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MG TD TF 1500 - Confused on dynamo

It is the confused one again :-)
A couple of days ago the car would not start. Not enough power on the battery. Being too brave the day before, I had driven my 53 TD with full lights on. It does not like that. But that it should empty the battery, I had not reckoned with. After a nights loading, no problems starting today.
So I went to some very helpful Bosch people, who measured the voltage to 13,2. It could be a bit higher, they said.
Then I went to the specialist shop in Oslo in regulators and dynamos.
A veri experienced man there said that my dynamo only produced 11 amp. He found that very little. He also remarked that my dynamo had no fan and no airholes. He suggested that I got another dynamo, and tuned the whole system.
And yes, he knew about the rev counter is coupled to the dynamo.
So what do you knowledgeable guys think about this?
Raymond Wardenaer

Rebuilding your stock unit should be easy for any Auto Electric place.... more experienced the I will comment on the output, but I thought it should be about 19 or so?
I have never had a problem running with all lights (driving lights as well) for extended lengths of time (over 8 hours). The system should handle it all.....
gblawson(gordon- TD27667)

The amperage of each headlight on main beam is watts divided by voltage.

That means 60 watt main beams using 12 volts is about 5 amps each. The rest of the system might use 3 amps, so 13 amps is required to drive the car with the lights on. If you have additional lights, you should be able to run one more 60 watt light (or so).

I run a spridget generator which puts out about 22 amps. Gordon is right that the original was about 19 amps.

Hope this helps,
dave

Dave Braun

What about the fan on the dynamo?
Raymond Wardenaer

Yes, it should have a cooling fan,,

SPW
STEVE WINCZE

Dave Brauns excellent site shows the holes in the rear plate of the dynomo
http://www.dbraun99.com/mgtd15470/Electrical/Starter%20%26%20Generator/slides/Starter%20Generator%20finsihed.html
STEVE WINCZE

There is also the issue that the terminals must be CLEAN and TIGHT for proper charging of the batery,,,

SPW
STEVE WINCZE

Here is a bad photo of my generator.

Raymond Wardenaer

Raymond,

Is it a Lucas dynamo? Should have lettering on side, C39, C45 etc. Rev counter 'right angled' drive is not original - tractor? and Lucar connectors indicate a later dynamo.

All is not lost, all Lucas C series dynamos can be swopped around and field coils, armatures rewound. I would find a different 'specialist', who is competent at rewinds, testing armature, field coils, basic stuff really!

Good luck,

John
J C Mitchell

That looks to me like a C40 generator. C40's are rated at 22 Amps. They originated on sprigets and can have the tach drive output. Additionaly they have a ball bearing on both ends of the armature. So no more problems with fan belts too tight.

The tipoff is the diecast front end plate,the TD units had cast iron end plates. The real indicator is the service P/N, the 19 Amp unit was 22265x, there was also a 17 Amp unit with a service P/N 22258x.

The TD units had C39 or C39/2 which meant the case was 3.9 in. dia. The C40 is 4.0 in dia. The TC unit was C45 and was 4.5 in. dia. But only 13 Amps.

I haven't gotten into the various air inlets and outlets so can't comment on that.
Cheers,
Bob
Bob Jeffers

John, that is interesting. The specialist I saw today said it looked like some industrial generator. And it had Lucas written on it. I could not see the other markings. Shall try again tomorrow.+ But why should I find another specialist? He sounded as if he could do anything I wanted.
Raymond Wardenaer

Identifying the dynamo.
I borrowed a dentists mirror today, to see the writing on the backside of the dynamo.
It said C40A and 22755.
And of course Lucas, 12V, Made in England.
Raymond Wardenaer

hi Raymond,

The C40 dynamo was used on later MGAs 1600s, also MGBs and many other British cars of the late 1950s. As Bob Jeffers has pointed out, the casing is slightly bigger than the correct C39 T Type, but hardly noticeable, unlike the much later models which had a stepped casing.

The T Type dynamos were identical to the very common C39 dynamos used on other cars, but had an extended armature to take the straight rev counter gearbox connection. I don't know of the right angled drive on your set up, is it early AH Sprite/MG midget, or a tractor? In any event, any good auto electric specialist should be able to check your field coils and armature, all you need is 20 mins. with a meter! The control box is also easily checked!

If you are going for originality C39 dynamos can be sourced in the UK at autojumbles etc, but C40s are more common, with original Lucas control boxes also easily obtained, being common to many cars. I would advise against the 'replica' boxes currently available.

The main problem is getting an armature with the rev counter extension and threaded end plate for the connector. A standard armature can be drilled to take a newly made extension by someone with a lathe. Perhaps get your current set up repaired, whilst looking for a correct C39 on ebay etc.

Hope the above helps.

John
J C Mitchell

Hello John,
I don't know where the angled drive of the rev counter comes from. One of the owners in all the years before I got the car must have put it in.
Thank you for your input.
Raymond Wardenaer

Just an additional comment, the original regulators had a number stamped on the side, like 370xx, this apparently had to do with the original setting of the regulator. I don't have a listing of the numbers and what cars they were applied too. But they had to do with the current setting of the regulator.

The original current setting did not limit the current but had to do with the way the regulator acted as the current increased in the original application. I believe it increased the voltage a few tenths of a volt as the current increased (to make up for drop in the harness?).
Don't hold me to that, the pamphlet I got that from was written in the 1930's. Which also discussed temperature compensation. This was dropped by Lucas, I think because they found, as I did, that the regulator increased the inside temperature more than ambient and therefore defeated the purpose of the temp compensation.

A takeoff for the tach drive can be easily made on a lathe. I have had a home made one on my C40 on the TD for over ten years and it has performed flawlessly for all those years. Look for a generator from an early MGB. They are rated at 22 Amps and the pulley is suitable for TD/TF's. (also late MGA's had C40 Dynamo's).
Cheers,
Bob
Bob Jeffers

Hi Bob,

Your points are well made, covering some of the advice I'd previously given to Raymond. As you say a take off from the armature for the rev counter drive can be 'easily' made by someone with a lathe, but in your adaption , did you have a correct threaded end plate, or did you have to modify a normal C40 plate?

Just interested and curious, and it might help Raymond as well.

Cheers

John
J C Mitchell

Hi Raymond,
Your dynamo looks like it came off a Ferguson tractor of the same vintage as your car.There is a thriving ownership of these tractors here.If you get a replacement you should be able to sell off the old one.
Ray TF 2884
Ray Lee

Hi Again,
The Octagon MG Car Club sell new dynos to members @ 76 and non members @ 91.
Ray
Ray Lee

The generator in the53 is a Lucas C40, 22744B, 2/66. Bud
Bud Krueger

I've rebuilt a couple of farm tractors and one was a 1955 Ford. Researching parts for it I crossed paths many times with Ferguson & David Brown parts suppliers. I agree with Ray Lee, that it looks like one from a Ferguson farm tractor with a tach drive. I'm probably wrong but, I think they only put out 17 amps. PJ
P Jennings

PJ,
that would make sense as it only had to supply lights (if fitted),ignition and starting. The tacho head was calibrated as a speedo in the different gears.
Ray
Ray Lee

J. C. Mitchell -- The C40 I modified to work in a TD was from a 1967 MGB. I machined the rear plate so I could press on a sleeve with the correct threads to accept the tach drive. Then I machined the armature so that an extension could be pressed in to lengthen the shaft with the proper fitting to drive the tach drive. It all worked out very well.

If you need sketches of the parts I think I can find them in my notes. Give me an email address.
Cheers,
Bob
Bob Jeffers

Bob,

Thanks for info. and offer - I understand how you did it now. Don't need to modify myself, I'm lucky enough to have a correct C39PV2 dynamo. Details could be very useful for those using the much more available C40 unit with ordinary end plate.

If the armature ever fails I can get it rewound 20miles away in Sheffield (of steel fame), but had already come to the conclusion that an extension could be done on my 1941 USA made Logan lathe - still accurate after all these years! Sent over to the UK in the early war years, and patience on ebay got me all the missing screw cutting gears.

Cheers,

John
J C Mitchell

J. C. Mitchell Glad to see you are interested in working with lathes. I now have a 10" South Bend, I have a bunch of extra gears so I can do 19 and 27 TPI. When I was younger I had the opportunity to work in a machine shop at the Hawk Eye works of Eastman Kodak. The shop was populated by men of German extraction. Of course they refered to themselves as dutchemen ( a mispronunciation of duetchman). Later I worked at Bausch & Lomb Optical, again the machine shop was populated by men of German descent. You were more likely to hear german spoken than english in the shop. But boy could they make those machines sit up and talk. It was a wonderful experience. Would not have happened if it was not for WWII. Kids today don't get those opportunities.
Cheers,
Bob
Bob Jeffers

Bob,
I would be very interested in the details of your tach-drive installation, and I'm sure others would be too. Would it be possible to post it or show a photo? I'm in early-stage contemplations on how to do a "clean" alternator conversion.

Jim
J Barry

Hi Bob

I would also like a copy of your drawings so I can modify my 1955 C39PV2 Generator (photo attached)

Please send to mvec at bigpond dot com

Stuart

Stuart Duncan

Jim Barry When you think about an alternator conversion remember that most alternators have pulleys for the modern flat belts not the "V" belts that our "T" series uses. One exception is the 55 Amp alternator from a Subaru "Justy". Which is quite small in diameter compared to the Mopar generators used on '80s Dodge trucks.

I tried to send you an email.
Bob
Bob Jeffers

This thread was discussed between 23/09/2011 and 01/10/2011

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