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  • SN95 4.6L Mustang Tech

Alternator help needed

  • Thread starter Thread starter 2003 Mustang Girl
  • Start date Start date Mar 25, 2018
2

2003 Mustang Girl

New Member
Mar 25, 2018
1
0
1
Mar 25, 2018
#1
  • Mar 25, 2018
  • #1
Hi all,

I need help.

Over the last 10 months we have put 3 alternators and one alternator harness on my 2004 4.6L with 128K miles

The first two and the harness went away under normal driving conditions last May. The battery light came on, the car shook and shuddered before stalling. We were always able to restart the car.

The third alternator came after drag racing the car in January. The battery light came on. No shake or shudder, car didn't die. We replaced the alternator right away. Raced the next day with no issues.

I made 4 passed yesterday then put the car away for the day. The most recent issue was today. On my fourth pass today, at about 300 feet out the gauges started going crazy, then I noticed the car wasn't shifting properly, auto trans was left in drive. By the end of the pass the call fell off by half a second. By the time I got back to my pit the car was shaking and shuddering, gauges going crazy and then finally died. It would not start. Battery appears to be fried as does the alternator.

Any thoughts? Anyone know of a good, solid alternator that will stand up to racing? Stock ones do not.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Mar 26, 2018
#2
  • Mar 26, 2018
  • #2
My thoughts are that you are over speeding the alternator. This is causing the alternator brushes bounce and loose connectivity at the slip rings and drop off.

Instead of trying to find a more sturdy alternator why not switch to a larger alternator pulley or a smaller crank pulley.

Another option is to switch to an alternator pulley with a clutch (like a sprag). Many later model year cars use these kinds of pulley to prevent "surging" that occurs when large power/RPM swings happen.
 

Neuron

5 Year Member
Nov 6, 2016
859
192
93
Mar 27, 2018
#3
  • Mar 27, 2018
  • #3
Is it new or rebuilt? Is the alternator the same one each time ie all same model from Autozone? Why the harness replacement?
 
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