1985 Toyota 4Runner Alternator Upgrade Project Installation

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the first and most important thing to do when you receive your replacement alternator, assuming it’s not a direct replacement, is to make up a simple measuring jig for it. This is nothing more than a 1′ or 1 ½” angle with 2 holes drilled to simultaneously hold both alternators by the rear of the lower (i.e. longer) mounting tab. See Figure 3 for the one I built in about 1 minute. This fixture allowed me to line up the pulleys, and then measure the difference between the back of the lower mounting tab and the front of the tab, giving me the new measurement for the lower mounting bracket Figure 3. Measurement fixture; OEM alternator in the rear, Powermaster PWM-47294 alternator in front. Pulleys are lined up; note how easy it is to measure the distance from measurement fixture (the 1 ½” angle) to the front of the lower mounting tabs of both alternators. The difference in this distance is the measurement that the lower mounting bracket needs to be lengthened. Note the use of the 8 washers to move the Powermaster alternator forward. Note from Figure 2 that the OEM lower mounting tab is slightly longer than the Powermaster 47294 (2.285″ vs. 2″). From the measurements taken from the fixture, I then cut the lower mounting bracket and rewelded it, making it approximately ¾” longer. For strength, I added a ¼” x 1″ x 2.5″ long steel flat bar to the side of the bracket. See Figure 4 for a picture of the lower mounting bracket as modified and installed. When I rewelded the lower bracket, I made it approximately one 3/8″ washer (~.085″) longer than I thought I needed. As it turned out, this was fortuitous since when tightening the lower bracket, it pulls the front tab and therefore the alternator and its pulley, to the rear by a very slight amount. This added length was just enough to keep the alternator pulley lined up with the crankshaft pulley