I've decided that I'm going to try and save the 84 frame that I was going to trash after I had parted the car. I'm going to get some people to look at the rust damage on the car to see if it's worth it.

What I would like to know about is reinforcing the frame after removing the roof section. I was dead set on an X-frame until I heard about Aus's opinion from Darklord. It's also stated in this thread:

https://www.fiero.nl/forum/Forum2/HTML/029817.html

Here is my rendition:

Would this make sense for reinforcement for the Fiero frame? I'm not 100% sure on the windshield portion of it(How did everyone else reinforce the windshield?).

I was thinking tube framing between the B-pillars underneath the passenger compartment carpet. And tube framing along the rockers bolted to the inner fender portion in front of and behind the doors.

I wasn't too sure about what Aus meant about reinforcing the center tunnel. If someone could clue me in, that'd be great.

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[This message has been edited by Street&Strip Performance (edited 04-21-2003).]

The reinforcement you have pictured behind the firewall would be much stronger if you made it an "X" structure. That would help in eliminating frame twisting as well as leave the area behind the fuel tank open.

I don't know why you'd want to reinforce the windshield area, once you cut the top off that ceases to be any type of a load bearing structure, it's just something to hold the glass in.

You have three areas of deflection to address. Picture the car small enough to hold in your hands and bend over your knee. Now think of trying to bend it with one hand on the front bumper, one on the back, and your knee at the doors. With the frame on your knee, push down. The door will come together with the jams. But that's not the load, the load is the OTHER way. Think of it sitting on the wheels and push down on the roof. You can visualize how the roof stops the car from bending in the middle. Now take the roof off. What will stop it? The doors, and that will cause the doors to get tight in the jams.

The other loads are twisting loads. Think of one hand at the Lrear corner, the other at the Rfront corner. Pull on one, push on the other. Your reinforcement will help a lot taking the place of the roof for that load.

Another one to stop is to keep the frame from "racking". With the hands in the smae positions, push forward on the rear and back on the front. One rail will try to move forward, the other back. That's what the "X" structure in the bottom is for, as well as aiding the frame rails from bowing in the first example.

From your drawing, my opinion would be that the windshield reinforcement is unnecessary, the firewall one is definitely a good idea, but the frame rail reinforcements would only address the bowing at the doors, and unless you're going to use some pretty heavy metal, not much of that.

Just my opinion, I'm trying to think this through along with you as I'm considering either a roadster or targa version for my next car.

John Stricker

Please, keep the opinions flowing! I want this to be a learning thread for everyone that is thinking of a convertible/targa/roadster project.

I agree with the X structure for the b-pillar reinforcement. Your visualization method helped immensely.

The reason for my thinking about the windshield reinforcement, would be for a rollover situation. You want something to hold the car up, I am putting roll bars behind each seat(a la Boxster) though, so this would probably scratch the windshield reinforcement idea completely.

I'm still brainstorming on the frame rail bowing situation.

Keep the ideas coming,
Derek

There are some pictures @ http://www.kitcar.ca/yabbse/index.php?board=3;action=display;threadid=1414;start=45 of the frame re-enforcement people are doing for their 355 kits

For rollover, what you want to protect is the head. Keep the head intact and the paramedics have a great chance of fixing the rest.

To keep the head intact, the windshield isn't going to be much of a player. I don't think you can do much to that big, open, rectangular area that would allow it to support even partial weight of the car. Concentrate on keeping the head protected and no sharp edges at head, neck, or chest height.

While your thoughts about the rollover on the front are good, in many cases it's just not practical to do. The only way to make it work, seems to me, would be to have a cage that's braced back to the rollbar. There's just not much of a way to make a convertible as safe in rollover as a fixed top, it's just one of those trade-offs.

John Stricker

quote Originally posted by Street&Strip Performance: Please, keep the opinions flowing! I want this to be a learning thread for everyone that is thinking of a convertible/targa/roadster project. I agree with the X structure for the b-pillar reinforcement. Your visualization method helped immensely. The reason for my thinking about the windshield reinforcement, would be for a rollover situation. You want something to hold the car up, I am putting roll bars behind each seat(a la Boxster) though, so this would probably scratch the windshield reinforcement idea completely. I'm still brainstorming on the frame rail bowing situation. Keep the ideas coming, Derek

http://www.home.earthlink.net/~oib/automoda_buildup.jpg

Just in case you wanted some visual aids for the project.

I think your design is good. You cant do much about twist (cowl shake), so the key is to keep it from bowing in the middle. Nice good square tubing... or round I guess if you can figure out how to weld it to the pinchweld, will be perfect. As for the firewall brace, it is a good idea. My top had a heavy beam at the bottom that solved that for me, so I didnt need to do it. But for sure put something across the top, and perhaps a couple diagonals if you feel the need.

Its technically not that hard. But it involves a lot of annoying overhead-welding ;o)

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87 Quad 4 HO convertible

Just to let you know, this post stems from ignorance on this subject . I always thought that factory convertbles had reinforced winshield frames for the purpose of rollover protection. Wouldn't it be possible to provide some sort of protection in that area?

no... just put "oh $hit" bars near the passenger door so you can lean over and hang on if you start rolling to get your head and body under the edge of the doors. That's all ya need to do. Besides... it's a fiero... like the thing would roll.

yes... i'm kidding by the way

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AIM: phool88fiero

The plan for my top is to be removable completely. It won't fold down, it'll be more like a hardtop with a removable center piece(like Chris Moore's Northstar convert).

For the rocker reinforce bars. Open up the ends of the rocker channel. Inside the wheel wells and run the new tub through the channel welded on the ends. Alot less work and way cleaner installation.

Does anyone have good pictures of a bare chassis?

Looking for side, front, empty engine bay, gutted interior, and a bottom view if possible.

Thanks in advance

The Fiero gets much of it's strength from the wide support that runs from behind the seat up behind the sail panels. The area near the door hinges is another area of strength. That area runs up the side of the windshield and the whole package it "tied" together by the roof's supports. Imagine a shoe box, with lid. Cut side holes for doors. It's still fairly strong, until you remove the top. Then the center sags and the top of both ends come together.
With the Fiero, you need a way to keep not only the floor flad, but to keep the dash and rear firewall apart. I think that support next to the gas tank will support the floor, however, there won't be anything stopping the twisting and not much to stop the dash from bending towards the firewall.
A retangular tube, running along the rocker panel area with the front bent in and up to bolt to the front suspension cross member, with the rear of the tube welded to a steel piece that follows up along the factory supports. Then, just like the frames on cars 30 years ago, a cross member to reduce twisting.
I think having the rear piece run up at least a foot up the space frame is critical to insuring the doors will stay latched when you hit a bump or go around a corner hard.
Scrimp and you'll have to go back and try to tack onto a poor design. Do it right and drive with pride.
Easiest way to design would be to have a junker you could roll onto it's top. Cut and weld together, drill holes, etc. Then remove and add to your future convertable.

I can confirm jstricker's post about the torsional flex of the Fiero when the B-pillar support structure is removed. I just bought a convertible Fiero for my wife and it does NOT have sufficient frame re-inforcement. Driving over railway tracks, or around a bumpy corner, produces noticble movement around the door opening. The best way to describe it is like the whole door rattles even though I know it is the chassis moving. It seems to me that this torsional force is transferred through the latch until the impact beam in the door counters it. In effect the door itself becomes a much more critical point in the structural integrity of the chassis. Since the hinges and latch are not solid points, like in a welded cage, it permits entirely too much flex.

We're driving the car for the summer but it will be coming apart this winter to get this corected.

I've been looking at the 'how to' of reinforcing the frame and come up with the following. I plan to box weld the centre tunnel with 1" stock, creating a much stronger central I beam through the middle of the car. Cross bracing both the front and rear will connect to a 2" square stock rail that will replace a section underneath the door sill.

If you're really worried about a rollover in a Fiero you might consider those little double bump roll bars that just go over the headrests. They can handle the impact much better than the angled windshield and give you a few more inches of noggin space if the car ever does end up completly upside down.

David

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His Fiero: 1984 2M4 Coupe

Her Fiero: 1984 2M4 Convertible

quote Originally posted by peabody: The Fiero gets much of it's strength from the wide support that runs from behind the seat up behind the sail panels. The area near the door hinges is another area of strength. That area runs up the side of the windshield and the whole package it "tied" together by the roof's supports. Imagine a shoe box, with lid. Cut side holes for doors. It's still fairly strong, until you remove the top. Then the center sags and the top of both ends come together. With the Fiero, you need a way to keep not only the floor flad, but to keep the dash and rear firewall apart. I think that support next to the gas tank will support the floor, however, there won't be anything stopping the twisting and not much to stop the dash from bending towards the firewall. A retangular tube, running along the rocker panel area with the front bent in and up to bolt to the front suspension cross member, with the rear of the tube welded to a steel piece that follows up along the factory supports. Then, just like the frames on cars 30 years ago, a cross member to reduce twisting. I think having the rear piece run up at least a foot up the space frame is critical to insuring the doors will stay latched when you hit a bump or go around a corner hard. Scrimp and you'll have to go back and try to tack onto a poor design. Do it right and drive with pride. Easiest way to design would be to have a junker you could roll onto it's top. Cut and weld together, drill holes, etc. Then remove and add to your future convertable.

I wish I did have a junker to work with, but the junker is becoming the convertible. It's going to be a frame up restore and build. So there will be a lot of paper design and consulting with people that have done this type of work before.

Automoda: What is the thickness of square tube framing that you used for your x-frame? Do you know the weight?

I want to keep the weight down as much as possible without sacrificing safety. It looks like the reinforcing will take the place of the weight of the roof and then some.

Bump...

What is that in the road.... ?? A BUMP...LOL

Box the B-Pillar to the rear firewall. Box this area including a cap not just a gusset. Extremely stiffened my convertible. Mark