ElliotV Posted May 24 Report Share Posted May 24 So I'm writing this just to put the information out there for those who would like to do this on their own. My 85 720 has been running fine with the 60a alternator but I really wanted more power to run my accessories and charge a second battery for camping. I saw on a forum post from years back someone mentioned that a 85 maxima alternator would fit but didn't find anything confirming it. For this project I used a 90a alternator out of a 85 maxima. I could not get one at the junk yard and the parts store were over 200 dollars so I found a Bosch 90a for 150 bucks on Amazon. The nice thing about the maxima alternator is it is nearly identical to the z24 alternator except it uses the serpentine belt since it's on a v6 motor. To get it to fit you will need to drill out the ears where the lower bolts go to 7/16in to fit the z24 mount and also shave the ear that has the steel insert just a little to get it to fit over the lower mount. The upper bracket does not have to be modified at all and bolts right in. The next step is to take the pulley off of your newly acquired maxima alternator and your 720 alternator. You will need to either make/buy/modify a spacer ring to go between the bearing and the pulley to space it above the case. The maxima pulley already has one on it but I looked to hard to cut off properly. What would be best is to find a 11/16 sleeve/spacer and shave it down to around 9mm or maybe thinner to get the v belt pulley as low as possible. Once these have all been done the maxima alternator uses the same connection as the later 720 alternators. You may want a shorter belt because the tensioner is near the max. Also a good idea to run a new + cable instead of the thin factory one. I ran a 4ga cable to my battery and now instead of barely charging at 13.9v my truck runs 14.4v and has plenty of power to charge my second battery. Quote Link to comment
DwayneOxford Posted May 24 Report Share Posted May 24 (edited) Problem I had was V belt slippage under heavy load, especially when raining. Serpentine belts pull better. All the v belt hi amp alternators had double pulleys w/2 belts. Edited May 24 by DwayneOxford 2 Quote Link to comment
ElliotV Posted May 24 Author Report Share Posted May 24 That is why I did not want to go with a alternator that was rated at more than 100 amps. Because from what I have found if you go past 100 amps it will start to slip. This one has not slipped even charging the second battery 1 Quote Link to comment
datzenmike Posted May 24 Report Share Posted May 24 100 amps at 14 v is about 1,400 watts and that is just under 2 horse power. There are inefficiencies so it will take a lot more than 2 hp to make 100amps. That's a lot of resistance to being turned by the pulley. Quote Link to comment
ElliotV Posted May 25 Author Report Share Posted May 25 8 hours ago, datzenmike said: 100 amps at 14 v is about 1,400 watts and that is just under 2 horse power. There are inefficiencies so it will take a lot more than 2 hp to make 100amps. That's a lot of resistance to being turned by the pulley. Yep which is why I really did not want to go with any alternators over 100a. I really don't need it either. And if this one goes bad for whatever reason it's much easier to get a replacement and all I have to do it swap my pulley setup onto it and drill out the lower mounting holes and I can just slap a new one in. Quote Link to comment
datzenmike Posted May 25 Report Share Posted May 25 I did find that at stops with headlights on they didn't flicker with the turn signals and the heater fan was now a tornado. Quote Link to comment
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