... even if it is not factory correct.
Skip forward to 18:14. Notice how nothing on the car is sitting still? Doors, quarters, deck lid, everything shakes.
I don't remember if they put subframe connectors on it, but they did add some stiffening to the front end.
Edit: Just watched the first episode again and they did put a level 2 US Car tools stiffening kit on it. So what does one have to do to get the chassis even stiffer?
That's probably due to the body being so stiff all that vibration and flexing has to go thru something. I'm no structural engineer but remember the sheet metal on these's cars are not that thick.
Lots of things can be done in genreally to stiffen a car...strut brace front and rear, weld-in-cage, glueing sheetmetal, extra-spotwelds, glue-in rear/front window...just depends on how far you wanna take it.
Most common on Mopars for sure are subframe-connectors and torque-boxes.
I like that Fishtail-Cuda in that TV-show, but keep in mind that they also run tires with a very sticky tread and that are really wide...so getting these rear-tires spinning as at 18min14sec on the vid also causes much more stress to the cars body then getting to spin some stock 14" bias-ply tires with a width of a pizza-cutting wheel. :alan2cents:
I really like it as well. I just thought that all that flexing in the quarters were an effect of a non-stiff chassis. I realize that putting super sticky tires on these cars will break something, unless care is taken. I didn't realize it was an effect of too stiff chassis.
I wonder if they used polyurethane bushings for motor/trans/diff mounts? Those things are nearly as hard as plastic, so they transfer a lot of the vibration from moving parts into the chassis.
I'll bet some softer (but still good quality) mounts would reduce vibration into the body of the car.
Quote from: Tunis on August 14, 2017, 11:10:05 PM
... even if it is not factory correct.
Skip forward to 18:14. Notice how nothing on the car is sitting still? Doors, quarters, deck lid, everything shakes.
I don't remember if they put subframe connectors on it, but they did add some stiffening to the front end.
Edit: Just watched the first episode again and they did put a level 2 US Car tools stiffening kit on it. So what does one have to do to get the chassis even stiffer?
It needs a cage, really.
I have a US car kit and can feel the doors bind when the car is on different height jack stands still. It's better, but it's not a BMW by any means.
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They would need to add a full cage with front and rear hoops to take the flex out of it. With these cars the entire unibody acts like a big torsion bar. That's why I've said unless you add in torque boxes, subframe connectors etc.... adding heavy sway bars is pretty much wasting your time. The whole car is a torsion bar. Eliminating flex somewhere will just add it somewhere else and stuff will break , crack, fail. It just the nature of the beast. Want to scare your self, jack up your car and notice how much it flexes before tires come off the ground.
I can pretty much bet with great certainty that they will be constantly welding up broken mounts, floorboards etc.... on this car until they add in a full cage.
Those little tabs they made for the sway bar is not adequate in my opinion. It needs to be gusseted into the entire chassis . It will break there at some point. Same with the k-frame.....too lightweight
As mentioned tires make a big difference. 99% of us are used to BFG T/a's which are really poor tires from a performance perspective. 25 years ago they were cool but not now. One good thing about them is your less likely to break something else due to poor grip. Biggest difference I noticed going to 315/30/18 up front was braking. Tires take much longer to lock up. At first I thought something was wrong with my brakes, but it was the wider sticky tires that changed braking performance.
Cool, thanks for your input guys! I have so much to learn, but that's fun and getting input from people that know what they are talking about is great! I think that adding subframe connectors is the simplest way to keep the unibody from cracking in the roof-quarter seam without going all out cage. But I somehow expected it to be better with less flexing. So I'm I correct that go full cage that tie each corner of the car together is the only way to stiffen up the chassis enough so that it will not flex at all?
Per
Quote from: Tunis on August 15, 2017, 08:18:58 AM
Cool, thanks for your input guys! I have so much to learn, but that's fun and getting input from people that know what they are talking about is great! I think that adding subframe connectors is the simplest way to keep the unibody from cracking in the roof-quarter seam without going all out cage. But I somehow expected it to be better with less flexing. So I'm I correct that go full cage that tie each corner of the car together is the only way to stiffen up the chassis enough so that it will not flex at all?
How are you going to use your car? All out race, road course, drifting? If you are just going to be street with maybe some strip time then subframe connectors are plenty, maybe add in a rad support. I added subframes on all of my cars and it made a huge difference.
If you are all out race, then add a cage. My point is a cage is overkill unless you really need it.
Maybe the flex in the front clip is because the k frame wasn't welded? I have a 6pt Wolfe cage in my other car. Definatly noticed better cornering now.
Funny how the front end shakes like it's a lift off fiberglass front end.
This thing definitely needs a cage for what they are doing, it's like going halfway on something.
Quote from: HP_Cuda on August 15, 2017, 09:18:45 AM
This thing definitely needs a cage for what they are doing, it's like going halfway on something.
I saw the car at SEMA and it was quite underwhelming...
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I'd say unless you have a valuable collector E-Body then adding in subframe connectors is a great idea . I built my own and it literally cost maybe $20 in materials.
I will use my car for normal street driving. I'm just afraid that I will torque-twist the poor thing without the subframe connectors. But I guess that is most unlikely unless it hooks really good, which it probably won't with street tires on a 15" rim.. I will add torque-boxes and I have started to fabricate some subframe connectors, just wanted to know if they add that much to the chassis before I weld them in. It has front and rear torque boxes. In either way, subframe connectors that are welded in place are not there forever. Heck, I replaced a few panels on my car, I think I can cut and grind them off if I wanted to, in the future.
QuoteFunny how the front end shakes like it's a lift off fiberglass front end.
This thing definitely needs a cage for what they are doing, it's like going halfway on something.
I know, the whole fender and hood area just rattles, same with the door. Makes me think that maybe they didn't have the most sound unibody to begin with. But what do I know, I'm still learning a lot. What about you guys dead hooking these cars without a cage on a drag strip. Does it shake like that in slow motion?
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.
Quote from: Burdar on August 15, 2017, 04:02:19 PM
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
Quote from: GoodysGotaCuda on August 15, 2017, 04:08:11 PM
Quote from: Burdar on August 15, 2017, 04:02:19 PM
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)
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.
Quote from: Burdar on August 15, 2017, 04:28:55 PM
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?
Quote from: Brads70 on August 15, 2017, 04:35:39 PM
Quote from: Burdar on August 15, 2017, 04:28:55 PM
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.
(https://forum.e-bodies.org/proxy.php?request=http%3A%2F%2Fwww.showcars-bodyparts.com%2Fchallenger72-74fender-inside-usedsteel.JPG&hash=154a6485484e0e49b5939f927897705985b05e72)
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.
Heyyyyyy
Stole my cars name. (https://uploads.tapatalk-cdn.com/20170817/c40b24a31ceae9950372069bd745bc9b.jpg)
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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.
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.
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.
Its fairly obvious that the car in question is not a street car.
:popcorn: