Alternator hookup...need advice and confirmation

[lopena]

Car is a '69 911S. I'm about to replace the aftermarket Valeo alternator (internal voltage regulator) with a Bosch unit (external VR). As expected, the wiring is different, but I think I have it figured out. I'd like some confirmation from the Forum that I'm doing things correctly.

Specifically:

- the fat red wire with the white tracer goes to either one of the terminals marked "B+"
- the skinny brown wire (which looks red in the photo) goes to the screwhead marked "D-"
- the tan wire with the spiral tracer goes to the terminal marked "D+"
- the black wire need to be spliced onto a spade connector then conected to either of the copper spades
- the braided ground wire goes to a stud on the fan housing

Is the above 100% correct??

Many thanks, indeed!

[304065]

Alan,

You have the right Bosch alternator for a 69 (a 55A version) but somebody cut the cannon plug off the wires that belongs on the harness.

Yes, B+ is the fat red with stripe. Do not under any circumstances let it touch bare metal or any other connector-- or you will have an 800 amp arc welder on your hands.

For the rest- DF is black, D- is brown and D+/61 is red. You need to remove those radio shack spade terminals and crimp on proper brass ones (1/4" faston, or 6.3mm) As you can see from the back of the alternator, DF (dynamo field) is vertical, and D- (ground) is horizontal. And the D+ is the remaining stud at the middle left.

BUT. . . because somebody has buggered the harness. . . PLEASE take a photo of the other end and post it up here, I want to see what colors go into the cannon plug for the external VR.

and CAUTION is warranted. . . death, burning the car down, frying the VR or alternator (both easy to do) await a wrong connection. . .

[lopena]

Your post was hugely helpful...thank you for that!

Here's a photo of the VR end of the harness, as you requested:

[304065]

Alan,

Your photo confirms my post above-- that the "blue wire" or D+/61 for the warning lamp circuit in fact turns to red at the cannon plug. This is the way it is on the early cars, like my '66, and evidently on 69 as well. . .I suppose in the 70- cars with the 11 pin plug when they made it blue all the way to the alternator.

So, reviewing: B+ is red with white stripe, D- is small brown to brush holder, DF is small black to brush holder, D+/61 is red to stud.

Don't forget the ground strap, it goes to one of the studs that hold the alternator to the fan housing.

If you want to renew the boots, either source something at your FLAPS (they are invisible to even the most fastidious Concours judge, e.g. me) or get the 356/912 version NLA-109-382-00 from Stoddard, expensive but you can put the boots on everything to be extra safe.



Be safe have fun!

[lopena]

Once again, I can't thank you enough for sharing your wisdom!

As you suggest I'll buy some new booties for my terminals.

I'll button all of this back up once I get my fan and housing back...they are wintering in Costa Mesa at Mark Motshagen's place.

Thanks!

[RSTarga]

Are you sure the old alternator will still mate up to your fan and housing?
I was under the impression that there was machining required to fit the Valeo IR.
I might be mistaken, but worth checking before you get it refinished.

[lopena]

Yes...I'm sure the Bosch unit will fit the fan & housing...it had been fitted there previously. Thanks!

[RSTarga]

Yes...I'm sure the Bosch unit will fit the fan & housing...it had been fitted there previously. Thanks!

So no machining was done to fit the Valeo?

[lopena]

I don't recall any machining being required to fit the Valeo, although it was some time ago and I wasn't personally involved...my mechanic performed the task. Maybe one of the experts on this forum can weigh in?

[304065]

The Valeo designed for SWB fits with no issues. If you try to use a later Valeo, such as the 90A version from an 84-88 Carrera, you have to machine both the mounting surface and the backside of the fan housing. Only reason you would do this is if you felt like winning a concours in the morning and illuminating a little league game (this means YOU Mark Morrissey!) that night. If you have that many lights, get a Carrera fan housing (and the Carrera motor to go with it!)

In any event, I salute your reversion to the as-designed External VR. A heck of a lot easier to diagnose for sure. And when I had the aforementioned Carrera alternator in my '71 race car (now you know how I can credibly comment on the above) every time the car would get hot, the VR would shut down, which would turn on the charge lamp.

Except that in a race car, the charge lamp coming on suggests that the belt has broken! So you immediately pit to check it out. . .

When Porsche went to the internal VR in 1982, they exposed a solid-state electronic circuit to heat cycles, that was located only 2" above a hot engine case with cylinders running in the hundreds of degrees. When the engine is turned off, all that heat rises up and cooks the VR. Not for nothing, the Paris-Rhone alternators on the SC were regarded as failure-prone, but I think the VR location had something to do with it.

Probably more than you wanted to know. . .