Re: Clutch stuff (long)

[DMCVegas@xxxx]

Black clutch fluid is bad. Especially if it has any viscosity or 
"thickness" to it. Clean clutch fluid (DOT4) should be a light-gold, 
yet transparent color. By the discription you've given, it sounds like 
bad fluid. The question here shouldn't be if the previous owner used 
new hydrolic parts, it's if he reused the old clutch fluid. New parts 
don't stand a chance against contaminated clutch fluid. Also a concern 
should be the hose connected between the reserviour and the master 
cylinder. The inner hose my car for example was slightly deteriorated, 
but the outside was rock hard. Using substandard parts isn't a good 
idea because the fluid can be corrosive and eat away at the rubber 
causing debries to form in the lines.

This is the best way to describe how the fluid works, and how/why it 
fails. Liquids can be compressed to take up less space then they 
currently occupy. The differance between water and clutch fluid is 
that it takes MUCH more pressure to compress clutch fluid then it does 
water. So, rather then using a rod or a cable to link the clutch to 
the pedal, clutch fluid is used. It ends up being almost the same, 
except now rather then something solid that would have to have been 
designed and accomodated in the car, a liquid can be used. Advantages 
include both less space required, less engineering involved, and it 
can go thru tighter twists and turns. Think of it like a liquid rod.

When clutch fulid fails (usually thru water contamination), the 
pressue that is nessisary to compress the fluid is reduced. Which is 
why you end up having to press harder/further on the clutch pedal. 
Another negative side is that it can become corrosive twards the 
rubber seals and hoses in the system. Another symptom can also be air 
in the line (also compressable). And since air can contain moisture, 
water can be absorbed from exposed air.

(DISCLAIMER: I know that there is ALOT more to the explanation of 
hydrolic operations and applications. But this is only a quick run 
thru to give a general idea.)

When ever you bleed or flush a hydrolic system be it the brakes or 
your clutch line, you MUST ALWAYS USE FRESH FLUID FROM A SEALED 
CONTAINER!

1. The fluid inside has already met with air/moisture/debries and 
should always be considered contaminated.
2. If not inside, the the bleeder screw and/or the container that you 
collect the fulid in is probably dirty.
3. In either case, at least one of the above factors will be true. If 
you put the fluid back into the reserviour, you will taint the entire 
system.

The blackness of the fluid is dirt and might be rubber that has been 
eaten off by the fluid from 1 or more components of the system.

Solution: Replace the hose from between the master cylinder and the 
resivour. Either buy a new one from your friendly parts vendor, or use 
a suitable replacement. If you choose to create your own, here's what 
to do: Remove the rubber hose, and take it to some place like 
carquest. Ask them for a hose that will withstand DOT4 brake fluid. 
Get the new hose to match the largest diamiter of the old hose (where 
it connects to the nubs). When sizing up the new hose, make it long 
enough to reach between the two connection points, but short enough 
that it doesn't bend up to keep air bubbles in the line. Bleed the 
system and see if that makes a differance.

Until you complete either this or any repairs, do not drive your car 
if you can help it. As you can damage the clutch.

How the clutch works:

Setup/location:
The clutch pressure place is bolted onto the flywheel. The clutch disc 
itself sits between the flywheel and clutch pressure plate. The clutch 
disc is connected directly to the input shaft on your transmission.
How it all works:
The pressure plate acts like a clamp. When the clamp is applied the 
clutch disc is pinned in between the pressure place and the flywheel. 
When this happens, all three componets will spin as one single unit, 
thus transfering power from the engine directly to the tranmission.
Why it can fail (1 reason):
All clutches will fail eventually. This is why they are considered 
wearable parts, and usually NOT convered by bumper to bumper 
waranties. How and when depend on 2 factors: The clutch system, and 
the driver.

Excluding normal usage (100K-150K miles), here is what causes 
premature clutch slippage. As you know, the pressure plate clamps the 
clutch disc. But, if the force of the plate pressure isn't fully 
applied to the clutch disc, then the clamp and the flywheel are not 
able to fully grip the disc. Even though you can still accellerate, 
the disc is spinning at a different speed then the flywheel and the 
pressure plate. Aside from not being able to fully utilize the power 
being put out by the engine, you are also damaging the clutch. As the 
flywheel and pressure plate spin around the clutch disc, they are both 
slowly scraping away at it's surface. When the clutch finally fails, 
the pressure plate and the fly wheel will not be able to properly grip 
the disc. The result will start as poor accelleration, and end up as 
no accelleration at all. In other words, it will literally slip 
through it's grasp. Thus the term clutch slippage. Both cases of this 
type of premature failure are usually caused by 1 of 3 reasons: 1. 
Defective clutch (rare). Misadjusted/defective clutch release system 
(hydrolic or cable. Can happen, but not common with normal 
maintenance/newer cars). 3. Driver error (hard rabbit starts, double 
clutching, or the most common reason for this is the drive always 
"rides" the clutch and doesn't take thier foot off). Driver error is 
usually the absolute most common reason for premature clutch failure.

There are also 2 other parts to the clutch system: The throw out 
bearing, and the pilot bearing. The pilot bearing supports the end of 
the input shaft on the transmission. And the Throwour bearing is what 
pushes the spring on the clutch to release it. Since these also help 
the clutch in it's task, that's why all 5 parts wear the same as 1 
unit, and should be replaced as so.

If your clutch fails, do not drive the car if you can help it. The 
clutch disc uses metal rivits to hold the clutch material in place. 
When the material is gone is when the clutch slips. And the rivets 
will cut into the flywheel. Anytime you replace a clutch, the flywheel 
MUST be resurfaced. But just like brake rotors, it can only be ground 
down so far. Too far and the flywheel will then need to be replaced as 
well.

Differance between the regular Centerforce Clutch vs. OEM:

Comparing the the two clutches side by side, I have only seen 1 
physical differance between the 2: Counterweights. As the engine spins 
faster, centrifical force pushes the weights out. This then causes the 
weights to apply extra pressure to the pressure plate above what it 
already has. This produces the extra gripping power that the 
Centerforce is able to boast. Clutch disc wise, I don't see a 
differance between the two. The look exactly the same, down to their 
manufacturers.


I hope that everything above helps everyone here to understand not 
just how their clutches work and fail. But also to help know how to 
take care of them to extend their lifespan. Hopefully this will not 
only answer questions that my be asked today, but tomorrow as well...

-Robert
vin 6585




--- In dmcnews@xxxx, Joe Palatinus <jpalatinus@xxxx> wrote:
> When I got my car the previous owner told me he replaced all the 
hydralics
> and I believed him he had invoices from DMC houston and the clutch
> cylinders don't look too old, but when I bled the clutch luid about 
a year
> after I got the car it was blacker and gunkier than 20 year old 
fluid. I
> put in new fluid, but I feel my clutch slowly deteriorating.
<SNIP>