C6 Clutch and Brake Fluid

[Patrick H.]

Re: C6 Clutch and Brake Fluid

Don,

Over on CF the Prestone DOT4 is the most popularly recommended replacement:

http://www.autozone.com/brake-and-power-steering-fluid-additives/brake-fluid/prestone-12-oz-dot-4-brake-fluid/433371_0_0/

Here is a good thread:

http://www.corvetteforum.com/forums/c6-corvette-general-discussion/2250773-take-care-of-your-clutch-preventing-or-curing-pedal-issues.html

Watch the video.

Remember, it takes 7 empty-and-fill cycles to say you've flushed the whole system. At 30-40 clutch pedal pumps per cycle you're looking at a lot of leg work. However, it really does not take a lot of fluid each time. I use a large syringe to empty it ( I have a good supply ), and make a linear hole from the edge to center of the metallic seal on the top of the fluid before dispensing. This does help minimize the splashing of the fluid, but I still hold a couple of rags around the reservoir.

[Larry M.]

[Don L.]

Re: C6 Clutch and Brake Fluid

Huh. I'm suddenly feeling abusive and neglectful. I've always (now used to) taken pride in maintaining the car. Heck, it's only gotten rained on once.

I'm on it. Luckily, I have a syringe just like the one in the You Tube video.

Thanks for the advice!

[Duke W.]

Re: C6 Clutch and Brake Fluid

Brake fluid material and performance specifications are controlled the the US Department of Transportation. That's why the prefix to the numbr is "DOT". DOT 3 and 4 are commonly available at auto parts stores, and I'm sure it's less expensive that the same thing from a GM dealer.

I use DOT 4 in all my cars -brake and hydraulic clutch controls. DOT 4 has higher wet and dry boiling points and it may also have a better anti-corrosion additive package.

Duke

[Gene T.]

Re: C6 Clutch and Brake Fluid

After reading this Thread, I changed my Clutch Reservoir fluid this past weekend. I own a '99 FRC which I have possessed for 11 years and it is still a 'virgin' to rain drops or a dirty road. I was amazed when I removed the rubber boot inside the reservoir and saw the dark fluid and garbage floating inside. I used the recommended 'turkey baster' to remove the old fluid. I did not drive the car after adding the new fluid. I will pump and repeat this process once I am back in town and able to so. Thanks for all of the tips on this easy process.

[Patrick H.]

Re: C6 Clutch and Brake Fluid

After reading this Thread, I changed my Clutch Reservoir fluid this past weekend. I own a '99 FRC which I have possessed for 11 years and it is still a 'virgin' to rain drops or a dirty road. I was amazed when I removed the rubber boot inside the reservoir and saw the dark fluid and garbage floating inside. I used the recommended 'turkey baster' to remove the old fluid. I did not drive the car after adding the new fluid. I will pump and repeat this process once I am back in town and able to so. Thanks for all of the tips on this easy process.

Gene,

You'll have to repeat it a lot more than once to get clear fluid.
Been there, done that.

Patrick

[Larry M.]

Re: C6 Clutch and Brake Fluid

After reading this Thread, I changed my Clutch Reservoir fluid this past weekend. I own a '99 FRC which I have possessed for 11 years and it is still a 'virgin' to rain drops or a dirty road. I was amazed when I removed the rubber boot inside the reservoir and saw the dark fluid and garbage floating inside. I used the recommended 'turkey baster' to remove the old fluid. I did not drive the car after adding the new fluid. I will pump and repeat this process once I am back in town and able to so. Thanks for all of the tips on this easy process.

Driving the car and shifting gears = pumping the clutch pedal for the "Ranger Method" we are using.

I simply drive my car and change fluid (again) the following weekend. It requires 6-7 changes like this to stay clear.

Larry

[Gene T.]

Re: C6 Clutch and Brake Fluid

I simply ran out of time. I fully understand it will take 6 or 7 times to get clean fluid. I don't drive the FRC very often and I will have to continue with the flushing when I return home.

[Ray G.]

Re: C6 Clutch and Brake Fluid

Hello;
We have made it a practice to change the reservoirs brake and power steering fluid every 5000 mile with oil changes in our daily drivers and periodically in classic Chevrolets and Corvettes.
There is a noticeable change in ABS and PS systems in vehicles with large tire footprints that are strained in parking situations like the Corvette
and Silverado SS pickup.
my .02
Ray

[Gene T.]

Re: C6 Clutch and Brake Fluid

Thanks everyone to those who have given tips on more preventative maintenance on our Great American Sports Car. The clutch reservoir has been overlooked by me, but will not be in the future.

Gene

[Joe L.]

Re: C6 Clutch and Brake Fluid

There was a bulletin on this issue...


#PIP4938: Discolored Dirty Dark Sludge And/Or Grease In The Clutch Fluid Reservoir - (Aug 4, 2011)

Subject:	Discolored Dirty Dark Sludge and/or Grease in the Clutch Fluid Reservoir
Models:	2004-2012 Cadillac CTS CTS-V
2000-2012 Chevrolet Corvette,
2004-2012 Chevrolet Corvette Z06
2009-2012 Chevrolet Corvette ZR1
2004-2006 Pontiac GTO
2007-2009 Pontiac G8
Equipped with manual transmissions

---

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:It may be observed on some vehicles that the clutch fluid in the reservoir appears to be discolored, dirty, have sludge or grease contaminates in it after being in service for a period of time.
The level of discoloration will vary with factors such as driving conditions, under hood temperatures etc.
This is a phenomenon that may occur with time due to the interaction between the clutch system rubber parts and hydraulic clutch fluid. Comments have been received about the fluid in the hydraulic clutch system being discolored. This discoloration is the result of carbon black used in the seal manufacturing process leaching into the hydraulic fluid used in the clutch system. The discoloration may also collect on the inside of the clutch reservoir at the top of the fluid. This discoloration does not affect the operation of the clutch system and should not be considered a reason to flush the clutch hydraulic system
The small amount of sludge or grease that may be noticed is, in fact, grease that has migrated from the master cylinder assembly. The grease is used during assembly of the master cylinder.

Recommendation/Instructions:Engineering investigations of returned fluid samples show that discoloration and grease in the fluid DO NOT negatively affect the performance of the clutch hydraulic fluid.
Field reports indicate that where clutch fluid and or clutch system components have been replaced to address this condition, the vehicles have returned with the same condition causing a repeat repair and a dissatisfied customer.
Discolored clutch fluid should not be replaced in a normal operating system. See latest version of tsb 07-07-31-001 and maintenance schedule for clutch fluid service.

For Clutch System Concerns and Diagnosis, refer to Diagnostic Starting Point– Clutch.
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.

John-------


The exact same condition has been present in my 1992 clutch hydraulic system for years. I always attributed it to the exact cause that the GM
Service Bulletin describes.

[Patrick H.]

Re: C6 Clutch and Brake Fluid

John-------


The exact same condition has been present in my 1992 clutch hydraulic system for years. I always attributed it to the exact cause that the GM
Service Bulletin describes.

I'll have to remember to change it.

[Joe L.]

Re: C6 Clutch and Brake Fluid

I'll have to remember to change it.

Patrick------


You've got to remove the ECM on 91-93 Corvettes to access the clutch master cylinder. It's not too difficult, though.

[Terry M.]

Re: C6 Clutch and Brake Fluid

That's a possiblity, but what evidence led to that conclusion? Also, if true, periodic flushing would likely have helped, and if true the design is deficient. And what about the possiblity of corrosion?

Any C5/6 owners who have to replace clutch master or slave cylinders should get the parts back, disassemble them and inspect for corrosion and debris.

In the meantime consider flushing the system.

Here's an interesting story. About 10 years ago the clutch began to drag on my '88 MBZ, and when I removed the slave cylinder the attached pushrod that bears on the clutch fork was worn and mushroomed. Disassembly of the slave showed the walls to be essentially brand new - no corrosion and no debris.

Bleeding an empty clutch slave can be difficult. The sure fire way to fill it up and purge air is to loosen the slave bleed valve about half a turn, then attach a bleed hose to a front caliper bleed screw. Then bleed the front brake calliper in the conventional manner, which will force fluid into the slave and up through the clutch master to the reservoir, which will quickly fill the system and purge air. The brake reservoir on the Merc also serves the clutch, but the inlet is well above the bottom, so if fluid is being lost, the clutch will quit working before the brakes fail.

Before I replaced the slave I flushed the brake system (It was about due.), so the clutch fluid was also fresh.

Duke

Duke,

One of the frequent posters in the Corvette Forum who goes by the handle of RANGER had his old clutch fluid analyzed and the results showed clutch friction material in the fluid. He posted a description of how he believed the cast off friction material gets into the clutch system, but a scientist would want more forensic analysis to confirm his beliefs.

The fluid change system that Jimmy, Patrick, myself and others use was developed and promulgated by Ranger. There are numerous reports on the Corvette Forum of improved clutch operation with frequent fluid replacement.

I do believe the GM bulletin that John D posted above is just so much whitewash. Like Jimmy, I can feel the difference with fresh clutch fluid in the reservoir even though I know it is not a complete system change. I carry the equipment to do the clutch fluid change with me in the C6 so I can do the change at stops ont he road. It only takes a few minutes and is in my mind worth the effort.