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1981 Triumph TR8: Upgrading the Alternator

Note: When working with engine electricals always ensure that you remove the negative battery terminal before you touch anything in the car. If you don't listen, arc something, fry something expensive or do the electricity dance don't say I didn't warn you.

The TR8 came from the factory with two alternators. One for A/C equipped cars, one for non-A/C equipped cars. This article covers A/C eqiupped cars using the larger 25 alternator. This alterntor was a lucas unit supplied with the TR8 and after 30 years they are a special order type item. For those of us who want to either run more power, or to be able to fix their car quickly if alternator issues arise, we've documented a conversion to a late model GM based alternator that was used in the mid 90's Saturn SL cars.

Watch the video!

At the parts store I had them look me up an alternator for a 1995 Saturn SL2. They only had brand new ones in stock, but that actually worked out well because the core charge that I would have had to pay made all the reconditioned units more expensive. The alternator is a Delco Remy 5912. In addition to this you need to acquire a V-belt pulley for the alternator, a GM alternator pigtail (3 or 4 wire) some nuts/bolts/lock washers and a couple butt connectors.

When you hold up your Saturn Alternator against the original you'll note that the bolt holes to not line up in the same pattern as the original alternator. This is ok. We're about to fix this. Start by removing the nut, lockwasher, serpentine belt pulley and fan from the alternator. Now, you'll note three bolts with 6-point heads holding the front and back of the alternator together. We are going to "reclock" the alternator to get the mounting holes in the correct alignment.

Using the appropriate socket bit for a 6-point headed bolt remove the three boltsw from the alternator. Once removed carefully pick the alternator up, and grab the alumium front plate on the unit. We're going to rotate it unit the mounting points realign to the correct location. Inherently, we're rotating until the old single point mount becomes a double, and the double point mount becomes a single. Once aligned correctly rethread the 6-point bolts and tighten the unit back up. since there's only a few ways the bolts can match up, you will either get it right or wrong, and it should be visually obvious.

With the alternator reclocked, replace the fan, add the V-belt pulley, replace the lockwasher and nut, then tighten them down. The original alternator had threaded mount points. This does not. You'll have to go to the hardware store and get the appropriate bolts, nuts and lockwashers for all three mounting points. Now that the alternator itself is prepped it's time to deal with the wiring.

The original alternator used a pair of posts with a single spade connector for all of the connections. The replacement unit is based on the GM connector which is the reason why we picked up the pigtail. Regardless of whether you acquired the three or four wire connector, the two wires of interest for our installation are the first wire and the third wire. The first will connect to the brown sense wire in the vehicle. The third wire will connect to the brown/yellow dash wire.

Strip the ends of the two wires in question and add a butt connector to each. Then add the pigtail to the wiring in the vehicle. Try to snip as little as possible off the Brown and Brown/Yellow alternator wires. If you're careful there will be plenty of wire left should you want to reverse the procedure down the road. Insert the wires into the correct butt connector and crimp down.

From here, remove the old alternator if you haven't already, and install the new one using the new bolts. If you're so inclined it's not a bad idea to replace the V-belt while you're at it. Tighten everything down and double check the V-belt tension. If everything is good there, connect the wiring to the alternator, reconnect the negative battery terminal and give the car a start. As the car idles watch the voltage gauge in the dash. It should read a bit past mid way. Alternatively you can hook up the appropriate testing equipment to ensure that the alternator is putting out the correct voltage.

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Contents copyright 2008, 2009 - Jody F. Kerr

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