This is why you should have subframe connectors...

[GoodysGotaCuda]

The front fender is doing the most flexing in that clip. The factory put a brace from the center of the wheel opening, back to where the fender mounts to the inner fender. That brace was probably cut out for tire clearance. That's the main reason for that flex IMO. If that brace was still attached, the fender wouldn't move like that.

Nope, it's stiffer than stock there.

https://www.engineswapdepot.com/?p=12467

[Brads70]

The front fender is doing the most flexing in that clip. The factory put a brace from the center of the wheel opening, back to where the fender mounts to the inner fender. That brace was probably cut out for tire clearance. That's the main reason for that flex IMO. If that brace was still attached, the fender wouldn't move like that.

Nope, it's stiffer than stock there.

https://www.engineswapdepot.com/?p=12467

I wonder who's k-frame replacement they are using? On my k-frame project I needed to lengthen the rack to get bump steer right not shorten it like they said?  (Depends on lower control arm length)

[Burdar]

That's not the brace I'm talking about. That's the inner fender to cowl brace.

There is a brace on the fender itself that supports the wheel opening. Without that brace, the fender is going to be all floppy like the video.

[Brads70]

That's not the brace I'm talking about. That's the inner fender to cowl brace.

There is a brace on the fender itself that supports the wheel opening. Without that brace, the fender is going to be all floppy like the video.

If it's one I think your referring to I think Cuda's didn't have it, only Challengers as I recall? I could be wrong though?

[GoodysGotaCuda]

That's not the brace I'm talking about. That's the inner fender to cowl brace.

There is a brace on the fender itself that supports the wheel opening. Without that brace, the fender is going to be all floppy like the video.

If it's one I think your referring to I think Cuda's didn't have it, only Challengers as I recall? I could be wrong though?

Correct.

[HP2]

The most non-obstrusive way to stiffen the body without adding any significant material/weight is to stitch weld all the seams on the main uni-body structure. This single change can increase all around stiffness of a uni-body chassis up to 30% over stock. This is such a significant increase, that SCCA forbids the modification to all stock class cars. However, it is a very time consuming mod and there is absolutely no way to perform it on a completed/painted car. Think of it this way, the spot welds on the factory car are like holding all your clothes together with buttons. What is the difference in stitching compared to spotting in that regard?

Sub frame connectors were developed in the drag racing world to resist beaming motion, or the longitudal bending of the car that is produced by a drag launch. however, since our cars are so flexible anyway, adding these do produce a very decent increase in rigidity all around. IMO, this should be done to every vintage mopar from slant six to hemi. It improves the door sealing, window sealing, wind whistles, panel gaps, everything.

Torque boxes were a factory solution to address similar deficiencies fixed by SFC. The boxes tie in the major sub frame structures to the door sills, which is a very tall structural member. Think of the door sill as a floor joist in you house. Do you want joists that are 8" tall or 12" tall and which allows more floor flex when you walk on them?

XV did the most modern research on structural rigidity of a street oriented mopar.  Their program of core support tube, inner and cross fender braces, and sub-frame connectors created the highest return on rigidity increase over weight increase and ease of modification. Certainly you can go beyond this, but then you would want to more closely examine your intended application, rules, cost, and effort.

Nascar white papers have shown that even in competition cars with extensive cage structures, the greatest stress and need for most rigidity originates right at the  heart of the car in the whole cowl and A pillar area. Which would also tie in well to the research done by XV with their inner fender tie ins and structural bracing to the cowl.

[FSHTAIL]

Heyyyyyy
Stole my cars name. 

Sent from my SGH-M919 using Tapatalk

[Marc70challenger]

Roll bars or cages aren't really a good idea for primarily street cars. If you get tossed around - even from a small collision at less than 20 mph, cracking your head on a bar could be bad news.

You can add noodles and such, but not really sufficient at any decent speed ... more for hitting your head getting in and out.  And the SFI roll bar wraps are made for use with helmets. Won't do much for open skulls.

For our Barracuda we took great care in measuring distances, etc so on street, snugged in real good, we can minimize the exposure. Won't hit top bar and will take lot to get to side bar.  But we had lots of room dropping the seats.   But if it were a cruiser .... it would suck driving like that all the time.

[HP2]

The issue with roll cages is not that they are harder than the structural steel of the car itself, but rather the typical cage installation is removed enough from the car's structure to allow full welding around the joints that their use can significantly reduce room within the cab. If you have seen  crash videos showing how much a body moves around inside a car during an impact, even when belted, the loss of 3-4 inches of space around your head can have deadly results.

In a competition car you do have padding on the bars as well as a helmet, but there also are 4, 5, or 6 point harnesses holding you  in place and in many cases, head, neck, and arm restraints that are designed to minimize the driver's body from moving much from their seat. The goal here is to reduce  body movement rather than pad it against the impact.

If your willing to remove the roof structure and integrate/embed the cage structure into the unibody of the car' itself, then you could have the best of both worlds.

[Burdar]

I didn't know that Cudas didn't have that brace.  It's obvious that the car in question need one though.  He probably doesn't want to add the weight but undercoating the inside of that fender would add a lot of rigidity to it.

[HP_Cuda]

Its fairly obvious that the car in question is not a street car.

[EB3-GranCoupe]