We had a track session yesterday and my SC belt shredded in piece and that not the worse thing, the safety pin that prevent the tensioner from full extension was also broken causing it to smash into the Alta crank pulley. Yep, the crank pulley was jack and most of the grooves were damaged.
Anyone knows a way to fix the tensioner without buying a new one? may be weld a piece metel rod or ? Any help would be appreicated

The prototype M7 2% crank pulley and the 16% SC will be install this time. I am trying to prevent the same incidence from happening.

 

From our English friends, I am giving one of these a try to prevent just that!



GTT TENSIONER LIMIT STOP

Should be here at the end of Aug.

 

Sorry to hear about this. Hope you get everything fixed up soon.

Maybe contact Randy Webb for any suggestions.

Sumwon,
Thanks for the link.
Quote:
This product prevents the tensioner pulley & damper smashing into the crank pulley (harmonic damper) should the drive belt snap. A snapped belt is bad enough in itself, without a destroyed crank pulley and tensioner assembly too! The STD OE system relies on a small 'T' shaped twist at the end of the tensioner spring to prevent overtravel should the belt snap.

In practice the force of the belt snapping is large enough to break this off, in fact it can even break off if you miss a gear at full throttle. (this happened on our car!) The GTT Limit stop prevents overtravel in a far more reliable way. Easy to fit, & highly recommended for any MCS.

£24+vat

 

Are they just using a machined plate to replace the damper? Everything looks the same as factoty except for that piece.

I'm thinking of using a bolt welded inside of the spring to replace the thin plate and that flat plate that has the logo on it is a good idea. I will have one made this week and try it out.

 

I believe the plate you see is actually installed on top of the damper...which is why you can see it in this pic.

 

Yes Biggripper, I see it in the pic. So that means it's like a suspender

 

See
https://www.northamericanmotoring.co...ad.php?t=20683

Contact JLM (he might be working on something similar) and Cosworth (they might have some info to help).

 

Just curious, are you saying your putting the M7 parts on because our parts caused your failure??? Seems like that is the case do to the last comment:

"The prototype M7 2% crank pulley and the 16% SC will be install this time. I am trying to prevent the same incidence from happening."

Just want to make sure that our pulleys were not to blame, or if the "preventing the same incidence from happening" is you trying to find out a new solution?

 

Just curious, how high were you letting the engine RPMs get before shifting? and did you notice about how high the revs were when the belt broke?

 

FYI, the crank pulley from Alta has nothing to do with this incidence, to justify my last post of the broken belt. It was the belt tensioner safety pin that was broke off alone with the belt, causing the damper to fully extension and smash into the crank pulley. I will add a bracket to prevent it from happening again.

The M7 products were sent to me for testing purpose only.

 

I was in 2 gear at around 6600RPM when it happended. That belt had less than 8000 miles on it with a 19%/stock size lightened crank pulleys.

 

for what it is worth, I have seen three failure modes with the stock tensioner:

-bearings wear out, causing the pulley to run out of true;
-the arm holding the pulley cracks, probably due to mis-handling the tension relieving tool and nicking the arm with the bolt end right above it
-the travel limit tab on the band breaks off, allowing the tensioner to run un-impeded into the pulley, should the belt break.
-one or two instances have been reported of the dampener failing, but i have not seen this personally.

 

I've had the SC belt break twice (I'm running 15% with the stock crank pulley). The first time the tensioner arm cracked (see jlm above), the belt shredded into linguine and the whole assembly fell into the crank pulley chopping it up. Aside from the tow, the costliest part of the repair was replacing the crank pulley/harmonic dampener. The second time the belt just broke, I pulled over immediately and all I needed was to replace the belt. Both times I was running the car pretty hard and shifting around the rev limit (6800). Ever since then I always shift at 6000 or below and I have not had any belts break. I'm told the car doesn't make much power above 6000 anyway so supposedly I'm not losing much by short shifting.

I've recently noticed that the twisted "t" portion on the top of tensioner tab (the thin metal strip with holes in it) has broken off my current assembly -- does this mean I'm risk of the tensioner falling into the crank pulley again if the belt breaks? Anyone know if MINI sells just a replacement tab or do I need to buy a whole new assembly?


jlm - the tensioner assembly is obviously the Achilles heal of our MCSs - have you abandoned your tensioner upgrade project, or is it still in the works?

 

The dealer sell the whole assemble around $ 170- 200. It can't be fix. The additional metal strap and maybe welding a piece of rod to prevent full extention is the ticket. I will do that to mine.