Rebuilding Alternator

[Jloutsik99]

HI everyone,

This is my first post here and my 1978 124 is the first car I've ever attempted restoring. I have a couple questions about the alternator, is it worth rebuilding the stock one (my dad has been an electrician with 40yrs experience and has rebuilt countless electrical motors and alternators) or is it better to upgrade to a larger amp one. We don't intend to put in much for stereos or other auxiliary equipment. Any advice would be greatly appreciated!

[spider2081]

I think your car has a Magneti Marelli 55 amp alternator. Personally I like the 65 amp Bosch alternator used on later models. I think they are a bolt on replacement wit no wiring changes. The 55 amp Bosch is physically identical. just slightly lower output.
This is always an owners decision. Upgrading to a new 95 amp alternator has some physical and wiring changes. There are many people who have had great results with the conversion. I feel the Bosch alternator is a well designed quality product that with proper maintenance will last forever. I have had no experience with the Magneti Marelli alternators so I can't really comment on them.
I measured the current draw on my 81 Spider with every electrical load operating including the added radio and fog/driving lights. It was slightly less that 50 amps. My car had a 65 amp alternator when I got it in 2003.

[18Fiatsandcounting]

This is my first post here and my 1978 124 is the first car I've ever attempted restoring. I have a couple questions about the alternator, is it worth rebuilding the stock one (my dad has been an electrician with 40yrs experience and has rebuilt countless electrical motors and alternators) or is it better to upgrade to a larger amp one. We don't intend to put in much for stereos or other auxiliary equipment. Any advice would be greatly appreciated!

Welcome, and my thoughts are similar to those of Spider2081 above. I still have the original 55 amp alternator in both my current spiders, and they work fine although my electrical systems are stock and without a radio/amp. If you do put in extra lights and especially with a totally righteous but power sucking stereo, the upgrade to the Bosch 65 amp version is a good idea. Just my opinion, but the 95 amp version is overkill unless you really have added some significant electrical loads (power windows, numerous high intensity outside lights, 200 watt subwoofer amp in the trunk, etc).

Keep in mind that the primary source of amperage in your car is the battery, but the alternator must be able to keep up with the amperage drain in terms of keeping the battery charged over time. So, putting in a higher capacity alternator is a waste of effort if the battery is on the flimsy side either in terms of age or capacity.

Try this simple test with the engine off. Turn on your outside parking lights, turn signals (either direction) and the heater blower motor. Then turn on the headlights. If the parking lights dim and the turn signals and the blower slow down significantly, you either have a weak battery or poor electrical connections.

-Bryan

[18Fiatsandcounting]

PS: I've rebuilt several alternators myself over the years, and it all seemed to work fine. Fortunately, I have not run across a bad diode (there are 6 in the alternator), as that could be problematic in terms of finding replacements. Maybe they're common items at alternator and starter rebuild shops, though.

-Bryan

[Jloutsik99]

Thank you everyone for your advice and help, we are considering going to LED lights to also help with the power usage so maybe the bosch 65 would be our best option. Thanks again!