[Shadow24V]

Ok, instead of hijacking the L-body picture thread again, id like to ask this question in its own thread. After seeing the pictures brent posted of a crumpled P-body and the 2-piece framerail it uses, what would be a good solution for a P-body?

a roll cage? if so, how would it be used to eliminate that buckling?

body/frame re-enforcing?

 

[Ondonti]

Does someone want to take pictures of the difference the P body has in lack of support from the drivers seat to the rear suspension? Someone with no snow lol.

Roll cages are nornally tied into the floor of the car but the P body has nothing of structural integrity where the cages bolts down because there is no underbody frame there.

Might be as simple as building a rail that fits over the existing one and extends farther to the back of the car so that you can tie your roll cages into something a bit stronger.

roll cages are something that usually should be left up to a fabricator who knows how to meet your racing associations rules (assuming you are not buying a kit).

 

[Turbo3.0]

If it's a full roll cage that ties into the front strut towers it might help significantly, but roll cages aren't usually a good idea for street driven cars for other safety reasons, aka head trauma.

 

[Turbo3.0]

Now that I think about it some more, a roll bar that has the main hoop tied into the B-pillars along with front support bars going down to the drivers feet might stiffen up that section quite a bit and is also a lot more street friendly than a full cage.

 

[Reaper1]

OK, this is a 1986 G-body. Notice that right at the rear of the door frame there is no cross structure on the floor pan. There is the rear front seat support toward the tunnel, but that's it. This is the least supported part of the structure. The ONLY thing that adds strength here is the rockers(hence why rusty rockers on these cars equals dangerous and death to the car). The front frame rails end right about where the front front seat braces are....about the middle of the door opening.

As for roll bars...the Autopower one that is in my '91 Daytona bolts to the floor directly above the rear jack points. The bolts under the car have thick washers on them too. That bar does not have the forward members like a 6-point, but it does have the rear members, a shoulder harness cross bar, and a diagonal cross bar.

Here's an A-body. Notice that where typically the door opening would be, there is a B-pillar instead. This will significantly increase torsional ridigity and overall body strength.

I'll see if I can get some P-body pictures, but they are going to look THE SAME!!!

 

[Ondonti]

I'll see if I can get some P-body pictures, but they are going to look THE SAME!!!

You are missing the point.
We are talking about the BOTTOM of the car. Thats not the bottom of the car. There is a frame rail on the underbody.

Looking at my spirit just now, the underbody framerail extends to the B pillar.

No B pillar in a 2 door P body so the car buckles at the end of the underbody framerail because the the chassis of the car is really weak between the rear of the doorframe and the end of the Framerail.

Thus why the 2 door p body collapses at the rear half of the door opening.

THe AA body does not extend the underbody framerail past the B pillar though and I thought it did.

 

[Ondonti]

Seems like an open and shut case to me

 

[Tim_K]

Some 1" or 1-1/2" box steel tubing welded to the underside of the floorpan / framerails would help. Extend the framerails so that they reach each other.

Also, putting some steel tubing inside the rocker panels from one end and then filling the rockers with some sort of expanding spray foam to keep the steel tubes in place and not rattling around would also help.

I think a couple modifications like that would make it a lot harder for the body to collapse in that area.

 

[Reaper1]

You failed to see my point. The floor pans are all the same for these cars. The frame rails all go the same length. You can see where the spot welds are for the frame rails on the floor pan. They all stop in the same place.

I've seen a LOT of wrecked EEK's in the yard...they typically don't have that kind of cabin intrusion. That wreck was at a pretty good clip, and as stated was against a much larger mass, so the other car had a lot more momentum and therefor transfered more energy to the P-body than if it had even just hit a wall.

I think we are seeing an instance that is not typical....

 

[90vntShadow]

The way I see it no matter what you drive it's going to cave at some point, if I hit any
small car head on with my 10,000lb Dodge Cummins something is going to buckle bad
I don't care what kind of frame rails you have.

 

[Ondonti]

You failed to see my point. The floor pans are all the same for these cars. The frame rails all go the same length. You can see where the spot welds are for the frame rails on the floor pan. They all stop in the same place.

I've seen a LOT of wrecked EEK's in the yard...they typically don't have that kind of cabin intrusion. That wreck was at a pretty good clip, and as stated was against a much larger mass, so the other car had a lot more momentum and therefor transfered more energy to the P-body than if it had even just hit a wall.

I think we are seeing an instance that is not typical....

I said I was incorrect about the frame rail length

But its pretty clear that this is a 2 door P body weakness. its not just a speed thing as a 4 door EEK probably would not have crumpled like that because the B pillar is sitting right there.

 

[dodgeshadowchik]

I know this thread has been idle for a while, but I inadvertently found this video last night and thought I'd share. It features a Dodge Spirit that was involved in a really bad crash. The video is actually about a weird photo that the lady belives is her guardian angel...as she believes she should not have survied that crash. Perhaps there's spirits within Spirits. lol! anyways, this car crumpled pretty bad.
Guardian Angel - Your Ghost Stories

 

[jmitch]

damn and thats the "stronger" four door. lucky woman

 

[jimduchek]

Can anyone say what they did for the p-body convertibles? There must have been some extra stiffening of the undercarriage in that region .

Jim

 

[jory]

Can anyone say what they did for the p-body convertibles? There must have been some extra stiffening of the undercarriage in that region .

Jim

Not as much as you would think.

 

[Ondonti]

damn and thats the "stronger" four door. lucky woman

The car looks damaged but it looks like the front corner of the car sideswiped a pole. The drivers side of the car isnt even damaged.

I would say the damage is more "looks" then reality. it ripped the front fender cover off and smashed the roofline a little.........

So not really a direct hit on the car. I dont think any car would look good after that kind of accident. Its possible a passenger would have survived with some head trauma (no airbag ) as the passenger compartment is pretty much intact. Just the corner of the cabin pushes in at the top.

 

[440trk]

Unibody cars (as mentioned) rely heavily on the rockers as part of the frame assembly. Anyone who has ever cut up any unibody car, can tell you, there is a LOT of strength in the rockers. That being said, it's pretty common to tie the frame rails together (as mentioned by Tim K) with box tube or pipe. That will add a significant amount of rigidity to any unibody, as well as help reduce body flex when cornering. (note: Autocross guys may want to check the rule to see if you can legally tie the frames for the class you are running). No real need to mess with the rockers, unless yours are heavily rusted.
Even a bolt in frame connector will stiffen the car up, and will help keep the floorboard from flexing in an impact. (providing it's installed properly.)

I'd have to look at my Daytona a bit closer...but I'm pretty sure making either a bolt in or weld in frame tie would be pretty simple. RWD Mopar drag racers and auto cross folks have been doing this for years. I'm guessing a quick search will turn up a couple of web pages showing a RWD frame tie install. Same basic proceedure for a FWD. I'll see if I can find any good links.

 

[440trk]

Here's one: Classic Barracuda Subframe Connector Installation - Mopar Muscle Magazine

Disregard the torque box install part...Torque Boxes only apply to RWD's... althougth the basic concept of them could possibly be transferred over to some suspension reinforcement on a FWD car, if needed.

 

[440trk]

Also, a properly designed frame connector, could also add additional support/rigidity to any roll cage. A little advanced planning could make a nice addition to the overall structure of ANY FWD car.

 

[Reaper1]

The problem is our front and rear subframes don't line up #1. #2 they are not at the same vertical level, the front subframe is significantly lower than the rear. Not only that, but there is no lateral connection between the rear subframe rails to connect to like shown on the Barracuda. I've been looking at this for YEARS. To tie the subfraims together under the car is not an easy task. It can be done as I mentioned earlier in the thread. I just wish I could remember where I saw the pictures, or how exactly it was done.