SN95 Alternator Replacement Options/Opinions

robb15033

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In hopes that i can help another brother with an alternator replacement, my thoughts after installing:
The alternator on the Cobra started to produce less charging volts when heat soaked. I purchased a 200amp unit and 4 gauge wire for a replacement.
-I did some researching prior to replacing it. Read somewhere that some 4.6L engines have alternator failures that include grounding issues that can damage batteries and even corrode heater cores due to alternators not grounded correctly. Anyone share opinion that 4.6L engine alternators may fail prematurely? Issues with PA Performance units not performing?
-Observations: My new alternator is functioning perfect. Car voltage regulator is controlling unit with gauge to right of "R". After installation & reconnecting battery, it took a day of stop & go driving to get the gauge needle steady and not dipping slightly when load was increased. It's consistent now.
-I installed a DB Electrical 200amp unit. I considered PA Performance, Mechman, and DB. Looked at replaceable/rebuilding parts available.
-Before installing new unit, I rubberized the back & bottom of alternator where it would make contact with engine, framing, or brackets. I applied a layer of grease on all bolts and areas of alternator that made contact. Ran 4 gauge wire with inline 150 amp fuse from top of alternator post to fuse box terminal. That's it other than plugging in top connector.
So far, so good!
DB ELECTRICAL LINK: http://www.dbelectrical.com/p-9802-alternator-high-output-200-amp-46l-mustang-2001-dohc-cobra.aspx
IMG_20140509_193523_2441_zps2ea499fc.jpg
 
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robb15033

robb15033

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Yeah, to clarify: I rubberizes the bottom of alternator where the two "U" shaped parts of alternator drop down onto bolts that secure it to frame and applied grease onto those connecting bolts. A small amount on bottom/back of alternator that rests flush against bracket. Tried to minimize any grounding effects from alternator through to mounting brackets & engine, anything making contact physically with alternator body. Hoping it would help prevent corrosion and integrity of assembly parts.
-Hope that makes sense or gives a better visual mentally.??.
-I did this while installing it, on the fly. No theoretical scientific method applied, just an idea I went with.
 

ttocs

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as he said that is counter intuitive because the alt uses its chassis to ground to the block. I guess at this point the bolts would still be carrying current but reducing the area that It has to ground to the block I can't think is a good idea. If it were me I would have sanded down through the powder to be sure there was a better contact area between the two. Did you upgrade the stock grounds as you did the power wires? If you didn't, your stock 8 awg ground wires are now your weak point in the chain and it really doesn't matter if you upgrade the power wires if the ground wires are the same size....
 
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robb15033

robb15033

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as he said that is counter intuitive because the alt uses its chassis to ground to the block. I guess at this point the bolts would still be carrying current but reducing the area that It has to ground to the block I can't think is a good idea. If it were me I would have sanded down through the powder to be sure there was a better contact area between the two. Did you upgrade the stock grounds as you did the power wires? If you didn't, your stock 8 awg ground wires are now your weak point in the chain and it really doesn't matter if you upgrade the power wires if the ground wires are the same size....
-YES. You are correct. Thank you for setting me straight. I had only added a 12 gauge wire from negative terminal on battery to firewall some time ago. I need to add a clean 4-8 gauge ground wire from alternator to battery, frame, or firewall. What is the best way to ground it properly?
Thanks for the help. I appreciate it. Alot.
 

ttocs

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There is more then one stock ground wire but 8 awg is about as big as they get. From battery to chassis(next to battery), chassis to block, and I also like to add one directly to the alt to the chassis.

I am also afraid that rubberized section might do more harm then good. Never heard of anyone doing this before did you read this somewhere or come up with it on your own?
 
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robb15033

robb15033

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Thank you. I saw a youtube video about 4.6L engine alternator replacement, the possibility of having a short to ground somewhere causing premature alternator failure. Alternator body being used as direct ground, least resistance, and finding heater cores corroded out because of it. -Something to that nature. I'm glad I mentioned it. I'm headed out now to add one from alternator to chassis. Thanks again.
 

ttocs

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try to use one of the bolts holding the alt on as one of the grounding points if you can so you know the alts chassis is grounded properly. I do that myself...
 
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robb15033

robb15033

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try to use one of the bolts holding the alt on as one of the grounding points if you can so you know the alts chassis is grounded properly. I do that myself...
I'm prepping wire now & I'll do just that. Thanks.
 

ttocs

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I wasn't sure if he meant where to ground too the alt, or where to ground to the chassis. My alt is a high performance alt with an off board voltage regulator and a specific grounding lug and I am grounding mine to the frame rail myself but I will more then likely drill and install a bolt/nut. Maybe its easier for me with the fenders/bumper off of mine or because at this point in the build drilling a few more holes is no big deal...
 

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