689478 PolyForce Belt Tensioner
PolyForce™ Belt Tensioners by Kit Masters replace the traditional spring with a longer-lasting, Polymer Torsion Core. They also feature upgraded pulley bearings to drastically extend the life of the belt tensioner.
PolyForce Comparison Video
No Springs Attached
Conventional belt tensioners use springs to hold their position and tension. However, springs can only flex so many times before they fail. PolyForce™ Belt Tensioners replace this spring with a longer lasting, new and unique Polymer Torsion Core. A compressed silicone replaces the spring, thereby eliminating the primary cause of failure.
The other common failure point in a belt tensioner is the bearing. The pulley bearing absorbs a huge amount of vibration and can often fail too soon. PolyForce™ Belt Tensioners have dramatically improved pulley bearings to give them extended life.
Our bearing is designed specifically for pulley applications and features:
+ Outer Ring Rotation
+ Anti-Vibration Grease (won’t separate)
No Spring = Less Heat
To demonstrate the difference between tensioners, we ran a PolyForce belt tensioner and a competitor’s belt tensioner along an oblong pulley, which causes it to flex back and forth.
After 20 minutes the competitor’s belt tensioner was 62.5% hotter than the PolyForce belt tensioner. Less heat leads directly to longer lasting components and assists in achieving lower under-hood temperatures.
Replaces OEM Part #: 38504, 49501, 89478, 3904370, 3907469, 3908163, 3911315, 3912246, 3914086, 3918944, 3922900, 3933725, 3934817, 3934818, 3934831, 3936201, 3936202, 3936203, 3937553, 3973822, 3973823, 3978022, 3914088, 3912248, VKM910015, 3802287, 3917485, 3922000, 3933620, 3934813, 3937223, 3938022, J918944, 5333477