Have done a 17% pulley upgrade but i realised i still have the stock belt on once it got back from a service at mini. how do i know if its slipping or not? car pulls fine and i dont hear any weird sounds

 

You definitely need to get a smaller belt. I have a 1374mm belt for my 15% pulley. You will probably need one slightly smaller. Someone else chime in for me please.

 

Napa 060539....

 

Just got back from a Jan tune in Tacoma, Wa and a couple of fellas had the recommended Alta belt that wasn't the 539 and they were slipping. The 535 is what Jan recommended.

 

Come to think of it that sounds right. I think my last 539 was slipping a bit and I dropped down to a 535. Sorry about that.

 

Dayco 5060535 aka 6pk1360.

 

jus tto add to this, I had slipping on a 535 on my 17% pulley, put on a 532 and it's solid!

 

532? wont that be too tight given that 535 is recommened?
Will mini fit these?

 

how does one know if its slipping? In the mornings when the car is cold, it sounds like it does but not sure if it is that but other than that it seems fine. This is 17% pulley with stock belt

 

MINI probably won't fit it and a stock belt on a 17 is likely slipping. The only real way is to watch the boost or if it feels like it is hesitant when you step on it. 532 is too small and 535 is the best route to go. If you get one too tight, you could snap the belt and if you don't have a stop on the tensioner arm, it could slam down on to the crank which will be a 400+ repair. I wouldn't go any smaller than a 535...

 

for me, the 535 would slip, a 532 is literally 2cm shorter and it made sense to me to use it because everyone with a 15% pulley uses the 535. as far as "too small", my tensioner is exactly where it was with the stock belt and pulley put it with a 532 belt. also, you'll know it's slipping by the loss of power and mine was a bit noisy and made it more apparentl

 

accidental duplicate post.