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Thanks to sowsley pointing out the Internet Archive: Wayback Machine, I was able to recover the original MK3 alternator install article by falconindy that used to be here ( Hopefully this will help some people now that it's back on where it belongs!

Mk3 Supra 80 Amp Alternator Install

NOTE:This swap can only be performed on the 84-86 5mge due to the way the belts are arranged. I assume you could swap start pulling more accessories and swapping pulleys to get rid of the dual v-belt setup on the 82-83 engine, but I'm not familiar with that.

The stock 60/65 amp alternator in the mk2 is barely even enough to power everything you need at night if you have even a mildly upgraded stereo. For those looking for a little more output, this simple install allows you to put an 80amp mk3 alternator in your mk2. I foraged mine up from Don Culbertson at for around $55US. If you go somewhere else, be sure to get the later year turbo mk3 alternator with automatic transmission. In addition to the alternator, you will need a new belt since the pulleys aren't the same, and cannot be swapped due to a conflict in shaft size. I bought a Gates K050375 belt -- which translates to be a 5 rib 37.5" belt. I paid 15 dollars, but for those purists, the genuine Toyota belt will run you 20 dollars. The new belt is 2 ribs narrower than the stock 7 rib belt. This will cause no problems in everyday usage, but over time, you will pay the price of requiring new bearings in the pulleys for the water pump and the alternator (thanks to PhilD for pointing this out).

80amp Mk3 Supra alternator​

This job can be done by a single person in approximately 1-2 hours. You will need the following tools:
-10mm, 12mm, 14mm, 19mm sockets
-14mm wrench (a racheting wrench is very helpful)
-vise grips
-an aggressive round hand file (no larger than about 1/4")

First disconnect the battery. You're working with very high output electronics and the last thing you want to do is toast anything, especially yourself. The lower engine cover also needs to be removed. It has 11 10mm bolts. Besides this, 2 belts need to be removed in order to get to the alternator -- the power steering pump belt and the a/c compressor belt. The power steering pump itself has 3 bolts to secure it in place -- 2 in the back and 1 in the front. Loosen all of these 14mm bolts and tilt the pump towards the engine to loosen and remove the belt. At this point, you don't need to remove the pulley itself, but removing it makes this job a whole lot easier. To remove the pulley, clamp the vise grips on on the shaft on the backside of the pulley and loosen the 19mm nut. Note: Be careful of the keyway when you remove the pulley. Also, you will want to be very careful about using a degreasing agent like wd-40 on tough bolts because you are working with belts that need to stay away from chemicals like this. Brake parts cleaner will not leave a residue but you will have to make sure that you wipe the pulleys clean before putting the belts back in.

Power steering pulley removed (alternator visible underneath)​

The second belt which needs to be removed belongs to the A/C compressor. Seeing as my car is and 18 year old project car and I bought it without a working A/C compressor, I decided the best route was just to cut the belt and forget about it. If you're blessed with a working air conditioner, loosen the idler pulley in the same fashion as the power steering pump, and then loosen the bolt on top of the idler assembly to loosen the belt until it can be removed.

Alternator as seen from below​

You now have access to the alternator and water pump belt. Working from underneath the car, unbolt the long bolt (shown above) with the 14mm wrench and socket. The adjustment bolt is a 12mm bolt and also needs to be loosen so that the alternator can be tilted towards the engine block and its belt removed. With the belt removed, it's time to remove the alternator. In the rear of the unit, there are 2 electrical connections -- one is a plug, and the other is a ring terminal with a 10mm nut over it. Remove both of these, remove the two bolts from the alternator, and remove the alternator.

The 2-piece bracket that both the power steering pump and alternator are bolted to need a slight modification. To remove the bracket, unbolt the 14mm stud next to the engine block.

Power steering pump and alternator mounting bracket​

The picture above shows the bracket removed and the red arrow points to the part of the bracket that needs to be modified. put the bracket in a strong vise and using the round file, grind down the thin part of the bracket about an 1/8". While the bracket was out, I chose to use a light grinding wheel on my dremel tool followed by some high grit sand paper to clean the rust from the bracket. Once this has been done, the bracket can be replaced and the new alternator can be installed "in reverse order of removal" (as the haynes' manual puts it).

New alternator installed with belt​

The new belt for the alternator should be tightened down rather tightly. Several people have confirmed that the belt needs to be a little tighter than the standard 1/4"-1/2" deflection. Rule of thumb is, if it squeals, it needs to be tighter. You can test run the engine without the power steering and a/c compressor belts to see if it squeals. Once you are happy with the tension of the belt, the other belts can be installed, with the deflection in the standard range given earlier. Replace the lower engine shield, reconnect the battery and you should be good to go!

The finished product​

If you have any questions regarding this upgrade, you can email me at [EMAIL OMITTED] (User inactive since 2007)
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