Making a 1968 hard top into a convertible

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Fliptophead
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Joined: Sat Nov 06, 2021 5:10 pm

Making a 1968 hard top into a convertible

Post by Fliptophead »

I bought a 1968 and someone had previously chopped the top off to make a convertible. Is that actually safe to do with the style of frame. Isn’t the 68 a “unibody”? And the solid roof provides some stability. Do I need to beef up the frames? Is it even possible? Is it ok to drive as it is?
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cacockrum
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Re: Making a 1968 hard top into a convertible

Post by cacockrum »

Ford switched from a unibody to a conventional frame in 1967.
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Alan H. Tast
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Re: Making a 1968 hard top into a convertible

Post by Alan H. Tast »

Considering the fact that frames on 67-71s were notoriously weak and rot out forward of the rear axle kick-up, adding support to the frame and stiffening the body shell to not only resist body sag but also twisting needs to be seriously considered. Without adding support you're driving a car that will fold in half at some point in time.
Last edited by Alan H. Tast on Sat Nov 06, 2021 10:24 pm, edited 1 time in total.
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
Fliptophead
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Re: Making a 1968 hard top into a convertible

Post by Fliptophead »

Any suggestions on the best way to stiffen the frame?
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Alan H. Tast
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Re: Making a 1968 hard top into a convertible

Post by Alan H. Tast »

Hire an engineer and be prepared for a LOT of fabrication work. I'm serious when I say that. Short of that, study how convertible frames and bodies of cars from the 50s-60s differ from closed cars, especially full-size Fords/Mercurys. You'll see things like large, heavy-gauge X-members and frame rails heavier than comparable open car frames, inner body structure with additional bracing and stiffening panels, and other nuanced modifications to help reduce twisting, flexing and add rigidity to the overall structure. The original 67-71 T-bird frame is not the best of frames to begin with, and I'm not aware of a frame from another car that you can swap the body onto without a LOT of fabrication work. Trying to make your car a structurally sound convertible conversion is going to be a very labor intensive (and potentially expensive) proposition.

As for the question "is it safe to drive it as it is," not really, especially if it's driven like a daily driver or a road race car or if the frame is weak or compromised (i.e. rot in the frame rails). I sure don't recommend "whackmaster" convertible conversions unless a person understands what they need to do to avoid structural failure.
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
Fliptophead
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Joined: Sat Nov 06, 2021 5:10 pm

Re: Making a 1968 hard top into a convertible

Post by Fliptophead »

Maybe I should just part it out…sigh… other than the missing roof, it’s in good shape too…
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cacockrum
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Re: Making a 1968 hard top into a convertible

Post by cacockrum »

Please let me know if you decide to part it out. I'm looking for a decent left-side windlace where the door interfaces with the rear quarter panel trim.

Art
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