6V Dynamator - first hand experiences...

[1938austin7]

Dash moved out to access the switch.  I disconnected the speedo, oil pressure gauge, and loosened brackets for starter cable so it could move out far enough.  The wire soldered to the warning ligh was only hanging on by a few threads so I removed it and attached a longer wire to go to the new relay that is required for positive earth dynamators.

Last photo shows new shiny red wires added to attach the relay.  They will all be tucked up under the dash and out of sight.

I also took the opportunity to fix a long term issue where the tail lights only worked when side lights were on.  I needed to move the red wire that I had attached to L to join up with the other red wires at T.

My fuel gauge has also not been working so I tested it while off the dash.  Direct 6v sentbit straight to full so I either have a wiring or sender fault.

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Thanks. Yes I saw that in the instructions. The light was glowing brightly on my old faulty dynamo so hopefully it will still be ok.

[John Mason]

Re fuel gauge problem I suggest you check the Earth on both gauge and sender.

John Mason

[1938austin7]

Thanks for the tip re the fuel gauge. There are a few different wiring diagrams around. The one I originally used only had two wires to the gauge. I found another diagram that has an earth wire as well. I attached an earth to the gauge and it sprang to life.

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Do make sure you have a working ignition light otherwise the unit won't work.

Relay for warning light fitted neatly in behind the dashboard.

[jansens]

Do make sure you have a working ignition light otherwise the unit won't work.

I learnt that one on my MGB with the alternator light. I replaced all the other warning lights with LEDs but the alternator light has to work in both directions and enough current needs to flow to excite the alternator coils when you first start the car up. 

Simon

[1938austin7]

I still have all original globes. I just did a trial fit to test wiring and the warning light came on when I turned the key. So far so good.

I need new bottom bolts to fit the unit as the dynamator does not accept the old ones. The thread is different. (They tell you the right type in the instructions)

[1938austin7]

Dynamator fitted and tested today. All good. I now have a car that charges again, with the added bonus of sorting out the fuel gauge and tail lights.

Here is a basic version of dynamator wiring diagram for cars with 6 V positive earth, a late model switch  and incorporating the relay.

Cheers 

Geoff

[Stuart Giles]

Do make sure you have a working ignition light otherwise the unit won't work.

I learnt that one on my MGB with the alternator light. I replaced all the other warning lights with LEDs but the alternator light has to work in both directions and enough current needs to flow to excite the alternator coils when you first start the car up. 

Simon

An LED will work as an ignition warning lamp as long as you put a resistor with a value that spoofs a conventional bulb in parallel with your LED -i.e. across both legs of the diode. The original bulb is usually about 2W, so a resistor of about 70 ohms will be good for a 12V system. There has still been enough current going through the LED to light it on the couple of cars I've installed LED ignition warning "lamps" on.

[rogersirs]

Hi Guys. I realise I’m late to the party, but is there any update to the above? I am about to fit a 6v Positive Earth unit to my 1936 Tourer, due to both cut-out and Dynamo being shot! I have transferred my original Dynamo drive gear to my Dynamator, but have a problem with transferring the Distributor Drive. My car has at some time been fitted with a CAV DEL Dynamo and the Distributor Drive Gear is different I.e. it’s to long for the Dynamator (it has a smooth stub on the gear). Therefore, do I use the Gear provided with the Dynamator (I think not), get the DEL gear machined down or search for an original Lucas Distributor Drive Gear? If the latter, can anyone suggest a source.

[Ruairidh Dunford]

Tony Betts has the correct gear for you.

[Robbie.watson@uk.bp.com]

Hi All
I spent all Sunday trying to (re)wire my uncles special with a 6v dynamator. He had it already wired up but it had not worked and I was called into help  ..
Anyway, after essentially ripping out the existing ignition circuit wiring (one wire was in 3 pieces joined with choc bloc) I managed to get the car started!! Great me thinks... I go to switch it off and nothing, it wont stop... I got the engine stopped and went through the wiring again and again. It seems like the ignition switch only works initially after start up.... It works when starting the car (IE when off the car wont start) and then if I turn it off immediately after starting the engine if stops the car.. If I leave it a few seconds and rev the engine then the key has no effect...… It is negative earth but it does not have an ignition lamp.. Its a bit cobbled together and does not have the standard switch panel... The cutout is now completely disconnected as per the instructions. I didn't see a relay and uncle has no recollection, but that isn't unusual lol - do I need one?

I've searched the forum but don't see anything for this specific problem. Attached is a copy of Vince's wiring diagram that I used with a couple of edits.

Any ideas on what I have wrong?
Thanks in advance for any guidance!
cheers
R