1st Gen R53 Cooper S Most liked posts in thread: Serpentine Belt on Drugs

I had exactly the same thing happen to me with a Gates 60535 at the track last year. It was less than three months old with less than 1K miles on it. I'm sticking with the NAPA 60535 now. I've had good luck with them.

NOTE: From thread lost in the great data dump - not all 60535 belts are the same length! The NAPA 60535 is the preferred belt for an R53 with a 15% pulley.

 

I'd take a good look at your pulleys and tensioner, catastrpohic failure like that is very unusual....

 

It's less likely the age or brand of (a relatively new) belt, and more likely that your belt failure was due to slipping over the supercharger pulley and/or your tensioner dampener having failed. When the dampener fails, the tensioner bounces off the belt, and can cause failures under heavy use. Check the body of the small black "shock" on your tensioner. Is it moist with oil? If so, it may has taken a crap. BTW, check that the oil is not from a leaky valve cover gasket above it--that can lead to a false diagnosis of failed dampener. Also check the bearings in the tensioner pulley and idler pulley (the one next to your AC compressor).

 

I had a belt go on the track

and it looked very much like yours. I was finding shredded bits of stuff for a while. I think that a lot of them look like this when they let go during hard use. Mine was a Goodyear, I think.

Anyway, each and every person who drives the car hard should change the belt every year, and carry a spare! Yes, it's a short service life, but if you really look at how hard these belts are worked on a supercharged car, it's cheap insurance for sure!

Matt

 

How about the crank pulley, did you check that?
A failing pulley will work fine on the street and throw belts on the track.

Ask me how I know that .

 

Real simple, I threw a belt on two consecutive track days (2nd session Sat, 3rd on Sun) with no apparent cause. Belt was replaced and I continued to run. The failed belts looked a lot like yours. During the next event, a month later, the crank pulley (harmonic dampener, or whatever you want to call that thing on the end of the crank shaft) totally failed and the outer pulley separated from the inner shaft. The rubber part had total failure. I replaced the stock part with an aftermarket 'solid' pulley and I haven't had a problem since.

(I will not participate in any discussion of the pros/cons of solid crank pulleys)

 

And you did check the supercharger pulley for free movement, right?

 

Yeah, this is somewhat consistent with my experience. I didn't throw any belts until the pulley completely failed - but I DID have some belt slippage occurring leading up to the catastrophic failure of the crank pulley. Also, new belts appeared to "stretch" soon after installation (e.g. after driving for a day or two) as determined by lack of visible holes in tensioner strap. What I theorized later is that before the rubber in the pulley fails completely, it develops more "slop" than spec - and the tension of the belt on the pulley can pull it out of alignment a bit - which the tensioner would have to take up as "slack". At least, that's consistent with the symptoms I was seeing in the weeks leading up to the catastrophic failure.

 

Honestly... knowing what I know now... the ATI damper would be one of the first things I would put on a 1st gen MINI that's modded and/or driven hard. I wouldn't own a first gen car without it. Why? Because, on hard-driven 1st gen MINIs, I think ALL the OEM dampers are destined to fail at some point. And when it does, it ruins your day. Big time.