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thehackmechanic

There is no such thing as a 2 1/2 mph (front) bumper

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For years, I've referred to the chrome bumpers that stand out slightly from the body on the mid-'72 through '73 cars as "2 1/2 mph bumpers." Other folks here on the FAQ refer to them this way as well. And we all refer to the big-ass bumpers that started in '74 as "5 mph bumpers."

As part of the proofreading process for my book, Bentley gently challenged me on it, saying that the DOT regulations say that 5 mph front and 2 1/2 rear bumper regulations came in on September 1st and were generally adopted for the 1973 model year.

They're right. Wikipedia has a good summary here.

en.wikipedia.org/wiki/Bumper_(automobile)

Scroll down to "First Standards."

Regarding the confusion over why the DOT rules for the 1973 model year seemed to mandate 5 mph bumpers, whereas we know that on our beloved cars there was only a subtle change in '73 (the chrome bumpers being slightly pushed away from the body), whereas the bridge abutments that we all call "5 mph bumpers" started in '74, the salient sentence is here:

"The 1973 model year passenger cars sold in the U.S. used a variety designs. They ranged from non-dynamic versions with solid rubber guards, to "recoverable" designs with oil and nitrogen filled telescoping shock-absorbers. The standards were further beefed up for the 1974 model year passenger cars with standardized height front and rear bumpers that could take angle impacts at 5-mile-per-hour (8 km/h) with no damage to the car's lights, safety equipment, and engine. "

So, that's it. The slightly-pushed-out chrome front bumpers mid-72 through 73 are technically 5 mph bumpers, but not designed for impact from any angle.

You learn something new every day.

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Thank you, Rob. I think. Sometimes I'm happier when I'm un-encumbered by actual facts.

Steve

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Or methods of transferring crash damage from one part of the

body to another...

t

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Oh god that picture... But yeah early and euro bumpers are purely cosmetic specially before they had the rubber strips.

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A number of years ago, while stopped at a red light, I had an 18-wheeler tractor from Mexico (thank God he didn't have his trailer behind him at the time) hit the back of my '75. Pushed the shocks in somewhat - and that was all. Didn't even mar the rubber profile. Replaced the shocks with some used ones from someone on the board here and all was well.

The jewelry-bumper boys can bad mouth the big bumpers all they want but I've been saved damage a couple of times by having them.

Bob Napier

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No badmouthing here, I fully concede that your bumpers are far better at bumper-ing than mine. I still like mine better for looks though :P

-Jake

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A number of years ago, while stopped at a red light, I had an 18-wheeler tractor from Mexico (thank God he didn't have his trailer behind him at the time) hit the back of my '75. Pushed the shocks in somewhat - and that was all. Didn't even mar the rubber profile. Replaced the shocks with some used ones from someone on the board here and all was well.

The jewelry-bumper boys can bad mouth the big bumpers all they want but I've been saved damage a couple of times by having them.

Bob Napier

i feel like such a traitor to the big bumper crowd Bob. i put jewelry bumpers on my 75....not for looks though! just for lightness. it is an odd feeling driving on the street knowing there just aint nothin' there....

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On my former 74 2002, I had a stock Chevy S10 crash into my back end when freeway traffic in the LA area came to a stop. The damage was similar to the pic that Eastbimmer posted above. The S10 cleared my diving board bumpers and did that type of damage to my rear panel. In this period of large pickups and SUV's, diving board bumpers will not help much if you are rear ended. AMHIK!

G-Man

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On my former 74 2002, I had a stock Chevy S10 crash into my back end when freeway traffic in the LA area came to a stop. The damage was similar to the pic that Eastbimmer posted above. The S10 cleared my diving board bumpers and did that type of damage to my rear panel. In this period of large pickups and SUV's, diving board bumpers will not help much if you are rear ended. AMHIK!

G-Man

And with that I guess you have to consider where you live and the average type vehicles around you. I'm in the stix and 90% of the vehicles are SUV's or pickum-up trucks. So I figured I'm done regardless. so lighter bumpers going on.....

IMG_6653.jpg

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