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What's the deal with alternators?

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#1
Sphinx

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I had one die at Barber. Picked one up from Auto Zone, only to discover after the weekend that it wasn't properly aligned with the other pulleys and was wearing my belt on one side of the pulley's grooves (instead of sitting square). Picked up a replacement only to discover that the "front" pivot bolt tab hole isn't threaded, like the OEM one - and it isn't big enough for the OEM bolt to slide through (so, no, the hole wasn't drilled through for a nut/bolt solution).

 

(Working theory is that the first one I got from AZ also had no threads, but my installation "pushed" the unthreaded hole forward (because it was effectively cutting new threads) and caused the pully misalignment. I didn't notice the unthreaded hole issue prior to swapping it out for the replacement; so, I can't confirm).

 

Picked up yet another from NAPA and it has the same problem as the Autozone one (no threads in the front hole) and (new problem) the distance between the pivot bolt tabs was too small - yes, I drove the little insert a mm or two but still about two mm too short to slip over the mounting sleeve.

 

Are others having the same experience? Is Mazda the only/best solution?



#2
tynor

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I recently had same problem - Autozone replacement was unthreaded.  So I returned it and got one at Advance - that one, as far as I can tell, was 100% compatible with the original. 


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Steve Tynor

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#3
Sphinx

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Mystery solved! Turns out that the rebuilder (likely Remy) is incorrectly installing the front cover on the alternators. They are installing it 180 degrees off of what it should be.  So, the threaded hole is at the top and top hole (which is unthreaded) is on the bottom. We removed the the 8mm bolts and tried to spin the cover, but it won't spin easily without further disassembly. Ain't no body got time for that - it went back.


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#4
LarryKing

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Buy an OEM from Mazda. 


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#5
Sphinx

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Buy an OEM from Mazda. 

 

At 2X the cost and without a lifetime warranty, I think id rather have a pair in rotation instead. But I did think about it. Didn't have a choice though since mine died in the middle of a race weekend.



#6
LarryKing

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I had two aftermarket rebuilds go bad ruining races. No problems with new in the box Mazda alternator. 2x times cost is cheap compared to entry fees.


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#7
Sphinx

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I had two aftermarket rebuilds go bad ruining races. No problems with new in the box Mazda alternator. 2x times cost is cheap compared to entry fees.

 

Agree - though the one that failed on me was a Mazda rebuild (made in the US).

 

Now this is becoming a scavenger hunt, just for giggles. One from Oriellys showed up today - same defect. Same factory in Mexico. So, ordered one from yet another retailer today - in the name of science. If that one fails too, then I'll have no choice but to try Mazda.



#8
Sphinx

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I recently had same problem - Autozone replacement was unthreaded.  So I returned it and got one at Advance - that one, as far as I can tell, was 100% compatible with the original. 

 

I had two aftermarket rebuilds go bad ruining races. No problems with new in the box Mazda alternator. 2x times cost is cheap compared to entry fees.

 

Update: So, one came in from the 4th major retailer with the front cover correctly installed. Yay!  Before installing it, I had them do an in-store test to make sure it was good. FAIL. Ok, "uncle." I give up. I'm ordering from Mazda today.



#9
Dave D.

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If they are just spinning it on a test rig, it's not going to charge if we're talking about an NB unit. The ecu gives a pulse width signal to control the output. Make sure that they are testing it correctly.



#10
Sphinx

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If they are just spinning it on a test rig, it's not going to charge if we're talking about an NB unit. The ecu gives a pulse width signal to control the output. Make sure that they are testing it correctly.


Yes, an NB unit. They hooked up a pigtail to it first. So presuming for use very reason.




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