ACT Clutch Disc--The splines are chewed up Gone!

[AudiVWguy]

So, the truck stopped moving forward on the way home from work the other day. Couldn't find anything until I removed the trans and saw this:





Anybody ever had that happen? I thought the spline area was hardened steel.
One possibility is that the spline area was not properly hardened.
The other is that if there was excess slop in the two joining splines, I suppose the trans shaft could have worked it's way through the clutch disc. Close up of the trans shaft still looks really good. I will contact ACT tomorrow and see what they say.

[J Z]

Have never seen anything that bad. Not even close 

[Patrick]

Had it happen on a BIG truck once. Double disc clutch on the back of an 855 c i cummins big cam 400 horse... Took out the splines on one disc. Traced back to running out of line. The bell housing on  a big truck is a 2 piece deal, one half on the block behind the flywheel and the other half goes on before the tranny. The bolts were loose that held the front half to the block, broke the alignment pins too. Drove it home from Iowa to Ontario with the clutch slipping enough I couldn't get over 55......

Don't know how you could be out of line, or how you could even check. Dial indicator ont he inside of the 2 piece bell did it for me.

[burn_your_money]

Close up of the trans shaft still looks really good.

It looks messed up to me. Look at the splines around the 3 o'clock position.

[AudiVWguy]

Yeah, it's not as good as it should be. This is a ACN trans, 3:67 with a .75 final. So, maybe its time to start shopping around for another trans. The 3:67 I felt worked well for a lot of in town work, but the highway could be better. I have a spare .71 to put in.
At scirocco.org there is a great list in the gears section. Staying with the 3:67, there are choices like:
AMC
DFQ
CHE
ATH
DFP
CHD
I could swap the .71 and try that.
Thoughts?

[theman53]

I personally wouldn't be scared to run that. But understand if you don't want to.

To me it looks like they hardened the hub too much. Sounds wrong, but what happens is it gets stronger when harder, but more brittle. When one goes then they all do, real fast.

[8v-of-fury]

Yeah, it's not as good as it should be. This is a ACN trans, 3:67 with a .75 final. So, maybe its time to start shopping around for another trans. The 3:67 I felt worked well for a lot of in town work, but the highway could be better. I have a spare .71 to put in.
At scirocco.org there is a great list in the gears section. Staying with the 3:67, there are choices like:
AMC
DFQ
CHE
ATH
DFP
CHD
I could swap the .71 and try that.
Thoughts?

When swapping from .75 to .71 you will not notice a change at all. It will iirc drop the rpms something like 175rpms. If you ask me? Not worth the effort at all.

[AudiVWguy]

I personally wouldn't be scared to run that. But understand if you don't want to.

To me it looks like they hardened the hub too much. Sounds wrong, but what happens is it gets stronger when harder, but more brittle. When one goes then they all do, real fast.

I know, I'm really sittin on the fence on wether to use or not. I've had really bad luck with clutches. The first two stock ones, something I never found was rubbing in the spring area until the spring fell out at about 15K miles. This one lasted about 30K. I gett'in really tired of taken this apart.
8v---yeah, it's 152 rpm difference. But in an hour drive it's 9,120 rpm less on the life of the engine. In a month of commuting it's 273,600 rpm. (This math thing is kinda addictive )

[R.O.R-2.0]

Yeah, it's not as good as it should be. This is a ACN trans, 3:67 with a .75 final. So, maybe its time to start shopping around for another trans. The 3:67 I felt worked well for a lot of in town work, but the highway could be better. I have a spare .71 to put in.
At scirocco.org there is a great list in the gears section. Staying with the 3:67, there are choices like:
AMC
DFQ
CHE
ATH
DFP
CHD
I could swap the .71 and try that.
Thoughts?

When swapping from .75 to .71 you will not notice a change at all. It will iirc drop the rpms something like 175rpms. If you ask me? Not worth the effort at all.

i think its more like 40rpms actually.. lol.

[burn_your_money]

It depends on your final and tire size. I would stay away from the mk3 trannys you have on that list unless you want to learn how to fix the reverse idler gear.

[AudiVWguy]

That is true, I put 195/50/15 in the calculator on the scirocco.org site. 152 rpm difference, kinda thought is would be more. I talked to ACT today, the guy I talked to said he had seen this before but it's rare (lucky me). And that it was other 4 cyl diesels. Let me purchase one at cost ($60) it will be here soon.

[clbanman]

I personally wouldn't be scared to run that. But understand if you don't want to.

To me it looks like they hardened the hub too much. Sounds wrong, but what happens is it gets stronger when harder, but more brittle. When one goes then they all do, real fast.

I know, I'm really sittin on the fence on wether to use or not. I've had really bad luck with clutches. The first two stock ones, something I never found was rubbing in the spring area until the spring fell out at about 15K miles. This one lasted about 30K. I gett'in really tired of taken this apart.
8v---yeah, it's 152 rpm difference. But in an hour drive it's 9,120 rpm less on the life of the engine. In a month of commuting it's 273,600 rpm. (This math thing is kinda addictive )

Keep in mind that the fit on those splines is on the side of the tooth profile.   Yours has been hammered out to the point where you have displaced the metal based on the picture that burnyourmoney commented on, so unless you replace it, there is no way you can get the original design fit and life.   How much it would reduce the life I can't say for sure, but odds are if you reuse it, you'll be taking it apart sooner rather than later.  All depends on how much risk tolerance you have. 

[AudiVWguy]

I know, I worried about the life-span also. I am searching locally to see what I can find. I'm not sure what's involved in replacing the input shaft. I would think it's like rebuilding the trans. This one shifts great, no syncro issues. A crap shoot on what I would find.
Happy Turkey Day!
-JB

[8v-of-fury]

i think its more like 40rpms actually.. lol.

143rpm if you wish to get technical. lol :p.

AudiVWguy, the rpms on the engine don't really matter.. The engine i took out that was original had the closest ratio trans available (more or less). and I know for fact it made the trip from Ontario to British Columbia (4300kms) a bunch of times. With 185/60/14 it would sit at 100km/h it would sit at 3200 rpms.. and it was never driven below 130 on our highways! lol. What i'm getting at, is it doesnt matter as long as you take care of it. run good oil and change it on time. I took the engine apart when i pulled it for shiggles, and it was still like new in there. No sludge, still had visible cross hatching, perfect oil pressure, and no ridge on the piston walls.. yet had 300k kms of high revving.

In the grand scheme, it doesnt matter. lol They sold diesels with the same ratio i used to have.. that have gone over 400k km on stock motors..

[AudiVWguy]

8v- great testament for not slacking on the maintenance.
I'm afraid if I can't find one before the weeks out, the old one's gonna hafta  go in.
Cheers,
-JB