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  Chicagoland MG Club:Tech Tips

MGB Headlamp Installation

By Wally Szempruch

I searched the web and found bits and pieces regarding the installation of the MGB headlamp assembly. The following is written to provide a little more detail of what I thought was missing so that it could be pulled together in one article.

Preliminary Quarter Panel Repair

A new headlamp mounting ring was needed on each side.
My rings were shot and I had to drill out the spot welds and remove the old rings while retaining most of the original quarter panel metal. The new rings had all the right holes but they didn’t fit well as supplied. The rings had a ridge around the circumference that interfered with the sides of the quarter panel. They just wouldn’t sit flush. I had to grind them off in spots, especially where the welded panel seam is found at the 9:00 position in the above picture. Care was taken to make sure that each ring rounded out the quarter panel since it does impart some structural strength to the nose. With the original ring gone, this area got a little flimsy. The goal here was to ensure that each new ring sat flat against the original metal. Rather than weld and grind the new rings in, they were glued in with “aircraft panel type adhesive” at the recommendation of the body shop owner. One advantage told me was that the adhesive will prevent this area from ever rusting again. Some Bondo and the two stage paint job covered up some of the holes I needed. The four holes for bucket attachment are at the 2:00, 4:30, 7:30 and 10:00 positions and were easy to find by using the bucket as a template to mark their locations. I used a tiny drill which easily penetrated through the hole and then I used it to carve down to the new ring’s natural metal hole. The two large holes needed for the adjuster screws are at the 9:00 and 12:00 positions.

Basic Parts Needed:

I cleaned, degreased, metal-treated, primed and painted the bucket and inner shroud using POR-15 products. From left to right;

The rubber lamp sealing ring, Moss # 164-060.
The bucket, which was painted gloss black.
The inner shroud rim which was painted silver.
The screws and spring fittings.
The outer snap-on chrome trim ring.
The inner chrome rim.
The headlamp.

Not shown is the electrical hook-up pigtail with grommet and color coded wires. Also not shown here but previously installed onto the quarter panel was the Mounting Ring, part # CZA81.

Screws/Fitments Needed:

From left to right;
Qty 4 - #12 1 inch L pan head SS sheet metal screws
Qty 2 - headlamp adjusting screws Moss #158-045 (mine were reusable)
Qty 1- spring
Qty 3 - #8 ½ inch L oval head SS sheet metal screws



Qty 2 - Nylon retainers NAPA part # 665-1311 (Which I modified slightly)

Assembly Details:

It’s important to note the position and holes used for the adjusting screws. The rectangular shaped hole with the round hole in the middle are both at the 12:00 and 9:00 position of the bucket and are key to the entire installation. Let’s call them the “butterfly” holes.



The rubber ring has two large holes with an enclosed tube molded in these same positions on the backside which allow for the depth of the adjusting screws and serves to keep them enclosed.



This picture shows the rubber ring mounted to the car. The bucket will sandwich this rubber to form a mud/ moisture barrier to inner bucket.



The rubber has molded indent features that line up with the four, #12 bucket mounting screws. I found it easier to align and start these screws through the center of these indents, thinking that the rubber will be more evenly fitted to the bucket on the circumference.

I inserted and seated the pigtail’s rubber grommet in the hole on the upper left side of the bucket.



I carefully located the 4 screw-hole positions and tightened the screws to the body.


It’s easier to show in these pictures how the ½ inch L #8 screws will sandwich the headlamp when finally mounted. The two rims will only fit one way because the holes are not evenly spaced. The silver painted inner rim needs to be mounted first as will be shown later.

With the bucket mounted on the car, I fitted and inserted the nylon adjuster screw retainers. There was about 0.015” of an interference fit that seemed too large to initially permit the nylon retainer to snap into the round hole of the “butterfly” hole. I used a small fine file and ran a few strokes uniformly around the OD of the nylon retainer until it would snap into place. Perhaps I had a paint build-up on the bucket. Note how square features of this part will prevent the retainer from rotating.



The hole of this NAPA part was too small for the adjusting nut so I drilled it out using about a 0.150” drill bit. This allowed the adjusting screw to be driven in without cracking the retainer and it kept enough friction for the adjusting screw. If you buy the Moss Adjusting Set 552-115, it looks like it comes with the butterfly hole plastic retainer and a new spring. I just didn’t bother. These slight modifications were real easy to do on the spot with a part I could obtain locally.


I attached the inner spring at the 4:00 position of the inner rim. Then I loosely fitted each adjuster screw into their locations on the silver inner rim. Note that there’s a space (see red arrows) between the head of the adjusting screw and a nut feature that must slide into the channel of the silver inner rim. This is what controls the movement up or down / left or right as needed to adjust the beam. Again, I found it easier to just start them in the hole so that I could fit the screws into the channel on the inner rim.

Once the inner rim was held in place in the bucket by the two adjusting screws and the spring, the screws were tightened uniformly until there was about a 1/2 inch gap between the bucket and the inner rim.



The only thing left was to plug in the headlamp and sandwich the headlamp between the silver inner rim and the chrome rim as shown in an earlier picture and insert the three # 8 screws to hold the headlamp.

I didn’t snap on the outer trim ring just yet shown in this picture. However I did use it as a guide to adjust the depth of the assembly. Since tightening the adjuster screws draws the assembly closer to the car, the placement of the trim ring on top gave me a sense where it would end up. I wanted to add power to the headlamps so that I could adjust the beam before I snap the trim rings on. I’ve read horror stories about scratching the paint while removing them so I stopped at this point so I only have to do this once.



A lot more to do on my “B” but at least now it has a pair of eyes!

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