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MG TD TF 1500 - Headlamp ground?

The archives are very helpful in verifying the problems I'm having grounding my headlamps. I will probably run my own ground wire to the chasis as suggested by some, but how exactly is the lamp "supposed to be" grounded? (I've verified this is the problem by using a separate ground wire.) The juice comes out the bottom to the big mounting bolt thence to the mounting arm to a mounting bolt and I've confirmed continuity there. But that arm is mounted on a big piece of rubber between itself and the front wing and is hence totally insulated from the wing! The bolts that go through the rubber are not threaded (on my car anyway) and make weak, if any, contact with the arm because of fresh paint. So how is the juice supposed to go on down through the front wing to complete the circuit to the chasis? I'm not going to remove the paint under the bolt head - that would show and look awful! What am I missing?

Flumoxed in CO,
Ed
efh Haskell

ed, wouldn't the big bolt that passes through the rubber and threads into the bracket give you a ground? regards, tom
tom peterson

The ground is supposed to come through the various bolts that hold the bucket to the bracket, the bracket to the wing and the wing to the frame. This is a tenuous path to start with and when you add to the mix, today's paints, you can wind up with no ground to the head lights. A dedicated ground wire from the frame to the headlight bucket is the best way to insure a good ground to the headlights. Cheers - Dave
David DuBois

"The bolts that go through the rubber are not threaded". Well, guess what? The left side is not but I decided to check the right and they ARE threaded! That is why I'm not getting continuity through that bolt! No contact points!! So I check my meager supply of bsf stuff. The threads are not 1/4 nor 5/16 bsf. Does anybody know what size the threads are that hold a headlamp bracket (#407-420) to the front wing?

Almost there,
Ed
efh Haskell

The ground can also go the other way into the big bolt that attached to the rad "tie bracket". I cleaned around that big bolt to solve my headlight ground problem,,,

.
SPW
STEVE WINCZE

I ran into this when I first got "Rocky"....I tried every concievable way to use the existing "bucket", and any other metal I could find, and finally gave up , and ran a separate wire to frame ground....Lights now work just fine.
I never did figure out how the factory expected things to actually work...but it's a moot point.
Edward
E.B. Wesson

Just noticed a subtle point in diagrams. There are actually supposed to be fixed "studs" in that tie bracket, not bolts like I have!! That is how the juice is supposed to flow to the wing! So I stripped some #14 wire, wrapped it around my bolts that hold ties to wing to make good internal contact, greased it up with dialectric, tightened the bolt and YAY, I have lights, and no separate ground wire needed.
efh Haskell

Ed,

Your problem is that you're looking for a ground. There's not many of them on British cars. The grounds are what let the smoke out so you don't generally find them easily.

You should be looking for an earth, there's lots of them!

AJ
A R Jones

AJ - a very good point! I think I finally understand the whole "earth" business. Now I can forget it!

Keep September in mind at the Morgan factory,
Ed
efh Haskell

Still working on the route. Mrs is ready to go shopping!
AJ
A R Jones

This thread was discussed between 28/07/2011 and 29/07/2011

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