What is up with this clutch pressure plate ?

[fastfredracing]

Was just getting ready to bolt this car back together, and upon opening the box, found this curious hole in the pressure plate .
Brand spankin' new Sachs clutch kit.
I've done hundreds upon hundreds of clutches in my life, and have never seen a hole drilled into the friction surface of a pressure plate .
I'm not comfortable using it . This is not from our host . Ever seen one like this ?
It looks like something is pressed into the hole, but it does not correspond with any rivets or bolts in the back side . I think the mill missed its initial target when it was made .

Mallory metal for balancing? Never seen that before.

[herr_oberst]

I'd imagine if you called Sachs, they might say it's for balancing the assembly? Weird.

In the bottom picture lower left at the surface finish, it looks like it's pitted, but I assume that's just staining?

[flipper35]

Looked chipped in that lower left pic to me.

[fastfredracing]

Looks like a great place for a crack to propogate, then explode and destroy everything in its path.
I sent an email to sachs. Curious to hear what they have to say .

[David]

Strange place for a balance hole but likely won't affect performance. Think drilled brake disks (which do crack but very rarely explode).

[fastfredracing]

14 hours labor to in and out it . Im not taking any chances. Its a p car . Not worth the risk in my book . It looks like it is drilled all the way through.
Im thinking it spins a whole lot faster than a brake disc also .

[Tobra]

that ain't right

Drilled rotors the holes are chamfered, that one looks like it has burrs around its periphery

[fastfredracing]

From Sachs. -Hello,

Thanks for contacting ZF Sachs in regards to our 3000 970 010 and your 997 4s. Yes the hole in the pressure plate near center is correct, I can see it in the stock image used for cataloging. I looked at our sales history and see 1,800 kits sold with this pressure plate without any complaints. Not sure what the hole is used for, possible manufacturing as an alignment hole.
.
Im still waiting for another tomorrow .

[911 Rod]

I would think this had gone through QC check for balancing etc. and someone would have caught it?
There all kinds of heaps and valleys in the clutch.
But I have no idea....
Edit (I was typing at the same time as Fred)

[LWJ]

Good eye for quality. I agree. Weird and not worth a 14 hour gamble.

[herr_oberst]

Needs a Vonnen Shadow Drive.

[Baz]

Fred - I see no reason why that hole should be there.

I could be wrong (there's always a first time ) but I think you're right to hold off.

Please keep us posted and good luck....

[sc_rufctr]

It could be a CIA tracking device

[Superman]

Originally Posted by fastfredracing

Im thinking it spins a whole lot faster than a brake disc also .

Yup.

[Dan J]

Fred,
We're doing the same job in our shop today. The Sachs pressure plate we got has no such hole
I've not ever seen one on the friction surface

[Arizona_928]

"The hole is correct"... Bull****
especially where the disc's friction material is at. I see that part blowing up causing a very bad day.

[porsche tech]

Don't use it. Seems like that hole would wear a ridge all the way around the clutch disc.

[DanielDudley]

Originally Posted by porsche tech

Don't use it. Seems like that hole would wear a ridge all the way around the clutch disc.

It won't. If I was a working mechanic I would tend to be wary though. It pays to take a cautious stance in the long run.

[DanielDudley]

Originally Posted by AZ_porschekid

"The hole is correct"... Bull****
especially where the disc's friction material is at. I see that part blowing up causing a very bad day.

It probably won't. But why would you do that at the factory ?

I will be interested to read up on what Fred hears in the follow up response.