Batray75

Any idea why 1974 had no black bumper pads, 1975-79 had them, and then they disappeared again for 1980-82?

SEVNT6

No pads in '73 either...

The front pads went away with the rear pads in '80. Why? Only the shadow knows....

4-vettes

In 75 someone at GM thought they were a good idea. By 1980 they decided to clean up the look of the bumpers and now they weren't needed.

67:72

I believe part of the soft bumper regulations had something about 5mph "crashes" inflicting minimal damage to the body; the black pads probably helped meet that regulation as before there would definitely have been paint and panel damage.

4-vettes

Granted. But those regulations remain in place to this day.
doesn't explain why they suddenly where no longer needed then. Perhaps they found they were just overkill.

Torqued Off

I actually like the looks of them. Even though they are fake. The real bumpers are inside.

4-vettes

Fair enough. I still have them on my 77 as well.

gbvette62

This is pretty close. The constant changes to the federal impact bumper regulations are why the design of the bumpers kept changing.

In 1971 the feds introduced new standards for bumpers requiring all cars to withstand a 5 mph front and 2.5 mph rear impact without any damage to the lights, fuel system or other safety features. This was fazed into effect over 72-73 and got progressively stricter in the following years. I think for 75 or 76 a uniform bumper height requirement barrier impact test was added to the regs, along with a zero damage requirement, which is what I believe led to the black bumperettes being added to the Corvette's bumpers. The bumperettes met the height requirement and allowed the Corvettes bumpers to impact the barrier squarely.

For 1980 the regulations changed once again, getting tighter and now requiring the bumpers survive a 5 mph impact from a swinging pendulum, with only a minor depth dent permitted by the impact. Now the bumpers weren't being tested square against a barrier, but were instead being impacted at different angles by the pendulum so the bumperettes were no longer effective in meeting the regulations. This allowed GM to eliminate the bumperettes in 1980 for much cleaner appearing bumpers, at least in my opinion.

The 5 mph bumpers were first pushed by the insurance companies as a way of saving consumers money, but of course they were really hoping to save themselves money on minor claims. The Federal government is always happy to pass new regulations, especially if they can claim that they're doing it in the name of saving people money, but as usually happens when a government entity passes a law to save money us money, the opposite usually happens, it costs everyone more. This is exactly what happened with the 5 mph bumpers. As the bumper requirements got ever tighter, they did reduced the cost of repairs in minor impacts, but in anything more then a slight parking lot bump the cost of repairs skyrocketed. In all other impacts the much more involved and expensive impact bumper systems ended up costing the insurance companies far more than they were saving on minor impacts. By 1983 the Feds under pressure once again from the insurance companies, loosened the 5 mph bumper regulations.

To me, the black painted bumperettes always looked out of place. I always considered them just an afterthought they were forced to add to a previously designed and much cleaner appearing bumper, to meet an ill advised government regulation.

4-vettes

A very interesting explanation to be certain. Although lacking foot notes to back any of this up.
Are you certain that 5 MPH bumper regulations have been dropped? Interesting idea on the method of testing changed. Although it sounds plausible. I've never heard this before.
I love this kind of stuff. But before I pass any of it on.....
Some kind of references?

69L88

These work?

gbvette62

I didn't say "dropped", I said "loosened", there's a difference. It was my understanding that in 83 or 84 the 5 mph bumper regulations or the testing procedure used was relaxed some, not dropped.

Thanks to 69L88 for posting the above information on the 5 mph bumper regulations.

If what 69L88's posted are not enough "footnotes" for you, the initial regulations in place through 1975 can be found by looking up Federal Motor Vehicle Safety Standard No. 215 (FMVSS 215). The changes made in 75-76 to the regs I believe can be found in United States Code of Federal Regulations 49 CFR 581.

I don't have the time right now to go dig up the actual regulations related to the later changes but the following is from Wikipedia and does explain them to some degree (the Iltalics were added by me to separate what came from them verse what was part of my post). In looking this up for you I find that I may be off a little on the years changes were implemented and the exact
details of the regulations, but I was just talking in generalities to start with, and I apologize for that.

Per Wikipedia:

Stringency reduced in 1982[edit]

The recently elected Reagan administration had pledged to use cost–benefit analysis to reduce regulatory burdens on industry, which impacted this standard.[50]

As discussed in detail under Physics, before 1959, people believed the stronger the structure, including the bumpers, the safer the car. A later analysis led to the understanding of crumple zones, rather than rigid construction that proved deadly to passengers because the force from impact went straight inside the vehicle and onto the passenger.[11]

NHTSA amended the bumper standard in May 1982, halving the front and rear crash test speeds for 1983 and newer car bumpers from 5 miles per hour (8 km/h) to 2.5 miles per hour (4 km/h), and the corner crash test speeds from 3 miles per hour (5 km/h) to 1.5 miles per hour (2 km/h).[51] In addition, the zero-damage Phase II requirement was rolled back to the damage allowances of Phase I. At the same time, a passenger car bumper height requirement of 16 to 20 inches (41–51 cm) was established for passenger cars.[48]

NHTSA evaluated the results of its change in 1987, noting it resulted in lower weight and manufacturing costs, offset by higher repair costs.[52]

Despite these findings, consumer and insurance groups decried the weakened bumper standard. They argued that the 1982 standard increased overall consumer costs without any attendant benefits except for automakers.[40][53][54][55] In 1986, Consumers Union petitioned NHTSA to return to the Phase II standard and disclose bumper strength information to consumers. In 1990, NHTSA rejected that petition.[56]

Bikespace

I don't mind the front bumper bumps on the 79, since the car is black, and they frame the license plate.

Fortunately, the 80 doesn't have them, and the 79 has a much better aftermarket rear bumper that was molded without them.

As with many things, it was added to meet a requirement, until something "better" (more aesthetically pleasing, or just cheaper) came along.

SEVNT6

About 6 months ago the crumple zone in one of my best friends WRX saved his life in a head on crash...

saber

The 73 was the first application of the new Reaction Injection Molding Technology invented by Cincinnati Milacron.
These first pieces had to be relativity simple, the back piece in the 74 were even two pieces.
This tech advanced rapidly and all of the mold thermodynamics and flow dynamics were being understood.
The bumper-etts? on the 75 came about because the understanding of the process allowed much more complicated geometry in the molded part which allowed a good fitment of a steel structure directly behind the bumper-etts.
BTY I worked on this as a co-op going to Engineering school.

4-vettes

Thank you gentlemen for the education. I do find this all very interesting. I understand your time looking this up is valuable. I really like to know the whole story. One day I may be finding myself passing this information along. I just like to be certain.
Thank you.
And , I actually like the bumperettes on my 77. They just look right to me.

dtamustang

my dad was in on the development of the rubber bumpers from the beginning , i remember a yellow 67 camaro with a " rubber " bumper that my dad would take to detroit from dayton pretty often. it was test mule for the impact structure under the bumper as well as the bumper itself. this was in 67 or 68 to the best of my memory. the first production use of the rubber bumper was the 68 GTO . i believe gm called it the " endura " bumper. my memory may be a little fuzzy but it seems to me one of the biggest problems getting the colors right , the gto bumper was molded in body color and getting that right was a big challenge , also for the bumper not to be easy to break in extreme cold weather they tended to sag in warm weather. back in the late 60's it was pretty advanced stuff. my dad followed prototype corvettes from phoenix in the summer to canada in the winter testing the government mandated bumpers.

SEVNT6

Some of the best car commercials of the late '60s were GTO Endura front bumpers getting beat on with crowbars, bats...you name it.

And they would still look perfect...