Alternator Upgrade

dbryant61 · dbryant61's Garage

I'm a rookie owner. I need to replace my alternator (already replaced the remote VR to no effect), and have read about "Technical Bulletin 1" which describes in detail the modifications necessary to go from the old Marchal alternator to the new one with the internal VR.

Does anyone out there know how I can find this techincal bulletin. It lists what additional parts are required, as well as a cut that must be made in an air box.

Thanks,

Don

MBAtarga · 06-10-2003, 08:59 AM

Recalling this being covered before, and using the search function, I found the article:

This Link

Don't know about the cut in the airbox you mention....

Lorenfb · 06-10-2003, 10:43 PM

Get your original '80 SC alt. rebuilt properly. The SC 70 amp alt.
is the best alt. Porsche ever used. If rebuilt properly, this alt.
will last 150K miles.

The Paris Rhone internal alt. at 75A will self-destruct and over-
charge. The internal regulator alt. is like putting your stereo
in the oven, because you have no other room in your apartment.
With all that heat from the 911 heads, an internal regulator
is not a good idea. What did Porsche save, one wire?

Get a good rebuilt alt. and solder all alt. wires.

Good luck
Loren
Systemsc.com

Jim Sims · 06-11-2003, 02:59 AM

The "cut" is in the plastic air nozzle mounted on the back side of the alternator. It is required to make clearance for the VR which is mounted on the back of the new alternators. I bought a very expensive ($500+) but comprhensive upgrade kit from another vendor (not Pelican) which included a new nozzle, resistor (for the alternator dash light circuit), wiring lugs to mount the resistor, new (rebuilt)alternator and new alternator shaft nut and new cuped alternator shaft washer. The kit was expensive but I was on the road and on vacation (made the repairs myself) and it was worth the money to be back on the road within a day. Cheers, Jim

dbryant61 · dbryant61's Garage

In response to Loren's comments, I'd like to ask the opinion of others out there. Do you agree that the original Marchal, rebuilt properly, and retaining the external voltage regulator, is more durable than a rebuilt Bosch?

targa80 · targa80's Garage

I agree with Loren, look at it this way what is easier and more practical. External voltage regulator that is easily swapped out and easy to troubleshoot both the VR and the alternator. I troubleshot mine without having to pull the alternator or the alternator with the internal VR that requires removal and bench test /troubleshooting. I have the external VR and fixed a problem by disconnecting one plug and hooking in a spare VR. If you are knowlegable about charging systems and can use a volt /amp meter then you could diagnose if the alternator is the problem with out removing it. Other than that I suggest you take the alternator out and have it bench checked/ rebuild if required.

In answer to your question I would not go for the upgrade because it would not be worth the trouble. If your car is like mine with over 100k and you do the rebuild it should last another 100k.

jmohn · jmohn's Garage

Quote:

Originally posted by dbryant61
In response to Loren's comments, I'd like to ask the opinion of others out there. Do you agree that the original Marchal, rebuilt properly, and retaining the external voltage regulator, is more durable than a rebuilt Bosch?

In a word ... Yes. (Well ... perhaps not MORE durable, but just as good.)

Jerry M
'78 SC

tsuter · 06-11-2003, 10:51 AM

Absolutely external! It amazes me the advice I get to "update" my alternator. - Even from Porsche "specialists". Well it just goes to show- you can get plenty of opinions - but good advice is hard to find.!

Superman · 06-11-2003, 11:20 AM

I've got the Paris-Rhone unit with internal VR, and I would agree with what's been said. Mine is rebuilt and I expect it will have a long and trouble-free life. But if I had my choice, I'd prefer the external VR system. It's like automatic v. manual tranny (I prefer manual), or manual windows v. power windows (I'd rather repair and maintain manual windows).

speedo · speedo's Garage

Since I am in the process of replacing my bad (sp) Marchal alt. in my 74, would I be advised to try and find a later model (80s SC) to replace it with? And didn't that have an integral VR? How does one deal with the electrics associated with removing the seperate VR and installing an alt. with the VR integrated?