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Registered
Join Date: Dec 2005
Location: Melb, Aus.
Posts: 407
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Impact Pipe v Impact Absorber
For the first time since I bought my car 3 years ago I have removed the front bumper and skirt (front embellisher as it's called in the parts manual) just to give them general clean and paint the underside of the skirt with some por15.
I was expecting the bumper impact absorber to have a heavy duty rubber bush but I seem to have just a solid pipe. Closer inspection of the workshop manual shows 2 different parts, 911.505.045.03 Impact pipe, 911.505.279.03 Impact absorber. I am assuming it is a case of having one or the other, not both. What's the point of having a solid pipe with no absorption? cheers
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Shane 1975 911 Coupe 2.7L 4Spd CIS Sporto 9115100500 1977 911 Targa, 3.0L, 5 Spd LSD, Zenith Carbs modified, SSI, Dansk 9117310158 |
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04-17-2008, 05:18 PM
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Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
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Shane,
Those are called "crush tubes" and designed to absorb small impacts without transmitting the proportional force to the chassis. As you can see, these are one-time-only devices and meant to be replaced after a shunt. US cars from '75-onward had the impact absorbers which return the bumper to its previous location but they are heavier than the crush tubes.
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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04-17-2008, 06:11 PM
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Join Date: Apr 2005
Location: outta here
Posts: 54,017
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Assuming you have the factory pipe, and not some home-made substitution, the difference relates to how much energy it takes to deflect the bumper a given amount in an impact. The absorber will absorb more energy and was used to conform with stricter safety laws. In the early '70's, the bumper laws got progressively more stringent each year. In 1973, Porsche began changing the 911 bumpers to meet the new rules, added the later style bumpers in 1974 and the standards got a little tighter in 1975. I'm not familiar with what Porsche used for bumper mounts in the US in 1974 and 1975 but, if it is similar to what the ROW cars got, they should have a deformed section that helps the tube to crush in an impact. The later absorber style mounts are also a fair bit heavier.
JR |
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04-17-2008, 06:15 PM
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Join Date: Dec 2005
Location: Melb, Aus.
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Steve and JR
thanks I see what is going on now, I have the pipes with a deformed section in my ROW '75 cheers
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Shane 1975 911 Coupe 2.7L 4Spd CIS Sporto 9115100500 1977 911 Targa, 3.0L, 5 Spd LSD, Zenith Carbs modified, SSI, Dansk 9117310158 |
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04-17-2008, 08:55 PM
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Join Date: Dec 2003
Location: MS.
Posts: 2,322
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Hi Shane, those are the "crush tubes" like mentioned before, they are considerably lighter than the impact bumper shocks, but they are pretty much a one time use item, then they have to be replaced. While the "bumper shock" style normally will live to fight another day. But... sometime those fail and need to be replaced. Tony.
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04-18-2008, 08:41 AM
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