: Clutch Fluid Life



fredcook
10-20-07, 04:16 PM
What's everyone using for clutch fluid?

I've been battling shifting issues, and have been looking at clutch performance... and conversely bleeding and fluid quality.

I've always considered, as a general rule, when clutch/brake fluid gets dark (from boiling?), it should be flushed. My fluid was (at 36k) coffee black. I flushed, bled, etc., to a nice clear fluid. I did notice it was noticeably easier to get into gear and shift. The feeling that the clutch wasn't fully disengaging went away... for a while. 1k later, I noticed it's black again. Again, flushed and bled, bled, bled until nothing but clear fluid was bleeding. Now I'm at 38k, and .... black again (and shifts suck again).

Anyway.. my question is, as stated, what is everyone else using? I've looked for off the shelf high temp fluid, and only found 400 degree stuff (have to special order the high temp fluid).

Also, does anyone know what GM's fluid is rated at?

darkman
10-20-07, 04:48 PM
I have been using some Gunk brand DOT 3 fluid rated at 401 degrees F. I don't recall anyone recommending higher temperature fluid for the clutch, including those among us that track their cars.

I don't think the dark color is necessarily caused by boiling. In fact, I thought it is from contamination from moisture in the atmosphere, and the gradual deteriotation of the hose, seals, and pistons in the master and slave cylinder. I like to flush the brake and clutch systems in all of my vehicles (cars and motorcycles) at least every two years regardless of mileage.

Given your shifting problems it could be that either (or both) your master or slave cylinder are binding and thereby amplying problems casued by partially contaminated fluid.

nikon
10-20-07, 05:22 PM
so eh, how hard is it to bled the slave cylinder?...brakes I can do...but wheres the bleeder valve/procedure on how to do the clutch.

mcfaddens17
10-20-07, 07:45 PM
so eh, how hard is it to bled the slave cylinder?...brakes I can do...but wheres the bleeder valve/procedure on how to do the clutch.

The FAQ page is a wonderful thing:
http://www.cadillacfaq.com/faq/answers/clutchbleed.html

50 4Ever
10-20-07, 10:56 PM
I use the same as I do for the brake fluid, PFC Z-Rated.

When you are having problems getting it into gear turn the engine off and try shifting. If the problem goes away you might have the same problem I had, the flywheel was 0.020" too deep and the internals of the tranny were always turning.

I've heard if the level is at or below the "MIN" line you might have problems shifting.

Naf
10-21-07, 03:39 AM
Once you notice a change in color for the fluid would be a good time to change the fluid.

Think of the clutch like the brake system. In a sense it reacts the same way, and is exposed to similar heat and stresses.

I used Dot 5 in my system and loved it...The higher the DOT value, the less prone you are to moisture, and higher tolerance to heat you will have...But be ready to pay out.

PSSST, there is always the operators manual in the glove box, it has recommended fluid changes in it as well.

Feffman
10-21-07, 07:50 AM
As the clutch is more difficult (for me) to flush/bleed, I have the dealer do it about every 2nd or 3rd oil change. Bit of overkill, but the fluid goes black fast. IN between I freshen the fluid in teh clutch reservoir. I guessing the hose is the main cause of the fluid color. Need to have a braided steel clutch line made up.

Feff

Naf
10-21-07, 09:58 AM
As the clutch is more difficult (for me) to flush/bleed, I have the dealer do it about every 2nd or 3rd oil change. Bit of overkill, but the fluid goes black fast. IN between I freshen the fluid in teh clutch reservoir. I guessing the hose is the main cause of the fluid color. Need to have a braided steel clutch line made up.

Feff

That would help get rid of the squishy feelin, but it doesnt really protect it from the heat. You need a DEI sleeve over the hose to protect it more from radiant heat...

If you make a hose with teflon liner and you cover it with a heat sheild you aught to be better off. Plus go with a higher dot for less moisture and more heat resistant fluid.

rheagrimm
10-21-07, 12:12 PM
I use Valvoline Syn Power high performance brake fluid. It exceeds DOT 3 and DOT 4 and is good for 500 degrees. Syn Power is fully synthetic and compatable with conventional fluids. Advance Auto Parts normally carries it.

WheelHop
10-21-07, 08:54 PM
Ok, call me a smart a$$, but the clutch does not have fluid. It's kinda like headlight fluid.. The fluid is for master/slave cylinders, not really the actual "clutch"..

Hehe, sorry. Carry on. :D

darkman
10-21-07, 09:40 PM
Ok, call me a smart a$$, but the clutch does not have fluid. It's kinda like headlight fluid.. The fluid is for master/slave cylinders, not really the actual "clutch"..

Hehe, sorry. Carry on. :D

And brakes don't have brake fluid either! Another break through!!

WheelHop
10-21-07, 09:54 PM
And brakes don't have brake fluid either! Another break through!!

Well, if you want to get technical, if they didn't label brake fluid "brake fluid", we wouldn't really call it brake fluid. Kinda like we ask for a Kleenex but itís really a facial tissue. Go into AutoZone and ask for clutch fluid...

darkman
10-21-07, 10:01 PM
Well, if you want to get technical, if they didn't label brake fluid "brake fluid", we wouldn't really call it brake fluid. Kinda like we ask for a Kleenex but itís really a facial tissue. Go into AutoZone and ask for clutch fluid...

Well it just so happens I went to O'Reily's recently to get DOT 3 fluid and they sell a product that does use the misnomer "clutch fluid." I have forgotten which brand.

WheelHop
10-21-07, 10:22 PM
Guess they decided to use a new marketing route. :D

fredcook
10-22-07, 09:43 AM
I use the same as I do for the brake fluid, PFC Z-Rated.

When you are having problems getting it into gear turn the engine off and try shifting. If the problem goes away you might have the same problem I had, the flywheel was 0.020" too deep and the internals of the tranny were always turning.

I've heard if the level is at or below the "MIN" line you might have problems shifting.

Shifts fine with engine off. In fact (and it may have been one of your posts I used), I used the .020 info and asked my dealer to consider that. They weren't interested, and just keep telling me it's "normal".

fredcook
10-22-07, 09:54 AM
I have been using some Gunk brand DOT 3 fluid rated at 401 degrees F....

Bought some this weekend...

fredcook
10-22-07, 10:55 AM
I use Valvoline Syn Power high performance brake fluid. It exceeds DOT 3 and DOT 4 and is good for 500 degrees. Syn Power is fully synthetic and compatable with conventional fluids. Advance Auto Parts normally carries it.

Compatible, but can it be mixed (I assume not)?

Also, I remember early on (when the syn stuff came out) there were concerns regarding seal damage. Any substance to this?

fredcook
10-22-07, 10:59 AM
Once you notice a change in color for the fluid would be a good time to change the fluid...

Exactly. The problem is, my fluid goes black in a week or two. I may start buying fluid in 5 gallon cans... :helpless:

fredcook
10-22-07, 11:03 AM
Well it just so happens I went to O'Reily's recently to get DOT 3 fluid and they sell a product that does use the misnomer "clutch fluid." I have forgotten which brand.

Saw it... made by Gunk. Almost bought it, but no DOT or temp rating. And cost $6 vs. $2 (for "brake" fluid).

rheagrimm
10-22-07, 11:48 AM
Compatible, but can it be mixed (I assume not)?

Also, I remember early on (when the syn stuff came out) there were concerns regarding seal damage. Any substance to this?

It is compatable, I have mixed it and I don't know of any seal issues. GM specifies super DOT 4 in the clutch and the Valvoline Syn Power was as close to it as I could get without actually buying the GM brand.

fredcook
10-22-07, 11:57 AM
It is compatable, I have mixed it and I don't know of any seal issues. GM specifies super DOT 4 in the clutch and the Valvoline Syn Power was as close to it as I could get without actually buying the GM brand.

(I need to read the manual!)

DOT 4? I never looked it up, since I personally watched a Cad tech put fluid in mine (it was low), and he commented that it was DOT 3!

darkman
10-22-07, 03:50 PM
The 2005 Owner's manual, which is what I have, calls for DOT 3 for the clutch hydraulics. The 2006 Owner's manual, which is in the FAQs, calls for DOT 4 for the clutch hydraulics. Given this revelation, I will start using DOT 4 in my 2005 V based on the assumption that GM's change was for some good reason.

fredcook
10-22-07, 06:43 PM
The 2005 Owner's manual, which is what I have, calls for DOT 3 for the clutch hydraulics. The 2006 Owner's manual, which is in the FAQs, calls for DOT 4 for the clutch hydraulics. Given this revelation, I will start using DOT 4 in my 2005 V based on the assumption that GM's change was for some good reason.

Hmmm. Mine is an 05... the switch to DOT 4 is on! (unless I talk myself into trying the synthetic Valvoline)

Here's another thread on the same subject (Corvette forum): http://forums.corvetteforum.com/showthread.php?p=1562369484

darkman
10-22-07, 08:04 PM
Hmmm. Mine is an 05... the switch to DOT 4 is on! (unless I talk myself into trying the synthetic Valvoline)

Here's another thread on the same subject (Corvette forum): http://forums.corvetteforum.com/showthread.php?p=1562369484

Interesting read, thanks. Since it appears that heat can be an issue for the clutch fluid the move to DOT 4 (or other higher temp fluids) makes sense. I don't drive all that hard, but heat (and moisture for that matter) is always a potential problem in the Houston area.

fredcook
10-24-07, 10:03 AM
Has anyone tried DOT 5.1? I know DOT 5 isn't popular since it's silicon. But DOT 5.1 is glycol based, like 3 and 4.

Also... anyone try some of the exotic high temp stuff? Like AP PRF (608 degree DOT 4 at $30 for 16oz)? Or Brembo's 601 degree DOT 4 (also about $30) and Wilwood's EXP600 (633 degree DOT 4)?

mbiker97_old
10-24-07, 05:12 PM
^^ Just stick to a nice Dot 4. When I switched my clutch fluid I also used Valvoline SynPower. My friends and I all used to run it in our brakes for tracking since a fluid change doesn't cost an arm and a leg, and it's readily available.

fredcook
10-24-07, 07:55 PM
^^ Just stick to a nice Dot 4. When I switched my clutch fluid I also used Valvoline SynPower. My friends and I all used to run it in our brakes for tracking since a fluid change doesn't cost an arm and a leg, and it's readily available.

My issue with the readily available fluid (300-400 degree) is it deteriorates so fast (goes from clear amber to coffee black in ~two weeks) in the V (at least mine), and the clutch starts to get 'soft' and shifting becomes more difficult. After each flush, shifting is great for about two weeks. Sure, it's cheap, but I really don't want to change fluid that often, especially when brake fluid is designed to have a two year service life.

How often are you flushing the SynPower?

atdeneve
10-25-07, 08:52 AM
Eagerly awaiting Stainless Steel Brake Lines from Luke in cajoots with UUC.

rheagrimm
10-25-07, 12:16 PM
My issue with the readily available fluid (300-400 degree) is it deteriorates so fast (goes from clear amber to coffee black in ~two weeks) in the V (at least mine), and the clutch starts to get 'soft' and shifting becomes more difficult. After each flush, shifting is great for about two weeks. Sure, it's cheap, but I really don't want to change fluid that often, especially when brake fluid is designed to have a two year service life.

How often are you flushing the SynPower?


Valvoline Syn Power is rated at 500 degrees.

Naf
10-28-07, 01:41 AM
Has anyone tried DOT 5.1? I know DOT 5 isn't popular since it's silicon. But DOT 5.1 is glycol based, like 3 and 4.

Also... anyone try some of the exotic high temp stuff? Like AP PRF (608 degree DOT 4 at $30 for 16oz)? Or Brembo's 601 degree DOT 4 (also about $30) and Wilwood's EXP600 (633 degree DOT 4)?

I have tried the 5.1, i even tried it in my brake system...All i can say is damn it was the most expensive upgrade i did. Went to a motorcycle shop to buy the canisters, and a simple box set me back 200$. Still have five canisters left over. Had to do the clutch twice, for i forgot the spacer. (i also broke the first one due to that mistake)

Felt really firm and positive.

fredcook
10-29-07, 02:00 AM
I have tried the 5.1, i even tried it in my brake system...All i can say is damn it was the most expensive upgrade i did. Went to a motorcycle shop to buy the canisters, and a simple box set me back 200$. Still have five canisters left over. Had to do the clutch twice, for i forgot the spacer. (i also broke the first one due to that mistake)

Felt really firm and positive.

$200 for how many/much?

I was considering Motul or Brembo... both around ~$20 for 16 oz.

Naf
10-29-07, 04:00 AM
It was 280$ for 20 bottles of 16oz...Took a look at the bill again.

So worth it though, but i would highly recommend upgrading the lines...

WheelHop
12-07-07, 05:46 PM
From the FAQ: open the bleeder valve (1) at the concentric slave cylinder to release trapped air.


Where exactly is this bleeder valve?? And is this just for bleeding the system of air or is it used for replacing the fluid w/ new??

darkman
12-07-07, 06:07 PM
From the FAQ: open the bleeder valve (1) at the concentric slave cylinder to release trapped air.


Where exactly is this bleeder valve?? And is this just for bleeding the system of air or is it used for replacing the fluid w/ new??

The bleeder valve is acessed underneath the car. It is at the slave cylcinder's point of entry into the bell housing where the clutch line terminates. It can be used for changing the fluid which is easier with two people. One to operate the bleeder valve and one to add fluid and depress the clutch.

If you are just doing preventive maintenance it is easier to: (1) remove fluid from the clutch master cylinder with a turkey baster and add new fluid; and then (2) pump clutch 20-30 times and repeat. Do this until the fluid stays clear after the clutch pumping part.

WheelHop
12-07-07, 06:29 PM
If you are just doing preventive maintenance it is easier to: (1) remove fluid from the clutch master cylinder with a turkey baster and add new fluid; and then (2) pump clutch 20-30 times and repeat. Do this until the fluid stays clear after the clutch pumping part.

That is exactly what I was wanting to hear :D

Thanks, Fella

WheelHop
12-07-07, 06:30 PM
Another question.. Do you need to leave the fluid res. cap on or off when you pump?

darkman
12-07-07, 06:35 PM
Another question.. Do you need to leave the fluid res. cap on or off when you pump?

Keep the cap on when pumping and wrap a cloth around it to catch any spillage - brake fluid does awful things to paint.

WheelHop
12-08-07, 04:17 PM
:thumbsup: