A couple weeks ago, I installed Gatorback part # 4060547. I was checking on my belt tensioner earlier today, which I know needs to be replaced, and the top hole of the tensioner can no longer be seen. What gives? I could be wrong, but I see no way that a failing tensioner could cause this. From what I could find, it looks like the OEM belt is 1388mm and this particular Gatorback belt is 1390. Could 2mm really make that much of a difference?

 

Holy crap, I just realized I may actually have a JCW pulley, if not entire supercharger on my car. One of the previous owners installed a JCW intake & even took the time to put a JCW badge on the back of the car (though, it was for a second gen & I knew it wasn't correct so I removed it haha). Anyway, does anyone know if I could maybe measure the diameter / circumference of the pulley I have to see if it's a stock S pulley on in fact a JCW pulley? That would certainly explain why the OEM sized belt wound up being too big....

 

Well, I was wrong about the pulley. I just went out & measured the pulley with some calipers & the diameter measured at 65.03mm, which is the OEM R53. I also double checked the part number on the gatorback & it is for sure the 4060547. I do have a new tensioner and idler pulley on the way, but I still don't mechanically see how either of those failing could cause the top tensioner hole to disappear. I went ahead and ordered a 4060537 belt, just in case that's the solution. Has anyone else experienced this?

 

So everyone knows, the 4060539 is what you want for the stock R53 pulley. It's a tight fit but it will go on & keeps the tensioner at the right spot with the pin removed (1 hole showing). I'll be installing a 16% pulley this weekend & using a 4060537. I guess the 4060547 technically works but causes both holes on the tensioner to disappear.

 

I used 4060537. I have a 15% reduced pully

 

Two things going on here....
A "stock" length belt is fairly long....folks found they did slip at higher rpms...
So most everybody uses shorter belts....
But you might have had the tensioner replaced....and the new one MIGHT have been reinstalled in the wrong hole on the side of the block...
Only know of one case (not on my car, but another).but it worked fine..belt length was just off a bit before it was discovered....
Kind of a neat thing yo know the hole is there if the bolt sheers off when doing a tensioner swap...