Gullwing Doors

These were made popular by classic Mercedes sports coupes. They were also used on the Bricklins and the DeLoreans. The doors hinge up at two (or more) places on the top of the roof. Pictured: Mercedes 300sl.

It might be hard to make this modification to your car since the roof is converted to be a part of the door. You would need to strengthen the roof in the center to handle the extra weight from the doors and also to take up any chassis flex that results after slicing the sides of the roof.

Butterfly Doors

These are found on the McLaren F1 and the Saleen S7 super car, among others. The doors open to the 10 and 2 o'clock positions (when viewed from front) and have 2 hinge points _ one close to the roof and one at the traditional location. Pictured: McLaren F1,

Scissor or Jack_Knife Doors

Found on Lamborghini Diablos, Roadsters and other exotics. They swing straight up, some as much as 75º. Pictured at Left: Lamborghini Phantom Roadster. Right: Close up of a real Lamborghini's door hinge. Photos courtesy of

Design variations include adding a second shock or using a hinge that twists the door slightly as it opens. In some cars, the doors pop out before they can rotate upward. This is prevalent in cars that have doors with sharp angled bottom_rear corners. This is the type of door that I'm going to use so I will analyze it in more detail as follows:

Scissor or Jack_Knife Doors Analyzed
Door Weight & Structure
Fully assembled Lambo doors are about 65lbs or so. If you are converting an existing car, making a fiberglass copy of your doors would help. I wouldn't use Lexan instead of the normal window glass because of DOT street legal rules and scratch easily. However, they do have plastic coatings that prevent this. I know many of you are worried about structural support and impact bracing when using fiberglass doors. First of all, you can use Kevlar in your fiberglass layup. It has a tensile strength of about 44,000psi and should make your door very strong and light. I've seen it run around $35 per sq yard in some catalogs. Secondly, depending on the clearance you have between your window glass (when rolled down) and your door skins, you should also attach support framing _ usually the easiest is square_tubed mild_steel stock. Two bars across the middle act as intrusion bars and the end attach to the steel in the door frame. All of this combined can result in a door much stronger than you would find on any mass production car bought today.

Door Geometry
I think the biggest problem to convert an existing door will be the door's shape. On very square doors, the bottom corner may hit the pillar when it tries to rotate upward. There are a few work_arrounds for this. You might be able to find hinges that throw the door forward as it rotates up. You can see this on the new Cadillac concept car as well as the car pictured here. Otherwise, you may also use another hinge setup that pops the door outward before rotating it up.

Door Hardware
All you really need is a single hinge and a strut. I've heard that Volvo tailgates, mid 90's Pontiacs, and Ford Explorer lift gates provide good salvage yard struts. For a specific strut contact RV shops in addition to the normal strut mnfrs. You will need to know your compressed and extended lengths as well as the force required, which will be more than the door's weight (especially if you locate the strut at some weird point). If you won't be using struts, there are other mechanical and hydraulic options but they will cost you more as well.

Sources for Hinges
There are a few Lamborghini kit car companies that provide hinges for about $100_150 a piece. If you can get them to sell to you, then you're better off than most people. Otherwise, you can try the Additional Links at the bottom.

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CLOSE UPS OF HINGES/DOORS
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These are photo's of different builder/kit hinges

This is the door hinge parts that came with my CRP kit.

These are photos and comments from other builders about there installation methods.

This is the door hinge _ it is very solid and makes for a very wide opening door. The hinge itself is a very nice piece of machine work. The only improvement I would want would be a grease nipple.

This is a shot of Passenger door in the raised position. I spent some time reinforcing the hinge and the part under the mirror, tying it into the area on the opposite side of the hinge mount.

Even with the outer door off the door has become quite solid. The other door skin will make this very solid. I discovered that grade 5 minimums are required to bolt the hinge as there is a huge amount of torque on the hinge area. The door also opens at least to the OEM point and then can be adjusted to open several more inches.

Chocolate Icing

Okay it is not chocolate icing. This is the hinge and door support. Starting with the first arrow on the left: 1) Notice the hinge, it has a big elbow in it which allows for a very wide swing on the door. The hinge uses 1/2" steel and 5/8" steel _ very solid 2)This is a 3/8" plate that I drilled out, welded on nuts and then glassed into the door. 3)This is a 3/8" plate that connects the hinge plate to the stiffener plate. 4) Behind all this goo is a oddly shaped 1/4" steel plate, it fills almost all the area behind the mirror, I drilled a series of small holes to ensure good bonding then glassed it onto the door and welded the pieces together _ fiberglass does burn _ I had to work fast. So this is kinda ugly but it is really really solid that was the goal.

Determining the Correct Strut Specs
This method uses more experimentation than analysis. I will try and come up with a more mathematical solution and will post that when it's ready.

Equipment Required:

Tape measure
Pencil or crayon to mark on door and body
A helper strong enough to hold the door at the vertical position
Scissor hinges which you will use (this is strongly recommended but not required)
A produce_type hanging scale. You could construct a crude version using a rope, pulley, and some counter weights (like from a dumbell set).

Procedure:

First, you should mount the door on the proper hinges. For a door mounted conventionally you should take it off of its hinges and position it in the door jamb so it is free to rotate up (or out).
From looking at a lot of pictures, the strut is usually mounted on the body about a foot or so down from the hinge. You can use this as a starting point.
The strut's compressed length will be the distance from its mounting point on the body, to the mounting point on the door itself.
[Compressed Length] =
Now rotate the door around its hinge point to the upright position. It is a good idea to have someone help brace it up for you. It will get tricky to hold a 50+ lb door up with one hand while you use the tape measure with the other. Now measure the new distance between the strut mounting points (as in Step 3).
[Extended Length] =
Your length of travel is the extended length minus the compressed length. If your Length of Travel is more than about 40% of your overall length, you will need to move your strut mounting point. The majority of struts will not have a Length of Travel more than this.
[Length of Travel] = [Extended Length] _ [Compressed Length]
If the door is empty, attach all of the trim, mirrors, interior, glass, actuators etc. You will need to simulate the weight of the final door. You may use dummy weights but be careful where on their placement. Adding 5lbs to the end of the door versus closer to the hinge will make a huge difference.
Now you will need that hanging scale, or you will need to come up with an alternative. Either way, attach the a hook to your strut mounting point on the door (you found this in Step 3), and pull up to the position you want. The max weight that the scale reads will be your force. The reading might fluctuate depending on the door's position, but it should read the highest when the door is at the closed position. Add about 15_20% to this as a safety margin. You don't want the door to close too easily, plus you should take friction into account and some wear and tear later on, which might degrade the strut's pushing force. Offhand, I know of a '95 civic that was converted and used 175 psi struts. If you don't have a produce scale, I will try to post an alternate method soon. This will not simply be the weight of the door. Leverage is working against you. The closer you mount the strut to the hinge (on the door) the more force it will need to push up. It also depends on the shape of the door and the location of its add_ons.
[Force] =

BELOW LINKS REQUIRE ADOBE ACROBAT READER.
Please print the files before links are changed.

DIY Door Conversion Blue Prints
Door Hinge Installation
Door Hinge Installation Reccomendations

Strut Installation & Info
Page 1
Page 2
Page 3

Abover Links are in use with permission from Street Dreams Customs.

Additional Links
Street Dreams _ This company has fair prices and I really like their hinge design
Decah _ He sells a vertical door conversion kit for "any car" for $1600. It's over my budget.
Minor Rubber_ Rubber boots to cover your whole assembly to give it that pro look
Autoloc These guys sell complete conversion kits from doors, trunk, hood...and others for a decent price

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MORE PICTURES AND GULLWING CONVERSION
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This is a photo of a Kit Car Lamborghini Diablo, what you are seeing here is the right door with the outside door skin removed.

A = the door hing (see photo below of the hinge parts)

B = car chassis frame around the door frame, this is a sub frame that

C = gas shock

D = car chassis frame (right front tire location).

Check this site out for all your hinges... Street Dreams Car Door and Hinge Products

This is a photo of a Honda CRX with the Door Conversion Mod...it can be done!

GULLWING DOOR CONVERSION MOD

To install the door hinges, you simply have to have these parts:

Two air shocks _ that work by switch (about 8 inches long each)
A welder
Steel tubing (for door reinforcement)
Thick steel sheet metal

You have to mount one shock onto a plate at the bottom front corner of the drivers door, mounted onto a flat plate that is welded to the floor/door structure of the car, under the carpet. The shock is not seen when the door is closed, the shock goes inside of the door and there is a plate welded to the door that also mounts to the shock at the tip of the skinniest shaft.

You have to reinforce the door for support. They take off the fenders do some cutting in below A post weld on about 2X3 square tube, then GMC or Ford E rear cargo doors hinge. Cut some off and add to it like 180* flat bar (now on that Honda they used 175psi struts).

When you hit the switch the door should slide out on that shock, now comes the pushing up part. You have to have the other shock mounted to the same plate, but it is about 12 inches long and runs up parallel to the door beside the seat and mounts to the door at the end of the shock. You have to have a shaft made to the door so that when the door pops out the shock slides on the shaft then when the door is popped out it catches and pushes the door open.

300ZX Nissan butterfly door

They use GM or Ford full size van cargo rear door hinges