How much does T-Tops effect the structural integrity of the frame vs. the stock sunroof configuration? I'm trying to decide if I want to convert my 88 GT to T-Tops. I noticed that the frame has some minor flex to it with the stock sunroof configuration when pulling into a drive with a steep curb ... you can hear the sunroof squeak on the seal as things shift. Is there anything I can do short of a roll cage that would stiffen up the frame and eliminate this flex if I decide to go with the T-Tops?

By the way, this is a S. Carolina car with no rust on the frame at all but 120,000 miles of wear and tear.

The answer I'm looking for is "weld a couple braces here" or something to that effect. I plan on re-welding some of the factory seams to add some strength while I have the car apart.

Don

Not as much as with a firebird but enough to feel the difference. If you intend to just do street driving then your going to be fine but if you intend to do ANY racing, forget T-Tops. I took a turn on a highway...a HIGHWAY..a little to sharp once and ended up donig a complete 360 right there. Came out without a scratch but I am more careful behind the wheel of a T-Top car now.

All Fieros have the hole for the Sunroof. It is part of the standrd space frame. So sunroof cars do not flex anymore than non sunroof ones. What you hear in Sunroof cars is the glass rubbing on the weatherstripping as the frame flexes. The frame flexes on non sunroof you just don't hear it.

T-top cars flex more.

I can't believe with all the modifications that you guys come up with that no one has found a simple way to add some strength to the frame without adding a roll cage. (bump)

Yep, there are numerous ways to reinforce the subframe, if your going to install t-tops. Biggest question is whether you are going to do it yourself or have someone do it for you.

You could use an external x-frame-box, like Bill Welch brought to us. Look for the thread about the Dirty Rat, it has one, I believe.

You could use a 2x2 steel tube installed inside the rocker frames, kind of like many of the Ferrari builders use.

You could use a few sections of 3/8 sheet metal inside the cab. Look into Archie's long thread, I think there are some pics there.

Or you could just make sure your chassis is very well supported before begining your t-top install. If you prevent any sagging or spreading when you cut the roof side-rails out, you will be installing a structural member down the middle of the roof for the t-tops ( I assume ). At that point, you would have as much structure as any factory built t-top out there.

If you did any of these extra reinforcements, the materials wouldn't cost too much. Your investment would be in tools and time. If you farm out the work to a knowledgable Fiero shop, I've an idea your looking at a direct cost thats going to be very close to what a full blown choptop runs.

David Breeze

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Pantera Rebody Kits

quote Originally posted by opm2000: Yep, there are numerous ways to reinforce the subframe, if your going to install t-tops. Biggest question is whether you are going to do it yourself or have someone do it for you. You could use an external x-frame-box, like Bill Welch brought to us. Look for the thread about the Dirty Rat, it has one, I believe. You could use a 2x2 steel tube installed inside the rocker frames, kind of like many of the Ferrari builders use. You could use a few sections of 3/8 sheet metal inside the cab. Look into Archie's long thread, I think there are some pics there. Or you could just make sure your chassis is very well supported before begining your t-top install. If you prevent any sagging or spreading when you cut the roof side-rails out, you will be installing a structural member down the middle of the roof for the t-tops ( I assume ). At that point, you would have as much structure as any factory built t-top out there. If you did any of these extra reinforcements, the materials wouldn't cost too much. Your investment would be in tools and time. If you farm out the work to a knowledgable Fiero shop, I've an idea your looking at a direct cost thats going to be very close to what a full blown choptop runs. David Breeze

That's what I'm looking for....thanks!

I plan on doing it myself. I have a mig welder and access to materials, the car is being disassembled to the point where these kind of modifcations are easy, and I have the skills and patience to do this type of work.

I was looking at several of the convertable threads and kind of liked the 2X2 tubes in the rocker frames. I thought there might be some small inconspicuous braces that could be added to the passenger compartment to enhance the structural integrity without effecting cosmetics or passenger comfort. I'm 6'2"/220lbs and have driven in a Fiero with a full roll cage and didn't like the passenger discomfort. It was OK for the 5'10" owner. Besides, I don't plan on racing it, just want to eliminate the flex of the stock frame design.

I'll look into your suggestions. For now the 2X2 square tubing and some cabin enhancements are my goal.

Don

try:

http://www.kitcarsforum.com/index.php?PHPSESSID=954f0a9a03f00917c95806eb3a5515e4&topic=6224.0

That might get you started.

Then do a serch in the tech section of that forum under "bracing" or "stretch", you will turn up loads of ideas.

Running a 1/8" x 2" square steel tube inside the rocker panels, and tacking onto either the front wheelwell or rear firewall does wonders. You can easily join the two sides by running another just under the rear firewall. Fishplating either 1/4" or 3/16" plating along the fueltank tunnel and upwards onto the rear firewall, and doing the same thing just aft of the door, going from floor to window height and bridging the space between the door and rear firewall.....does even more.

David Breeze

I may be way off base here, but aren't most of those fixes designed with convertibles and targas in mind? It seems to me like the goal there is mostly to keep the car from flexing front to back which would cause it to sag in the middle. The H-frame for the t-tops is just as strong as the stock roof in that respect and doesn't leave much room for the car to sag. It has been my understanding that the problem with the t-top conversion is that it replaces the two outboard structural roof members with a single central member. This makes it easier for the chassis to actually twist around the longitudinal centerline. Aside from maybe the x-brace, I can't think of anyplace you could reasonably weld something in that would fix this flex while keeping the stock appearance and cabin configuration.

That point is well taken.

That's why I originally suggested that once installed, the t-top should provide the basic reinforcement needed.

But, if your 220 lbs and drive like your 22, you might want a bit more rigidity.

Personally, I'd go for the addition of the rocker panel inserts, tied together by a single bar across the bottom of the firewall. There's plenty of room. In my mind, that would lend both front-rear flex reinforcement, and racking or twisting reinforcement.

David Breeze