Ok. Here is a wild thought................... My autocross car is a gutted out 88 Formula that has been a work in progress for the last 8 years. I have it down in weight about as much as possible right now (2250#) Thinking about welding up the doors in there openings and cutting the roof off to make it a roadster. If I were to fully weld up the doors do you guys think it would be structurally sound enough to cut the roof. In my mind it should be OK but my mind is a bit different than everybody else's. Remember... this is just a thought now. How much does the roof structure actually weigh? I have a roll bar in it now and would need to keep it.
The top of a fiero weighs very little. We cut the top off of our chumpcar and tied the a pullers into the strut towers with the cage. After removing the top I estimate it only weighs 15 pounds. We never weighed it but it's a very light structure. Like mentioned before removing or gutting the doors will provide much more weight savings.
On a related note a fiero roadster would be tons of fun and make a great auto cross car. I would cut the too and remove the doors and build a structure to tie the space frame together in place of the doors and hang the bare door skin on that.
I cut the top off a parts car as I was scrapping it. I would guess it was closer to 25 lbs...but I was just lifting the metal structure. If you were turning it into a roadster, you would also be losing the back glass and sail panels. Might want to check into the rules for where you want to run the car....most will only allow a topless car if it has a roll cage, and that would likely weigh more than the roof.
The rules allow a roadster as long as the roll bar is 2" above the driver's helmet. Doors are optional too but would require side bars/cage. For track days a full fire suit would be required as well (20#)
I just sent you a PM. The roof structure weighs 25 lb without the sunroof and rear glass.
With regard to welding the door in place, I think it would certainly stiffen up the chassis. However, since the door structure really doesn't touch the chassis except at the striker plate and hinges, you'd have to span the distance with some extra metal I guess. Unless you let the hinges go and push the door tight into the frame. I've never seen how they weld doors shut but I'm guessing there is a specific technique. Best of luck. I hope you post details on how you do it.
You'd end up with a heavier car due to adding the roll bar that would be required to autocross a topless car, adding bridging metal to weld the door structure to the frame, and adding the extra unplanned reinforcements to the chassis to keep the thing safe to autocross in.
Not a good idea from any angle, IMHO. You'll end up with a heavier and weaker/less safe autocross car, even if they'd allow you to use it as such after your changes.
------------------ Patrick W. Heinske -- LZeitgeist@aol.com
1988 Fiero Formula - Automoda convertible repainted PPG Ferrari 'Giallo Modena' yellow
Wouldn't save much weight, but it would keep the air clean for your wing, like this:
I've seen several DP Miata's with the windshield cut off to keep the air clean, but in their case it's to keep the air cleaner for their spoilers. DP cars aren't allowed to run wings.
It wouldn't save much weight in my case, since the front windshield is already Lexan, but any weight saved up high would lower the cg, even if you added the weight back bracing the car at a lower point.
I just re-read the original post and the OP said he already has a roll bar. I think the rules only require a roll bar in a convertible, not a full cage. I would think adding a longitudinal brace like in the Fiat would stiffen the chassis, especially if you added bracing in the doors. But I'm not an engineer..
[This message has been edited by bse53 (edited 11-09-2013).]
Ok. Here is a wild thought................... My autocross car is a gutted out 88 Formula that has been a work in progress for the last 8 years. I have it down in weight about as much as possible right now (2250#) Thinking about welding up the doors in there openings and cutting the roof off to make it a roadster. If I were to fully weld up the doors do you guys think it would be structurally sound enough to cut the roof. In my mind it should be OK but my mind is a bit different than everybody else's. Remember... this is just a thought now. How much does the roof structure actually weigh? I have a roll bar in it now and would need to keep it.
There is a LOT on the Fiero that you can remove. I don't know what all you've removed, but depending on your class, you may be required to keep a lot of that.
That said, the roof is pretty important to keep the vehicle rigid. I'd totally cut the doors, I mean completely, even cut out the metal around the inside of the doors... remove the locks, glass, everything.
You can pretty much remove 80% of the crap up front too under the hood except the braking stuff. If you don't need windshield wipers, remove all that stuff. You don't need an overflow tank, at least not one that big. Any A/C stuff left? Get rid of all of that too.
Guys, The car is totaly gutted now. Everything has been removed, even most of the wire harness. The car weighs 2250# now. Lexan windshield no other glass. The only thing I haven't removed yet is the front bumper beam and will be taking that out this winter. Looking for another 100# if possible. Have a passenger seat (aluminum race type with harness) that will be coming out too.
Doors may be lightened and may be replaced by ones of alternate materials. Doors may be pinned, but not bolted, to prevent their opening in case of an accident. Quick release fasteners (e.g. Dzus fasteners) are allowed. Standard door hinges and latch mechanisms may be removed, but the doors shall be capable of being opened or removed. Interior door panels may be removed or replaced and the door window slots may be covered.
Nice looking car. Your class minimum is 2100 lbs, right? I wonder if you could just pin the fiberglass skin to the car and remove the door structure.
My car is also about 2250#. Minimum weight in XP is 2100 lbs with a 5 liter engine. Getting that last 100-150 lbs is pretty hard without possibly weakening the space frame integrity.
Have you done anything to address the front geometry. As far as I can tell, the upper A arm adjustment affects both caster and camber, and if you want one, you can't have the other. I've thought about deepening the slots, which should allow more static negative camber while retaining some caster. That and fabbing some new upper A arms and moving the upper ball joint back about 1". From what I've read, I would like about 6-6.5% caster and 1.5-2 degrees static negative camber.
Actually I have redesigned the front suspension and built a adjustable coil over set up as well as set the camber @ -2 deg, caster @ 6 deg. ( I like it a bit heavy) toe is zero (I like is at that setting had 1/16" toe in each side but was a bit twitchy). While we do use SCCA classing here we are a non affiliated, non mark club and minimum weight is not a factor for F Prepared. Rear deck has been lightened and cut. front hood has been lightened as well and all hardware removed (hood pins). Have removed my rear Lezan window since the picture was taken. The scoop only weighs about 1 # but keeps the rain out of the custom intake setup.
Hi mcguiver3, I was cleaning up the shop this afternoon and found the other portion of the roof structure I had removed. It was 5 lbs so a total structure weight of 30 lbs for the roof. This left a couple inches of metal across the top of the windshield.
I took the door off and without the skin, but with the interior panel, it weighs 28 lbs. I will be pretty easy to make a bracket for hinges directly to the door skin, and a pin arrangement to hold the door closed. Should save about 50 lbs total, without affecting the structural integrity of the car.
If it's just an autocross car I think I'd weld a 1 1/2" bar across the top of the door openings & attach the skin with dzus fasteners. Then cut off the roof, removing as much as possible of the inner part of the rear roof (& put it back on). Leave the little triangles above the front of the doors & cut the windshield at the top of those so you'll have a little windscreen for looks. Should save you 80 or more lbs. ~ Paul aka "Tha Driver"
