Pressure Plate Finger Grooves, caused by the throwout bearing Options

[r_towle]

Got it....
Again, it's a risk, but if it's free or super cheap, and you are ok replacing it eventually, go for it....but know it's an issue that will need to be fixed...soon.

[SirAndy]

if it's free or super cheap

I have yet to receive the beer i asked for it ...
(IMG:style_emoticons/default/biggrin.gif)

[JStroud]

if it's free or super cheap

I have yet to receive the beer i asked for it ...
(IMG:style_emoticons/default/biggrin.gif)

That's only because I haven't seen you yet!! (IMG:style_emoticons/default/beerchug.gif)

Come by the shop.....all the beer you can (IMG:style_emoticons/default/beer3.gif)

[JStroud]

Got it....
Again, it's a risk, but if it's free or super cheap, and you are ok replacing it eventually, go for it....but know it's an issue that will need to be fixed...soon.

How soon....are we talking 5000miles, 50,000 miles. (IMG:style_emoticons/default/confused24.gif)

If the tip of the fingers break off, what happens, anyone see that?

Thanks
Jeff

[DBCooper]

I thought ideally your throw out should hover just out of contact with the pressure plate fingers ...

Not on a 914, at the very least! Remember, the 914 has a spring on the pedal cluster that pulls the pedal down in the "press the pedal" direction. That means there is always pressure on the throwout bearing--though not a lot.

I don't think so. There's also a much larger spring on the transmission's clutch arm that pulls it back, disengaging. You need free play at the top of your clutch pedal, meaning no contact between the release bearing and the pressure plate until you press the pedal past the free play. I think those grooves are created from the friction of the "spin up" of the stationary release bearing as it matches speed after contacting the spinning pressure plate. When the grooves are deep that metal's gone and not coming back, so it's time for a new pressure plate.

When you sit at a stop light with the clutch disengaged you're wearing the throw out bearing, but much worse is that you're causing unneeded wear on the engine's thrust bearing. It's what limits the front-back movement of the crankshaft, and every time you press the clutch the pressure opens the pressure plate, but it also presses the flywheel and crankshaft forward, against the thrust bearing. And it's a heck of a lot more expensive to replace a main bearing set than a throw out bearing. You check how many miles are on the bug's T1 engine by pulling and pushing the crank pulley? Any movement is end-play from a worn thrust bearing, meaning a lot of miles on the engine (or a lot of time at stoplights with the clutch in) and an impending engine rebuild.

[Dave_Darling]

I don't think so. There's also a much larger spring on the transmission's clutch arm that pulls it back, disengaging.

What transmission do you have? Because you're not describing a 901-based 914 transmission here--there is no spring on the throwout arm at all. Maybe the 915 version out of the mid-year 911s...

--DD

[DBCooper]

Ahhchh.... you're right, Dave, that spring is on a VW transmission, not a 901. The principle's the same, though.

[a few loose screws]

Wow, What a dumb design. glad i read this. Another thing to modify as I slowly get this crate together. Neat little car, but lots of room for improvement no doubt.

[McMark]

Got it....
Again, it's a risk, but if it's free or super cheap, and you are ok replacing it eventually, go for it....but know it's an issue that will need to be fixed...soon.

How soon....are we talking 5000miles, 50,000 miles. (IMG:style_emoticons/default/confused24.gif)

If the tip of the fingers break off, what happens, anyone see that?

Thanks
Jeff

Google images shows some of these with broken fingers, so it does happen. Worst case scenario you lose some or all of your ability to disengage the clutch. Then you get it home, pull the transmission with the engine still in place, and swap in a new pressure plate. If it were my personal car, I'd run it and plan on swapping it out in a year or so.

[DBCooper]

Wow, What a dumb design. glad i read this. Another thing to modify as I slowly get this crate together. Neat little car, but lots of room for improvement no doubt.

It's not just this car, it's every older car. Those clutches work fine for decades... just not forever. I've never seen a failure because of wear on the clutch fingers, the rest of the clutch is toast first.

Actually now that I think about it maybe I have, but it's not common.

[DBCooper]

Fingers broke on my son's Kennedy pressure plate just recently, but we think from a cracked diaphragm, not from common wear. If it fails it will make noises, won't disengage, and you'll know it ahead of time.

[Bartlett 914]

A lot of the comments seem to point to the throwout bearing spinning on the fingers. While this would cause wear, it may not be the problem at all. Each time you press on the clutch, the throwout bearing pushes in on the fingers even with the throwout bearing and the pressure plate spinning together (no circumferential slipping). Here the bearing must slide metal on metal without lubrication. This is going to cause wear. Grease would help but who wants grease so near the clutch. Harder bearing and softer fingers means the fingers will wear first.

[a few loose screws]

I was referring to the clutch release bearing having slight contact all the time. I don't like that. nothing wrong with the clutch itself. Sachs makes good stuff.

[r_towle]

Got it....
Again, it's a risk, but if it's free or super cheap, and you are ok replacing it eventually, go for it....but know it's an issue that will need to be fixed...soon.

How soon....are we talking 5000miles, 50,000 miles. (IMG:style_emoticons/default/confused24.gif)

If the tip of the fingers break off, what happens, anyone see that?

Thanks
Jeff

Google images shows some of these with broken fingers, so it does happen. Worst case scenario you lose some or all of your ability to disengage the clutch. Then you get it home, pull the transmission with the engine still in place, and swap in a new pressure plate. If it were my personal car, I'd run it and plan on swapping it out in a year or so.

(IMG:style_emoticons/default/agree.gif)

[JStroud]

Got it....
Again, it's a risk, but if it's free or super cheap, and you are ok replacing it eventually, go for it....but know it's an issue that will need to be fixed...soon.

How soon....are we talking 5000miles, 50,000 miles. (IMG:style_emoticons/default/confused24.gif)

If the tip of the fingers break off, what happens, anyone see that?

Thanks
Jeff

Google images shows some of these with broken fingers, so it does happen. Worst case scenario you lose some or all of your ability to disengage the clutch. Then you get it home, pull the transmission with the engine still in place, and swap in a new pressure plate. If it were my personal car, I'd run it and plan on swapping it out in a year or so.

(IMG:style_emoticons/default/agree.gif)

Thanks, appreciate the input, I guess I'll plan on using it so I can get my car back on the road. Then I'll just have to start saving up for a new one, maybe change it next winter......if it makes it that long (IMG:style_emoticons/default/driving.gif) my throw out bearing is fairy new, so that may help....and no riding the clutch pedal.

[edwin]

Most clutches that I've replaced have looked like that at the end of their life.
I replaced one in the Saab I drive that had lost about a third of the fingers at the end. The big problem in that clutch though was that the driven plate came to pieces.
Worth looking at newer cars and how they run their concentric slave cylinders now. The bearing is designed to be in constant contact with the pressure plate. Throw-out bearings are typically a high clearance design and engine speed is hardly going to worry a bearing designed for 15krpm max. What kills bearings inside their design range is shock and pressure. The shock of a bearing coming from nothing to engine speed every time you touch the clutch will wear it faster than it resting lightly against the pressure plate all the time.
I really need to find the time to finish my concentric slave to replace the pull type I'm using now.