rrt898

I have an 86 coupe with 105 amp alternator. The other day it started to rain. I put on the wipers, headlights, and the A/C. I know thats alot to have on. The volt guage dropped to around 12.2 at idle but; when the cooling fans came on it dropped to 11.8 at idle. When the car was moving it only got up to 12.8. I did check the battery and alternator with a tester and both are fine. Is the 105 alternator enough or should I replace it with something a little bigger?? Or is this normal with that many accessories on at once. With nothing on the car is steady at 13.9.

thanks

1986coupe

That is normal for 1986.

No need for a bigger alternator unless you plan on filling your car with audio/video systems.

coupeguy2001

I have an 86, and had the same problem, except in the middle of summer on a 115 degree day, the solder would melt off the stator, and I would lose the full charging capabilities of my alternator.
So, I installed an alternator off of a 94 corvette., It plugs into your harness, fits in the original position, and uses the same belt.
I did modify the upper bracket to use the upper mount hole on the 94 alternator, but one from an 85 works without modifying it.
The 94 alternator is 135 amps, and has the stator segments closer than the 105 alternator, giving it a higher voltage at idle.
I did fabricate a longer rear bracket that replaces the one that goes from the exhaust to the original alternator, and in 3 years, it has not given me any trouble. I paid $35 for the alternator used, and just took it to autozone and they checked it for free.
BASICALLY, IT IS A BOLT-ON.
You will have to file a little on the original bracket to keep it from hitting the hood. or file a radius on the underside of the hood on a corner molded into the hood.

oldalaskaman

SunCr

At idle, your 105 amp alternator is putting out about 25 amps. All of your accessories easily exceed that load, so it's on battery. Upgrade for low rpm output; not max. More info at www.alternatorparts.com

rrt898

Thanks for all the help...