Voltage Issues

[Bert]

Hi group. I have a 72 with an original Alternator 44A Marelli with the typical external voltage regulator. I noticed my headlights are oscillating and checked my voltage at the battery. It is jumping from 13.5 to 16.5 volts so I replaced the Voltage Regulator. Still no change.
I assume it's my alternator. Id like to keep things original so should I just have mine rebuild locally (in Canada) or upgrade it. If replacing is the best option, where is the best place to source and if upgrading to an internal higher output, are there instructions on the rewire available. I searched the form and could not find any. Many thanks from Toronto.

[18Fiatsandcounting]

If the diodes in your alternator are leaking or going bad, that can cause the voltage to fluctuate like you describe. They are there to convert the alternating current (AC) generated by the alternator into direct current (DC) that your car uses. Diodes do fail eventually, and an alternator rebuild shop should be able to replace these.

As for upgrading to an alternator with larger current capacity, opinions are mixed on this. A '72 original spider doesn't have that many electrical gadgets, so there is really not much need for the upgrade. However, later model years with power windows, killer stereo systems, high power headlights, etc. could very well need a larger alternator. It's your call, but I would first call a few auto shops and see if they can rebuild yours.

-Bryan

[aj81spider]

There are a variety of opinions on switching to a larger capacity alternator. I did the switch and the only real issue is belt squeal on startup (there is a thread on this). The alternator comes with instructions on how to rewire (it's pretty simple). I can also email you my before and after wiring diagrams for my 1974 if you are interested. PM me your email address if you are.

If everything was working prior to this I agree with Bryan the easiest, cheapest course of action, and least likely to cause additional issues would be to rebuild the current alternator.

[spider2081]

For early Spiders with the 44 amp alternators and external voltage regulator swapping to a later spider Bosch 55 or 65 amp alternator with its regulator is a fairly easy mod as no mechanical changes are required. The Bosch fits the original mount, the pulleys line up and there is no belt squeal issues, The Battery warning light relay is removed and 2 of its wires are spliced together to complete that circuit.
I would think most of our vendors would sell an alternator outright with not trade in.
A number of early Spiders have been upgraded to later Bosch alternators.

[Bert]

Many thanks guys. I will go the rebuild route for now given I am in Canada. If It still has issues I will upgrade to the Bosch 65. Again, thanks.

[DieselSpider]

I went with a local re-builder because mine with the diesel uses an even more uncommon Hitachi alternator than the original engine and was very pleased with the results. The Hitachi Alternator is diesel specific and has a mechanical vacuum pump on the end of it driven by the alternators shaft to provide for the needs of the brake booster and any other vacuum powered items on the car since a diesel does not have any intake manifold vacuum due to not having a throttle body with throttle plates or a choke butterfly.

[spider2081]

I will go the rebuild route for now

I think you are made a good decision.