Originally Posted by
mac853
I have not used any of it or anything similar.
But, I would not use the belt tensioner they have shown. It is a nicely integrated piece but I don't think you should put the take up on the bottom of the belt. If there is any slack in the belt that needs to be controlled it's on the top side because the bottom side will have the majority of tension when under load. With the take up on the bottom it's just one more turn for the belt to overcome while it's loaded and will stress the belt and be less efficient. At the same time the top will still be allowed to flop around all it wants under power.
IMO the belt tensioners should not be used strictly to make a belt tighter but to keep control of the loose section of the belt. That makes it smoother, last longer, and stay on the pulley when weird things happen to the car in a crash or other bump. When the belt starts to bounce around uncontrolled it can go anywhere, including off the pulley but that's pretty rare. Leaving this on top stops that and keeps the belt guided properly to the front diff. Most modern cars have enough belt tension built into the diff eccentric that you don't need these to keep the belt tight.
Yep, when you hit the brakes the top is then the tight side, won't matter much unless you're at a high grip track with a mod motor. Even then I'd rather keep the belt controlled and running smooth on the top as it feeds onto the pulley.