TR6 Alternator Issue for 72 TR6

[mfmcauliffe]

I have had my TR6 since January. No issues until it arrived in MA for the summer. My ammeter gauge sporadically shows positive charging for a moment or two, but mostly it is negative drain both idling and driving. I used a voltmeter to test the terminals while the engine was running and saw no charging. I then used the voltmeter to test the alternator itself and it appears to not be working (assuming I did the test correctly). As a result, I need to replace the alternator. However, when I look at Moss and some other sites, I see a confusing array of choices. I don't think I need to upgrade given the car is a weekender kept in a garage. Any suggestions on where to source? I also may need to buy an adaptor for the plug depending on the alternator (and pulley). Why am I seeing some rebuilt models for $4-500 and the straight replacement alternator for $130? I am using this as my first do it yourself project (40 years after selling my last British roadster). Any and all insights or suggestions are appreciated. Michael

 

[poolboy]

Maybe you could remove the alternator and bring it to an Auto Zone or even better an independent Starter and Alternator shop if you can find one still in operation...have it tested and if it fails buy a replacement.
AZ will issue a 'lifetime warranty' if you end up buying on from there.
BTW, that alternator in the picture looks to me like the Bosch unit from the `Ford Fiesta 78-80 with AC & Rear Window defrost...NAPA part # AL86X BSH or Auto Zone 131071

 

[Gliderman8]

I like poolboy’s suggestion. Remove it and take it to a starter shop. If it tests bad maybe just have them rebuild it.

 

[charlie74]

A couple of years ago I had to replace mine and got one from RockAuto. It was about $130 (a rebuilt unit) IIRC and it’s worked fine since.

 

[PatPink]

Poolboy is correct...that is a Bosch alternator. I would by a new replacement if it is bad. The Bosch is way better than Lucas.
I put a Ford alternator with external regulator on my TR6 30 years ago...still works fine. Problem with the stock alt is that built in regulator diode thingy. It sucks!

 

[PatPink]

Also, maybe the Bosch is not wired correctly.

 

[mfmcauliffe]

The alternator worked perfectly for the initial five months of my ownership. It was after its arrival up north for the summer/fall, the alternator now appears to only work sporadically. I don't mind replacing it (so further testing by a shop doesn't seem like a necessary investment of time), I just am somewhat overwhelmed by the actual selection of an alternator for a 72 TR6. It does appear that the one installed currently is a slight upgrade/more amps than the original spec unit. I live on an island with two primary car places and one parts store so I intend to order one online. I wonder what specific model PatPink installed and his TR6 model year.

 

[DrEntropy]

Usually, simply replacing the brush pack on a Bosch unit doing what you describe will cure the problem. Should be a plate on the alternator with the model info, which should lead you to the right pack.