FF3931, do you find that you lose any rigidity by using the smaller tubing that doesn't intrude on the floorpans at all? I've done a couple of sets, particularly one on a friend's Demon, where the floor was notched... not as attractive as yours from an interior standpoint, but they were welded to the floor for about 15", and the rear anchor area laid inside the frame rail by about 6". They were the most effective frame ties I've seen so far--using a bumper jack would get 3 tires off the ground. [smilie=e: I've never done a low-profile set like that... but then again, nothing I've done was caged, either. Maybe it's just more important to use larger tubing (and more tie-in) with a car that's not going to be caged... thoughts?[/quote]
Jass, i looked at a lot of options and the weld in (floorpan)style was one of them. The frames/floorpans are very solid on this car...it was pretty stiff before the connecters went in. I guess we could have gusseted the connecters to the floorpans but that seemed un-necessary given that a cage was going in. The 45* downbars coming off the main hoop are welded into the frame connecters, which are welded front and back to their respective subframes....
The front and rear bars are also attached to the subframes, so this thing is really tied in (tiangulated) together. There is no welding to the floorpans....everything is bolted in with plates. Welding in the baseplates actually weakens the floorpan area and the plates don't need to be welded as per the rules. In fact, up until recently, the bars had to be bolted in, but the nhra is allowing them to be welded in now.
My buddy in Detroit has a 69rt/se with a 496 e-head stroker and the same frame connecters as mine (welded in/non gusseted). I've been in his car and it's really stiff, and there's no cage (or SF gusseting) either. You can jack it up on the frame in front of the rear wheel and the front tire rises just as much as the rear....no sag ! I guess it just depends on the application, but after numerous talks with the chassis guy, we concluded that the weld in option wasn't the best route to go. He's seen some torn floorpans what had stuff welded in...the problem becomes more pronounced when the car hooks and is making good power....the sheetmetal floorpans just aren't that strong...
If you're just looking to stiffen up a weak chassis, welding into the floorpans might be the best way to go. If the car was a rattlebox before, that kind of mod could only show a huge improvement. For racing, i'm not convinced that welding the frame connecters to the pans is the right way to go....the chassis guy convinced me not to.
My take on it is that if i were building a driver that wasn't going to be raced, the frame connecters welded front and back and gusseted to the floors....is what i'd do. This would be a car with no cage either...and one that i didn't intend to run slicks on.
The current chassis setup on mine is probably overkill for a 540hp 446, but this won't be the last motor going into the car. I've got a spare block and mp 4.15 stroker crank sitting on the shelf, so a 493 is in the works. Along those lines, i've got a dana60 on order as well which we'll be installing in preperation for the next motor....i allways try to plan for the future because i hate doing and paying for things twice...don't we all !! [smilie=e:
Ron
