Overheating coil?

[mgcjag]

If you look at the wireing diagram you will see that the 12v feed to the coil in a ballast resistor Cct is provided via a relay(type 33231).....the same relay puts the 12v to the starter......in a standard set up you still have a starter relay but all it does is put power to the starter.......so you will only have one relay.......Ash was intetested in removing any wireing that was to do with the ballast Cct so he was pointed to the relay........i dont know if his ballast cct is even in use so a previous owner may have replaced the ballast relay for a standard one or just removed the wireing....the easy way to tell is check the voltages as said in a post above.....without looking at someones car we have no idea how it is wired.....it has been suggested why even use a relay, just take the 12v off the key switch...its down to the owner to work out what they have on there car....we can just point out whats in the original diagrams

[christopher storey]

The ( factory ) diagram that I have in fact shows no ballast at all ! It does, however, as you say show a relay , but this is between switch and starter solenoid, and its purpose looks to be to facilitate the inhibitor switch in cars with automatic transmission . My car ( manual ) in fact is unballasted and I wonder whether different circuits were used for different markets ? Interesting isn't it ?

[mgcjag]

Hi Christopher......
Ballast Resistor Ignition. Useing Resistor and Relay C32576

Fitted to cars from Chassis Nos. 1R.1393 - RHD, 1R.11052 - LHD (OTS), 1R.20486 - RHD, 1R.27051 - LHD (FHC), 1R.35643 - RHD, 1R.42850 - LHD (2+2)
Above info from SNG parts list

[mark10337]

and post #13 in this thread as per xkebooks

[Hugo]

My Series II OTS US import has a resistor next to the coil. No idea about relays though, as all that stuff is now scattered about in various cardboard boxes. There were three relays next to the battery; one for the horn, one for the voltage regulator & one for the air-con. Two of those I am going to lose when it goes back together. I honestly don't recall whether I took any other relays off the car when I stripped it however.
It seems to me that the relay is not specifically for the coil circuit; if you want to bypass the resistor for starting, you can take a feed off anywhere you like on the starter circuit. They just happen to have taken it off the relay. This is just my reasoning however; I don't speak from a position of any authority.

[mgcjag]

Hi Hugo....so after all that...assuming how the resistor Cct works it turns out that you actually have one....suggest you get a diagram and find out how Jaguar made it work.......why they did it this way i dont know.....but if anyone has a ballast resistor Cct on there E type it would make sense to wire it as per the Jaguar diagram.....Steve

[Hugo]

Indeed there is one on my car - I never meant to imply otherwise. But I have ripped everything to bits right now so I have no idea how it was wired up. When it goes back together I will figure it out. One thing I won't do is do it a certain way "because that's how Jaguar did it". Maybe there's a better way - maybe not. To my mind, if there's a relay operating the resistor by-pass, that introduces a level of complication that I could live without. And if there's a relay operating the resistor itself - that's even worse. I follow the precepts of aircraft design wherever possible - "Simplicate and add lightness".

[AshM]

You know when you post something and start a post chain...

Thanks for all of the posts and views. This forum does make me smile.

I can 100% guarantee that my car is standard (from a wiring perspective) as it came out of the factory. Its been in the family since it was 3 years old. Me putting on the 123 is it's first change.

So my 1970 FHC has the standard 5 relays - Horn and Starter/Ignition (positioned where Hugo references his), Fans, Hazards and HRW.

Following the wiring diagrams for the 1970 FHC which have the ballast resistor, the relay in question is incorporated in the Starter/Ignition wiring. So that obviously has to stay.

So still not sure whether I can remove the Ballast Resistor.

It runs really well and starts on the button so maybe I just leave it.

cheers

PS As an aside, I have a facility for colour printing larger versions of the wiring diagrams stored on here. A3, A2, A1, A0. They are great for studying problems / pinning to workshop walls. Message me if anyone wants a copy.

[Hugo]

Well yes, after all the argy bargy - you've answered your own question; - if it starts & runs perfectly with the resistor in place, I would guess it's ok!

[ralphr1780]

Maybe of help...on my S2 (LHD) the subject relay is on the right side (inside) just next to the glovebox, fixed to the scuttle. It does click when you turn ignition on and it supplies the starter solenoid AND the coil.
If any is keen for a picture, please ask.

[Hugo]

I presume you mean it clicks when you turn the key to the 'start' position? I would still question why a relay is necessary. The starter solenoid is itself a relay, so why employ a relay to operate a relay? Just something else to go wrong?

[mgcjag]

What is the current rateing of the ignition switch?....maybe the relay which provides the Cct for the 12v to the lower rated coil and the 12v to the solonoid can carry more current than the key switch...thats why relays are usually used

[JagWaugh]

Hugo,

With a ballasted system you want the ballast resistor in series with the ignition when the engine is running, but not when you're turning the starter.

When the starter is turning then the load will drop the system voltage down to about 9V depending on various factors.

So the idea is... make your coil so that it works optimally at 9V, then it is great for starting, then when the engine is running (i.e. the starter load is gone) connect the resistor in series with the ignition to reduce the voltage to 9V, or thereabouts.

You can do it with contacts in the starter switch, or a relay, or a combination of the two. Using a relay means that you can take the load off the ignition switch, which is a weak spot on the E.

[Hugo]

Quite frankly, if a car will start ok with a 12 volt coil and no resistor, I would leave it out. No need to inroduce another thing to go wrong. And if the ignition/starter switch can't handle the current both to the coil and to the starter solenoid, just as all cars have to do, then there is something wrong with the ignition/starter switch. Yes, you can put a relay in there to take the load off the switch, but you are effectively putting a relay in the circuit as a fix for a weakness in the switch. I would prefer to just fit a stronger switch.

[JagWaugh]

Quite frankly, if a car will start ok with a 12 volt coil and no resistor, I would leave it out. No need to inroduce another thing to go wrong. And if the ignition/starter switch can't handle the current both to the coil and to the starter solenoid, just as all cars have to do, then there is something wrong with the ignition/starter switch. Yes, you can put a relay in there to take the load off the switch, but you are effectively putting a relay in the circuit as a fix for a weakness in the switch. I would prefer to just fit a stronger switch.

Hugo,

We're on the same page. If there were some appreciable advantage to running a ballasted ignition (other than the mfr being able to save a couple of pennies per car) then there would have been retrofit kits all over the place since the late '60s.

And the problem with the ignition switch on these cars is mostly that it is about 50 years old by now. Adding additional load to it for efans, stereos etc doesn't help matters either.

My preference, on a complete rebuild, is to fit a new loom, and a new ignition switch and if there are some new loads to be carried, fit a relay for them, but otherwise leave things pretty much as they were (Some Jags have unfused circuits, which I usually add a fuse for).

For an upgrade, like stronger lamps, or an efan, I generally fit a relay and a supply fuse.

The last couple of switches I fitted to Es (because the original was toast, so it was just a switch replacement job) were from holdens.co.uk, and they're still holding up, so the replacement switches that they supply are up to the job (or at least used to be).

[Hugo]

Agreed - but the issue here is just with the starter side of the switch, not the 'run' position. A starter switch ought to be able to power the starter solenoid plus coil. Where a relay might make sense is to disable all the other stuff that's going on (lights, blowers, radio, HRW, fans etc etc) when you turn the switch from 'run' to 'start'. I have no idea whether the Jaguar switch already isolates ancilliaries when you turn to 'start' - many switches do just that - but as you say, once people may have added extra loads over the years it all gets a bit more complex.

[mgcjag]

Hi Hugo...i think the issue here is that you dont seem to understand that there is a relay in the Cct whether or not a ballast resistor is used........not if there is some other way to do it.......have you any idea how much current would go through the ignition switch to power the coil and starter solonoid.........I have no problem with individuals doing what they want to there own cars or explaining to others how they have done it....or comming up with improvements.....but understand how the Cct works first befor posting contradictions..... Steve

[Hugo]

I don't see the contradiction? Yes, I understand that there is a relay in the circuit, but what I don't understand is WHY it is there. And no, I have no idea how much current a starter solenoid plus coil draws - I have never measured it - but I do know that every car has the same arrangement and they do it without a relay.
I'm not trying to lay the law down - I'm just asking a question about something that to me makes little sense. I have very little knowledge specific to E Types, but there is nothing unique about this aspect of their design - they have standard Lucas electrics as fitted to practically every car of the period.

[JagWaugh]

I don't see the contradiction? Yes, I understand that there is a relay in the circuit, but what I don't understand is WHY it is there. And no, I have no idea how much current a starter solenoid plus coil draws - I have never measured it - but I do know that every car has the same arrangement and they do it without a relay.
I'm not trying to lay the law down - I'm just asking a question about something that to me makes little sense. I have very little knowledge specific to E Types, but there is nothing unique about this aspect of their design - they have standard Lucas electrics as fitted to practically every car of the period.

A relay driving the remote solenoid isn't all that uncommon.

I'm guessing here, but I'd say that a typical remote starter solenoid draws between 3 and 6 Amps, depending on the size of it's coil (which is directly proportional to the strength of the spring which breaks the circuit to the starter motor, which in turn is directly proportional to the maximum rated load of the remote starter).

Your ignition draws something in the order of 4A.

The fuses are surplus to requirements... until something goes wrong.

Jaguar built these cars to a price. There is _very_ little that is surplus to requirements on them.

[Heuer]

Hugo

Jaguar developed the E-Type over many millions of miles in partnership with their suppliers, Lucas being one. As Mr Arthur Whittaker, Jaguar Chief Buyer, had been tutored by Sir William in the fine art of purchase management and penny pinching he would not have condoned paying for a relay if it were not strictly necessary. Which means it was put there for a reason which may may be able to guess at or, using the wiring diagram and known current consumption for every component come to an informed answer. Jaguar were are major manufacturer of vehicles since the 1930's with some hugely talented people working for them and we are rank amateurs in comparison.

Work your way through the diagram: S2 Colour Wiring Diagram (by Bill Molloy): https://www.dropbox.com/s/dx7f9jvz6pvca ... r.jpg?dl=1 and maybe you will come to a conclusion of why the relay is there.

The S1 3.8 and 4.2 do not have the relay so something changed the designers minds!

Actually I did a write up on using a relay in the ignition switch circuit as some people were concerned about its current carrying abilities and stories of the key getting hot. You will find it in the Upgrades Forum.