914 bumper shocks: Are they rated at only 5mph?

[theKbStockpiler]

Hi ,I'm panning on stiffening up my beetle and want a bumper shock that is stiff like the ones audi foxes had. 914 ones look like I could make them work but are they weak like beetle ones?

Thanks in advance!
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My beetle is not competing with your beetle. I have the yellow beetle in my town. There is a red one, a green one ......
Use all safety devices including a mask.

[raygreenwood]

They are all 5 mph. ...even the beetle ones. They simply work differently depending on what the bumper was made of and how the shock was designed to function. Many are a one time latching mechanism. Just designed to absorb or slow down force.....not designed to exert any back pressure. The beetle ones are like this......so in short they are really designed to be stiff. Ray

[theKbStockpiler]

They may be stated as (5mph) but the ones on a Audi fox where 10x stiffer than a beetle one. I got rear ended in a fox at about 30 mph and the bumper shocks actually accelerated the car when they decompressed.
_________________
My beetle is not competing with your beetle. I have the yellow beetle in my town. There is a red one, a green one ......
Use all safety devices including a mask.

[raygreenwood]

[theKbStockpiler]

I want the bumper shocks to absorb energy. This decelerates the car and the shock stores the energy. I'm going to install a sub frame in a super beetle so the car could utilize` a stronger shock ,maybe from a heavier car. The mass behind a beetle at 5mph is 1/2 of a buick at 5mph. They cant all be the same except for the mounts. The type 1 bumper shocks are just a reusable bumper bracket that have a crush-zone. I have one good beetle shock to experiment with. 914 are light so maybe I should consider a 944 one. They are for sale once in a while. Domestic shocks usually have a design that goes inside the unibody frame so too much work would have to be done to modify them. I had 3 foxes , one of them a vw and I don't think the shocks freeze to the extent that beetle ones do. I got in two bad accidents with 2 and the radiator supports is what totaled both of them. The shocks did not stay compressed.

Hey , I remember back in the day when bumper shocks came out that some people felt that they were dangerous because if you go rear ended ,the shocks could accelerate you across an intersection or the like. I don't think that all of them are designed for 5mph.
_________________
My beetle is not competing with your beetle. I have the yellow beetle in my town. There is a red one, a green one ......
Use all safety devices including a mask.

[raygreenwood]

Yes....they were all designed for 5 mph. Whether some could protect to a higher or lower extent....who is to say.
However I would say that you are reading far more into the design parameters (size, mass etc.) as one could never know what YOU are going to be hit by regardless of the mass of YOUR vehicle.....add to that ...if you are on the brake and get nailed by a 4000 lb Buick....it makes no difference. It didnt work anywhere near what the spec said it should.
There was no way to plan or discern...in the testing....whether you were hitting something (and whether it was stationary or what its weight was)....or whether something was hitting you....and what its weight was.

I would say.....think about that. Whether 5 or 10 mph (and there was a 10mph spec at one point).....5 or 10 mph crash resistance against what weight and under what condition?

This is why the "shock absorber" theory for bumpers went by the wayside long ago. Modern bumpers are made with large plastic cellular inserts and flexible plastic outers. Not many have shocks at all any more.

The other reason why these never really prevented damage is because largely everything after about 1974-76 was crash cell/ crumple zone construction. If you make the bumper shocks stiff enough to actually prevent contact with the sheet metal.....the metal the bumper mounts are bolted to flexes the metal farther forward.

Through the years at least over on the STF there have been numerous discussions on the bumper shock issue. Its hard to see them other than simply a mounting bracket any more. Ray

[bluebus86]

some of them bumper "shocks" are dangerous. In fire fighting we learn not to stand in front or behind a car so equipped if it is on fire. if the bumper shock gets too hot in a fire, it can explode the bumper off the car, knee capping any near by person. I believe they eventually fixed this issue with a metal stop to prevent the shock from flying apart. But for some models of cars this is still a danger. I stay clear of the shock mounted bumpers when there is a car fire, approach from the side when fighting a car fire.

Of course all this 5 mph or 10 mph bumper stuff is nonsense when a jacked up SUV goes right over the low slung bumper. many vehicles are much higher up than our old 914's and Bugs.
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Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[tisius]

Anyone wants to test their 914 bumpers???
I have a nice concrete wall behind my house

If you want to be sure that you have proper safety devices in your car, then buy a modern car; in that case you're definitely looking at the wrong car if it's a classic aircooled VW... if you get into an accident with an aircooled VW then you better start praying, because that's your only safety device
In short..... forget about it.
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drive it like you just robbed the bank
you don't have to be crazy to be into VW's, but it sure helps!!
.... if it ain't dutch, it ain't much!

[raygreenwood]