First off .... what I'm hoping to find out about is not the usual bumper mount issue .... so with that said, here is the deal. I'm in the latter stages of building a 1940 IHC Hot Rod COE, and have discovered that building a new stronger bumper mount system might be aided by using what Ford used in the 70's + for the Federally mandated 5 mph bumper setups. I have a pair of the very simple tubes with mount plate mounts that are named "energy shock absorbers" by Ford. Looks like they are meant to withstand having the bumper whacked up to 5 mph, and still retain their original shape?? I've asked Ford mechanics, and parts guys, but so far no idea if these mounts have a designed collapse distance and then will recover, or are throw aways that once hit are to be replaced. Sure would be helpful IF anyone might know how these are constructed, and what will happen when hit. I don't want the body to be damaged at all with a low speed bumper thump, but just don't know how these 5mph units might work. Thanks in advance ....... RRG in Spokane, WA
I worked for a body shop in the late 70's to mid 80's. Our guys would replace them. From memory, once they collapse, they've done their job and need to be replaced. Now, whether that designed changed, I don't know. They weren't too expensive from the dealer and the junk yards used to be full of them. Good luck.
I've tried to forget everything that came about after 1972, but I believe the very early ones may have had some rebound to them. If so, it quickly went away and became use once & replace type thing. You could possibly make your own and engineer in some form of spring to allow a bit of rebound. -Dave
Kinda like these? https://www.ebay.com/itm/OEM-78-Cad...y:3.8L&hash=item1ed86884d1:g:LI4AAOSwnJVZnZvx
mercedes in the 70'/80's used a set up much like what you describe. they used an aluminium bolt/pin that would shear in a crash over 5mph. i did replace the pins once. going from memory....
Throw aways.. I was a bodyman back then, they were a big joke. Ford made millions selling replacement fenders, wheel wells, core supports, bumper valance "splash pans" and header panels because of them.
Pretty sure they're one-time use, and if one goes in straight and the other does not, it's fairly easy to tweak the bumper with those. Factory 40's and 50's car and truck bumper brackets are basically a bent-up leaf spring, anyone who's ever tried to cut or weld on those brackets know what I mean. It takes a ton of effort to bend one, way more than a 5 mph bump against a modern plastic car. Some of the factory 30's and 40's Chevy truck brackets bolt to the ends of the frame horns and actually even look like springs with big arcs in them. That'd be what I'd want on the front of a truck if I was worried about hitting things.
You could mount some suspension 'coil overs' horizontally......might be a bit bulky, but effective. Possibly house them in some tubular covers. Ray
Working in a bodyshop in the 70's you had to be careful removing bent up bumpers with those struts in them. If collapsed they sometimes would pop back out, without warning, and if you were standing in front of them they could break your leg.
I'm like Town Sedan, I think the real early ones did rebound and go back at least on the Chevys we had around with them on them. At least that was supposed to be the original concept that you could be hit and not have damage but as the others said that soon went away.
My '75 Maverick has a style on the front that is an I beam inside a box that bolts to the subrail. Rubber blocks are bonded between the I and box. I guess under mild impacts the rubber will stretch and spring back, like a rubber suspension bushing that twists and springs back. The rear bumper has the small tube type.
The 5mph bumpers were not suppose to prevent any damage, they were suppose to prevent damage to the headlights, hood latches and radiator (I believe) in a straight on, solid barrier, head on impact. The requirement was that the car could be driven away from the "accident" and the safety items on the car would still be intact. There was no concern about related damage, as long as the car could still move. The early ones were mostly big hunks of rubber attached to the bumper faces with little reinforcing behind the bumper, or the bumpers were extended out a couple inches to accomplish the goal. The mounting brackets were intended as a 1 time use item. The 5 mph bumper came about because in the late 60s and early 70s several cars had very little front end structure. A bump when parking could resort in a car having to be towed away because the radiator, the headlights, and/or the hood latch could be destroyed. Bumping into the front end of a 71 Vega while parking in a parking space would result in a Vega with a ruined front bumper, hood, radiator, and would have broken the head lights and turn signals. The Vega's were not alone with that issue, most cars of the time had similar results. Most of the late 20s through the end of the 30s bumpers were better at protecting the front end of the car then even the government required 5 mph bumpers. I believe the government even used a 30s car as an example of what they wanted from the car companies. Gene
I remember hating the looks of the then new 1973 & '74 cars with their federally mandated big bumpers. Hated the '75 cars even more because they came with fowl smelling catalytic converters as well as the style offending bumpers. There was a TV commercial at the time (early 70's) showing something like a Model A in a 5 mph "crash" and it just bounced off the barrier. They were trying to demonstrate how the new for '73 bumpers were to work. You could put a tube into a slightly larger tube with a coil over spring inside, as Hnstray suggested, with your bumper mounts welded to either end. Or, take a lesion from the auto industry and forget about it. By 1983 the 5 mph bumper was deregulated to a 2.5 mph bumper and today we have crumple zones instead of bumpers that protect the vehicle. To much of this seventies talk. Next thing will be folks wanting to add EGR and electronic fuel and ignition controls. -Dave
My memory is sort of foggy but I'm not sure there ever was a government mandated "5mph - 0 damage" bumper that was focused on the vehicle cosmetics. My rusty recall is that the government could have cared less how much an under 5mph impact cost to repair. I think this was a time when "Safety" was becoming a growing issue. "Safe" for both the occupants and the critical systems in the vehicles. I found this on the 'net but as usual, take anything on the 'net with a grain of salt. This could only be a part of it with a lot left out of the quote......... "The standard prohibited functional damage to specified safety-related components such as headlamps and fuel system components when the vehicle is subjected to barrier crash tests at 5 miles per hour (8 km/h) for front and 2.5 mph (4 km/h) for rear bumper systems."
You can try looking at euro cars Volkswagen mk1 ( first gen rabbits) And others had shock absorbers to mount the bumpers Back in high school we used to drill out the shocks to release the oil and gas charge so we could push the bumpers into the body for a more euro look ! Lol!! So yeah if your looking for safety and something that doesn’t fold like a Chinese lady at a laundry mat maybe look at this .
Hey, thats a functional looking old part, tried to find it on the web, no luck! Can you forward a link? Thx! Sent from my iPhone using The H.A.M.B. mobile app
The shock looking things Vandenplas posted are a lot like what GM used to hold the bumpers on nearly all the mid to late 70s GM cars. Think 78 - 88 Monty Carlo. Gene
This might be non-traditional & overthinking a minimal % chance you're rear-ended, but I was thinking of putting this in my wife's OT daily driver. Maybe there's some ideas here you could re-engineer to your application? http://sparebumper.com Sent from my SM-G955U using Tapatalk
Some of those bumper absorbers were spring loaded, GM I think. I remember straightening car frames back then with those on them and if they were stuck in a good smack with a hammer and they'd pop right back out. If they had replacements I'd weld the tubes together and use them to pull the frame with. Did they work? I'd say yes on lower mph wrecks, seems to absorb some of the impact to the frame producing less frame damage.
The 'original' '72-78 5-mph bumpers weren't supposed to prevent any damage, but were supposed to limit it. And initially, there was a dollar amount attached to this, which I believe varied depending on some sort of formula based on the car's price and weight, but this proved so unwieldy that that part was dropped. In '79 (phase 1), it was changed to no safety system or exterior body damage, but damage to the impact system was allowed. '80-82 (phase 2), minor cosmetic damage to the bumper and up 3/4" bumper displacement was allowed. In '83 they dropped the mph by half, and reinstated the phase 1 rules. I recall a guy I worked with that rear-ended somebody in a '80 or '81 AMC Hornet; the bumper pushed in, allowed the other car to take out both fenders, grill, lights, and hood, then popped right back into place with just minor marring of the vinyl trim on the bumper... oops....
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