Trailer plugs

Submitted: Monday, Mar 21, 2005 at 08:31
ThreadID: 21394 Views:1996 Replies:6 FollowUps:8
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Is there a standard or preference between a 7-pin flat trailer plug and a 7-pin round?
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Reply By: old-plodder - Monday, Mar 21, 2005 at 08:47

Monday, Mar 21, 2005 at 08:47
I still run a 7 pin round since most of my trailers and friends trailers are set up this way. But it is the older design. My father with a newer car runs a 7 pin flat and uses an adaptor. I still like the 7 pin round metal fittings for the robustness.
AnswerID: 103254

Follow Up By: Moggs - Monday, Mar 21, 2005 at 09:28

Monday, Mar 21, 2005 at 09:28
I'll second that. I was having heaps of problems with bad contact / broken pins, plug dislodging etc with a 7 pin flat plug - changed over to a Narva metal round 7 pin and have not had any problems since. They also lock the plug in via the cover of the female plug and it cannot come loose over the rough stuff. Not much more expensive than the plastic flat plug if I remember rightly.
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FollowupID: 360845

Follow Up By: pjchris - Monday, Mar 21, 2005 at 11:37

Monday, Mar 21, 2005 at 11:37
The flat sockets also lock in via the flip up lid.

As far as bad contacts go I've had bad contacts in both round and flat. A quick squirt of WD40 or an electrical cleaner and everythings go for another six months.

My preference is is for the flat as they mount up higher on our 4by's as we bent the round ones on both our cars the first time we went off road.

The round ones can be more rugged if you use the metal ones. A lot depends on where they are mounted on the car.

Peter
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FollowupID: 360857

Follow Up By: Moggs - Monday, Mar 21, 2005 at 12:58

Monday, Mar 21, 2005 at 12:58
ok, well my flat plug always worked loose - might have been a different brand and the locking mechanism was therefore not effective.

I have mounted my round plug up in the bar itself with the wires coming in from the top - just drilled and tapped 3 holes in the face of the bar - there is nothing below the bar to get ripped off.
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FollowupID: 360871

Follow Up By: pjchris - Monday, Mar 21, 2005 at 22:49

Monday, Mar 21, 2005 at 22:49
You do realise that drilling in to the bar creates holes which will rust and simply drilling into the bar weakens it?

You should never drill into a structural member, be it in a house beam, car chassis, bridge member etc.

Unless, of course, it was designed to be drilled into.. In which case the plug would have been mounted there already.

Peter
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FollowupID: 360928

Follow Up By: Moggs - Monday, Mar 21, 2005 at 22:56

Monday, Mar 21, 2005 at 22:56
Maybe so re: rust - but I painted the hole with primer and rust paint prior to installing - don't know why I bothered though - everywhere that has copped a bash or scrape on it has surface rust. The holes are also completely filled by screws - don't know how they could possibly rust as they are sealed by the screws. As for drilling 3 tiny holes in the face of the towbar - you have got to be kidding - if that weakens it then I should have bought a different bar!

Maybe I am wrong, but I feel quite safe in doing it.

LOL, I bet the three holes each side drilled into the bar where it mounts to the vehicle make the whole thing pretty weak then as they are much bigger than the holes I drilled ;-)
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FollowupID: 360929

Follow Up By: pjchris - Tuesday, Mar 22, 2005 at 23:51

Tuesday, Mar 22, 2005 at 23:51
Actually, yes the monting plates with the three hole would be significantly weaker than a piece the same size without the holes.

But you are probably correct on the impact of the holes you've drilled. They will amke only a slight difference to strength and under normal towing loads I don't think it would make any difference. But...If you snatch with the towbar the load on the bar can be upwars of 5-6000kg which is comfortably double the weight limit on the bar and there is a slight chance that the bar would bend where you have drilled your holes.

Me, I would prefer to play it safe and you'll never catch me drilling in to anything I'm going to really load up later.

A friend of mine bought a car with a towbar that some dill had decided to drill a hole in the tongue of all places. The FIrst time he put a trailer on with any weight in it the tongue bent. Without the new hole it would have been fine.

Peter
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FollowupID: 361041

Reply By: Kiwi Ray - Monday, Mar 21, 2005 at 10:57

Monday, Mar 21, 2005 at 10:57
Hi Chris
Stick with the round ones more bobust unit and more fitting options
Ray
AnswerID: 103265

Reply By: MrBitchi - Monday, Mar 21, 2005 at 11:43

Monday, Mar 21, 2005 at 11:43
I've swapped all mine to the 7 pin flat type. Less bulky, therefore less likely to catch on anything and get torn off. Also the pins are a bit bigger giving more surface area for better contact, therefore better conductivity.

Cheers, John.
AnswerID: 103268

Follow Up By: Moggs - Monday, Mar 21, 2005 at 12:56

Monday, Mar 21, 2005 at 12:56
I don't know where you got your flat 7 pin socket from but the one I originally used had oins about 1/2 the size of those found in the round metal Narva plug.
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FollowupID: 360870

Follow Up By: MrBitchi - Monday, Mar 21, 2005 at 13:55

Monday, Mar 21, 2005 at 13:55
Moggs,
I originally had the Narva small round 7 pin plug, fairly standard up this way. The pins in the 7 pin flat are quite a bit larger, but smaller than the Large round 7 pin connector.

Cheers....
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FollowupID: 360878

Reply By: ChrisB - Monday, Mar 21, 2005 at 13:01

Monday, Mar 21, 2005 at 13:01
Thanks for the replies everyone.

I’ve currently got a 7-pin round (plastic) that is damaged as it protrudes below the tow bar. You’ve made my mind up, I’ll change to the 7-pin flat, cause on my tow bar there is an existing mounting bracket (for the flat) on top of the tow bar that will keep it out of harms way.
AnswerID: 103283

Reply By: old-plodder - Monday, Mar 21, 2005 at 18:49

Monday, Mar 21, 2005 at 18:49
The flat does give more clearance.

Did catch my 7 pin round a few times in it's std position.
So have drilled a hole in the rear bumper and have it up there.

Can remove the tow bar now too for more clearance off road, and not disturb the electrics.
AnswerID: 103343

Reply By: duncs - Monday, Mar 21, 2005 at 19:40

Monday, Mar 21, 2005 at 19:40
Chris,

I use an eleven pin flat and have never had a problem.

The 11 pins are arranged in two rows. The standard 7 are on the top (the way mine is set up) underneath are 4 extra large terminals for additional accessories. I use them for charging the trailer battery.

Most people say you should use an Anderson for this but mine has been doing it for about 4 years now without a problem. A standard 7 pin flat on the trailer will plug in to my car again with no problems.

As others have said I feel the flat plug can be tucked more neatly out of the way, but that depends on your vehicle etc.

My previous car had both flat and round plugs on when I bought it. (you could try that, its not overly expensive) They were mounted in the same place either side of the tow bar. It was the round one that got ripped off. That is why both my trailers now have flat plugs.

Have I confused you any. Hope not.
Duncs
AnswerID: 103348

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