Perrin: Lightweight Crank Pulley – Install FAIL?

Note 2: I talked to Perrin on the phone, and they said that Subaru has multiple versions of the FA20 service manual. I stressed to them that these instructions do not make sense, so they sent me new instructions using a different FA20 manual. The updated instructions look correct, so I will be making a new installation video soon. Basically, Subaru changed the instructions without telling anyone, so they kind of screwed all of us, hard.

Note: I have labeled this install as a “FAIL?” because I believe that Perrin’s instructions are wrong. The way the instructions are written, it is being suggested that the crank bolt is a “torque to yield” bolt, because Perrin tells you that the bolt should rotate a full 45-degrees when torqued from 33 ft-lbs to 94 ft-lbs. This makes no sense. After doing more research, a bolt of this size would not yield at 94 ft-lbs unless it was defective. Therefore, I believe that this crank bolt is not a “torque to yield” bolt, and as such, the rotation of the bolt should have no effect on the results, so long as your torque wrench is properly calibrated, and achieves the 94 ft-lbs. However, I will be keeping a very close eye on my pulley, and will check it with a torque wrench every day for the next two weeks. I called Perrin and left a voicemail, but have not received an answer.

The PERRIN Performance Crank Pulley weighs just 1.2 lbs, which is 3.7 pounds lighter than the stock OEM crank pulley. This reduction in weight from the crank shaft is equal to removing more than 100 lbs of vehicle weight! Throttle response, horsepower and torque are all increased with this easy to install part.
(Description courtesy of Perrin)

(Scion FR-S) (Subaru BRZ) (Toyota 86)

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