TR2/3/3A C39/C40 question

[Snigolet]

Hi All,

This is a great source of expertise. I'm trying to get my 57 back on the road after 23 years of rest. It was born in Feb of 57.
I just pulled the dynamo because it wasn't working. It seems to pass the tests but only puts out about 9V (eliminating the control box). I get 5.9 ohms from the field coils and .3-.4 ohms at the commutator and no apparent ground faults so I'm stumped. I'm going to try putting a cheap off brand in temporarily and in the mean time, I also discovered that the dynamo is a C40 (22704) with a 62 date code. I want to try to find a C39 (22258) with an appropriate date code (late 56) but would like the additional amperage of the C40. Questions for the experts...

1) I want to confirm that if/when I get a C39 yoke, can rebuild the C39 with C40 parts? I realize that there are differences between the two in terms of nuts and woodruff key but if I swap everything but the yoke, I get the extra amps with a correct date. I'm pretty certain that the armature and field coils will fit.

2) Does anyone know of a C39 yoke with a late 56 or Jan 57 date code?

3) Are all 22258's the same? I found some for other uses and parts (like International tractors) that I can get cheap for temporary then spare usage.

Thanks for your expertise. I'm sure I'll have other questions for you all.

GC

 

[CJD]

I once rebuilt about 5 dynamos at once. I can verify that there have been several internal differences over the production years, but I think you are right that the internals can interchange. Of course the 39 is 19 amp, and the 40 is 21 amp, the main difference being the control box. If you use the C40 box on a 39 dynamo you will over heat and melt the solder out of the armature. It sounds like your field coils are good. Checking the armature with an ohm meter is problematic, as the coils are cross wired across the commutator. You get readings, but other than the ground check you made, they don't really tell you much. A growler is the only way to check an armature. I bought a 150 year old growler off ebay for about $50. It works great, and between uses is a great antique decoration for the house.

As far as finding the correct date yoke, try Marv Gruber first, as he has a substantial collection of parts to draw from. After that, you will have to watch ebay. It took me 2-1/2 years to find a matching date yoke, so patience is important.

Here is a thread of my rebuild that may or may not help?!?:

https://www.britishcarforum.com/bcf/showthread.php?97573-Generator-Configurations

 

[sp53]

I am not sure of this exactly, but years ago I wanted to have a generator with no step in the case and suggested mixing some parts together to make one without the step in the case and Randal comment that there was some kind of problem in doing so. Randall has pasted on and I consider John the go to guy for that now plus he has a growler and I have never seen one. Yes Marv would probably know also. I did see one a while back on ebay without the step in case. There was a guy in Vancouver BC craigslist selling one with other older parts, but I do not see him much anymore.
steve

 

[Snigolet]

Hi John, thanks for your reply. Any idea how much time the dynamo precedes the car build date? Mine is a Feb 57 build.

Also, how can I get in touch with Marv?

Thanks a bazillion.

George

 

[TRopic6]

Hi George, Inspired by John's efforts, I recently rebuilt a C39 stamped 1 59 for my TR3A built in late Feb 59, and a 62-dated C40 for my TR4, built Nov 62. I got the generators back in the 90s when they were lots to choose from. The 'date' is secondary to the quality of the refurb, but it is a 'cool factor' if you're trying for authenticity (I kept the cars positive ground too).
'
I've rebuilt 3 more, and have a "4 59" C39 to do next. For the ones I had and looking at others on ebay, I don't recall seeing anything stamped past 11 until the late 60s. I've read that the Lucas date code is 'week - year', so maybe they genned up for generators in the first quarter of each year. Maybe its a month - year instead for generators; would be interesting to know. Most Lucas stuff is date stamped; I'll have to look at some old spares to see how they run.

The brushes on the C40 are slightly longer (but slightly thinner) than the C39; not sure that would make a 2-amp difference. The C40 uses a much more open rear bracket - better ventilation/cooling? I have a C40 all apart - I'll compare armatures. Good luck finding the 'right generator' - all part of the fun! If I find one close I'll let you know.

Jeff

 

[CJD]

Hi John, thanks for your reply. Any idea how much time the dynamo precedes the car build date? Mine is a Feb 57 build.

Also, how can I get in touch with Marv?

Thanks a bazillion.

George

Hey George. I would think as late as feb 57 would be a viable date. I would not go earlier than about 6 months. While earlier than 6 months is possible, in general the date will be closer than that. Marv is a member of both forums, but I will PM his phone number...

 

[1lakeman11]

i HAVE a 1960 TR3; the car is equipped with the fuel shut off valve, which of course, leaks. what have members done to eliminate the fuel shut off valve and stop the leaking?

thanks.

 

[charleyf]

First you are best off to start a new thread with a different question as you have here. You will get better responses.

I use an in line fuel shut off valve from a motorcycle. It is small unobtrusive and effective. It is part number 12121. These are on Amazon but I note that the first ones I got were part metal and now the ones on Amazon are all plastic.
You do not need the shut off valve. They eliminated it from the cars in about 1960. The time when it comes in handy is when you you want to work on the fuel pump or dump the glass bowl on the fuel pump. Either can still be done if you either pinch the rubber hose shut or tilt the car so that the fuel tank is well below the fuel pump area.