Though the procedures for installing SBDS tensioners are described in great detail at install.gates.com and in the Gates app, we feel it is important to highlight the most important instructions here as well. After all, a failure to correctly execute the last tensioner movement will lead to a difference in belt tension between the tight side and the slack side – a situation that will, in turn, lead to tension peaks and can ultimately cause engine failure.
Move the tensioner from minimum to nominal position
Automatic tensioners are characterised by a wide spring-loaded ‘from-minimum-to-maximum’ working area. This means you will never obtain the correct tension in the belt drive system without following the instructions to the letter. The first step when installing an SBDS tensioner is to move the tensioner from the cold stop position to 10° beyond the nominal position and return to slightly before the nominal position, then set to nominal. Having done this, you can tighten the nut or the bolt. This movement of 10° beyond the nominal position serves to reduce variations in belt tension during installation, specifically damping and loose spans on the slack side.
Rotate the engine through at least 2 full revolutions
Once the tensioner has been installed, you should manually rotate the engine at least two full crankshaft revolutions in the operation rotational direction. Some applications ask for four or even sixteen revolutions, so we cannot stress enough how important it is to check the Gates installation instructions. The reason for the two (or more) engine rotations is once again to ensure a uniform belt tension between the tight side and the slack side.
Afterwards, you should verify the tensioner pointer position. If the pointer has moved away from the nominal position, loosen the tensioner mounting bolt or nut (make sure the tensioner does not make contact with the cold stop once the bolt or nut is loosened), adjust the pointer back to the nominal position and then torque the mounting bolt or the nut.
Note: how to remove the retaining pin
Several of our tensioners feature a retaining pin to hold the tensioners at their maximum position. This pin should be removed once the timing belt has been installed. Yet it is vital that you don’t pull it out abruptly, because that will deliver an enormous blow to the belt which can cause internal belt damage. The key to removing the pin is to use a wrench to gently manipulate the tensioner, gradually releasing the tension until the tensioner touches the belt. Even while removing the retaining pin, you should keep the tensioner in place with your wrench!
By way of conclusion, we want to stress once more that, though this article provides you with a couple of general tips and tricks, it remains crucial to follow the Gates installation instructions to the letter.