no damage on a 5mph impact?

[rowjelio]

so we know GM uses the rubber spacers, and ford pushed the bumpers forward, but how does chrysler mititage the 5mph bumper with NO damage to the body? the front header panel is all fiberglass isnt it? wouldnt it get damaged on a 5mph impact? the way i see these bumpers, i feel like if it got squished in, it would crush the fiberglass, front and rear

 

[Big_John]

so we know GM uses the rubber spacers, and ford pushed the bumpers forward, but how does chrysler mititage the 5mph bumper with NO damage to the body? the front header panel is all fiberglass isnt it? wouldnt it get damaged on a 5mph impact? the way i see these bumpers, i feel like if it got squished in, it would crush the fiberglass, front and rear

The 5MPH bumper does not guarantee that no damage will happen.

The standard was that you could hit the car from any angle at 5MPH and all the lights would still work.

I searched and found a decent article on the standard. Two years that changed cars forever: 1974 (bumpers) and ’75 (smog) - Hagerty Media

 

[rowjelio]

Dang so Chrysler did the worst job then, since GM and Ford were protecting the body as well! Bummer! Still look great though

 

[RemCharger]

so we know GM uses the rubber spacers, and ford pushed the bumpers forward, but how does chrysler mititage the 5mph bumper with NO damage to the body? the front header panel is all fiberglass isnt it? wouldnt it get damaged on a 5mph impact? the way i see these bumpers, i feel like if it got squished in, it would crush the fiberglass, front and rear

We had the big shock absorber bumpers

 

[rowjelio]

They all had shock absorbers behind the bumpers, but if you hit the Chrysler it would crush the lower panel thingy I guess

 

[CBODY67]

They all had shock absorbers behind the bumpers, but if you hit the Chrysler it would crush the lower panel thingy I guess

Seems like the bumper standards were implemented in two levels. The front bumpers at 2.5mph and then the rear bumpers came later. Chrysler, with the use of the "big bumper guards" in 1973 models, plus some stub frame and other stiffening, got the first standards done easily. Although the added length also cost them more to transport the cars (as noted in the Iacocca book on his time at Chrysler).

As noted, the standards were more concerned with localized damage that would make the cars inoperable, rather than "invincible".

GM went with the hydraulic energy absorbers from the start, which Chrysler and others started to use in the 1974 model year. That was the 5mph standards. The bumpers had a heavy stamped reinforcement that went behind them and to which the energy absorbers attached to. For the 1977 downsized cars, GM used a "High Strength Low Alloy" (looked like heat treated aluminum) as the bumper reinforcements, which decreased weight a LOT.

Camaros and Corvettes went down a different path. Corvettes used some specialized bolts to absorb the energy. Camaros had some heavy leaf springs that went behind the bumpers to absorb and "spring back".

It was noted that with the "bumper guards" in 1973, in a b-body forum, that the strength upgrades to the stub frame and such gave the cars a more solid feel and help them fend-off collision damage better than the earlier B-body cars of that platform did.

In later years, the management of crash energy is much more highly evolved than in the earlier days. UniBody-type cars were always stiffer and stronger in these areas than similar body-frame cars. In a 1969 model intro Petersen Publications book, it was mentioned that a UniBody car took about 50% more crash energy to permanently deform the body than a body-frame car did. At the time, the only UniBody cars in production were Chrysler Corp cars, plus mid-size Ford vehicles, Lincoln and T-Birds, Camaros and Firebirds, and other shorter-wheelbase GM and Ford cars.

In the middle 1970s, some GM brands got a bit creative using spring-hinged grilles so that when the front bumpers moved rearward, the grille moved too, keeping it generally undamaged.

CBODY67

 

[Milo]

I seen a big Chrysler with front bumper big shocks and rubber bumper guards Hit a mustang II in the rear and the mustang was totaled it even broke the rear glass. The Chrysler had one very little mark on one on the bumper guards and no other damage we checked it over good

 

[Rustyrodknocker]

It's never been my experience that a unibody cars sustains less damage especially post front sub frame cars. Cars with structural front sheetmetal get wasted in a side front impact.
Don't forget Nash Hudson AMC. Unibodies since the 40's

I could understand them transferring less impact energy to the occupants for sure because they crinkle rather than send energy down a steel frame rail like a railroad.

I know my 70 elcamino has been walloped hard because I can see where they welded hooks or eyes on each corner of the frame and they ripped out during the pulls on the rack. I had it aligned on Saturday then when back and talked to the old timer that did the work.

He said it is good and square which was pleasing because I was going to re frame it at one point. I did have one tacoed four link in it before I replaced them with tube style.
It drives beautifully minus the rough ride from the aftermarket suspension.
I don't know that I would bet on my B or C bodies fairing as well.

 

[CBODY67]

GM full-frame cars CAN be variable as to how well they endure impacts, front or side or rear, by observation. I saw that in being around body shops which were our parts customers, for over 40 years.

The amount of "structure" in the front end of the 1960s-1970s cars varied by carline. The front fenders of a Catalina were much heavier than those for a similar Caprice, for example. When GM downsized their full-size cars for 1977, that was the first platforms using CAD tech to do the design and virtual testing. When the first ones came in with a frontal collision damage on them, I was impressed as all of the damage was in front of the cowl and "bolt-on" stuff. BUT the first side collision of one I saw, not good. Nor the second one, either! IF they were hit in the rear, the body bent down rearward of the rear window, kinked over the wheel. On a frame rack, repairable. Rear bumper would be almost touching the ground, which meant kinked rear frame rails over the axle. BUT most of the time, only the front end is involved in collisions.

The Slabs and earlier cars have a very stout front section, cowl forward. Fuselage cars not so much. Formals got back to the stout front sections, by observation. After all, they had to have structures strong enough to meet the Fed standards.

The majority of current/recent model year non-truck chassis SUVs and other cars are unibody vehicles. If you watch the crash testing videos, they are built "like a brick" and bounce off the barrier, or ricochet, as the body/frame truck-based vehicles just collapse around the barrier. With the lh frt wheel intruding into the driver's footwell quite a bit! Quite a difference. In the process, GM car bodies have become quite stout and impact resistant to side impacts, too!

By observation, the "strong frame" under GM Intermediates of the late-'60s were known to absorb frontal crash energy by bowing the frame rails under the passenger compartment outward a bit. On a friend's '70 MonteCarlo, the car drove fine, but the transmission mount was barely hanging on, just sitting on the crossmember, to his shock and surprise.

Just my observations and experiences,
CBODY67

 

[MoPar~Man]

I am currently dismantling my '73 Satellite, my objective is to remove the engine + trans, so I've been taking everything off the front end. The (plastic) grill is in pretty good shape. I've posted a parts/car available thread on FBBO.

Anyways, I took the front bumper off, removing the 4 bolts to the frame, so it came off still attached to the brackets. It has the big rubber bumpers. The bumper itself is in very nice shape, it would polish up well. BUT IT WEIGHTS A TON. It has a thick plate, like 1/4 inch, running horizontally behind the bumper surface, sort of form-fitting. I think that did more for the 5 mph survivability than anything.

I have another front bumper, also still connected to the brackets, '67 Monaco / Polara. For the heck of it today I weighed it. 57 lbs. The '73 Satellite - 76 lbs. That's a lot of weight hanging out there way out in front.

 

[Xcudame]

I hit my mom's 68 Imperial with my 70 Challenger. The passenger side big axe on the rear put a dent in my front bumper! Mom came running out of the house and was almost made until she saw zero damage to her Imperial and the dent in my bumper. Then she started laughing at me and my puny car! This a reason the Imperials were the first cars outlawed from demolition derbies!