400i dual alternator

Once I had mine rebuilt, no problems whatsoever. Other than the fact that the belt for the lower alternator is tough to change, the setup seems to work well. An added benefit is that, if one alternator fails or the belt on one breaks, the other one can keep the car running until you get home or to your shop as long as you take it easy on the a/c.

I suspect that the reason for the two instead of one is that the uprated amps of the 400i made it difficult to fit a single alternator in the space available. Perhaps there are single units that are more compact than in the 80's that would work but I don't see any reason to go out of your way to make that change.

 

Injected boxers have the same set up. It is nice that if one packs it in you're not stranded. Whenever I have these alternators rebuilt I have higher output internals put in.

 

Your belt break or alternator failure better be in day time and not raining or else lights and wipers will run system down in an hour or less. These cars are amp hogs.
Ken

 

I have thought about up rating my alternators too. My concern is will those thin belts be able to dissipate the heat of a greater load and not have a slippage issue?
If I remember correctly the 128 Spyders Fiat built use one of these alternators but with a more conventional belt drive. The owners have the same issue with a need for more capacity with added features in current years and there now is a 115 Amp unit that is a bolt in. Two of those would end the worrisome energy management experiences with the much lower rated units in the 400's. What's your thought about the drive belts?

 

Put them on and go.