Are tensioners worth it?

[TubaMorg]

I assume you mean for a chain? A swivel motor mount is also an acceptable way for tensioning. Two things to keep in mind:

1. Whatever tensioning method you use should be robust enough to not spontaneously loosen. For example, simply having a pivoting motor mount would not be enough because it would just pivot back under tension. You would have to figure out a way to lock it in place.

2. Your chains WILL LOOSEN with use. They stretch and will fall off if you do not check them periodically. For that very reason, even if you mount things so that the chain is tight initially, the chain will stretch. Without a tensioning system you may have a lot of heartache.

[Josh Drake]

Another thing to consider with the window motors is that the sprocket you attached is on a nylon splined shaft. The hub needs to be supported on the other end. If you have a good size load on the motor, the sprocket will come out of alignment and cause more chain problems.

[JesseK]

Whichever fixes the problem and will keep the problem fixed is the best solution. Honestly, you have to tension the chain and either option requires more work/maintenance.

[Teched3]

If you choose to go the window motor pivot route, you should install an adjusting bolt in a bracket with double nutting the bolt so it will hold the motor in proper tension position. Similar to what you see on a motorcycle rear wheel axle mount to tension and hold axle position.