Triumph Sports Cars

engine swaps and other performance upgrades, plus "factory" V8s (Stag and TR8)

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hguess
Hank Guess

(2 posts)

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08/26/2010 01:26PM

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how to convert Triumph TR-4 from positive to negative ground?
Posted by: hguess
Date: April 12, 2013 11:59AM

I have a 1962 Triumph TR-4 with positive ground and want to convert to negative ground. Can anyone provide instructions?




(moderator updated thread title to make it more descriptive)



Edited 1 time(s). Last edit at 04/12/2013 12:02PM by Moderator.


Moderator
Curtis Jacobson
Portland Oregon
(4411 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: Moderator
Date: April 12, 2013 12:06PM

Welcome to BritishV8, Hank!

I've never personally converted a car to negative ground, but I'm sure many of our guys have. I bet you'll get good tips for the conversion here shortly.

When you have time, why not post a snapshot of your TR here? We love pictures!


hguess
Hank Guess

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08/26/2010 01:26PM

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Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: hguess
Date: April 12, 2013 01:53PM

Home - Room Addition 002.JPG


Dan B
Dan Blackwood
South Charleston, WV
(972 posts)

Registered:
11/06/2007 01:55PM

Main British Car:
1966 TR4A, 1980 TR7 Multiport EFI MegaSquirt on the TR4A. Lexus V8 pl

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Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: Dan B
Date: April 14, 2013 03:39PM

Are you planning on keeping the generator or putting an alternator on it?


88v8
Ivor Duarte
Gloucestershire UK
(667 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: 88v8
Date: April 15, 2013 05:46AM

This may help
[www.tr-register.co.uk]

Elsewhere on that forum it mentions that if you fit an alternator you need to make a heat shield to protect it from the exhaust manifold.

Ivor


Moderator
Curtis Jacobson
Portland Oregon
(4411 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

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Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: Moderator
Date: April 15, 2013 12:40PM

I think if you or a previous owner have fitted aftermarket parts, they may need special attention. Example: windshield washer pump may need terminals reversed. (Did TR-4 come with a manual washer pump?)

Does the horn change pitch when its polarity is reversed?


DiDueColpi
Fred Key
West coast - Canada
(1259 posts)

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05/14/2010 03:06AM

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What if the Hokey Pokey really is what it's all about?

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Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: DiDueColpi
Date: April 16, 2013 01:21AM

It's been a while since I've done one. But as far as I can remember it's a dead simple change.
Swap the leads on the coil and the amp meter. Swap the cables on the battery and re-polarize the generator. And your done.
The starter and wiper motor don't care about polarity as they have field coils. The gauges are unaffected as well. The fuel pump and horn are not polarity sensitive either. The only other issue might be your signal flasher depending upon what has been installed over the years.
The original will work fine but some aftermarket ones won't. If needed, swap in a good old HD12 style flasher and all is good.
Like Curtis said, make sure that there aren't any non factory accessories that may release some non OEM (Lucas) smoke.
Hope that helps
Fred

I guess I should add, polarizing your generator.
Remove the smaller wire from your generator. This is your field wire. Connect a jumper from the field connection on the generator to the positive terminal on your battery. Only make this connection briefly, ie. a second or two. Reconnect the field wire. Start your car. (It should not have been running during the polarizing procedure) It should now be charging correctly.



Edited 1 time(s). Last edit at 04/16/2013 01:34AM by DiDueColpi.



Dan B
Dan Blackwood
South Charleston, WV
(972 posts)

Registered:
11/06/2007 01:55PM

Main British Car:
1966 TR4A, 1980 TR7 Multiport EFI MegaSquirt on the TR4A. Lexus V8 pl

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Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: Dan B
Date: April 16, 2013 01:57PM

There is also something about polarizing the Control Box. You should ask my brother Jim about that....; )


tbo
Tim Body
St Thomas Ontario
(214 posts)

Registered:
01/27/2013 06:47PM

Main British Car:
1954 Triumph TR2 stock 2 litre

Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: tbo
Date: April 18, 2013 10:00PM

Just out of curiosity. how do you repolorize a generator?


88v8
Ivor Duarte
Gloucestershire UK
(667 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: 88v8
Date: April 19, 2013 02:41AM

Is it in mint condition?


bsa_m21
Martin Rothman
Vancouver, Canada
(205 posts)

Registered:
01/06/2009 11:41AM

Main British Car:
1980 TR7V8 Rover 3.9L

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Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: bsa_m21
Date: April 19, 2013 02:32PM

Re: "How do you repolorize a generator?"

Simple. The polarity is determined by the direction of the last current through the field windings.

Use a set of battery cables. Hook to battery. Connect ground to body/ground of generator. Touch positive to the generator output stud. Only a split-second or a spark is required. You are done.

M.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5812 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: how to convert Triumph TR-4 from positive to negative ground?
Posted by: BlownMGB-V8
Date: April 21, 2013 08:39AM

Yeah, on that control box... (regulator)
There might be a problem there.

Several decades back when Dan got his basket case '66 TR4-A on the road, (and a fine job of it I might add) everything was working fine until we decided to fit a late model radio and had problems insulating the case from ground. At that point we decided to convert to negative ground. All went smoothly, or so we thought, and everything was working. I think at the time I was driving the car as I had blown up the engine in my MGB and one fine day out cruising around the car decided to suddenly release horrendous volumes of Lucas smoke right out on the street in front of God and everybody. Obscene I tell you.

The culprit was the regulator, and the cure was to remove the offending parts and wiring and fit an alternator. Dan can tell you what alternator he has now but there was no need for a heat shield. The conversion was straightforward, only requiring the wide generator pulley to be mated to the alternator and a modification of the adjustment bracket.

At any rate I would recommend a bit more research on this. Everything was wired correctly and the parts were in good order so I do not know why the regulator melted down but it was a direct consequence of the polarity reversal.

Jim


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