Please Educationalize me on Clutches...

I have been conversing on another thread about Transmission Oil and throwout
bearing noise and my ignorance of such is monumental....

So I thought another thread is called for.

First - in the '93 Metro 3 cylinder 5 speed manual transmission, where is the
"throwout bearing" located?

Second - where does all the ground off clutch material go as the clutch
wears down?
I am wondering if that material ground off the clutch plate can get into any bearings.

Third - how does the "throwout bearing" get lubrication?

Forth - would it hurt if an additive were added to the transmission oil?
Specifically, Shucks sells an oil additive (the plastic gear turning demo on the
counter) that "clings" to the gears like STP.

Fifth - is the clutch "dry" or is it bathed in oil? Maybe a dumb question
because oil would make it slip - I presume....but, you never know!

More questions to come.

DoctorBill

pilot bearing and throwout bearing are a sealed prelubed bearing. once grease dries up or get contaminated over time by clutch dust it will start making noise. only on some HD applications like tractors and industrial equipment do they have a fitting you can grease them with. the throwout bearing moves in and out on a round collar sticking out of the front of the transmission case. the clutch on cars is a dry unit, oil or fluid getting on it will cause it to chatter or slip. the clutch dust will usually collect on the inside of the bellhousing and over time will some will usually fall out the bottom where the cover plate is. as far as additives most are ok but if they are thicker than normal oil will be a little harder to shift till the tranny fluid warms up and thins out

pilot bearing and throwout bearing are a sealed prelubed
bearing. once grease dries up or get contaminated over time by clutch dust it
will start making noise. only on some HD applications like tractors and
industrial equipment do they have a fitting you can grease them with.
So those bearings are "greased" then.....That term "Prelubed" bugs the Hell
out of me....just another way of saying, "Replace the bearing" just because
the lube went south!
Damned stupid if you ask me! One used to be able to oil motors and grease
parts via a Zirk fitting....bunch of crap!
Now electric motor bearings wear out because the "Pre-lube" dried out and
if one could put a drop in oneself, the motor would last 5x as long....

Preset obsolescence again....that's Industry for you!

The throwout bearing moves in and out on a round collar sticking out
of the front of the transmission case. the clutch on cars is a dry unit, oil or
fluid getting on it will cause it to chatter or slip. the clutch dust will usually
collect on the inside of the bellhousing and over time will some will usually fall
out the bottom where the cover plate is.
Can one get a stream of water up in there to wash that "dust" (probably quite
abrasive...) out?

As far as additives most are ok but if they are thicker than normal oil will
be a little harder to shift till the tranny fluid warms up and thins out
I'd like to try that Sticky Oil I saw in Shuck's Demo on the front counter....
Seems like a good idea - just a few ounces to leave a film for the short period
upon startup when surface oil has drained away.

The old "STP" arguement....

DoctorBill

DoctorBill
It would take a hole book to tell everything about clutches.
first thing on clutches as with brakes the drivers foot is the life of a clutch.
Newer clutches as with brake pads and shoes are mostly non asbestos material.
So not much problem with clutch dust. Some dust collects in bell housing and some of it just blows out into the air.
The sealed throwout bearing is almost trouble free anymore.
If it has a good seal no dirt or moisture or air can get in and no grease can get out. But the key is a good seal. If sealed good it will last a long time or outlast clutch plate.
The main killer on throw out bearings is running all of the time.
So keep that pedal adjusted or have a little free play in it.
There is two kinds of pilot bearings one sealed bearing and one bronze/babbit that is presoaked in oil.
The throwout bearing will be in the bell housing mounted on transmission input snout.
And pushes the clutch pressure plate fingers to release the clutch plate.
Back in the 1950 cry had some oil type clutches.
But all newer auto/light truck clutches are dry clutches.

And last but not least leave that oil additive alone.
It can do more harm than good.
Just service the transmisson with what ever type of oil the manf says to use in it.
There is brass shifting rings and other areas in there that requires the proper oil to keep them going and lubed right.

Go easy on the shifting and keep it adjusted right on the ones that require adjustment and the clutch will give you many K miles of service.
And if the clutch plate goes out your local parts places have brand new clutch kits with a new matched clutch and pressure plate and a new throwout and pilot bearing and also a plastic line up shaft.
MT

Look at it this way Doc....To the best of your knowledge,You've gotten 160K miles out of the original Clutch, Pressure plate, Throwout bearing and pilot bearing on this car...This says alot for the sealed (Prelubed) bearings and these setups have come along ways in recent years (Well most of them anyways)...Only way I can think of to "Attempt" to wash some of the clutch residue (Dust) out of the tranny would be to pull off the black half moon inspection plate (2 Bolts) on the lower L side of the trans (Next to the oil pan) and run some water up in there.....It might wash some of the clutch dust out of the bottom of the trans but dont spray it too hard in there! It could be worse Doc.....I put in a low mile 3.3 V6 engine in our still excellent shape 91 Buick Century last summer and a couple of months later, The DS front wheel bearing assembly (Sealed bearing setup) decided to start occasionally squeeling after 148K miles......These assemblys cost $125.00 a piece to replace! DS is done and the passenger side is getting a new one next month..... .:crying: .

DOC;
Like everything else the automotive world has seen changes over time; some good, some not so good. I believe the changes were largely for the better.

As you mention maintainable assemblies can outlast sealed units but (and it is a BIG BUT) that is only if properly maintained. Since the majority of drivers no longer do ANY of their own maintenance I think the auto industry went to sealed bearings in self defense. Imagine the outcry if your bearing lasted 50k miles and disabled the vehicle when it failed (even if it was the owners fault because no maintenance was done). Most of the people I know would blame the manufacturer and spend the rest of their days bad mouthing that brand.

Like you I prefer maintainable assemblies and have gotten better about performing the maintenance they need. Keep in mind that 1) I care at least a little bit 2) I am somewhat mechanically minded 3) I like to know how things work and 4) I am not enamored with more power, fancier creature comforts and/or more features. Most of my friends do not fit in even one of those categories so you can imagine what sort of work they do on their vehicles.

When I get the opportunity I will choose a maintainable assembly for replacement purposes, otherwise I just get the best one avialable. I wouldn't worry about your clutch too much, mine went 198,500 miles without an issue. The car finally burned a valve (due to my ignorance on needing to keep the egr passages cleaned), when I swapped in a JDM engine I also swapped the clutch 22K miles later its still going fine.

not sure i would want to stick a hose up in there and wash anything out, it might get more stuff into the bearing on contaminate the clutch disc, just leave it alone till you change clutch. its not hurting anything