I WOULD LIKE TO CUT OFF A PORTION OF THE ROOF OF MY COUPE, ALA FERRARI 308. IT LOOKS POSSIBLE IF I ONLY TAKE THE AREA THAT WAS BOUNDED BY THE SUN ROOF CUT-OUT. I AM WILLING TO INSTALL A BRACE IF NECESSARY. DOES ANYONE HAVE ANY EXPERIENCE WITH THIS? THANKS CHUCK

There are a couple of guys here that have a targa style roof.

You WILL have to add bracing under the car as is done for a convertible.

I would like to expand on the good advise that Fierobuzz has given. I built an own a 85GT Fiero convertible and can verify that a subframe is necessary.
A subframe made of 1" x 2" 1/8" wall steel tubing must be fabricated and welded to the frame supports PRIOR to cutting the roof off. If you don't do this, without a roof,the frame will flex and shut tight on the doors. My subframe is welded at the front cross member and in a V shape runs each side back to the unibody frame rails. It then conitunes to run under the body, runs at an angle outward, then goes up and and picks up at the back unibody frame rails where the crsdle bolts. The back ends are welded there. I also added a frame piece that runs under the gas tank to the frame.. At the ends of this frame piece are flanges with two holes. They bolt to the subframe. This way it is easy to drop the gas tank if necessary.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://turbofiero.fierojoe.com/turbo.htm

quote Originally posted by Dennis LaGrua: I would like to expand on the good advise that Fierobuzz has given. I built an own a 85GT Fiero convertible and can verify that a subframe is necessary. A subframe made of 1" x 2" 1/8" wall steel tubing must be fabricated and welded to the frame supports PRIOR to cutting the roof off. If you don't do this, without a roof,the frame will flex and shut tight on the doors. My subframe is welded at the front cross member and in a V shape runs each side back to the unibody frame rails. It then conitunes to run under the body, runs at an angle outward, then goes up and and picks up at the back unibody frame rails where the crsdle bolts. The back ends are welded there. I also added a frame piece that runs under the gas tank to the frame.. At the ends of this frame piece are flanges with two holes. They bolt to the subframe. This way it is easy to drop the gas tank if necessary.

Hiya Dennis......is there anyway you can sketch a pic of the frame reinforcement and email it or upload it......scan it or something? I want a Targa on my Fiero too!
Thanks buddy.

Phil

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GTDude
OVER 25 years GM experience

quote Originally posted by GTDude: Hiya Dennis......is there anyway you can sketch a pic of the frame reinforcement and email it or upload it......scan it or something? I want a Targa on my Fiero too! Thanks buddy. Phil

Phil: Let me dig into the arhives of my literature and I'll try to find the blueprint.

KEWL DENNIS..........THANKS!!!!!!!!!

Phil

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GTDude
OVER 25 years GM experience

disreguard the shadows at the top of the photo

THANKS DENNIS AND OPM !!!!!

MERRY CHRISTMAS!!!!!!!!!

Phil

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GTDude
OVER 25 years GM experience

Thats an Automoda subframe. Totally overkill. All you need are the fat tubes on the sides that weld to the rocker panel. It doesnt hurt to add the parts that stick up, but I doubt they help a whole lot. The X part of the frame is not needed, as your frame isnt going to "diamond" unless you drop it off a cliff, and the X isnt strong enough to do anything about it anyhow. Just be sure your cooling pipes will fit inside the rocker panel tubing and you're all set. Have fun overhead-welding.

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87 Quad 4 HO convertible

>>Thats an Automoda subframe<<

Beg your pardon, it's a Bill Welch subframe, a direct copy of the Warlock subframe, originally used on the two Fiero/Ferrari's in "The Rock".

Not shown are the four upright pieces which continue this subframe into the wheel wells (to extend the "bite" of the subframe on the unibody).

The subframe is tacked together while jacked & jigged into place, under the car. It is then taken out and final welded. Then it is put back in place and easily mig welded to the unibody.

The "X" gives torsional rigidity, just like the trammel braces in a ribbed two spar airplane wing. They are designed not to counteract compression forces, rather they work in tension.

If you've been around hotrods very long, you will appreciate a custom chassis that has "X" bracing, ...quite a step up from not having them.

I really like the removable center sections which allow fuel tank removal.

Hey guys, ok I have seriously considered cutting a targa top on my car and I have a friend who welds and can give me good deals. I have a question about where it "exactly welds" and if the cooling pipes have to run inside those side rails? And one more question is how do they make those rmovable center sections for the tank? is it bolted in there or what? Thx!

The two side pieces of the subframe fit up into the unibody channel where the coolant pipes normally fit. This does mean that those pipes have to be fitted inside of the subframe. And that does mean that a small crook at one end of each pipe has to be sawed off, so the coolant pipe can be inserted into the frame. This removed piece is replaced with typical coolant hose & presents no big problem.

The X and the center section of the front cross-member are removable. They bolt together. The sections are made of a combination of C-channel, bar stock, tubular steel, and healthy sized bolts.

There is some cutting of the unibody to fit the subframe into place, but this is just removal of small edges, or interference fits, and presents no big problem.

At final welding, the subframe is jacked firmly up under the unibody and it is stich welded wherever convenient. It isn't necessary to have the entire subframe seamlessly welded to the unibody. You just run a 1" bead, skip a few inches, run a bead, ...

There are four extra short steel tubes not shown in the pic which are welded into the wheel wells, that add considerably to the load transfer process.

I have a frame laid out in my shop now, so I'll take a photo later this morning, so you can see the removable sections.

I have to agree with Automoda here. An X frame is total overkill and not necessary on a Fiero. Strengthening of the sills and the a and b pillar areas is more than sufficent. If you want overkill strengthen the fuel tank tunnel with plates for a extremeley rigid car. I spoke to an automotive engineer on this matter and he recommended the above to be legal with stringent Australain registration laws and to pass an engineers inspection.

He also pointed out an obvious fact that is often overlooked. Look underneath most factory convertibles compared to the coupe models of the same cars and you wont find x braces in most cases.

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The Fiero Shop International

WHAT ABOUT THE MODELS THAT CAME WITH THE TEE ROOFS? DID THEY HAVE ADDITIONAL UNDER CAR BRACING, OR WAS THE REMAING ROOF PORTION, (PERHAPS WITH ADDITIONAL BRACE WITHIN) SUFFICIENT?

I'll throw in my 2 cents here. I have had plenty of experience with convertible and T-Top frames and the Fiero chassis has plenty of lateral strength. Torsion is not the problem, the weak forward dog leg is the car's achilles heel. I've seen stock frames split at the forward dog leg!

My solution is more elegant but harder to do. I actually cut the ends off the rocker panels (two layers - be patient) and slide 20 wall 2" steel inside the length of the rocker. You need to drill a hole for the seat belt bolt and then weld some steel inside the front and rear doglegs running up 8 to 12 inches. Then re-cap the rockers and you have a SUPER stiff frame that looks stock (no visible steel anywhere).

I'm just an eyeball engineer, and would suggest you talk with Bill Welch, he's built many convertable Fiero's. I do know amongst most Diablo builders who have to contend with 300 to 450 hp and a chopped off roof that torsional rigidity is a concern. As pointed out, you will have cut off 1/2 of the unibody "eggshell" when you build a convertable, seems logical to put back the strength that you just took away. I offer this information only to share.

This is the front brace, removable section:

This is the center brace, removable section:

This shows both. Most of these pieces are not welded, and are slightly seperated to show their construction:

[This message has been edited by opm2000 (edited 12-27-2002).]

COME ON GUYS, I`M NOT PROPOSING TO MAKE THIS INTO A CONVERTIBLE, I WOULD LIKE TO LEAVE ABOUT 4 INCHES AT THE WINDSHIELD AND THE USUAL REAR ROOF SECTION AT THE BACK WHERE THE REAR CLIP MOUNTS. ARE YOU TELLING ME THE CHASSIS WILL SAG AT THE DOORS? IF SO, WOULDN`T A BRACE AT THE ROOF, ALA T-ROOF TAKE CARE OF THAT?

A. If you are making a targa top, it is the same as a convertable in that there is no continuous path of metal from the top of the hood to the rear behind the doors.

B. Take off the caps lock please. It is considered to be yelling and is very rude.

Well, here is a link to a company that builds sub frames for F bodies, and you can see that there is not as much to their frame vs the above posted one...maybe they would consider making something for the Fiero

http://www.kennybrown.com/fbodysubs.html

Tim

[This message has been edited by Mickey_Moose (edited 12-28-2002).]

On my old 69 Firebird convertible there was a thing called an X-brace that bolted onto the bottome of the car. I had seen it in car restoration books for years but had never bothered to look under the car to see what it was like. Once I finally did I was shocked to see that it was only about a foot square! I thought it covered the whole bottom of the car!

Now I know that our Fieros are not built like a 69 Firebird was, but the Bird was still a unibody car. Would something like this not work on our cars? I have no idea, that is why I am asking...

On a side note, I later found out that most Firebird/Camaro/GTO convertibles were missing this x-brace and it was very rare to have one still on the car. But the cars were fine anyway even without them.. I guess that shows that those cars were built a little stronger than our little cars.

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Hey guys,step back a moment. You can rationalize anything away to oblivion....kind of like those guys that use a logging chain to hold the engine down in their pickup truck...shoot, who needs engine mounts anyhow, this chain works just fine....

I think it's best to err on the side of caution....either do as Toddster or I suggested....or go get yourself a logging chain.

If you ever sell what you have created, it better be survivable.

quote Originally posted by opm2000: Hey guys,step back a moment. You can rationalize anything away to oblivion....kind of like those guys that use a logging chain to hold the engine down in their pickup truck...shoot, who needs engine mounts anyhow, this chain works just fine.... I think it's best to err on the side of caution....either do as Toddster or I suggested....or go get yourself a logging chain. If you ever sell what you have created, it better be survivable.

Well aside from the whole logging chain thing, I agree 100 percent, I have no idea what a loggin chain is, so that point totaly flew by me. Anywho, who cares if it is overkill, just as said above err on the side of caution. What is two more bars when you are allready doing a project like this. It is better to be safe than sorry. Even just because of the chance that an accident may have weakend it. There is no point in arguing the fact. you dont want the x-frame, then dont use it, you want it, then use it.

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Thanks hallsman!

I've cut the roofs off of two Fieros. From my experience they do need something to provide torsional rigidity. I challenge anyone who has a convertible or targa without an X or a V under it to do the following: Jack the front of the car up under one of the front control arms. I bet you don't get both tires off the ground without pinching the doors shut or at least seeing a very noticeable amount of twist. I've done it and I didn't like the results. The side rails don't do much to prevent it from twisting unless they are connected together.

To me cutting the top off and bracing the frame seem like minor issues compared to a way to latch the top and seal it with weatherstrips.

Does anyone have any experience with doing this part of the job? This is the part that concerns me the most. Is there a kit? Where do you get the parts from? Any other help would be useful. Thanks.

Phil

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GTDude
OVER 25 years GM experience

and two more pictures from the LA Machine assembly manual:

Yes the t top cars have a steel brace in the roof. It is like 6 inches wide and grabs the header at the windsheild and at the back window.

I would use the rocker rail idea with a long flat piece inplace of the tank cross member. Like the mustang convertables bolted on.

I'd like to second Phil's (GTDute) comment.
What about a latching and weatherstrip system once the roof section is cut out?
How far back from the top of the windshield would you make the cut? And what about finishing the rough edges? Could you use some type of rubber cap?
As for a latching system, you could probably adapt a set of latches from some other convertible car like a Mustang. There are tons of aftermarket Mustang parts catalogs and the parts are relatively cheap.
A note to Phil - I notice you live in Virginia. I do too, just outside Petersburg.
If you find anyone locally that can do the welding or fabrication please let me know.
My email address is timw@erols.com
Thanks!!

There are a few companies doing convertible and/or targas for mini trucks. You can find their ads in most custom truck mags. They must have seals and latches that could be adapted pretty easily.

GTDude,
Your quite correct, why reinvent the wheel? I hate to keep bringing Bill Welch up, but way back when I bought my subframe from him, he had several convertables under his belt. That sunny day in Florida, he had a Ferrari conversion in his driveway which he was putting together.

The neat part of that car was the t-top he was putting onto it. He had visited the local salvage yard and had the latching mechanism of some production car (I think it was something easy & cheap to get that came with factory t-tops). All he really had to do was resize it to fit the Fiero roof section.

Bill is still around.

David Breeze