Hi all,

I just got back from being tuned on Tuesday. While on the dyno, the SC pulley belt became loose. I tightened up the tensioner and locked down the nut again.

I drove it hard when I got back, and the belt became loose again. This doesn't seem to happen when driving regularly, but only after driving hard. For instance, today I did the same process of loosening the bolt, adjusting the pully to correct tension, and tightened the bolt down as hard as I could. I am using one of Sideways' special "Mil Spec Locking Nuts"as seen here:



This allows me to tighten the bolt from the side using an extended 9/16 wrench. I put ALL my might into tightening this sucker as much as possible and can't tighten any more. This makes me thing that it's properly locked down, but somehow the tensioner pulley gets scooted back ever so slightly until eventually, after about five to six 3rd & 4th gear redlines, you can visibly see the arch in the belt when the engine is running.

Has anyone ever experienced this or can they think of what may be the problem? All input is appreciated.

Thanks so much!

Troy

 

The belt is stretching, replace it.

 

It's a brand new gatorback belt with less than 100 miles on it. I can see that the actual pulley itself moves back, I just don't know how that's possible with a fully-tightened lock nut.

Normally I would test the tension screw to see if I can move it with a fully tightened lock nut, but I know that's a no-no.

Another thought was that the lock nut I have on there isn't properly working, but I don't see how that could happen either -- Sideways uses the same thing!

 

Gatorbacks do stretch, re tension the belt. If you can see that the pulley arbor has moved you are not getting it tight enough.

 

 

I’m not sure how long your belt is, but a mistake some people make is getting a belt that is too small, as long as you have enough throw in the belt tensioner, the longer belt is better as it wraps around the pulley more adding more surface area grip. You might be able to move up one size on the belt and gain some traction. It also may solve a tentioner that wants to back off if it’s not in its leverage sweet spot. I’m a CT guy, but it likely translates to VT also.

 

You need to inspect the mounting plate and arbor for wear at the contact. It should not move and should sit flat.

Belts will stretch during the first 100 miles but should not stretch beyond that.

 

Well, what I did was loosen the tensioner pulley and tightened the pulley nut at a spot where I could get the full closed-end side of the wrench onto the nut. I loosened and re-tightened at tension and it hasn't moved since!

I like to give the tensioner screw a tiny "check" after tightening the bolt to make sure it's not moving in the slightest. (no torque, just slight hand check)

I think I will go with a larger belt when this one needs replacing so I can get more grip like you said, junky.

Thanks for all the responses!