MKIV Trunk Lid on a MK3 How-To

[frankeeski]

For any of you still working on a MK3 and wanting to install the non-perky MKIV truck lid and asking will it fit? The definitive answer is YES. With that, it really is not a direct bolt on because FFR changed to an under-mount hinge system and the MK3 does not have the brackets welded in place for the new style hinges. The lid itself does follow the contour of the body better than the MK3 lid I previously had mounted. What I am doing here is making my own hinge system. I stole this design from Dan Ziol and I'm putting my own spin on it. It does however resemble his and I actually made a template of his hinge arms as a starting point for mine. I will be updating this thread as I continue to move forward but I am nearing my 6th year of the build so it may be a while before this project is complete. I hope to have the car back on the road by April so we can attend the Huntington Beach Cruise-In, so wish me luck.

Here is where I'm at so far. I drilled some oversized holes in the mounting area provided on the bottom side of the trunk lid. I also drilled and tapped mounting plates which slid in between the inner and outer skin of the lid. Here you can see them with 1/4"-20 machine screws and washers holding the mounting plate in position.

Next I made 2 more mounting plates, this time for the surface of the inside of the lid. This is where the hinge arms will be welded.

This next picture is a bit grainy, I'll try and take another one and upload it later. Here you can see the hinge rod. This piece will bolt through the 3/4" arched frame support under the body and provide a pivot point for the hinge arms.

Close-up of the hinge rod and the sleeve that will provide the movement for the hinge system.

[frankeeski]

The next two pictures show the hinge rod with the sleeves in place and the 1/4" bolts welded in place. You can just catch a glimps of the hinge arm next to the Sharpie in this pic.

The bolts will go through drilled holes in the 3/4" arched frame rail under the body. The length of the bolts will allow for fine adjustment of the truck lid.

[frankeeski]

Frustrating weekend. My first design of the trunk hinge arm was an epic failure. Second attempt today was not any better. But like Thomas Edison, I have found 2 ways so far not to make hinges. On to number three. Below are a few pictures of the hinge rod mounted in the trunk and to events leading up to it. At this point I am going to take the lead from Breeze and FFR and move the hinge pivot to the rear of the crossbar and try again. Wish me luck.

Located and drilled holes for hinge rod.

Holes are drilled



Hinge rod installed .

[frankeeski]

Success! Today was a much better day. The third iteration of the hinge arms allowed the truck to open up and back, now not contacting the body of the car. The goal here was to make a low intrusive hinge arm that did not project down into the truck cargo area to much. I think I came up with an arm that does that. If any of you have gone on a week long trip with the wife in one of these cars, you know exactly how precious trunk space is. Losing any space in the trunk can be a catastrophe. We should still be able to get two full size bags, the umbrellas, the cooler and the 2 folding chairs in there. Below are some pictures of this afternoons progress.

I've got a ton of adjustment fore and aft, probably a good 1/2" side to side. I do have it pretty well lined up right now. This is a picture of the passenger side hinge arm with the truck lid all the way open.

This picture is of the drives side, again with the trunk open

Here is one a little farther back with the trunk all the way open

Picture of the truck closed.

My plan for tomorrow is to tackle the trunk lid supports and the electric latch. I have a set of Mike Everson's truck lid supports. I previously had those mounted on the MK3 lid. Looks like I am going to have to do a bit of fabrication to the brackets that mount to the lid. The trunk latch shouldn't be too bad, I can use the previous one as a pattern for the new one.

[rlampman]

Hinges look great. they are a lot like the design of the Tristate trunk hinge I have. I want to follow this as I want to have an electronic trunk latch as well. I haven't put much thought into it and want to see what you come up with.
Rod

[frankeeski]

Here is the electric latch system I previously used on the MK3 trunk lid. I am cleaning it up a little for the install on the MK4 lid. This time around I am glassing in the mounting plate rather than thru-bolting it as I did before. I used this electric latch out of a 94 donor Mustang.

I fabricated my own latch bar and attached it to this flat metal plate mounted to the trunk lid.

I mounted the Mustang latch recessing it into the trunk deck and this is what it looks like.


The electric latch works great and does not need a popper even without the trunk molding mounted yet, my car is still in gel-coat. I drilled out the cable release that would normally go to the keyed release for the trunk. I mounted a 1/4" bolt in its place and this acts as an emergency release in case I loose electric power (it can be seen in the first picture I posted above). The battery is in the trunk so if it fails I will need a way to get into the trunk with a no power condition.

[frankeeski]

Spent the better part of the afternoon in the shop working on the trunk latch and finishing up the support struts.
Here is the backing plate, it is mounted with Evercoat polyurethane panel bonding adhesive and then glassed over with resin and fiberglass mat.



Here is a picture of the strike bolts, the new one versus the old one on the right. The prototype on the right was a bit big but knowing I was going to be doing this all over again for the MK4 lid, it didn't need to be pretty. The new one, on the left, is much smaller and a bit more attractive.



I used low expanding foam behind the hinge backing plates mounted inside the trunk lid. You can see a bit oozing through the threaded mounting holes. It will act as an adhesive and also allow the plate to move a bit in the future if I need a little more adjustment.

Last one for today. I got the lid mounted back on the car late this afternoon and attached the support struts. Looks like everything is lining up well.

[Jeff Kleiner]

Well done Frank!

Jeff

[David Hodgkins]

Outstanding. You never cease to amaze me Frank.

[rlampman]

Thanks for the latch pictures. Looks very finished and "factory" like. I will be looking for a mustang latch assembly for mine. What metal did you make the strike out of and how did you bend it? It turned out great but I am thinking that metal hard enough to hold up may be hard to bend.
Rod

[frankeeski]

Thanks for the latch pictures. Looks very finished and "factory" like. I will be looking for a mustang latch assembly for mine. What metal did you make the strike out of and how did you bend it? It turned out great but I am thinking that metal hard enough to hold up may be hard to bend.
Rod

I bent the rod using a 30" metal brake but you could used some heat from a propane or Mapp gas torch and bend it pretty easy in a bench vise. The rod is just 3/16" mild steel rod you can pick up from a home center or metal supply house. The latch itself is available at most pick & pull yards for less than $25. Don't forget to get the activation button from the glove box and both pigtails. The one for the button and the one for the latch.

[JJ'snakepit]

Hey Frank .... Awesome job on the hinges. I am sure glad you piped up on the other forum and provided a link. I have to start looking over here more often. JJ

[frankeeski]

Updated picture of the MK4 trunk lid.

[jayguy]

Nice work!

Hey Big Blocker, you seeing this?