Positive/Negative earth?
#1 Positive/Negative earth?
Are there any advantages to converting from Positive earth to Negative earth and as a rough guide, what parts would need exchanging on the car?
Steve
Technical Adviser to a
S1 2+2 4.2
1966
Technical Adviser to a
S1 2+2 4.2
1966
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#2 Re: Positive/Negative earth?
See similar topic below.....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc
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#3 Re: Positive/Negative earth?
Hi Steve, I had already read through that one, more of a 'advantages' sort of question, we just realized that we have put a neg earth radio in! ha ha, luckily, no battery has been connected thus far so that's the only advantage I could think of which seems a lot of trouble to go through when we could just buy a pos earth radio.
Steve
Technical Adviser to a
S1 2+2 4.2
1966
Technical Adviser to a
S1 2+2 4.2
1966
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#4 Re: Positive/Negative earth?
You can get a radio polarity convertor.....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc
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#5 Re: Positive/Negative earth?
Or buy a polarity converter to connect between feed and radio. I used one to allow my neg earth hidden Bluetooth receiver/amp to work in my pos earth car.
Richard
Previous owner and restorer of a S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504 (now sold and headed for Athens)
Previous owner and restorer of a S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504 (now sold and headed for Athens)
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#6 Re: Positive/Negative earth?
Just as an update, all S1 4.2's were/are Negative Earth so problem solved!
Apparently, the change was made in 63/64 with the introduction of the 4.2 engine with alternator? fitted from the 3.8 engine with dynamo/generator? fitted from factory.
Information from a very reliable source and standing by for incoming.
Apparently, the change was made in 63/64 with the introduction of the 4.2 engine with alternator? fitted from the 3.8 engine with dynamo/generator? fitted from factory.
Information from a very reliable source and standing by for incoming.
Steve
Technical Adviser to a
S1 2+2 4.2
1966
Technical Adviser to a
S1 2+2 4.2
1966
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#7 Re: Positive/Negative earth?
Sounds right, my Feb64 3.8 has positive earth. On mine a previous owner has fitted a 123 distributor and alternator - do these need to be replaced when converting from Pos to Neg earth?
Darryl
1964 S1 FHC 3.8 opalescent maroon
1964 S1 FHC 3.8 opalescent maroon
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#8 Re: Positive/Negative earth?
Too technical for me to answer that one Darryl, I'll sloping shoulder that and let someone with more knowledge answer for you.
Steve
Technical Adviser to a
S1 2+2 4.2
1966
Technical Adviser to a
S1 2+2 4.2
1966
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#9 Re: Positive/Negative earth?
Darryl......123,s are polarity contiouse......u get pos and neg ones.....however u have an alternatof so sounds like previous owner may have converted it to neg eth.....just look at your battery connections....or test with a meter...Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc
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#10 Re: Positive/Negative earth?
I checked again Steve and the earth lead to the body is definitely from the positive battery terminal. Presumably the alternator is specific to positive earth
Darryl
1964 S1 FHC 3.8 opalescent maroon
1964 S1 FHC 3.8 opalescent maroon
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#11 Re: Positive/Negative earth?
When I swapped out my dynamo for a powerlite Dynalite, I had to specify +ve earth configuration, same for my 1-2-3.
Richard
Previous owner and restorer of a S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504 (now sold and headed for Athens)
Previous owner and restorer of a S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504 (now sold and headed for Athens)
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#12 Re: Positive/Negative earth?
- You gain a small advantage in less corrosion of the bodywork
- You can fit any modern electronic accessory without problems
In addition you need to change the wiring polarity to the in-tank fuel pump and flash the dynamo field winding over for -ve earth so it comes up and charges correctly. Likewise reverse the connections to the ammeter or it'll read discharge on charging.
Alternators are almost universally -ve earth and certainly as fitted by Jaguar when they moved over to using them.
John
1969 Series 2 FHC
1969 Series 2 FHC
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#13 Re: Positive/Negative earth?
Evidently the old pos earth clock won't work if you switch to neg earth.
Randall Botha
'64 3.8 fhc & '51 Mk 7
'64 3.8 fhc & '51 Mk 7
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#14 Re: Positive/Negative earth?
This aricle from our Knowledge Base explains everything you need to know.
Positive to negative earth conversion guide: https://www.jcna.com/positive-negative- ... nversion-0
Positive to negative earth conversion guide: https://www.jcna.com/positive-negative- ... nversion-0
David Jones
S1 OTS OSB; S1 FHC ODB
1997 Porsche 911 Guards Red
Add your E-Type to our World Map: http://forum.etypeuk.com/viewtopic.php?f=1&t=1810
S1 OTS OSB; S1 FHC ODB
1997 Porsche 911 Guards Red
Add your E-Type to our World Map: http://forum.etypeuk.com/viewtopic.php?f=1&t=1810
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#15 Re: Positive/Negative earth?
Having discovered I’ve got an almost new +ve earth Dynalite alternator and 123 distributor I don’t think it’s cost effective for me to switch to -ve earth. Shame. In all other respects it looks a fairly simple job.
Darryl
1964 S1 FHC 3.8 opalescent maroon
1964 S1 FHC 3.8 opalescent maroon
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#16 Re: Positive/Negative earth?
As mentioned earlier in the thread. Until the twenties british cars tended to be negative earth. It was noticed that corrosion built up on the positive battery terminal causing loss of conductivity. The response was to change to positive earth, however after some 30 years it was observed that the corrosion occurred on the main body of the car. This was less acceptable so manufacturers reverted to negative earth. The advent of transistors re-enforced this choice of polarity.
Stuart
1969 e type 2+2
1932 MG Montlery replica
1936 MG TA
1954 MG TF
1969 e type 2+2
1932 MG Montlery replica
1936 MG TA
1954 MG TF
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#17 Re: Positive/Negative earth?
So would it be prudent to disconnect the positive earth cable when the car isn’t being frequently used, to reduce the impact of body corrosion ?
Darryl
1964 S1 FHC 3.8 opalescent maroon
1964 S1 FHC 3.8 opalescent maroon
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