Welcome to our Site for MG, Triumph and Austin-Healey Car Information.


TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR6 - Alternator Mod

The charging system on my TR is acting up again. Ignition light does not go on and dash gauge does not show the system is charging. I talked with the rep that rebuilt the alternator previously. He has suggested a mod on the alternator that according to him will eliminate the need for wiring back to the ignition light set up, etc.
Is anyone familiar with this mod? Bad, good, etc. Thanks. Shawn.


Can you please give us a little more info?
1)What year is your car?
2)Which alternator did you install? (ie: GM, Ford etc)
3)When you say it's acting up again, does that mean
that after you installed your new and improved
a)The ignition light did go on and now it doesn't?
b)The dash gauge did show the system was charging
and now it doesn't?
4)Can you upload a picture of the wiring to the

I just read your response. I thought you already did the mod. mistake. I did install the GM alternator and never looked back. My opinion is that the original alternator is to expensive to replace and just doesn't have enough amps. Here's a picture of my installation to a 1971 tr6. Note how easy the wiring is. You'll need to get another bracket that goes on top. It needs to be cut shorter. You'll also need to grind off some metal on the top mount to the alternator. That's it.


Benji...very nice underhood finishing. Some time I'd love to stop in on trip over the line and see your machine first hand. I am hoping that my late model 43amp alternator will do the job OK.

Cheers, Rob

ps 90% of electrical troubles are poor connections... start there.
Rob Gibbs

Shawn, the alternator your man talks of is probably a "one wire" type. The ignition light doesn't have any effect on charging, it's internally regulated. There's some debate about this method, arguing that it's better to have a sensing wire closer to the battery. And it's nice to have a light telling you that the charging system is working OK.

I think Benji's is wired traditionally. These GM/Delco alternators are so common and inexpensive, I think they are a good choice for replacing tired Lucas stuff. The Delco model number for these is 10SI.

I have heard of a model that will fit easier, I'm sure someone will respond that has done that.

Shawn & Tom,
The easier alternator is the 78 Fiesta with rear defrost and A/C. The alternator is available, the problem being it doesn't come with a pulley and fan, which apparently made of unobtainium! Unreasonably hard to find. It took me less than 10 minutes, closer to 5 to remove the old Lucas and install the Bosch. Bolts on and plugs in, no modifications to anything. The retainer for the plug hooks right over the original plug. If you can find one complete, that's good, otherwise, I'd probably go look for a Delco. Hope that helps........

Rod Nichols

There is a company that sells the Bosch unit complete. Go through the archives,it might take a minute or 10 to find it.

All, thanks for the feedback. My alternator was repaired yesterday. The regulator required replacement. The repair shop was great. They cpmpleted the entire repair at no cost. Need to buy the owner a bottle of scotch. Still suspect of the Lucas alternator whereas this was the third time in two years that it required service. I will check out the archives.


I saw a Bosch one that claims bolt on convenience on ebay. I think it was $75 buy it now.

Go to After many attempts of finding one w/pulley and no prevail, someone here on this forum told me about this company. They build a high quality product and may be the only company to supply the pulley.
W Macleod

Your welcome

The only conversion I've done is on my TR4, and I used a 12SI model Delco, it has a nicer fan if nothing else. Very happy so far with the conversion. It's the first time in years that I haven't had to mess with the charging system.

This thread was discussed between 13/07/2007 and 27/07/2007

Triumph TR6 index

This thread is from the archives. Join the live Triumph TR6 BBS now