How much stiffer with solid or tied in roof? Options

[Mueller]

New car has no cage, I know the 914 tends to flex and that the factory welded steel roofs on the 916 for what I guess was to help stiffen them, or was it for other reasons??

The 'glass top should help a little, but I was wondering about attaching tubes or the like from the factory roll bar to the windshield hoop to stiffen the car up....

Has anyone played with this before??

[TravisNeff]

Thanks Brett, that illustrates a lot. Was starting to dawn on me what you were talking about, with the open box cavities of the trunks (and trunk sub sections), but was not sure if you meant "box" as in the imaginary box that runs side to side between axles and fore/aft beteen the front and rear axles.

For the lower tunnel (dunno what to call it) where the steering rack goes, I guess you could make a bolt in panel with some beef (16 guage) and use a brake to make 90degree bends on the perimiter and weld them up (so it would look like a shoe box lid upside down. to give it more spine you could do rectangular stock or strap running front to back or in an X that becomes the mounting boss for the attachment bolts.

With the Engman kit, you could run some flat stock triangles (like 2-3" triangles) to gusset the outer corners to the longs/floor, inner corners to the tunnel/floor, stitch weld the tunnel to the floor, as well as the seat mount U channels, gusset the front facing corners on the floor, and the rear facing corners at the top of the tunnel to seat channel/top of the seat channel to long. Could probably even do a gusset at the rear corners at the top edge of the kit as well without any problems with the rear upholstery panel. Stitch weld the tunnel to the floor, as well as the seat adjuster channel, gusset that at the top (rather than the floor, since no one will see it, or wont get in the way). Bracing/reinforcing the seat channel to the longs/tunnel is right close to the weak spot in the cockpit, could even do flat bar stock on the floor in the side to side stamps at that crtical point, welding that to the long to tunnel and stitch along the floor. It would seem that you would need and X there to really get some strength, but that could be intrusive or very evident looking at the carpet (unless you have backing pad on your carpet that you could cut out the X so it lays smooth.

Maybe run 18 guage steel across the front gastank firewall and wrap the wheelwells to finish the box structure of the Engman kit (as well as a kickout to mount along the floor surrounding the pedal mounts. this would be double duty, one tying the front sections of the "U" to make a box of that Kit, then also reinforce the MC mount, and kickout to reinforce the pedal box mount (mine is super flexy). run spaced out stitch welds along the top and bottom of the engman kit, and stictch the tunnel to the kit. for the sake of giggles a heavier guage plate could be welded to the fore/aft ending sections of the tunnel to the firewalls (whether it is done in the gastank or engine compartment side, or inside the cabin - I dunno). and of course stitch weld the structure panels (upper to lower firewall, trunk, etc.)

The lower brace for the Suspension console is a given, I am up in the air about the top of the firewall to the shock mounts, I am trying to think of a way that those fore/aft tubes can run out of sight and out of the way. Along the upper firewall with rectangular stock doesn't bother me too much, but I would think you would need to ditch the battery location for the fore/aft tubes, or run them more inward getting in the way of working on the engine.

I have to figure out what parts to fab for the suspension console, inner scab plates, straps (like Brants' setup) the outer portion of the suspension consoles and whatever else makes sense (and someone may recomend). what about welding some sheet metal at the bottom of the suspension console to complete the box there? Could go so far as cut out the cover plate of the rear frame rail, weld a panel over the long (like the factory kit), butt weld the cover plate back on and grind down the welds so it'd be stealthy.

I will do the windshield frame reinforcement, what about changing the style of a rectangular piece, to an L, going along the windshield frame/door frame, and then inward on the inside of the cowl a touch. From Eric's photos, what about a sheet metal plate on the underside of the cowl corners on the trunk side? Just another thought.

I am going to drill out the spot welds on the front facing rear trunk panel, weld/reinforce the long to the shock mount (maybe an L piece on each side), could even (if there is room) to run a tube from long to long (maybe overkill to tie the shock towers together, but I would guess the longs could use the help. then weld the panel back over, so you wouldn't see it.

I have to weld in a front trunk floor to patch the A/C cutout, the trunk floor is very flimsy with this huge chunk gone. What about a bar to tie the front torsion bar mounts?

Like I said, just got my welder and I am finding all sorts of stuff to do, that of course will be very much overkill for what I need. But hell, it's gonna be a fun project. and I wanna throw out some ideas and have someone say, good, or your stoopid. And hopefully not have the car weight 3k when I get done, weld too much and mess up the chassis regardless of bracing while welding or whatever. Just trying to get some good ideas to ponder or try.

I am sure someone is going to ask, what are you planning on doing to your car, race, street etc. Probably HD street and some autocross, don't care about class placement right now since I will start from the ground up. All I know is I am gonna start welding, fixing the bad stuff, reinforce the problem spots, and maybe try something new along the way. mostly street I guess, it has ugpraded 150lb springs (at the moment), 22mm t-bars and koni sport shocks w/adjustable perches. No swaybar, yet - but that is coming.