Ok, so I have a 2003 R50 and I installed an R53 transmission. Car ran great for about two and a half months then for some reason wouldn't go into gear one day and couldn't drive it. Took it to the shop finally and they took out the transmission and this happened.
The flywheel, pressure plate, and throw out bearing were all in perfect working order. But the clutch disc had a major flaw. Keep in mind this was a brand new clutch kit installed in May. The clutch disc as you know is made up of an outer disc then is kind of connected if you will to a small ring in the middle by four or six splines. I can't quite remember exactly how many. Anyways, my mechanic called me today and said that the splines had totally been destroyed. He said that the disc looked as though the splines had never even existed. He has been racing BMW and Mercedes cars for over twenty years and he said he had never seen anything like that before.
Now what the hell could have caused that? I know that one of my oxygen sensors on the exhaust was out and needed to be replaced but could that honestly have anything to do with it? I personally doubt it. But what could have caused that to happen? Luckily it won't cost too much to fix the car but I don't want to fix it in another three months either. If you have any real experience I would truly appreciate some input.
And I just want to say thank you for any input. That is one of my favorite things about being a MINI owner is because so many people care and give their input. I'm attaching a really bad drawing of mine as a diagram to show exactly what part of the disc was missing.

 

Wow, that interesting... They were obviously there at one point given that your car was moving under its own power.

I am at a complete and total loss. I would love, love, love to see the actual clutch plate. It would have taken a nasty manufacturing defect or some sort of major shock (thermal, kinetic, or both) to break those off like you describe.

I am at quite a loss here.

 

is poor temper in the metal. It would take quite the shock for it tear them all. One possiblitity is a combination of not having a good fit and vibration or work hardening really weakening the metal. If the splines on the clutch disc couldn't slide on the transaxle input shaft this could wear the part. Did the car shift smoothly before this all went south? Make sure that the place that does the work checks the health of the splines on the input shaft, and that the clutch disk moves freely on the splines, otherwise I fear it may happen again.

Matt

 

What do you mean?

 

slides on a shaft as it wears. There are inner splines on the hub of the disc that engage with the spines on the input shaft of the transaxle. If this can't slide easily, then those parts that failed will get bent back and forth every time you engage the clutch. This can cause metal fatigue leading to weakness and then failure. Don't know if it happened, but it's possible.

Matt

 

That seems like the most probable explanation.

So no pictures of the actual disk?

 

if the outer disc of the clutch broke off there could be a number of reasons. During my time working in the clutch industry the top 3 leading reasons have always been.

1. Misinstallation, first most common being the center hub has excessive grease. The second being the mechanic damaged the disc with the transmission spline shaft while trying to get it centered into the disc.
2. Driver Error/Abuse of the clutch
3. Damaged during shipment


I don't know what company clutch you used, but I know that Sachs/Luk and Exedy's rate of failure is 0.001%.



Dr. O's explanation would be cause for a different scenario of failure. HOWEVER, the hub portion of the clutch disc is supposed to flex to a degree on it's own, it is never perfectly straight sliding back and forth between the pressure plate and the flywheel. If the clutch disc did indeed flex that much it would cause uneven wear on the disc, and upon removal the outer portion of the contact patch would be completely worn out where the inner half of the contact patch would look practically untouched.

 

Thanks for sharing...

Matt