With the Air Pump removed and the Greddy Pulleys installed, I picked up a Pineapple Racing Idler Pulley to fill in the gap. This pulley serves a simple but important purpose. Without the Air Pump in place, the leverage for the water pump pulley is reduced. The alternative is to compensate by over-tightening the belt, but this is a poor solution as slippage can still occur at higher RPMs. Secondly, you never want to over-tighten the belt because on top of reducing bearing life, it increases the stress on the crank pulley and by effect the eccentric shaft.
When the Idler Pulley came in, I had to take a moment to survey the parts more closely. I almost immediately noticed the superb level of detail and quality. Apparently, after talking with Pineapple, the machinist that makes these parts has a long track record and was even contracted to make pieces for a lunar project. It takes one to know one, in my opinion; most people who don’t work with cars to this depth probably wouldn’t give more than a second glance… yet this kind of stuff brings out my inner geek. Just check out the consistency of the nickel finish!
Installation was a straight forward bolt-on, but the space in its location was tight. In the end, everything went on just right.
With the Idler Pulley in place, you can see just how much more belt surface area the water pump pulley is able to obtain (almost quadrupled).
I adjusted the belt’s tension to have a deflection of approximately 3-5mm. Another good rule of thumb to go by: you should be able to grab a section of the belt in the middle and turn it a quarter-turn (until the ribs are facing you) without too much effort.
Just a heads up, I installed this on my FD and about 500 miles after installing I noticed the belt was wearing funny. It was actually hitting some slag on the underside of the coolant neck due to clearance issues. The guys at Pineapple did a good job with the kit, the manufacturer of the neck (presumably Mazda) didn’t do a great job with the molds/cleaning up the parts. I thought I had the clearance Pineapple specified, but turned out to still run. All it took was some Dremel action and a new belt to fit perfectly.
I read an article a while back that Goodfella posted on the forums about main bearings wearing prematurely because of an over tightened belt! Looks like you got it covered. Keep up the good work, it’s coming along great.
Thanks for the heads up Kent, I’ll keep an eye on it. The clearance by the water pump housing is definitely very close.
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