Modern-day Miura

[heinke]

The next item up on the Miura project task list is figuring out where and how to mount the headlights. The original Miura used headlight buckets from a 1965-67 Fiat 850. These were used in a “pop-up” configuration on the Miura such that when not in use the protective glass cover formed the fender/wing top.



And when in use, the whole headlight bucket raises upward out of the fender.



The Fiat 850 headlight buckets have a distinctive oval shape and unfortunately, due to low import numbers and a very high rust related mortality rate (Fiat had a buy back for 850s due to rust related safety recall in the 1970’s), the headlight buckets are hard to find and thus expensive. I looked at alternatives like Porsche but decided it was worth it to spend the extra money to get the “authentic” look when I found a pair of 850 buckets.

Here are the parts that make up the standard 850 headlight bucket.



These were then modified at the Lamborghini factory to convert them into a pop-up configuration. Basically, they added a hinge to the front and used an electric motor to raise the rear when in use. Needless to say, the Miura conversion parts are even rarer than the 850 parts so I decided to make my own.

Firstly, I needed to figure out where to position the headlight buckets. I used the station buck to get these measurements. The headlights move with the tilt-up front clip so all mounting needs to tie to the front clip framework. Pieces of 1” by 1.5” tubing were added to the right and left of framework as the basis for headlight mounts and provided for this positioning.



Trying to keep it simple, I purchased some 4” tee hinges from the hardware store for mockup purposes and hopefully they will be adequate. Here’s the headlight mocked up in down position.



And with about 3" movement at the rear part of bucket, in upward up position



I plan to use the electric motors and gearboxes from power side windows to lift the headlight buckets. That will need to be the subject of another post once I’ve come up with a design and mockup.

[Antoine_P]

Looking good, thanks for sharing your progress!

Cheers

Antoine

[Fargoman]

Do you think the T hinges may have enough play in the hinges to allow a slight rocking motion of the lights.

A automotive door hinge, suitably modified, would take out the play and perhaps allow for some adjustability.

Just a thought.

[heinke]

Originally Posted by Fargoman

Do you think the T hinges may have enough play in the hinges to allow a slight rocking motion of the lights.

A automotive door hinge, suitably modified, would take out the play and perhaps allow for some adjustability.

Just a thought.

Fargoman: thanks for the suggestion. Yes, from the mockup, I think the T hinges have a little too much play. I think I'll look at door or rear hatch hinges to see if I can find something with less play but still compact and simple.

[heinke]

The Mirua front clip skin has some unique shapes pressed into it: recess for Lamborghini hood badge and concave highlight line up the center. Here’s a picture for reference:



I think a hammer form is the best approach for the hood badge recess. I bought a replica hood badge (factory originals are way out of my price range) to get the shape and then used a router to experiment on a scrap of MDF.



After annealing a piece of scrap 3003 .063, a little bit of hammering later and I had a decent result.



For the highlight line up the hood, I think I can do most of it with the bead roller, except the very front and rear. The front tapers down to a rounded point and the rear is squared off. So I made up some hammer forms for the front and rear to see if those portions could be hammered in after the bead rolling. Here are the forms and a test piece.





Obviously the prototype is too short in length, the actual highlight line is about 4 feet long, but it does serve as a decent proof of concept. The main challenges I can foresee at this point is that I don’t think I can do the whole 4 foot length of the highlight line in one sheet; maybe if it weren’t for the two vents on either side of the highlight line, but I think that part of the hood skin will need to be done in at least two sheets. If so, then I’ll need to weld the sheets together across the highlight line and dress the weld seams while still keeping straight edges in the line. Hmmm…could be a challenge.

The other challenge is where the line goes between the vents. I think the highlight line will need to be put in after the skin is shaped to the raised edge of the vent openings, otherwise the highlight line will get distorted as the aluminum is stretched for the raised edges. I have hammer forms built into the station buck for shaping the vent openings and I plan to use a TM Tech flow forming tool to put in the raised vent edges.

Here’s another closer up picture of the highlight line and vent area on another Miura for reference. Given my Miura is 105%, I elected to space the vents about ¾” further apart to mask the extra width but I think the challenge is there all the same.



I’ve got some ideas on the sequence of forming operations and how to approach the vents and highlight line but I’m open to any and all suggestions from those of you who have experience with something like this. Thanks in advance.

[heinke]

Well it was back to the drawing board to come up with a better design for the headlight mounts after the hinges used for the initial mock-up proved to be a bit too wobbly. I decided to do further research to understand the core design for original Miura headlight mounts. It turns out they were mounted on a single shaft that when turned caused the headlight bucket to pivot up out of the hood. Here’s the pictures I was able to find for some original units taken while a Miura was being restored.





I decided to go with a rotating shaft design on my headlight mounts as well. A piece of ½” DOM tube was used for the shaft and pillow blocks with bronze bushings for the pivot points. The shaft will be coupled to a stub shaft on the final drive gear from the electric motor. In this mock-up, the shaft turns freely in the pillow blocks but has virtually no wiggle/free play in it.





The extra side window lift framework obviously needs to be trimmed away. I’ll do that once I get the electric motor mounted to the front clip framework.

Next up is figuring out how best to attach the headlight buckets to the shaft in a way that will keep the headlights steady but also provide a small amount of adjustment for setting the headlight trim ring flush with the body opening when headlights are retracted.

[Mr fixit]

Not experienced at car building, but you might look at the linear screw shaft motors like for 3D printers and other projects. Here is a link to what I'm suggesting. The setup you have seems kind of big for the application.
Would you be able to look at an original car and how the hinging portion works to try and copy?

https://www.amazon.com/Motor-M355MM-.../dp/B07556CZL1

Just me thinking outside of the box, as I often do.

TX
Mr fixit
Chris

[heinke]

Firstly, I’ve got to say that designing and fabricating these headlight mounts/mechanisms has turned into a very time consuming endeavor. Maybe it’s that I’m trying to locate something with an oval face that sits at a slightly upward sloping angle, needs to be positioned with symmetric accuracy so both sides will look the same, and requires a rigid mounting such that the headlight beams won’t bounce around on roads with a rough surface. In other words, I’m trying to position something that has no flat surfaces, no corners, and no part of it resides in true horizontal or vertical planes. This translates into taking many measurements and many re-measurements using a ruler and small level to verify the headlight bucket positioning as the fabrication goes from cardboard templates to sheet metal parts, to a welded/fastened together unitized assembly.

Given that context, I determined the best way to mount the donor Fiat 850 headlight buckets was to wrap them in a sheet metal can that clamped down snuggly on the donor bucket. I discarded the idea of welding or screwing mounting provisions directly to the donor buckets because they are made of very thin sheet metal and I didn’t want any of the mounting bits to be visible when the headlights are viewed through the outside oval glass covers.



Some bucket positioning adjustability is achieved on the legs that attach the mounting can to the pivot shaft by having oversized holes with fender washers to clamp the parts securely together. Shaft collars are used to attach the legs to the shaft. I added a second set screw to each collar for better gripping on the shaft along with drilling/tapping the 6-32 screw holes in the collar sides for attaching the legs. You’re probably by now starting to see why making these mounts has been so time consuming.



The electric motor gearbox has a 5/8” round shaft with a 1/8” wide slot across it. The shaft/slot was used to hold a spiral spring as part of the window regulator mechanism. With the spring removed, this shaft/slot provides a secure, non-slip attachment point for the headlight pivot shaft. Using a lathe, I turned up a connector with ½” ID on one side, 5/8” ID on the other and welded a piece of 1/8” flat stock across the larger opening for engaging the slot in the gearbox shaft. Here are all the parts assembled for first trial run at raising the headlight.



It worked!! There are still some smaller details to work out but the basic design seems to be solid. The headlight raises and lowers smoothly and the only wiggle is some free play in the electric motor gearbox. I think this free play can be addressed/mitigated with a spring or perhaps a cam with indents for up and down positions. Now to repeat the process to build the headlight mount for passenger side, hopefully this will only take half the time of the first one.

[Gojeep]

Glad you got it all sussed out. I'm sure less than half the time for the second one.

[Rick Mullin]

I feel your frustration after having repaired original Miura lamps. The factory just welded all of the mechanisms to the lamp housings and then ground and sort of soldered the imperfections smooth. There is really no adjustment available on the original. After having made a new hood skin, I found how critical the fit of the lamp is despite my efforts of exactness in fabricating the skin. Some slight mounting tweaks were required of the headlamps once the hood was skinned. My advise to you is to make the mounting as adjustable as possible and to perhaps wait to perfect the final mounting design until you have a skin to project to. It will be easier to tweak the mounting of the lamps than the sheet metal once crimped in place.