At 17, I was estatic to learn that my new/used car was a '93 Dodge Shadow ES ragtop. I’ve been in love with convertables ever since my aunt used to take me for rides in her Mustang. pauses for personal reverance
I love that car. Since then, I’ve ridden in a few other ragtops, and they all seem to share the same [unappealing] trait.
In the middle of the [tiny] back seat, there seems to be a strong metal wire/bar making a ‘hump’.
Is there any structural reason for this hump? I don’t recall seeing it in many other cars. My mechanic wasn’t up on his convert anatomy.
Anyone know if it would be possible to remove the ‘ass wedge’ (as my social circle affectionately refers to it)?
Seems a shame that only 2 can be seated comfortably back there. Plus I could get some shuteye on lunch.
I imagine it’s there to help hold the vehicle together and compensate for the lack of a roof doing that.
Convertables are usually heavier and have to be a whole lot more rigid than other cars because they lack a solid top keeping everything together. Otherwise they’d just kind of flop open.
WAG here: Maybe it’s there on purpose to make sure you only try to seat two in the back, for safety reasons. There are only two seat belts, right? And in a federal-seat-belt-standard sense, there may only BE room for two seat belts in the back, each seat belt requiring X number of inches wide. So the designers maybe put that hump there to discourage you from trying to rearrange the seat belt arrangements and retrofit a third seat belt (because of course you would never be so reckless as to try to seat three people in the back without seat belts. :eek: )
Is the car front or rear wheel drive? You may have a rear-wheel drive car here, and that hump is for the driveshaft. (And if it’s a sporty convertable, you’re better off with rear wheel drive. Better control.)
It’s a front-wheel drive. I thought of that too, and crawled underneath, but couldn’t find anything to suggest its origin.
Incidentally, it’s a verrry light car, even for a ragtop. The 'Stang is made from heavier steel and is quite a tank…but mine is so light that my weight is sometimes figured in when balancing…or so the last fellow said.
And yeah, I thought maybe 5 passengers may be a bit of a load for her, hence the ‘divider’. I just remember riding in a friend’s Durango, which had a bench seat about 4’ long that was supposed to be able to seat 3.
I’m pretty sure that first and foremost, the hump is for longitudinal reinforcement to help prevent the car from crumpling like an accordion in a front or rear collision. However, I have heard gearheads call it a “raceway,” which implies that it also serves as a conduit for various mechanical or electrical connections. There are a great many ways that it can be used.
One example is the Porsche 911, a rear-engine, rear-wheel drive car. To improve weight distribution, much of the transmission is in the front end of the car, as well as twin batteries on some models. The “hump” conceals both mechanical and electrical lines. Furthermore, since old 911s were oil-cooled, the oil lines were run from the engine to the front of the car and back to the sump, presumably through the protected hump.
The 911 Cabriolet, incidentally, picked up the extra structural reinforcement it needed by tubular reinforcements which ran through the perimeter of the passenger “tub,” including the doors. The convertible Cabrio actually had better body-roll characteristics than the Targa, which had a rear window but a removeable roof. Targas have a nasty habit of becoming “wallowers” over time because they don’t have the Cabrio’s extra reinforcement. They still have humps, of course.
Then there’s the Porsche 928, a front-engine, rear-wheel drive. Hump contains both a driveshaft and ducting for the rear air-conditioning system.
Virtually any car (not an SUV) is going to be low enough to the ground that its going to need a hump. It lowers the center of gravity, and protects the driveshaft or other components that need to be run through it. This may be one reason why cars don’t need running boards any longer.
Without a true roof, the remaining frame of the convertible has more of a tendency to flex. The roof makes the car into more of a box, and that makes it stiffer.
All cars flex, but excessive flex in convertibles leads to poor handling, loose stability, and the classic convertible door that doesn’t open, or is very difficult to open/close.
So, look under convertibles and you’ll notice various supports added to stiffen the frame. From the outside, they are very noticable running wheel well to wheel well on cars like Chevy Cavalier Convertible, but might be less noticable on other cars from the outside.
Some cars have extra supports that run front to back as well as side to side.
Some cars which are designed to be convertibles right from the start (Porsche Boxster), have a rigid frame designed in, so you might not see noticable supports.
I doubt it has anything to do with structural rigidity. The “seat” itself isn’t going to make a damn bit (or at best extremely little) of difference. However, if you took out the seat and saw that the floorpan was renforced under there I wouldn’t bet against it then.
I think the most logical reason would be that most back seats on smaller/compact cars (which yours belongs too) is made to seat 4 more comfortably than 5. So, since it is likely a better idea to have 4 people in comfort (2 front and 2 back) and 1 in discomfort than 2 in comfort (front seats) and 3 uncomfortable (all in the back).
My guess.
Another thing I just thought of, it could just be a simple “style” thing as well to make the car “appear” to be a Rear wheel drive.
Hey thanks, Sofa and Phil…I don’t think I could have come up with that in a week of research.
I know a lot of people who’ll be intrigued with these findings.
~A
Nope. The Mustang (at least until about 1970) was an extremely light vehicle. The ragtops were made from the same body and frame design as the hardtop. Unfortunately, without the hardtop, the Mustangs were too light and had little reinforcement to prevent twisting of the frame. Ford added extra metal to the undercarriage to provide stiffening. If the plates were not there, you could probably tear the car apart just by driving it. Even with the reinforcement, the cars still flexed seriously. If I still had my old 65 Mustang GT convertible, I’d take you for a drive and show you the body flexing with a yardstick.
Anyway, heavier vs. lighter has nothing to do with it. The old Mustangs were body-on-frame construction, and all modern cars are unibody construction with no frame.
Trust me dude, it’s heavy. I may not be a wiz with the internal workings, but I can push my car out of the mud much easier than that. She takes either 3 strong men, or one strong man and a tractor. (don’t ask). But it ~is~ a '72.
Usually I’m wary of strange men picking me up. But for a GT I guess I’d make an axception.
(And yes, Iawoot, I had a damnedably hard time wording the subject of this thread.) “Do I need a hump in the backseat?”
Having owned a 93 Shadow Convertible, the answer is twofold. First it is there for Structural Integrity. This keeps the rear part of the car strong enough to be as safe as the front. (Actually, speaking of the physics of it. With a Front wheel drive, the rear is pulled along. With The inertia of the rear, technically, the car would stretch out. This hump moves the center of the forward motion more toward the front. Physicists and Auto designers can explain it better.)
Secondly, the hump is sort of a “pseudo Bucket Seat” That is it makes the rear seat sort of like the buckets in the front but still keeps a Bench Seat persona.
BTW, how in the heck do you get three people back there, it is, what, maybe three feet wide with about, oh, 2.5 inches of leg room.???
