Hole in Trans! Are 5-spd and 6-spd cases the same?

[Sveach756]

Can you expand a little more on the rattling exhaust? I have the same on a new car I bought and it almost sounds like an AC compressor going bad rattle at times, is this your experience. Feel free to PM me to stay on topic.
Thanks
Shawn

[maytag]

Originally Posted by Sveach756

Can you expand a little more on the rattling exhaust? I have the same on a new car I bought and it almost sounds like an AC compressor going bad rattle at times, is this your experience. Feel free to PM me to stay on topic.
Thanks
Shawn

I revived a previous thread about "fleabay catback muffler". Let's move this particular conversation over there.

[Gilles]

Maytag,

Is there a possibility that the previous owner somehow hit the bottom of the bellhousing (transmission) and that a piece fell off and got inside the clutch assembly creating the chaos you ended with..?

It seems that the bellhousing could be welded, good luck!

[911monty]

Have you scanned the DME for stage 2 over revs? Might show something. I saw something similar where an individual thought it was a good idea to leave the trans in first gear while coasting down a hill with the clutch depressed. Can't even imagine the RPM that clutch disk saw before exploding.

[maytag]

Originally Posted by 911monty

Have you scanned the DME for stage 2 over revs? Might show something. I saw something similar where an individual thought it was a good idea to leave the trans in first gear while coasting down a hill with the clutch depressed. Can't even imagine the RPM that clutch disk saw before exploding.

Thanks Monty. There are plenty of over-revs stored in the DME. And heck, I'm guilty of some of them myself, at the track. But a simple over-rev of the motor (what the DME is recording) shouldn't cause this sort of failure. What you are describing, (coasting down the hill with the clutch depressed )wouldn't have registered at all in the DME.
But you got me thinking:
I did this at the end of the front straight at UMC (Outer Loop). I only got two laps before this happened, but in those two laps, I was hitting 121mph on the straight, then braking to around 85mph as I start to turn-in at turn one, but continuing to brake down to about 60mph at the apex. When I went for the brakes and depressed the clutch simultaneously, then tried to go for 3rd gear, it wouldn't go in. I tried again; wouldn't go. So I took my foot off the clutch to coast through the corner, but the pedal didn't come up.
SO: I can only guess at what speed I tried to grab 3rd gear, because I was braking aggressively, and I can't see my hands in the HLT video; but I would guess around 90mph. That should not be an issue for 3rd gear (that's about the MPH where I upshifted to 4th. And on a different track configuration, I hold 3rd to 98mph before braking). Yes, I rev-match as a force of habit (I'm a motorcycle-guy, it's truly a habit, haha).
So let's say I was REALLY fast on that particular lap, and hit maybe 130mph (I doubt it). And let's say I was trying to enter turn one much faster than before (possible, as I had some clear track ahead of me, having passed the corvette I had been waiting on previously). Let's say I hypothetically tried to grab 3rd gear REALLY quickly, at 100mph. I really don't know if this is plausible... I don't have enough data. I find it unlikely, but possible. If the synchros engaged and rapidly spun-up the clutch to the RPM's it would need to engage 3rd gear at 100mph, then I would think this sort of failure is, well, possible. I guess. But I would hope the clutch could take that sort of spin-up, should'nt it?

I just found someone on Rennlist who posted these top-speeds for the 6-speed, with stock tire size:
1st=~42 MPH
2nd=~70 MPH
3rd=~102 MPH
4th=~127 MPH
5th=~154 MPH
6th=~190 MPH

seems about right. I just can't fathom me trying to grab 3rd at 100mph should create this sort of catastrophic failure.

I'm ready to learn if any of y'all have a different outlook on it?

[911monty]

Well Maytag you asked for it! I'll take a stab here (pun intended..) .

Let's see if we can get some responses. Wish I could separate your pics for annotation would make life easier., But looking at the first pic of the carnage this is what I see.

First your pressure plate did a decent job of containment could have been worse.
Now look at the 10 o'clock position. You can see the friction disk that remained together attempted to extrude between the gap of the pressure plate. This was repeated @ 3:00 and 6:00 but successfully ejected

At the 1:00 position you can see the friction material crushed/depressed as it impacted the pressure plate bolt flange. Also repeated in several areas.

Notice how all but one (at 2:30 still has a small piece attached) of the friction disk to the hub attaching points separated. Now look at the 5:00 position and you will see the only attachment point that still has 2 rivets. Notice the puckering in the center? This is from a tension break, It appears they all broke simultaneously at the same instant.

In summary this appears to be a high speed event to me.

[maytag]

Originally Posted by 911monty

In summary this appears to be a high speed event to me.

You are very observant, Monty. Thank you for taking time for me.
I don't think that there's any question it was a high speed event.

The question (to me) is what sort of high speed event should a clutch be able to tolerate? Is this a weak clutch, destined to fail? or did I do something that will result in this same result if I do it again? And if the latter, then what, exactly?
As near as I can tell, it occurred either when I depressed the clutch pedal, or when I poked at 3rd gear, going no faster than 100mph (and probably less than that). Even if I had a brain fart and didn't rev-match (I doubt it, as it's so habitual for me, I even do it on the street) shouldn't the clutch tolerate this spin-up?

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[maytag]

Originally Posted by Gilles

Maytag,

Is there a possibility that the previous owner somehow hit the bottom of the bellhousing (transmission) and that a piece fell off and got inside the clutch assembly creating the chaos you ended with..?

It seems that the bellhousing could be welded, good luck!

Nope. Good thought, but nope.

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