Change to neg earth-update +radio pics!

[Space54]

Hello again all!
Further to my introductory post last week, I've decided to go for the Tokai LAR 216 Radio/CD as suggested by Jack! As Jack says, not exactly 50's looking but distinctly retro, highly functional and not a bad price!
http://www.b4udirect.com/Head%20Units/T ... 5115?ai=40

This will however necessetate converting the vehicle to Negative Earth. I've looked on here and elsewhere on the net and if I'm considering doing it then it must be relatively straightforward! In short the procedure appears to be as follows:-

1) Disconnect battery
2) Reverse wires going to ammeter
3) Reverse wires to ignition coil
4) Turn battery thro 180deg and connect negative to chassis and Positive to starter motor (may require new clamps due to size differnece?)
5) REPOLARISE GENERATOR! Here I note there was, shall I say, a difference of opinion between Messrs Andrews and Lockyer when the same subject was discussed some 4 1/2 years ago specifically with regard to the Bradford Van. http://jowett.net/forum/viewtopic.php?f=3&t=339
Has anyone had any direct experience here with a Jupe?

That's basically it apart from 2 uncertain areas:-

a) Fuel Pump- Does this have 2 connections enabling simple wire reversal or is it normally fed positive through it's metal body? If the latter applies then I presume a new negative earth pump will be required?

b) Heater- I have read away from the forum that early heater blower motors were usually "field wound" and not polarity sensitive. Anyone know if this is the case with the Jupiter? If it is not the case and the blower motor therefore likely to run in reverse, again are there 2 wires to the motor enabling swapping of the wires to correct that situation?

Thanks again for the warm welcome and (in advance) your responses to the above1
See you at Gaydon!
Keith

[Amy]

Keith,

I'm pretty certain there is quite extensive guidance on this on the forum, possibly in the gallery. We've changed the polarity on my jupe and it's relatively straightforward - forumadmin will no doubt be along shortly with a link

Glad to hear you'll be making it to Gaydon, I suspect your car may be getting quite a lot of attention!

[Keith Andrews]

The stuff I poste up in the old thread....I have actually done it, several times over the yrs, and the source of my info, was /is a very close friend who did his appreciceship with NZ motorcorp...morris, austin, leyland.

Things like fans try before swaping...which way they spin up...
Some things like heater fans, windscreen wipers, windscreen washer pumps, fuel pumps often dont have the circuit going from Battery/switch/unit/ ground...but can be wired in the loom independant.....
I am not familar with jowet wiring looms/diagrams as to this...my experiance is more old morris/ austin/ hillman/ Chev/Holden.
Easest way to test is using a multi meter to sort polarity before swaping anything.

[Forumadmin]

technical tips
Changing Polarity
Circuit diagram
Another circuit daigram

[Space54]

Thanks Guys!
The instructions given here:-

http://jowett.org/jowettnet/dt/tech/mod ... rnator.htm

are clear and concise and make no mention of heater or fuel pump so as soon as my radio arrives i'll swap the ground polarity accordingly!

Thanks again
Keith

[Jack]

Thanks Guys!
The instructions given here:-

http://jowett.org/jowettnet/dt/tech/mod ... rnator.htm

are clear and concise and make no mention of heater or fuel pump so as soon as my radio arrives i'll swap the ground polarity accordingly!

Thanks again
Keith

Hi Keith,

Not sure if you've considered the potential to swap the earth on the radio instead of the entire car? It might be doable, though I don't know if the radio, being fairly modern, will have components that won't work this way. You may save yourself a lot of time and effort with only a few days to the rally if you can find a retro radio with negative earth (or perhaps wait until the rally to discuss it with the experienced owners there who can show you the things on the car required) - a positive earth radio that suits must exist. I would, however, be very interested to see the Tokai unit in the flesh, I have a few friends who've bought them for 80s cars and are very happy with them, but I haven't seen one fitted yet.

Only piece of advice I can give (despite having basically rewired the entire car for Amy) is that the heater does indeed have two wires coming off it, and reversing these reverses the direction of the fan. I have to say that even if you just leave it and let the fan run backwards the heater will be about as effective as it is in forwards - not very.

On the fuel pump we should be able to check this for you - last I looked I think we had at least 1 or 2 spare, they are a very simple mechanism and there should be a strip down guide somewhere (possibly SC rebuild thread?) from when we had to do some work on Amy's. If you reverse the polarity I do not know if this will pump fuel the wrong way or something odd, if it is not mentioned in the guides I would suspect that no change is necessary, but someone will be able to confirm. Our car is negative earth and the fuel pump is a standard unit, not sure if it has been modified however, or if wires were swapped - I think, from memory, it just has two wires coming off it, one is earthed and one power on ours.

Final piece of advice. Many many cars have already been converted to negative earth over the years. Make completely sure that you are currently running positive earth before you swap anything.

Jack.

[Keith Andrews]

Not sure if you've considered the potential to swap the earth on the radio instead of the entire car?

Only had to figure that out once ...
Most old cars of that era where getting changed over because they wanted to put a radio in....
The car an old American ford, we isolated the radio body, kept feed orginal...then had issues with the areial ground
One cant simply swap these old raios over...even it valve or reatly transitor...has to do with diodes and in the case of valve recirifyers and such.

If you reverse the polarity I do not know if this will pump fuel the wrong way or something odd, if it is not mentioned in the guides I would suspect that no change is necessary,

It depends on how the pump is driven...most are diapham or pistion which usually are not sensitive to polarity... the valves are what determine flow.

[Forumadmin]

Some older electric pumps have a polarised capacitor in them which would be upset at the change. These can be changed to a modern capacitor.
I do not think the capacitor in the distributor is polarised; but to keep the flow of electrons going the right way in the spark plugs you might want to change the coil polarity. This stops the spark plug core evaporating due to ion flow.
If you have electronic ignition, electronic rev counter, electric temp gauge or any other stuff that is positive earth then clearly you need to change them over.
An electric rad fan would also need to be reversed.

All these things have been discussed before so use the search facilities!

Of course, changing polarity opens up the world of modern gizmos to the Jowett. You can even install a car charger socket for the sat nav and mobile!
Note if you do not change polarity be very careful about any exposed metal parts on the added devices. If they touch any part of the car they may blow up your device.

[Leo Bolter]

Keith C said:

Some older electric pumps have a polarised capacitor in them which would be upset at the change. These can be changed to a modern capacitor.

See my post at http://jowett.net/forum/viewtopic.php?f=1&t=1980 for the up-date modification I used on a SU solenoid type fuel pump. The fact that it's polarity insensitive is a bonus with this cheap modification to improve points longevity.
Cheers.
Leo.

[Space54]

Changing ground polarity did indeed prove fairly simple-if not particularly quick as (not for the first time!) I struggled with less than ideal tools! Leaving the battery in same position, simply reversed the leads after swapping the different sized terminal connectors. Swapped over the wires to the ammeter-bit fiddly, but no real problem! Swapped the 2 wires to the ignition coil-took an absolute age as didn't have right size socket or spanner! Small adjustable not much good as too "fat" at business end and kept fouling on the housing where the HT lead goes to the distributor.Eventually prevailed largely by using a pair of pliers to grip and turn the small nuts! (Much cursing and scraped knuckles!) Finally, repolarised the dynamo. Having removed the wire to the smaller field terminal tried at first to "flash" this terminal with a small length of wire attached to the larger terminal-not the slightest sign of any sparking so presumed that this didn't work? Then defaulted to Pat Lockyer's recommendations whereby a long wire (2 Jump leads joined together!) is lead direct from the positive on the battery and this is "flashed" on the field terminal. This action did result in the production of a very gentle blue spark, so repeated a few times and withdrew-being very careful not to touch the "flashing wire" any where against the car! Fuel pump required no action at all still works just fine!

With negative ground now established, this enabled the fitment of a modern but retro looking Tokai LAR 216 radio/CD as suggested by Jack. Herwith before and after pictures of the dash:-



I find it quite amazing that the dash cut out is exactly right to fit a modern DIN size radio! The recently fitted "Lucas Style" door mirror can just be seen thro the quarter light in the "after" picture. There is just enough room to fit a modern 4" speaker in the side frame forward of the door with the "guts" of the speaker locating near to the old trafficator:-



Nearly ready for Gaydon on Saturday-hope to meet many of you good folks there!
Keith

[Jack]

Hi Keith,

Great update - perhaps worth having a thread for all the work you are doing on the car - it's really rewarding to see the photos from the beginning over a couple of years, and we can drop in to see what is going on and progress.

Don't know if you are aware, but your interior looks like it was almost certainly done by PJM. I'd know those door cards, carpet and seat anywhere. I look forward to having a good look at the car this weekend, their work seems to be very good quality, our SC was done by them at the end of the rebuild.

The radio looks good. I was a bit cautious after I had recommended it because the photos online look a bit modern, but in place it looks to be a reasonably subtle modification, not massively different to the radio in ours or the original one from a distance. It would be interesting to see how bright the screen is when switched on in normal daylight.



Jack.

[Jack]

One other thought looking at the interior photos - you could cover the support bars in the footwell with vinyl or carpet - from the back with the hood down they are visible on the SC (not sure about the SA) so they would be less noticable. Personal preference and all that, I covered the upper ones in the SC because of the design of the dashboard, still have to do the lower ones properly when we see how much vinyl we have left after the work on our hood.

Jack.