Clutch release bearing - how does it work?

[RSW]

This sounds a bit of an obvious question but I affraid I simply aren't certian of the answer - hence the post.

My problem is that I can sometimes hear my clutch release bearing when I set off - which is straight forward enough.

The thing that is strange is that I can some times hear what I believe to be the same noise as I am driving (only sometimes and for longer durations)

So, having bought the Bently manual and the 101 project book I am half convinced that replacing the C/R bearing will solve my problems. My theory (or my understanding) says the C/R bearing is spinning as I am driving and only stops spinning when I press my clutch in - thus releasing pressure form the 'fingers' of the pressure plate and allowing the clutch plate to part from the fly wheel.

If anyone could correct me on my understanding I would be most gratefull - Thanks

Ps. the gearbox is a G50 if it makes any difference.

Thanks
Richard

[dickster]

hi,

the bearing is under load (and spinning) when you push the clutch pedal down, and that is when it should make most noise if its worn.

an easy way to test is with the car stationary (engine running)and out of gear, push the pedal down slowly. the noise from the bearing will maybe audible, esp. if its worn.

whether or not it needs replacing. well, bearings make a rumbling noise when they've had it, like wheel bearings - if thats what you can hear it needs replacing.

it can spin slightly when you are driving as the clearances tend to be close - but i wouldn't think you could hear it. that may be another source. wheel bearings perhaps? or some other gearbox bearing or diff whining.

can you describe further??

hope that helps.

[82SC]

this isn't specific to your question but this site really helped me

www.howstuffworks.com

it teaching things like clutch tranny engine stuff in a very easy to understand way

and I think the tranny link has cool animated diagrams that show you how they work

sound when you are pressing on the clutch pedal is not a good thing...I had a really high whine which was indicitive of a sheared TO bearing...one of the more common clutch problems...

hope things work out

MJ

[RSW]

I think I know what you mean when you describe the sound made when the clutch is pressed in the stationary car - sort of a clatter sound. To be honest I've not noticed it on my car.

Are you familiar with the sound I am hearing just as I lift my clutch in 1st and set off? Sort of a singing note for a split second. The other noise I hare is just like that - but is sometimes heard while booling along in say 3rd gear (other wise I don't think you'd hear it for the engine noise)

It's the same sort of note but lasts for longer - I forget if it goes away if I dip the clutch (i've got the engine out at present).

In all fairness it actually seems to be coming from the passenger side foot well or similar but I was convinced it was just deseptive and felt sure it was the C/R bearing.

Richard

[RSW]

Thanks MJ - I'll check that site out.

RIchard

[FAST FREDDIE]

SOMETIMES WITH G50 TRANNY, THE CLUTCH WILL MAKE A LOW PITCH GROWL SOUND WHEN STARTING OUT. IT APPEARS ALSO IN MY CORVETTE SOMETIMES.

[dickster]

if you got the engine out check the t/o bearing. hold it and turn it on its races in your hand - if it doesn't feel creamy smoooooooth, its had it. or just replace anyway?

the first gear thing may be a "normal" sort of whine (as fast freddie said) - same as reverse?? thats ok.

if the noise changes when you dip the clutch its the t/o bearing.

passenger footwell sounds like wheel bearing.

btw - the fact that its a g50 shouldn't matter.

[Rick Lee]

Hey Richard,

I my T/O bearing was fine when I did my clutch job, so I don't know how a worn one sounds. But if you haven't done the G50 clutch update yet, then you probably have that job in your near future, in which you can just replace the whole shebang. A Sachs clutch kit comes with a pressure plate, T/O bearing and clutch disc. You'll also need the updated release fork and shaft with new bushings too. I'm pretty sure the '88 3.2's still had the needle bearing problem in the release fork. It's a matter of when, not if. So start rounding up parts and tools for this job. I actually had a lot fun doing it. My clutch is silent and buttery now.

[RSW]

Thanks folks - I'll check that bearing when I get it out tonight. The How Stuff Works site is realy quite good.

I'm not sure it's a wheel bearing as they make more of a wurring sound and it isn't that - I think it is just deceptive as regards the foot well, you know how sounds appear to travel.

Richard

[RSW]

Can anyone enlightlen me as to what a "dragging clutch" could be? Could this be my problem?

[Superman]

Make sure your horseshoe wpring is going "over the top." That big spring pushes the clutch arm in two directions. When you push on the clutch, it helps engage the clutch. When you release, it pushes in the other direction, helping keep pressure OFF the TOB.

Disconnect the cable at the arm under the tranny. Use a large screwdriver to pry the arm, and spring, toward the front of the car, until the spring snaps the arm back toward the pedals. Then reconnect the cable and go through the adjustment procedure (you know, 1.2mm and then 1.0mm). If you do this properly, that horseshoe spring will ensure your forks are not acting on the TOB while you're cruising down the road.

[Rick Lee]

Originally posted by Superman
Make sure your horseshoe wpring is going "over the top." That big spring pushes the clutch arm in two directions. When you push on the clutch, it helps engage the clutch. When you release, it pushes in the other direction, helping keep pressure OFF the TOB.

Disconnect the cable at the arm under the tranny. Use a large screwdriver to pry the arm, and spring, toward the front of the car, until the spring snaps the arm back toward the pedals. Then reconnect the cable and go through the adjustment procedure (you know, 1.2mm and then 1.0mm). If you do this properly, that horseshoe spring will ensure your forks are not acting on the TOB while you're cruising down the road.

I think we're dealing with a hydraulic G50 here.

[Superman]

Nevermind.

[CamB]

It may be (probably is) completely unrelated but both my 915s make a fairly nasty sort of rattling sound at <1500rpm in too high a gear (I've got no business being in that gear anyway so no big deal).

[jmohn]

Originally posted by CamB
It may be (probably is) completely unrelated but both my 915s make a fairly nasty sort of rattling sound at <1500rpm in too high a gear (I've got no business being in that gear anyway so no big deal).

This sounds very much like pre-ignition - a very bad thing. These engines don't like low-RPM lugging. Pre-ignition will, at the least, hole your pistons.

Jerry M
'78 SC

[CamB]

Nope - its not the (death) rattle of pre-ignition. I am relatively convinced.

I can't describe the sound in a way anyone will understand (poor command of the english language - I came last in my last high school english class).

I was sort of under the impression they all did it as:

- my '69 does now it has a 915
- the '75 did (when it was running)
- I have found contemporary reviews from the '70s where they referred to "gearbox rattle"

Anyone else get it?

[RSW]

Well - Last night I removed the G50 from the motor removed the studs that hold the pressure plate and (after much prying with various tools) removed the pressure plate and thus the clutch plate.

Thus raising some more questions that I would be most gratefull of your opinions:

The shaft that holds my fork arm to the bell housing has te small roller bearings - is this the update that is mentioned in the Bently manual?

The clutch disc itself is not as I expected at all - it has no springs arround the center and appears to be pretty much one solid part. If I was to place it flat on the floor it would be about 10cm high. Does this sound normal or is it a special clutch plate?

Any advice or thoughts.

Thanks
Richard

[Rick Lee]

You have the original rubber centered clutch disc. They are known for some problems (like exploding) and it's best for you to upgrade to the Sachs spring centered clutch disc. I don't have my Bentley's handy, but I believe it gives you the more difficult of the two release fork upgrade options. Drilling the bell housing is a huge PITA. Get the Weltmeister kit with the new shaft, fork and broze or brass bushings. It fits right in there and will make your clutch operate like butter. Do not reinstall the kit you have. Those "roller" bearings are needle bearings and they WILL score your shaft and eventually fail. You'll also need a new guide tube and O-ring, as they got a little shorter for the upgrade. Send me a PM and I can give a parts list. You have some shopping to do.

[RSW]

Thanks Richard - I've sent the PM.

How can I check to see if it is a "rubber centre" clutch? I don't recall noticing any rubber at all?

RIchard

[RSW]

I'm hoping to retain my current Sache pressure plate as it seems to be in good condition - I've looked on the Pelican site for the Weltmeister shaft kit but the only one on there describes having the drill the bell housing so I guess thats the other version - can anyone point me ar a URL where I can get the Weltmeister item from? also do I need to get the tube and guides separate or do they come with the kit?

Any ideas/views?

Thanks
RIchard