View Full Version : TR2/3/3A Alternator

07-22-2019, 04:08 PM
Hi Guys,
Has anyone used this Alternator on their TRs?


07-22-2019, 04:22 PM
Yes, I have seen small Nippon Denso alternators on racing TR3s.

07-22-2019, 04:47 PM
Might not be exactly the same, but I put a small Denso on my TR3 and it worked out well. Much better than the larger Ford unit I used before.

If I'm lucky, you can see some photos here

07-22-2019, 05:18 PM
Looks just like the ebay unit I used with the moss thin belt kit.I tried to remove the pulley with a proper puller to use the moss pulley but felt like I was going to break something so I left it on and it works well with the thin belt.
Mounting was pretty easy.No electrical problems.

07-22-2019, 10:43 PM
Yes, I have one on my TR3.

During the 'up-grade' I removed the pulley and installed a wide pulley from a generator. After a few thousand miles, I realized the reason for the key in the shaft of the generator. The pulley spun into the housing and overheated the bearing and threw the belt. Then, I used a dremel and cut-off-wheel to add a key-way to the shaft, and several several thousand miles later, the same alternator is working fine. -If you stick with the narrow pulley, you'll probably be ok, but if you want to use the wide pulley, you should add a key so the pulley can't spin on the shaft.

I also had to use a different size belt. The spacers for the cross bolt can be a little challenging. -And I removed the guts, re-clocked the output wires to be away from the manifold and painted the case black so it's less obvious. I recall slightly drilling out the bolt holes to the nearest non-metric size (and using grade 8 bolts). Here's a picture of the replacement spacer made from a front-end sleeve and washer.

Joel M
07-22-2019, 11:26 PM
I bought a brand new OEM Denso 50A unit on ebay about six months ago. Nice alternator, but I could not mount the Bastuck thin belt conversion pulley due to interference with the Denso case, which stands slightly proud and close around the output shaft. Instead of having a relief machined (as shown in Randall's pictures), I purchased another 3/8" pulley that would fit. Just something to keep in mind if you are going with a Denso and it does not come with the right sized pulley.

Interestingly, the vendor I purchased from is still selling these things for $57. I think that's a good deal for a new OEM Denso alternator, assuming you can manage the pulley swap and machining operation (if required) at minimal cost.


07-23-2019, 08:58 AM
I like the looks of the alternator posted by Joel M. It has two bottom mounts, which in my opinion is preferable to only one bottom mount. The Denso version I installed on my TR3 has only one bottom mount and it was difficult to get it stable on the bottom.

Graham H
07-24-2019, 07:39 AM
I purchased one that looks just like that one from amazon and there are a few things to look out for, it wasn't internally exited and it didn't have an ignition light circuit so I had to find a new regulator which solved the light problem.