Cracked pressure plate

[Shaun @ Tru6]

Anyone ever seen something like this? How does it happen? Fork was rubbing on it.

[Flieger]

The rust certainly wouldn't help things. I had a BMW 320i pressure plate crack in one place and the metal wasn't rusty. Just a part that happened to fall below normal fatigue life I guess. In your case the rust would weaken it and start the cracks.

[TimT]

I think the rust is all post disaster...

Some kind of T/O bearing failure? Notice in the last pic, the diaphragm is warped and the T/O bearing is not all happy happy joy joy inre the pressure plate

[TimT]

And those cracks are "radial" some sort of sudden differential acceleration between the driving force and driven force occurred.... That path is the throw out bearing

[Shaun @ Tru6]

Originally Posted by TimT

And those cracks are "radial" some sort of sudden differential acceleration between the driving force and driven force occurred.... That path is the throw out bearing

Tim, what does that mean? What would cause it? Motor runs fine, it's an 86 3.2.

[kodioneill]

It's rusty and worn out possibly brittle.

[Reiver]

Throw out bearing (besides the rust) looks like toast. If that bearing freezes up you are putting a lot of stress on the flanges.
Also, was the clutch cable adjusted correctly...over depressing the clutch (why there is a stop) can flex those elements past the point they were designed to absorb.

[TimT]

I just think, from looking at a few pics.

That it has some thing to do with the throwout bearing..

Those big holes on the ends of the slots... are there do distribute loads.... Seeing five cracks radiating from those large hole makes me say hmmm..


Maybe flexing the pressure plate over center for way to many cycles could cause this..haven't seen it..

Motor runs fine, it's an 86 3.2.

I'm sure it does.... how does it shift?

[Shaun @ Tru6]

Originally Posted by Reiver

Throw out bearing (besides the rust) looks like toast. If that bearing freezes up you are putting a lot of stress on the flanges.
Also, was the clutch cable adjusted correctly...over depressing the clutch (why there is a stop) can flex those elements past the point they were designed to absorb.

Good question, can't say, but here's a new element I should have put in. This is an 86 Cab I recently got that sat for 4 years. Clutch pedal was to the floor so I thought the cable was broken. Cable is actually fine and free from the clutch lever, works properly: cable pulled taught with pedal up shortens when pedal is depressed.

A good thought on over-depression.

Originally Posted by TimT

I just think, from looking at a few pics.

That it has some thing to do with the throwout bearing..

Those big holes on the ends of the slots... are there do distribute loads.... Seeing five cracks radiating from those large hole makes me say hmmm..

Maybe flexing the pressure plate over center for way to many cycles could cause this..haven't seen it..


I'm sure it does.... how does it shift?

Seized bearing with driving pressing too hard? Limited slip 915 seems to be OK, shifts by hand easily but haven't driven it.

[HawgRyder]

That throw out bearing looks terrible.
If I am looking at damage on the inside of the bearing...and metal displacement there...I believe that was the starting point of the whole problem.
Bob

[RWebb]

post a good close up of the TO bearing

also, work it in your hand & report

you should frame that pressure plate and hang it up somewhere - it is an important artifact

[Shaun @ Tru6]

the throw-out bear spins freely and only slightly wobbly.

[theclaw]

How many miles on it? I've got mine out too. Looks ok but I'm wrestling with replacing it if I don't have to. Puttin in new TOB,clutch plate, fork and some seals.

[Shaun @ Tru6]

Car has about 150K on it, but no idea on the pressure plate. Given that no one has seen this before, you are probably safe with reusing yours.

[KTL]

Take off the clutch so we can see what's going on inside!

[Shaun @ Tru6]

disk looks close to new Kevin

[fastfredracing]

About two years ago, my buddies 3.2 carrera, started to have slight clutch release issues, I adjusted the cable a few times, it finally got worse, to where no amount of adjustment would let the clutch fully release.
Pulled the motor, and found a mirror image of what you are showing. The car had been sitting for about 2 years prior, and the pressure plate was similarly rusty.

[KTL]

What's the date stamped on the fingers?

How's the clutch housing "foot" look inside under the busted fingers?

[Shaun @ Tru6]

Thanks for weighing in Fred. Any thoughts on what would cause this?

Kevin, I'll dig it out tomorrow and take some pics.

[lonewolf]

looks like it has just gone through too many heat cycles.
steel has become brittle and lost it's flex.