Trunk lid will not stay open

[Stanglover]

Interestingly enough now that I redid my trunk lid and the spoiler was moved to the correct location, it stays open on its own. I didn't think about it at that time, but before the spoiler was in the wrong location a couple of inches further back, which placed more force on the rods. Now it stays open as it should. That said, the location of the spoiler is something else to think about.

interesting Tony. Good point.
On my car it had a repop spoiler added to the dimensions shown in NPD's instructions. These dimensions are 1" further back than the dimensions shown on the 429 mega site. My trunk does stay open, just. Any further back and I certainly can see it not staying open at all.

 

[tony-muscle]

interesting Tony. Good point.
On my car it had a repop spoiler added to the dimensions shown in NPD's instructions. These dimensions are 1" further back than the dimensions shown on the 429 mega site. My trunk does stay open, just. Any further back and I certainly can see it not staying open at all.

Those are the dimensions that the shop followed.

 

[JJHStang]

I have viewed many pics and also measured the location from front of trunk (rear window) and the first screw is 9.5”.
Based on a picture I received of correct measurements my spoiler is positioned correctly.
I have made a prop stick. Last car show was at the wind was blowing in back to front so no issues with trunk lid shutting. Didn’t need the prop rod.

 

[JJHStang]

I have viewed many pics and also measured the location from front of trunk (rear window) and the first screw is 9.5”.
Based on a picture I received of correct measurements my spoiler is positioned correctly.
I have made a prop stick. Last car show was at the wind was blowing in back to front so no issues with trunk lid shutting. Didn’t need the prop rod.

Thank you Stanglover for the measurements.

 

[rcadd1ct]

And for those following this don’t be like me.

the strut pictured does NOT work on a FB.

I welded some custom brackets. Pop riveted the mount to the trunk then found out it wouldn’t close.

new struts ordered to see if attempt two will work.

 

[Austin Vert]

And for those following this don’t be like me.

the strut pictured does NOT work on a FB.

I welded some custom brackets. Pop riveted the mount to the trunk then found out it wouldn’t close.

new struts ordered to see if attempt two will work.

Hi there,

Sorry to see you didn't get a win there. Fitting gas struts to the hood or trunk lid can be a tricky process in general terms. For my convertible trunk lid, i did a DIY job,and guessed the length of rod i would need, and the mounting positioning of the two ends. In my case it turned out very well with no issues. I would imagine setting up for the fastbacks would be similar but maybe not quite the same exactly. I have never attempted to do that, so i can't speak with any experience to help you along there. In any case, the length of rod, the amount of gas charge, and the strut positioning are the crucial things to make it all work.

I got a professional installer to install my two hood struts as the setups were beyond my skill level. If you look at my pics below, it may give you some clues as to a mounting procedure that may be of help to you to follow. The red Mustang photo was sent to me by a fellow Forum member several years ago. He told me he had a win with his setup. Best of luck with it all.

Greg.

 

[rcadd1ct]

Hi there,

Sorry to see you didn't get a win there. Fitting gas struts to the hood or trunk lid can be a tricky process in general terms. For my convertible trunk lid, i did a DIY job,and guessed the length of rod i would need, and the mounting positioning of the two ends. In my case it turned out very well with no issues. I would imagine setting up for the fastbacks would be similar but maybe not quite the same exactly. I have never attempted to do that, so i can't speak with any experience to help you along there. In any case, the length of rod, the amount of gas charge, and the strut positioning are the crucial things to make it all work.

I got a professional installer to install my two hood struts as the setups were beyond my skill level. If you look at my pics below, it may give you some clues as to a mounting procedure that may be of help to you to follow. The red Mustang photo was sent to me by a fellow Forum member several years ago. He told me he had a win with his setup. Best of luck with it all.

Greg.

Ya. Just a minor setback.

I needed a win today as I destroyed my rear window trim on install.

 

[Austin Vert]

Ya. Just a minor setback.

I needed a win today as I destroyed my rear window trim on install.

Hey,

Looks like you came up with a working solution there from your report above. That's great!

Thanks for the photos on your installation. A great reference. If you're happy with your setup, then that should serve as a help and a guide for other Forum members as well.

Greg.

 

[rcadd1ct]

Hey,

Looks like you came up with a working solution there from your report above. That's great!

Thanks for the photos on your installation. A great reference. If you're happy with your setup, then that should serve as a help and a guide for other Forum members as well.

Greg.

Your mount at the hinge was way easier than what I fabricated.

I just hope the info on the gas strut will help someone else

 

[JJHStang]

I figured out a simple solution to my trunk lid not staying open. Just took a piece of wire and a pliers.
I have attached a picture. I will make it look better and maybe make one for the other side.

 

[boss49472]

Does anyone know the material specification (AMS or ASTM) Ford used for manufacturing trunk lid torsion bars? I had a set made for my 1972 fastback with sport deck using ASTM A853-19 steel and they are not strong enough. BTW the aftermarket bars that were available several years ago are 0.200" diameter. It appears there are Ford originals that are 0.225" diameter that were intended to be used with cars with spoilers

 

[boss49472]

My trunk lid on my 71 Mach1 with spoiler will nit stay open.
I looked and it is on the 3rd notch already.
The only time I would like it to stay open is at the Charity car shows.
Is there a way to keep open without replacing the torsion bars?
From what I have seen it is not an easy task.

Took a little time to solve this issue and produce a vintage correct solution. The heavy duty torsion bars for the cars with spoilers are 0.225" nominal diameter "music wire" material (ASTM A228 material spec.). The ones I had made are 0.236" diameter as this size is in production on a Ford application. I tried several other steels but none of them had the yield strength of A228, they would hold the trunk open for one or two open close cycles then deform. It was a bit expensive to have them made, but they hold open the trunk easily on the second notch and the install is pretty easy.

 

[Cleveland Crush]

Took a little time to solve this issue and produce a vintage correct solution. The heavy duty torsion bars for the cars with spoilers are 0.225" nominal diameter "music wire" material (ASTM A228 material spec.). The ones I had made are 0.236" diameter as this size is in production on a Ford application. I tried several other steels but none of them had the yield strength of A228, they would hold the trunk open for one or two open close cycles then deform. It was a bit expensive to have them made, but they hold open the trunk easily on the second notch and the install is pretty easy.
View attachment 87946

Who fabricated the trunk spring for you? Thanks.

 

[rio1856]

Hey boss49472 I was wondering if you can point me in the right direction so I could also get a set of torsion bars made like the ones you had made for your car. I to, am in search for the correct torsion wire for my Mach so the trunk lid could stay open with the attached rear spoiler. Thank you I hope you can help.

Rio

 

[boss49472]

spring dynamics in Almont Michigan.

Also check Blue Oval Car Barn, Spring Dynamics made a couple of sets for them

 

[boss49472]

Hey boss49472 I was wondering if you can point me in the right direction so I could also get a set of torsion bars made like the ones you had made for your car. I to, am in search for the correct torsion wire for my Mach so the trunk lid could stay open with the attached rear spoiler. Thank you I hope you can help.

Rio

Spring Dynamics Inc. in Almont Michigan.

Check with Blue Oval Car Barn, A couple of pairs of springs were also made for them by Spring Dynamics

 

[boss49472]

Who fabricated the trunk spring for you? Thanks.

I also made this neat installation tool

 

[boss49472]

Spring Dynamics in Almont Michigan

Also, check with Blue Oval Car Barn, they have a few pairs from this run of parts