1974 Duster t-top conversion

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Max_118

Max_118

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I have a '74 Duster, and I am planning on giving it t-tops. It's going to be a replica car from a movie. When I started this project, I thought the car had a frame. (T-tops would be easy to do if it did.) Then I learned it's unibody, so I know if I cut out those chunks of the roof that I'm messing with the structural integrity of the car. I've asked around, and I've received several different answers:

1. No modifications necessary.
2. A heavy duty roll cage will have to be installed.
3. Reinforcing the frame along the bottom of each door with square tubing will be sufficient.
4. Cut off the entire roof and weld in a replacement t-top from a Trans Am/Camaro/etc

So I thought I'd ask here. I know it's an unusual idea, but still, I hope it makes for a good discussion. Any help would be appreciated!

- Dave
 
At the very least do one of 2, 3 or 4. Or do at least a couple of them. Doing the trio of them would likely be the best option.
 
Well, the factory made convertibles. They rolled off the assembly line with torque boxes, so, I'd stay that would be a good start. Subframe connectors would be a good addition from there. You could also look into reinforcing the rockers, or tying them to the subframe connectors in a few places.

Don't forget that reinforcing around the T-tops will help too, you need to tie the existing hardtop structure into the T-top frame. Obviously you're going to be adding the T-top structure from another car to the Duster, so there's going to be a lot of custom work. And how you tie the t-top structure into the existing roof structure will be important. Something as small as some additional gussets between the roof structure and the T-top structure can make a big difference.

I kinda hate to admit that I've actually thought about this. Kinda like how I hate to admit I've thought about adding a more modern sun roof more than once. Sorry, I spent more than a few years driving a roadster and sometimes having the sun shining down on you is just a nice deal. At this point I wouldn't do it to any of my Mopars, too many hassles with leaks etc. But I get where you're coming from.

The bottom line is that if you have the skills to graft the T-top structure into the roof line, matching those curvatures etc, then you have the skills to do the chassis reinforcement. Honestly the chassis reinforcement will be easier.
 
Hey thanks! I really appreciate it. I'm leaning towards fabricating essentially a rollcage and putting that in. But I want to get other's thoughts on it before I get started.
 
Max_118 said:
Hey thanks! I really appreciate it. I'm leaning towards fabricating essentially a rollcage and putting that in. But I want to get other's thoughts on it before I get started.
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Well a full cage would make it a non-issue, that's for sure.

But I don't think a full cage is necessary. Torque boxes, subframe connectors and a careful installation of the T-top structure with gussets and reinforcements of the roof should be more than enough.
 
You ain't need a roll cage. Convertible cars did more with less.

Just copy what the convertible cars had for frame reinforcement and you're fine.
 
What kind of reinforcements DID the convertibles have?
 
This will be a challenge for sure! After watching crafts people like the Martin Bros. and Dave Kindig's crew modify cars though, I won't call anything impossible. Me, I would look to the 78-79 Dodge Aspen for structural ideas and even grafting the t-roof components as they were factory built with t-tops. Again, not going to be a straight swap and much fabrication involved . As 72bluNblu suggested, torque boxes, frame rails, gussets, and internal roof reinforcement are the name of the game here. At least with the Aspen components, you will be able to source mopar replacement parts, T-Top glass, seals framework etc..

looking forward to seeing the progress of this one as I like "different " !!
 
I believe the dodge Aspen plymouth volare t tops were done by the now defunct cars and concepts as were the dodge magnum tops. A lot of the t top conversions on most cars in the 70s and 80s were done by C&C. Dodge Daytona, second gen camaro/firebird, fox body mustangs & capris. Even the pontiac fiero. Good luck finding weather stripping, and getting it to seal. I think subframe connectors and torque boxes would be enough for this. Heck, on the FWD daytonas they never even modded the chassis under it. I would look at whichever T top conversion you can readily find repop weatherstripping for and start from there. Measure roof widths and curvatures from all those different cars if you have access to them. You will need to get the glass and T bar frame from somewhere to make this. Preferably glass that has a similar curvature as your duster roof, or this ain't gonna look good.

Good luck.
 
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Max_118 said:
What kind of reinforcements DID the convertibles have?
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The primary reinforcement for the convertibles was just torque boxes, I don’t think they had much else actually. Maybe a ‘vert owner can add more detail.

That’s not all I’d do, the factory convertibles were pretty flexy. Hell the regular cars were pretty flexy. But torque boxes, subframe connectors and a well thought out roof structure could make up for the addition of the t-tops. A standard roof car would still be stiffer with the same chassis reinforcements, but I think you could make it better than they left the factory.

moparmat2000 said:
I believe the dodge Aspen plymouth volare t tops were done by the now defunct cars and concepts as were the dodge magnum tops. A lot of the t top conversions on most cars in the 70s and 80s were done by C&C. Dodge Daytona, second gen camaro/firebird, fox body mustangs & capris. Even the pontiac fiero. Good luck finding weather stripping, and getting it to seal. I think subframe connectors and torque boxes would be enough for this. Heck, on the FWD daytonas they never even modded the chassis under it. I would look at whichever T top conversion you can readily find repop weatherstripping for and start from there. Measure roof widths and curvatures from all those different cars if you have access to them. You will need to get the glass and T bar frame from somewhere to make this. Preferably glass that has a similar curvature as your duster roof, or this ain't gonna look good.

Good luck.
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The weatherstripping deal is no joke! It’s a problem for people that have t-top cars.

As for the roof curvature, I think the late 70’s camaro’s and firebirds would be pretty darn close.
 
I have 2 NOS sets of T roof weatherstrip for my 88 daytona shelby Z. Payed a fortune for em years ago. Carefully stored in a box in my bedroom closet. They are not for sale. Probably payed over $700 in weatherstripping years ago. If this car is in real decent shape, I hope you dont cut this thing apart and then realize you made a big mistake. Once you hack into it with a sawsall and a cut off wheel, your kinda committed to it.

If your wanting to make a replica of the road warrior bad guy vehicle that's in your avatar, that was a Holden Monaro. Back in the early 1980s when the road warrior was made. This stuff was $800 1970s used car lot fodder that was hacked into, modified, used for movie stardom, then discarded to the scrap yard when filming wrapped up. It was never made to be functional, livable, and useable on a daily basis. The Monaro was a full frame car like the Chevelle it was based on.
 
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A good friend is restoring a 79 Aspen/Volare/Roadrunner T top car, when he stripped it down there was some pretty cheesy work down to install the T tops originally. It was done by whomever did it at the factory, or maybe it was done by a contractor for Ma Mopar, who knows. He really has no idea, other than he bought it new off the dealer floor. The car has a sag to it because of poor reinforcement which is being cured with torque boxes & sub frame connectors. He has now found out that what he thought was going to be a fairly straight forward restoration is going to be a multi year project now, but he is sticking with it one step at a time. I have owned a 79 Dodge Magnum T top car & there was sever body flex & twist, to the point the core support & the area between the tops stress cracked. Putting T tops in a unibody car is a poor idea without greatly reinforcing the entire car.
 
My current 88 shelby z I plan on adding subframe connectors to. My original 88 Z didnt have them, and used to creak and pop pulling into the driveway. Never leaked though.
 
Demonracer said:
A good friend is restoring a 79 Aspen/Volare/Roadrunner T top car, when he stripped it down there was some pretty cheesy work down to install the T tops originally. It was done by whomever did it at the factory, or maybe it was done by a contractor for Ma Mopar, who knows. He really has no idea, other than he bought it new off the dealer floor. The car has a sag to it because of poor reinforcement which is being cured with torque boxes & sub frame connectors. He has now found out that what he thought was going to be a fairly straight forward restoration is going to be a multi year project now, but he is sticking with it one step at a time. I have owned a 79 Dodge Magnum T top car & there was sever body flex & twist, to the point the core support & the area between the tops stress cracked. Putting T tops in a unibody car is a poor idea without greatly reinforcing the entire car.
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If the T bar panel was pop riveted in, and the glass locks into a center T channel strip, it's more than likely a C&C top. That was like a trademark thing they did.
 
Subframe connectors are more than the convertibles ever had, and I'd recommend them. There were reinforcements in the structure ahead of the rear wheel well, too, maybe?

There was guy that making all the stuff to create E-body convertibles. Look him up and see what he offers. I read about it in Mopar Action a few years back..

I never knew the T-tops was a conversion thing. I thought the factory did them.
 
moparmat2000 said:
If your wanting to make a replica of the road warrior bad guy vehicle that's in your avatar, that was a Holden Monaro. Back in the early 1980s when the road warrior was made. This stuff was $800 1970s used car lot fodder that was hacked into, modified, used for movie stardom, then discarded to the scrap yard when filming wrapped up. It was never made to be functional, livable, and useable on a daily basis. The Monaro was a full frame car like the Chevelle it was based on.
Click to expand...

Yep, it's going to be like that Monaro. If I had the cash I'd just import an Australian car, but I'd be looking at 10K just for shipping. That's just a little outside my budget! This will be something like the 10th Road Warrior 'replica' I've built.

It's not going to be a daily driver, and it will rarely go over 40MPH. It just has to be functional enough for Wasteland Weekend; check it out. :)
 
The whole point of T tops was to NOT have to reinforce the frame or add subframes.

The stress was handled by the reinforcement of the T bar area.

What movie had a t top duster?
 
YY1 said:
What movie had a t top duster?
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The Road Warrior had a Holden Monaro with t-tops. I'm not going to import an Australian vehicle, so the closest American car to that body style is a Duster.

Monaro1.jpg
 
Or a 1970-1972 chevelle. Since the Monaro is a full framed GM car with the same wheelbase
 
Uh, OK.

Actually for the amount of work involved.....

You can import AU vehicles fairly reasonably sometimes.


...and I bet the movie car was simply cut out and never intended to have actual glass inserts and seals.

...and also wasn't required to survive any longer than the movie production schedule (or the final battle scene).


Also, they are rare but 1973-77 "colonnade" body gms had t tops as an available option.

A 73-74 cutlass might work for you.
 
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