slave).

Note: The volume of fluid in the entire system is a very few ounces. One ounce is in the master cylinder reservoir until diminished as you depress the pedal and create the flow described above.

Hope that helps.

Ranger

Thanks for posting. I have a 05 Z51 6 speed and that will be beneficial information for care and maintenance of my Corvette.:thumbs::cheers:

After this procedure, did anyone notice a difference???

Placebo effect?

Hi Ahmer. You might want to read the thread. Plenty of members have answered that question.

Ranger

Ranger,

I spoke with my service department regarding my situation, to which I explained in detail. I ended my sentence with...is this covered under warranty. He kind of danced around the question and said that it's quite normal for Corvettes. I'm thinking to myself, they're trying to avoid servicing it (should I take that route) because of GM's deadline tomorrow.

Your thoughts/opinions, or advice. I'd like to make sure that I'm fully armed with info if I decided to take her into the shop.

My suggestion is to follow the protocol as self-help. Dealer will deal with it under warranty if the pedal is sticking to the floor. But...that would mean the tech might want to check it out for himself by hammering the car....If they bleed the system the dealer-way, they will get clutch fluid all over the inside of the bell-housing. If it splatter on the clutch disc, you'll be worse off still.

Much easier and less risky to follow the protocol on a do-it-yourself basis.

Ranger

Where is the bleeder valve for the clutch?

I'm used to my FBody, and have installed a remote bleeder, so I just use that to flush out my lines, is it possible to do something like that?

- Corvette Newbie

Bleed valve is not easy to access without dropping the exhaust and tunnel cover. here are two pictures of a C5. C6 is very similar.

http://www.rangeracceleration.com/ho...tor_slave1.jpg

http://www.rangeracceleration.com/ho...tor_slave2.jpg

From my files:

Open quote

Bleeding a Clutch Via an Installed Remote Bleeder

Courtesy of “wrencher,” a moderator on LS1Tech.com and a GM Tech by profession

A remote bleeder and Mity-Vac are absolutely essential to making the procedure a one-man operation.

Connect a Mity-Vac to the outlet on the remote bleeder. To ensure a tight seal, apply a little “sil-glide” to the threads on the bleeder

Then drain the reservoir with a syringe. Refill with clean fluid.

Then proceed to pull a vacuum & pull the fluid in normal flow direction w/ the Mity-Vac brake fluid bleeding attachment.
Keep doing it till the fluid comes out clean. Make sure you keep the reservoir at the proper level throughout.

I usually keep an eye on the fluid color & flush by the look of it.

I drag race my car a lot. I flush before and after every track visit.

When I don’t, the pedal changes & I know it's flush time.

I do a fluid change & all is well again.

By following this routine, I’ve kept my master cylinder working correctly for 3-4 years now. Close Quote


I put a remote bleeder on my cars...for the flexibilty of the next owner. For me, swaps via the reservoir are more effective and simpler. The two openings in the clutch actuator (slave) are less than two inches apart. That causes shallow flow during remote bleeding and won't rid the actuator of accumulated crud (clutch dust). That's a central purpose of the full and aggressive pedal pumps in my protocol, to bring the actuator and master crud into suspension and allow the particulate to be evacuated.

But that is the procedure for remote bleeding if you decide it's best for you.

Ranger

I will begin this process this weekend.

Can you advise me where to purchase the syringe?

Look at post #14...

Nice work! Thanks.

I did it... NICE AND BROWN at first... I had to repeat the procedure about 5 times until I lost the brown streaks in my clutch reservoir... I hope this makes shifting smoother...

Ranger, thank you very much for taking the time and effort! I will get on it this weekend.

New Information. I've edited the following into Post #1 on the thread....

------------------------------
Update February 17, 2009
------------------------------
Today I spent time at the workbench with two Chevy master technicians (one who’s worked on Corvettes since the C3 was first released). We examined the operation of the Corvette clutch actuator and concluded following:

1. The bell housing is fouled with blown clutch dust during aggressive driving.
2. Clutch dust is penetrating the accordion shield on the actuator main shaft. That is obvious from visual inspection.
3. The piston slides along the shaft sealed by an O-ring. The shaft has a film of lubricant or clutch fluid on it. During aggressive driving, this film gets coated on each stroke with a fine layer of blow clutch dust. That is obvious from visual inspection.
4. The O-ring slides along the shaft and squeegees some of the clutch dust down the shaft where it contacts the clutch fluid and is infused.
5. The conclusions were unanimous and seemed obvious from a physical exam of the surfaces involved.

Plus, keep in mind that it is confirmed that clutch dust is getting into the fluid. The question is how. We believe the answer to that is in points 1-5 above.

Ranger

Ranger, just wanted to say thanks for the heads up. I would have never known. Just finished mine this afternoon and it was just as easy as you made it look. Got all the materials at wal-mart and everything worked great. Thanks again .:flag:

I presume prestone brake fluid dot 4 is an acceptable replacement?

That's been a very helpful discovery. None of my other cars ever had this problem, so I guess this is a characteristic of modern Corvettes transmission/clutch design and location. I'd noticed the dirtying of the fluid since the first week I had my C6 and had always supposed it was leaching from black rubber lines or some such.

Now that we know for sure it's clutch dust, we can prevent the failures associated with having that abrasive in the system by replacing it as needed.

You detailed that the engine compartment reservoir replacement strategy is effective, and that the design (small volume capacity and substantial displacement during usage) is such that it can be cleaned out in a short time, using inexpensive and commonly available Prestone DOT 4 brake fluid, and without special tools (bleeders) or the need to get under the car.

My car is just 8 months old, and I expect to be keeping it for many years. I'm glad this potential trouble area is now covered by my DIY maintenance program.

Thanks Ranger!

Hi BAMF AE,

Prestone DOT4 is in my video because I have used it and verified it works well in a Corvette clutch hydraulics. There are other good fluids out there. But I only recommend those I have personally checked out.

Ranger

Where can you get the remote bleeder from? Also using the remote bleeder do you open it up and then the cap on the reservoir and let it gravity bleed?

I asked the question in the same thread in the tech section about is there a way to hose the inside of the bell housing down with some brake dust remover for wheels to reduce the amount of dust?

I assume the powder residue on the back of the car after driving it is the clutch dust huh?

Where did you say you got the extractor?

Thanks , makes sense to me.

Last but not least......YOU'RE AWESOME!!!! A major asset to the corvette community! I cant thank you enough! I worked on it last night, and it took approximately 4 cycles to get it from black to clear. I will continue to check on it regularly.

If it gets murky in the next couple of days, then that means I didn't cycle it enough, and will just have to repeat the process until it stays clear for at least a week.

I'll keep you posted!

:thumbs:

Ranger, Thanks a lot for the info. I just did my vette no problems. It is as easy as you say. I looked at my owners manual and it does not even list checking the clutch fluid on a regular basis. In fact it states that it is not necessary to regularly check clutch fluid unless you suspect there is a leak in the system. You may have just prevented me from having a problem with my clutch. Once again thanks a much.:cheers:

Checked mine last night .OMG, couldn't belive how dirty the fluid was, and i only have 9K on my 08 . Thank you for the GREAT information.

Ranger,

Great info! I checked mine after reading & watching your post last night and when I got home from work I checked the fluid. Sure enough, with less then 2200 miles on the clock, the fluid needs replacing.

Priceless information!

Thanks for that.

I forgot to ask...once this procedure is completed..how long should the fluid remain clear? days, weeks.....

That depends mainly on your driving habits.

My video at 6:28 provides the guidance on repeats.

Ranger

Added this thread to the C6 FAQ under Fluids and Maintenance. :thumbs:

Just checked on the price for GM's brake/clutch fluid . . . $18.00??? Prestone it is for me.

Thanks for this great info. I picked up all the materials tonight. One question - is there a recommended "fill level" marked on the reservoir? I looked but didn't see anything. Thx.

oh yeah - the Prestone works just fine...:yesnod:

half way between the max and min line or a wee bit more should be just fine. Check it after a tank of gas.

I picked up a 60cc irrigation syringe at a medical supply place. Cost was about $1.50

Walmart has them...

Great post very imformative and descriptive.

Thanks:cheers:

Ok, first off this thread offers the most informative literature I have ever read! Thanks Ranger! :thumbs:

I just performed my fluid swap... The initial fluid in the resevoir was murky and appeared very dark. I sucked it out with the syringe and cleaned the resevoir out. Poured new fluid and pumped the clutch pedal 30 times. Came back out and only seen a few dark swirls of clutch dust. Maybe it wasnt that bad, but I will keep my eye on it the next time I take the car out.

can i use a dot3 brake fluid.

did my fluid swap today came back murky twice so i did it about 4 times and now it looks great.....this is def the most informative bunch of people i have even come across thanks guys and it makes owning a corvette just that much more fun knowing that you have this wealth of information from so many people available

The owners manual says to use Super DOT-4 brake fluid why ask for trouble? :willy:

I did mine today also, yesterday i had the car out and the pedal got stuck to the floor. I cleaned mine took it for a short ride and it got darker again. I hope I didnt blow a seal that its getting dark fast like that.

I am from SI too! We probably passed each other on hylan!

Welcome to the forum and congrats on your new vette! You picked the right color too!

First mod should be to take the stock mufflers off and replace them with some stingers...
B & B and Corsa are fine also but the stingers give it a subtle growl.

I think the first time you do it that it will take 5-6 times to get it clean. I changed it out 3 times, drove it a few days and it is black again. I am going to change it out 6 times this weekend.

That is comforting to know, I better buy another can of DOT 4.
Pumping my clutch pedal (car parked) isnt cycling it well. I just figured driving the car (creating dust) and a blown hydraulic seal that was the reason it got dirty really fast.

When doing the pedal pumps after swapping the fluid, be sure to allow the pedal to cycle into the full-up position on every stroke. If you miss the top by even a scant 1/8 inch, the valve to the actuator (slave) remains closed, preventing the mixing of new and old fluid. Full top-to-bottom-to-top cycles of the clutch pedal is what you want.

That said, driving the car works too; just add to the protocol duration.

Ranger

Thanks for the info

George Ware

well its good to know another staten islander is on here....btw i was driving today and i checked the fluid afterwards and it still looks good no black grime so i think so far so good.....:cool:

I think this is what I was doing wrong... I sort of kept my foot on the clutch (and it probably did miss by an 1/8"

I will do this again tomorrow bright and early, thanks for the heads up!

Good news, mine has black in it still. I may have to repeat this about 5 - 6 more times.


Ranger 1 quick question?

Is there a way to determine if I blew a hydraulic seal???
I keep thinking I did just that when my pedal stuck in the down position the other day during a hard launch.

It's not unusual for the clean-up process to take 20 swaps or so.

Regarding the hydraulic seals, once the fluid is clean and remains so, then you'll know whether or not a seal is compromised if pedal issue become chronic.

But pedal hangs on a hard launch can also reflect too slow a release of the clutch pedal. High-rpm pedal hangs with real clean fluid indicate a hardware issue.

Ranger

Thank you for sharing all this great information.

Prestone DOT 4 is $3 at WalMart.

I did have the RPM's up to abour 3500 or so, then pulled the pedal to the half way mark (as the clutch bites). This time it only came up about 2 inches and hung there while I had my foot on the gas. The engine was revving higher as I pushed on the gas but the car wasnt moving. It was then I looked down and seen the pedal still down near the floor. I tried stepping on it and it wouldnt move until I took my foot off the gas. Then I noticed this strong smell of something burning... (smelled like brakes do when they get overheated). I suspect it was the clutch that took the brunt of this ordeal. It smelled like that for a while and then went away. I pulled over and popped the hood, I knew it had something to do with the hydraulic fluid. It was black and directly on the MIN line. At that time I drove the car easily back home, I kept thinking the clutch wasnt grabbing like it used to (probably in my head). But if I heated the clutch up that badly I assume it wont work as efficiently as it should. (when brakes get too hot they lose efficiency also).

I was just thinking... Do you think GM should fabricate and/or retrofit some type of filter for that resevoir to prevent the fluid from getting contaminated too quickly?


A filter would capture the dust and not bleed it back into the line. And it would be alot easier to swap the filters out when needed.

You glazed the clutch by allowing significant slip on the launch. The C6 clutch does not tolerate that well. That said, once the clutch cools down again, it's fine. Clean up the clutch fluid and all is back to normal operation.

Ranger