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MG TD TF 1500 - Switch to alternator

Once again, I'm playing with the idea of switching to an alternator, and disposing of the + grnd issue once and for all; especially since I want to up-date the TF lighting to LED, where possible.

This begs two questions: a) which alternator seems to be then best to adapt to our cars? b) What pulley should I use? I plan to mount the standard rev-counter gear box, and so keeping the same ratios would obviously be desirable.

Gord Clark
Rockburn, Qué.
Gord Clark

Gord
The previous owner of my car had fitted an alternator and it works very well. However, I am thinking of fitting one of those alternators which look like the original generator but they are a bit pricey. When I got the car, the rev counter obviously did not work. I got around this by ripping out the mechanical guts of the rev counter and had an electronic rev counter installed. Works beautifully and no one knows except the afficianados. I think it is the only accurate instrument in the dashboard.
I will see if I can identify the alternator used and get back to you.
Richard Wilson
TD 0460
R A B Wilson

I believe that your cars use a C39 dynamo with mechanical take off for the revcounter the same as for the Mk1 Sprite.
Both of my Sprites use a Dynamator from U.K.based Bad Boy Classics. They are comparable in price to a new Dynamo.
Alan
Alan Anstead

Gord, see http://www.ttalk.info/Alternators.html and http://www.ttalk.info/Dynamator-for-Lazarus.html. I made that switch last year. The pulley gets swapped over from your dynamo. You can do the wiring change so that it's virtually un-noticeable. You can even stick with your positive ground if you insist. Drop me a line if you have any questions. I'd suggest A/S as a source. Bud
Bud Krueger

Gord, I managed to source LED replacements for all lighting except headlights on TF 2071 without having to change from + earth. With the reduced current load I dont see the need to change to an alternator - particularly as the PO had had the generator rebuilt.
Just my 2c worth,
Chris
C I Twidle

'However, I am thinking of fitting one of those alternators which look like the original generator'. Does anyone have a few pics of these so that a comparison can be made. I assume they are not identical and that the differences would be obvious to a Concours judge? Cheers
Peter TD 5801
P Hehir

Peter, I was idly thinking of the Dynalite unit as described by Bud. On my next trip to the UK, I was hoping to find one and have a look at it. On hold, for the moment but check them out on the internet.
Richard
R A B Wilson

Dynamator, from U.K. Bad Boy Classics, as fitted to my Sebring Sprite Replica.
Alan


Alan Anstead

Dynamator. Looks very similar to the original dynamo, but a mm or two wider. Also available from the MG Octagon Club and other places. Costs much less than a Dynalite and appears very reliable. Also need to upgrade the wiring to the battery.
Dave H
Dave Hill

My Dynamator that came with my new XPAG engine before and after. Fits fine looks stock. MICHAEL. OHALLORAN.





Michael O'Halloran

Looks like Dynamotor is the way to go. But nobody seems to know what the load rating is, and I do want to make a comparison to an alternator before deciding.

Abingdon sell it for $220 (US) which is a fair price, but they are out of stock.

Most small alternators can be adapted and I can pick up a low amperage (45 amps or less) from a breaker for around $20, but then have to get my local machine shop to adapt the rev-counter G/B. Probably a saw-off.

From my archives, attached are some pix of two adapted alternators, but I must admit that Richard Wilson's conversion appeals to me, but I would need more details. I have all kinds of spares, but not a TF rev-counter.

I have enough projects at hand right now starting with my new aluminium radiator, and that will keep me busy for a while, so the alternator project will have to take its place in the queue.

Gord Clark
Rockburn, Qué.




Gord Clark

The nominal output rate of the Dynamator is 45Amp. Accuspark also sell all the variants. I fitted one several years ago and never regretted it.
Dave H
Dave Hill

CI Twidle, FYI:

Abingdon now supplies LED headlights that are rated for both positive and negative ground so you can kiss that huge current draw
goodbye!
https://abingdonspares.com/blogs/tech-tips/installing-led-headlights-mg-td?_pos=2&_sid=77d96b1d4&_ss=r

Regards,
Jim
James Auer

I just don't have the electrical load to justify (tome) the conversion to an alternator. I don't drive much at night, some but not much. I have no radio, no power accessories, no heater, no power seats, door locks, windows...no power anything! I periodically rebuild the generator as needed...generally measured in 5-10 year intervals.

Brian W.
ZBMan

With LED lamps fitted there would be even less electrical demand. If you have the need, then go for it, if not...why change and go to the trouble?

Brian W.
ZBMan

Gordan, if you're looking for total invisibility, as Peter would demand, you won't find it. The feedback wire for the Dynamator is quite visible on top of the unit as shown in the attached image. Except for that wire, a negative ground Dynamator's wiring can be a clone of the OEM dynamo. That's shown in the other attached image. A positive ground Dynamator requires the installation of a secondary relay, along with the regular wiring. The next entry shows images of the control box wiring for a Dynamator. One of the images shows the view inside of the control box. Only thing in there is a 40 amp fuse.

My motivation for installing the Dynamator was to get around battery drains from running along at idle for a couple of hours for parades. Lazarus can readily handle running along in first gear at idle speeds. But the ignition lamp is glowing. The alternator can give me the current that I need without a lot of clutch slipping. Bud



Bud Krueger

Sorry, I missed the second image in the previous response. I'll add in the next one. This one shows the wiring at the Control Box with the cover on and off. The component under the cover is a 40 amp fuse. Bud





Bud Krueger

This shows the wiring with the use of a wiring strip and no sign of the Control Box, along with the 40 amp fuse. I haven't installed the Dynamator to obtain more current than the generator could deliver. I'm taking advantage of its ability to provide more current at low engine speeds. A couple of times a year Lazarus and I get into parading.. That means piddling along at idle speed for and hour, or 2, in first gear. Lazarus can readily handle first gear at it 600-700 rpm. But, that's with the ignition lamp showing it's red head. The Dynamator can more readily provide the wanted current at low speeds. I'm quite happy with it. Bud



Bud Krueger

This thread was discussed between 28/07/2020 and 04/08/2020

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