Topic: 67 Headlight Feed Harness

[bmcgc]

I bought a reproduction headlight feed harness from NPD for my 67 200/C4 coupe.  Part # C7ZZ-14290-AG

I laid the new harness next to the old harness and its a pretty close copy of the original.

There is an issue with the firewall grommet.

The wiring harness hole for the grommet is punched in the firewall and has a lip on the inside of the hole, that makes the hole seem as if it is in metal that is about 1/8" thick.  Far to thick for the reproduction grommet.  The original grommet is thick enough to accommodate the lip.

The only way to make the new grommet work is if I grind the lip off the hole.

The holes for the speedo cable and washer hoses do not have this lip.

Thoughts?

[J_Speegle]

Bottom line is you need to address the problem. If you grind the edge what will the finished diameter be? And will that be too large for the grommet to seat and hold correctly. I would consider pounding (carefully) out the lip using a dolly to back it up on the flat side but I'm not there looking at it and have no idea how much access you have but you asked for thoughts

[67gtasanjose]

If the grommet is wrong, the grommet needs to be addressed, not the hole.

[ruppstang]

I have used the aftermarket harness with no problems. I would suggest that you warm the grommet in some very hot water then dry it off, add some dish soap then have some one on the outside to push on the grommet lip while you are pulling from the inside. They do not go in easily when new.

[jwc66k]

I'm not a 67 Mustang type, so I've got to ask the question that hasn't been asked. Which is correct, the hole or the grommet?
Jim

[carlite65]

well the harness he says is a repro..........need i say more.

[jwc66k]

well the harness he says is a repro..........need i say more.

This is not political - state it - which is correct? Being that one of the forum members is directly associated with NPD, that is called FEEDBACK.
Jim

[midlife]

I have many 67 headlight harnesses (used) with intact grommets.  If someone wants me to measure the inside diameter of the grommet and its thickness, I can do so tomorrow Noon.

[196667Bob]

Randy : I think that would be good information to know, and "file away".

Bob

[bmcgc]

Comparing the original and repo grommets side by side, they are different.  The original has a thicker groove in it to seat in the lip.  The repo groove is made for a flat firewall without the groove.

Yes, I heated the repo grommet and used soapy water.  It wasnt going in.

My solution:

I cut the repo grommet off with a razor knife.  My original grommet was in excellent condition.  I cut the original off and put it on the repo harness with the cut at six o'clock.

It went right in and is secure.  With the cut at six o'clock, you cant see it

You will really need to know your Mustangs to see that the harness is a repo.

I mulled this over for three days.  I considered grinding the lip off or drilling a new hole where the clutch rod exits the firewall.  Im not keeping this car 100%, but I hate altering metal or original parts in case I or someone down the road wants it 100%.

Thanks

[J_Speegle]

I'm not a 67 Mustang type, so I've got to ask the question that hasn't been asked. Which is correct, the hole or the grommet?
Jim

His description sounded like the edge of the sheet metal had been deformed and was now 1/8" thick from face to edge of hole. The reason I suggested what I did. One later of firewall sheet metal would not be that thick

[bmcgc]

Doubtful that the hole is deformed.  It is perfectly symmetrical and looks like it came that way from the factory.  The original grommet fits perfectly.

This is a Dearborn car, very late 67, a few days later and it would have been a 68.

Maybe different plants punched the hole differently.

[ruppstang]

It has been my experience that most if not all 67-68 has the rolled edge on the head light harness. Here is a picture of a Dearborn May 68 car.

[midlife]

Sorry I'm so late, but I was unable to get to my work place the past couple of days.
I measured 3 random 1967 headlight harnesses for firewall grommet dimensions.  All 3 were very similar: the groove in the harness is a nominal 1 3/16" in diameter, with a groove width of 0.154 inches or a touch bigger.  I measured the latter with a set of feeler gauges, but one side of the groove is the larger flange and there is some flexibility there in terms of how tight it would fit. 

I suggest that the original poster's issue may have more to do with the flexibility of the rubber of the grommet than it's actual measurement.
Randy

[Bossbill]

It has been my experience that most if not all 67-68 has the rolled edge on the head light harness. Here is a picture of a Dearborn May 68 car.

My 67 has the same rolled hole. Never noticed that before!