51 BMW 1973 R75/5 Repair Paint on Headlight Shell and Switch Housing

I did not want to remove the wiring from the head light shell under the principle of letting sleeping dogs lie. Disturbing 40 year old wiring inside the shell seemed like asking for problems not to mention the fun of installing the wiring again. So, I removed the wiring harness from the frame and left it connected inside the headlight shell.

The headlight shell, although grungy, had original paint in very good condition. This bike had a Wind Jammer fairing from almost day one installed by the original owner. One advantage is it protects the head light shell from dings, bug guts and to some extent keeps it shaded so fading is minimized. Plus, for the last 35 years, the bike has always been garaged.

97,553 miles, 2 owners

Headlight Shell After 40 Years, 97,553 miles

Headlight Shell Underside Detail

Headlight Shell Underside Grunge

After I cleaned it up, other than some dings and scratches, the original finish shown through.

Nicks in Headlight Shell

Nicks in Clean Headlight Shell

Nicks in Headlight Shell

Nicks in Cleaned Headlight Shell

I decided that the nicks could be repaired in place and I posted a note to the Airhead BMW Club (ABC) for some advice on the best way to repair the paint.

NOTE: If you haven’t joined ABC, do it. The mail reflector is a great resource and font of wisdom and knowledge about Airhead BMWs. I’ve learned a great deal from folks who are very generous with their time and advice.

I got a detailed reply from Gale Gorman a man with a lot of paint experience.  Here is his advice.

“That old finish is beautiful and I’m sure it was lacquer. Look for black lacquer touchup paint. I don’t know who sells it but a Google search might turn one up.

If that doesn’t do it, I can put a little black lacquer in a nail polish bottle and send it to you.

Clean spots with a good pre-paint cleaner. Eastwood sells PRE, DuPont sells Prep-Sol, and all the other players sell something. If you don’t have an automotive paint store nearby, NAPA keeps a small inventory of Martin-Senour products and Carquest usually has a little bit of DuPont. If you have acetone or lacquer thinner that will do it.

Once the spots are clean you can apply the first coat of black. No need to paint outside the lines. The paint will be thick as compared to ready to spray so allow it to dry probably an hour but if you’re in no hurry, several hours. Apply one or more coats until you think you have enough buildup to sand it smooth and not leave a crater. My goal would be to make the repair invisible. VERY CAREFULLY sand the repair with 600 grit until it gets close to flush and switch to 1000 grit. The finer grit merely removes the scratches left by the coarser.

Next step is rubbing compound and that may be too harsh. Try polishing compound first to see if the scratches disappear and a gloss starts to show up.

Final step is a cleaner type wax.

And that is approximately why paint and body shops seem to charge outrageous amounts.

Good luck,”

This made sense as it’s a variation on the standard drill for repainting.  But, I’d also seen some comments about using Testor or other model paint instead of touch up paint. So, I figured I would do a little experiment and see which was the better option.

I found Dupli-Color makes touch up paint that matches various shades of car paint. My local NAPA store has Dupli-Color, NGSF 100, ScratchFix 2in1 “Universal Black”, which was on the shelf. And the local Hobby Lobby has gloss back model paint.  I also have some Dupli-Color Lacquer paint pre-mixed for spray painting.

I had already stripped the paint from the switch housings, so I could use them to see how well each paint bonded and how well the gloss matched the headlight shell.

Which To Use for Headlight Touchup? Duplicolor Universal Black, DupliColor Lacquor, Model Paint

Candidates: Dupli-Color Universal Black, Dupli-Color spray paint, Model Gloss Black

The first to be eliminated was the pre-mixed Lacquer spray paint as it goes on way too thin. Here is the Dupli-Color on the left and Model paint on the right.

Left-DupliColor Touch up, Right Model Paing

Left-Dupli-Color; Right-Model Gloss Black

I let these test areas dry for 4 or 5 hours. Both seemed to match the amount of gloss in the headlight shell paint. I took 220 grit sand paper and sanded each to see which bonded best to the bare metal.  The winner was the Dupli-Color touch up paint. It was as hard to remove as the original paint I sanded off the switch housings.

I sanded down the test painted areas and then cleaned up the housings with Lacquer thinner and then hand painted them and let dry for several hours. The housings looked like new.

Hand Painted Switch Bracket with DupliColor

Dupli-Color Touch Up Paint Hand Painted on Switch Housing

The push buttons had faded to dull grey. I originally tried soaking them in Armor-All but they faded after a month. I received a note from a reader with a recommendation to use Forever Black. I tried that and it restored them to a nice black sheen. Then I used some “303 Aerospace Protectant” instead of Armor-All which was also recommended by the same person. These are going to look very nice when mounted on the powder coated controls.

Forever Black Plastic Restoration

Switch Before Treament

Treated Switch

Next up, working on the headlight shell. I applied the touch up paint using a small paint brush set for painting models that I picked up at Hobby Lobby. I let the paint dry for an hour or so before adding another layer.

DupliColor Touch up Paint Applied

First Coat of Touch Up Paint

I ended up with three coats on the deep scratches and only a single drop was needed on the small dings to fill them in.  I let the paint dry over night before staring to sand out the touch up paint.

I started with a small piece of 600 grit wet paper dipping it into water with a drop or two of dish detergent and sanded out the touch up paint.

Headlight After 600 Grit

Touch Up Paint After 600 Grit Sanding

Headlight After 600 Grit

Small Ding After 600 Grit Sanding

There is a slight bright outline of original paint around the touch up paint so it’s a little bit proud of the original paint.  Then I used 1500 grit moving to 2000 and finally 2500 grit. Lightly passing my finger tips over the surface told me if the touch up is still proud of the surface.  I find when I close my eyes my fingers are a bit more sensitive to any high spots. When  I was done with the 2500 grit, I could not feel any high spots. There is still a slight shiny perimeter around the touch-up paint, but its not detectable to the touch. I did not want to burn through the original paint, so I stopped when I couldn’t feel any high spots.

Headlight After 2500 Grit

Touch Up Paint After 2400 Grit Sanding

You can see in the above picture I managed to burn through some of the original paint at the edge of the bezel.  I put some touch up paint on it and very carefully smoothed it down staring with 1500 grit instead of 600 grit. Sharp edges and protruding transitions are easy to sand through so being light in your touch and even starting to sand them with finer grit than flat surfaces avoids burning through the paint.

I used my Griot’s 3 inch random orbital polisher and the #1 polish (coarse) to start to bring out the shine.

Griot 3 inch Random Orbital Sander

Griot’s 3 Inch Random Orbital Polisher with Foam Pad

Griot Polishing Pad with #1 Polish

Griot’s #1 Polish on Foam Pad

Here is what the repair looked like after polishing with the #1 polish. The reflections make the repair look like bare metal is showing, but it isn’t. It’s very hard to get good pictures of a glossy surface and avoiding a flash is essential to seeing some of the detail.

Headlight Touch Up After #1 Polish

Touch Up Area After Griot’s #1 Polish

I worked my way down through the #2 and #3 polish (very fine). I polished the entire shell using the #3 polish to make the level of shine consistent and this is how the shell looks after the paint repair.

Headlight Paint - Like New

Headlight Paint Repair – Like New Again

Last, I used Armor All on the sheath of the wiring harness and brought back much of the original sheen and shine.  The head  light and wiring harness are ready for installation in the powder coated frame.

18 thoughts on “51 BMW 1973 R75/5 Repair Paint on Headlight Shell and Switch Housing

  1. Pingback: 1973 BMW R75/5 Rebuild: Refinishing Headers, Headlight and Steering Damper | Motorcycles & Other Musings

  2. great job Brook, thanks for posting this.
    I’m putting a swb/5 together… headlight bucket on my bench as we speak.

    I see your posts on ADVRider, saw your blog earlier too but haven’t had time to look much.

    thanks for the inspiration,
    aka Renner

    • Scott,

      Cool beans, thanks for stopping by. If this content helps you on your project, well, that was my goal.

      Best of success with /5 project.


  3. I’m in the midst of a similar rebuild and this was so helpful as I was torn on how to handle the switchgear… perfect, THANK YOU for being so thorough.

    • Hi Ben,

      Thanks for dropping by. I’m glad this material helped you. I’ll be adding more content as I go.


  4. Another great post!

    I think I’ll try polishing out my paint as well, instead of taking the wiring harness apart.
    As for the switches, there is a product called “Forever Black” for exterior plastic and trim. I’ve used it on the bumper trim on my 1990 BMW 3 series
    Also, instead of armor all, I use a product called 303 aerospace protectant. Its originally designed for aircraft interiors, which get lots of UV exposure.

    • Hi Monte,

      Thanks stopping by again and for the comments and recommendations. I’ll look into trying both the Forever Black and 303 protectant.


  5. Hi Brook,

    First of all, I can’t thank you enough for the fantastic resource you’ve put together here. I’m in the process of restoring a ’71 R50/5 — a personal project for me, as it’s the motorcycle I learned to ride on 20+ years ago — and your site has been a tremendous help (and will likely continue to be for some time).

    I wondered if I might get your thoughts on something. Right now I’m facing a dilemma similar to yours…in an ideal world I’d replace all the wiring on the bike, but the thought of wading into that rat’s nest of connectors in the headlight scares me (especially considering that the bike has no electrical problems I know of). BUT…my headlight paint isn’t quite as good as yours. The overall condition is pretty good, but there’s a much bigger area on the bottom/front where the paint has chipped away entirely (where the tab for the headlight ring fits).

    My current thinking is that I’ll attempt to repair the paint using methods outlined above, and just see how it turns out…and then, if it’s a mess, I’ll give in and send it to the pros (and also give in and do the wiring).

    Sorry for the long prologue: What I’m curious about is this: Now that some time has passed, do you regret at all not replacing the wiring harnesses? Part of the internal argument I’m having with myself says, “You’re putting all this time and money into the thing anyway, why not replace all that aged wiring while you’re at it?”

    Anyway, appreciate any thoughts.


    • Hi Brian,

      Thank you for the kind words about the content. Some times pictures tell a better story than 2 pages of Haynes and Clymer 😉

      When I looked at the wiring harness, my conclusion was the insulation was in very good condition. Cleaning the connectors is a good idea to reduce the chances of carbon/corrosion creating a faulty connection. The bike was not outside and always garage stored, so there were no opportunities for water damage to the wiring. Before I stored it for six years prior to doing the rebuild, it had not had any electrical problems. So, I took the approach of “let sleeping dogs lie” and did not go to the expense and trouble of replacing the harness. Your situation maybe different.

      The good news is (was?) that the price for a new harness was not expensive, unlike replacing an 1150RS harness. I did remove and reinstall the harness so I could have the frame powder coated. My pictures helped me get the routing correct and hooked up to the correct components. So, despite my fear that getting the harness installed correctly would be hard, it wasn’t.

      I hope this helps you with your decision.


  6. Hi again from UK

    I stripped the headlight and had mine powder coated as it was in a poor condition. I now have a problem i.e. how does one replace the switch parts into the headlight bowl? I assemble the parts and then find that I can’t hold the parts together against the spring and fit the circuit board. Do you have any suggestions?

  7. Mr Reams,

    The paint on my light shines up to a beautiful rich gloss but I had to repair about a third of the paint with touch-up due to chips on the bottom and right side. Yes, it was bad.

    Any good tips/tricks to avoid burn through of the good paint? So far, I’ve learned that (1) I have better luck with 1000 grit or higher, (2) barely any pressure whatsoever, and (3) use a hard flat backer for my sandpaper (not my finger and not even a rubber bottom sanding block, as both would result in eating the nearby paint faster than my touch-up). That said, for ever 2-3 chips I get perfect, I end up with at least one more burn through spot to repair…

    • Hi Dee,

      I have used masking tape and pin stripe tape to tape off the original areas. 1000 or 2000 grit isn’t going to cut through it. It can be “fiddley” to layout the pin stripe tape so the edge of the original is all that’s protected. Then I cover the rest of the “over sand” area with masking tape.

      Hope that helps.

  8. My Duplicolor paint is very thin no where the thickness I see in your test switch. It has the viscosity of water. I question if the paint is defective very odd. Granted humidity is 83 %.
    Any Suggestions ?

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