Tensioner location/config

[Scott Davis]

As I understand it, in chain drive system a tensioner should be located on the slack side and a pulling configuration is preferred. Is there a optimal location and config for Serpentine belts? I almost always see the tensioner directly after the crankshaft or close to it and can't see any preference for pull or push. Someone mentioned push may be more efficient where pull is more stable.

And then more of a silly question that has gotten a different response from everyone asked. In building a manual tensioner that uses a square drive hole and torque wrench to apply tension to the belt. Where should said torqueing location be on this example wheel? Assuming this spins about the center and the star is the pulley location. Should the square drive be on the INSIDE OR OUTSIDE? and location at 1,2,3...o oclock? Is there a different answer for max torque on pulley/belt vs a more accurate FT-LB on pulley/belt?

 

[Scott]

I designed two serpentine systems; one for the supercharger and one for the accessories. I spent a lot of time looking for guidance and, other than some whitepapers, I found very little. I've attached two whitepapers, but I didn't find them useful for my purposes. I used automatic tensioners on both loops. It seemed that the OEM and aftermarket supercharger tensioners were placed on the slack side between the supercharger pulley and the crank pulley, with the tensioner located as close to the supercharger pulley as fitment allows. I took the same approach for the accessory serpentine. Time will tell if it all works out.

With respect to your question regarding the square drive and torque. IMO you should place the square drive wherever it's most accessible. At that point, I'd just adjust it until you achieved the desired tension. If the engine OEM specifies a specific torque, you could measure the moment arm on the OEM tensioner and, if your moment arm is different, take that into account when calculating how much force to apply to your moment arm. That said, all that matters is the belt tension.

 

[Scott Davis]

I designed two serpentine systems; one for the supercharger and one for the accessories. I spent a lot of time looking for guidance and, other than some whitepapers, I found very little. I've attached two whitepapers, but I didn't find them useful for my purposes. I used automatic tensioners on both loops. It seemed that the OEM and aftermarket supercharger tensioners were placed on the slack side between the supercharger pulley and the crank pulley, with the tensioner located as close to the supercharger pulley as fitment allows. I took the same approach for the accessory serpentine. Time will tell if it all works out.

With respect to your question regarding the square drive and torque. IMO you should place the square drive wherever it's most accessible. At that point, I'd just adjust it until you achieved the desired tension. If the engine OEM specifies a specific torque, you could measure the moment arm on the OEM tensioner and, if your moment arm is different, take that into account when calculating how much force to apply to your moment arm. That said, all that matters is the belt tension.

Appreciate the feedback, and it was spot on regarding accessibility, because I had gone under the car to see how I would do a belt change in finishing the design. Tightening the tensioner while also torqueing it was going to be tough.

Fitting the manual tensioner was the easy route. I'm going to try harder to fit an OEM tensioner. The issue I was encountering was how far they stick out and interfere with the alternator bracket. Just going to have to use the little brain power I have left to figure it out. I don't want to keep adjusting the manual tensioner for belt wear especially considering the tight squeeze to tighten it.