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-   -   alt questions, wiring & rebuild Q (http://forums.pelicanparts.com/porsche-911-technical-forum/149981-alt-questions-wiring-rebuild-q.html)

vash 02-22-2004 01:06 PM

alt questions, wiring & rebuild Q
 
ok i got the old school version, with the external VR.
my wires were nothing like the haynes book, but that doesnt prove anything, here is what i had:

black wire to -DF
two brown wires to unmarked post
no wire on the DL post
blue wire to +61 post
two reds (one big, one med) to B+

no ground strap. do i need a ground strap?
the connections were nice and clean and tight. my red light comes on at idle, and i only get around 12.6V when it is happening. i was checking connections to troubleshoot.

but additional problem, previous mechanic only had two of the nuts on the airguide installed. why, you ask? because the rest of the studs look crossthreaded and slightly bent! which makes taking the alt out of the housing a real joy. will i get new bolts in a rebuild? or should i start the search now? re-tap them?

cliff

304065 02-22-2004 01:37 PM

Ok, on the bolts, it depends on the rebuilder. A good shop should change them out, or at least chase the threads with a die.

Black DF
Blue D+/61
Red B+
Brown D- (Ground)

Do you need a ground strap? Do you need a ground strap? (joking exasperation). Think (always) of the ground strap as another wire in the circuit-- the ground strap is as important as the red wire, and the amperage load is the same at all points in the circuit. You have a HUGE red wire going forward to the positive terminal on the starter. That's where the majority of the current coming out of the alternator goes. It goes to the starter, forward through the fat black cable, to the battery, through the battery plates, through the big silver ground strap, into the body of the car, back to the spot where the transmission ground strap attaches, into the trans ground strap, over to the engine case, up to to the top bolt at the case parting line and into, you guessed it, the GROUND STRAP and into the alternator, completing the circuit!

Which is a long-winded (not surprising, you know me by now!) way of saying, yes, if you don't have one, make one up out of some grounding braid and a couple of connections, and make sure it's tight to the D- terminal. That's the only terminal that you can see basically makes contact with the case of the alternator, that's how you're sure its a ground. http://www.action-electronics.com/braid.htm

And continued good luck with your electrical demons. How is your supply of Talisker holding out?

vash 02-22-2004 01:47 PM

thanks john cramer. i was waiting for you response! so i just share a braided ground strap with the two browns? ok, i get dumb right about now, where did the factory connect the other end? why the heck did my version, not include an additional ground strap? hope is solves my demon! be gone DEMON!

cliff

yelcab1 02-22-2004 01:50 PM

Yes you need a ground strap.

Don't drink that Talisker Islet stuff. Do drink Macallan 18 years, or Lagavulin 16 years, or Oban 14 years, or Glenmorangie 12 years, or at least Glenkinchie 10 years are the stuff to drown your sorow.

Did I say you need a ground strap?

Jim Sims 02-22-2004 01:55 PM

Braided ground strap OEM part number: 91161223300 available from Pelican Parts for $5.11. One can also make one from larger ring lugs and heavy gage wire. It connects to a case bolt on the top rear centerline of the engine; look for it there. Sometimes the previous mechanic simply forgot to connect it back up to the alternator. Jim

vash 02-22-2004 04:20 PM

thanks, i am all over it!

my basic day to day, bread and butter scotch is johnny walker black. i think good bang for the buck, for a blend. but i am a cheap date, i cant drink that much.

vash 02-22-2004 04:26 PM

i just looked at my alt. i had nothing hooked to the D-. but the past mech elected to used the non labeled post next to it. but i looked like a ground also. so my plan is to hook my two browns to the unlabled one like it was, and my new braided ground strap to the D-. sound right? or screw it and stick all the grounds to the D-?

holy crap i hate electrical stuff.

cliff


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