Alternator Upgrade

patkeefe · 09-01-2005, 02:52 PM

I'm putting in a new internal regulator 75A alternator in the 78 SC, which had the old style external regulator. Am I correct in assuming that the ground strap should be connected to the alternator ground screw? I have the upgrade technical bulletin from one of Warren's old posts (Thanks, Warren!).

Thanks!
Pat

RoninLB · 09-01-2005, 07:53 PM

confirn continutity with the case and stud, if a ground wire was installed instead of a strap get a new strap or use 8ga AWG marine wire, clean engine case ground area, use dielectric, recharge battery with your charger not the alternator, tightning the alternator air deflector to shroud may angle the fan blade, confirm fan isn't rubbing shroud...

fwiw the best alt gr is to the ground stud on left inner fender or down to the tub ground stud foreward of the tranny leaning 1st against the tub stud . Technically it should be run to the battery directly.. all imo unless you need me to confirm with text.

unclebilly · unclebilly's Garage

Quote:

Originally posted by RoninLB
...use dielectric,

Ronin, instead of using dielectric grease at the gounding point, wouldn't he be better using an electrically conductive grease (or copper paste) to improve continuity in the connection???

RoninLB · 09-01-2005, 08:30 PM

Quote:

Originally posted by unclebilly
Ronin, instead of using dielectric grease at the gounding point, wouldn't he be better using an electrically conductive grease (or copper paste) to improve continuity in the connection???

sounds good in logic but it's a no go.

Those grey conductive greases you see in electric stores have impurities that could distort the elec's to sensitive items like computers, pc boards, or afaik ignitions. This was explained to me by an F-14 EE who's group was flown all over the world to troubleshoot the convoluted computer systems on that plane. F-14's live in salt air. When I started hanging here I soon found that Warren was a big fan of dielectrics.. Made me wonder what black projects he's in on.. meanwhile I hate to say, in all humility, his word is bible text, but I pay attention to every word written by Warren. My bud isn't around any more..

unclebilly · unclebilly's Garage

ok

patkeefe · 09-02-2005, 03:47 AM

Thanks, Ron:
My 78 had a ground strap on it. I see a connection for a ground on the alternator. The tech literature says on the 82 models, some didn't
have a ground, so if you develop funny conditions like radio interference, retofit one. I loke to try and get it right the first time. I don't think I'm going to pull it all apart again to do this. I'll slap it together tonight and see how it works.
Pat

bigchillcar · bigchillcar's Garage

god i hate the air diverter..it's such a pita to work with. i now tighten down the 6 long thru-bolts, which pass thru the alternator with the nuts PRIOR to attaching the air diverter..then i only use a few extras nuts to attach my battered diverter on top of these. as we all know, if you don't get uniform tightening across the six nuts, the alternator sits crooked in the housing and the blades rub..grrrrrrrrr..always a zen experience to r&r the alternator in my car.
ryan

Early_S_Man · 09-02-2005, 08:22 AM

It is always funny/hard to try to explain why your fan/engine sounds like a whole herd/flock of crickets chirping ... when just one of the eleven fan blade tips is rubbing lightly on the housing because the alternator isn't quite seated properly in the housing! Oh, and the extra thrill of getting the tension set just right on a new fan belt complicates matters, too, because the fan belt squirming on a pulley can add a slightly different 'chirp' to the cacophony, as well!

patkeefe · 09-02-2005, 08:48 AM

My alternator is being replaced due to collapse of the front bearing of the old alternator. Well, it's missing a few balls. It did contact the fan housing. Fortunately, I shut it off immediately.

So, Warren, on the new 75A units, why in the world would the factory have decided against grounding to the case on some 1982 SC's?

Early_S_Man · 09-02-2005, 09:22 AM

Pat,

I suspect too much Lowenbrau on their lunch break on a Friday afternoon ...

Some of their decision-making process is a mystery ... might have been trying to eliminate extra noise from a ground loop, or someone may have thought grounding at the electrical console panel [through the engine harness] would be 'good enough' ... and would save money, and impress the bean-counters!

Truthfully, I have seen plenty of this type of 'lame-brained' design in the corporate world, and it can be exclusively be lain at the feet of a mentality that places 'new-hires' [engineers fresh out of college with no experience or common sense] in charge of maintaining or documenting old or existing designs!

patkeefe · 09-02-2005, 10:49 AM

Warren:
I concur. I have always felt Porsche did too much engineering at the brauhaus.

I have had engineers come in here and tell me my chiller plant won't work; I had to explain to them that it's been working for 30 years. Uh.

Lorenfb · 09-02-2005, 04:52 PM

"why in the world would the factory have decided against grounding to the case on some 1982 SC's?"

Total nonsense! The additional ground strap causes NO problems & provides
a more reliable overall alternator ground system without relying on the aluminium
alt. & the magnesium fan housing interface. Connect the all the grounds!

unclebilly · unclebilly's Garage

The number one rule of value engineering is:

Cost is exponential with part count.