Cab Owners, replaced your engine vibration damper?

[reachme]

Cab's have the vibration damper in front of the fan (referred to in May issue of Pano/extract from Randy Leffingwell's upcoming book.

The article also discusses the reason for this damper is during early testing the resonance freq of the body was opposite that of the engine and in early cab development an engine fell out due to engine mounts failing during test.

This sounds like an important part but I've also read threads here where people have tossed this from their cab years ago with no ill effects.

Has anyone replaced this? How did you know when to replace it?

thanks

[frannyB]

I was told in my PPI that it is a lifetime part and never needs to be replaced... I'm not entirely sure I believe that though...

I suppose if the engine mounts are what the part is saving, that might be a good place to start in determining if it is still operating as designed.

It sure does make getting the fan and shroud out a pain!

Franny

[ganun]

That was one of the most interesting articles, like "get 10 off the line and pick worst" for torsion testing and devlpmnt. Also the torsion testing method and the addition of material "by experience trial and error".
And it goes on....
George

[1982911SCTarga]

I could be wrong, but I thought the small shock absorber for the cab engine dampener mount was unobtainium. I checked mine when I rebuilt my engine and it showed similar resistance when pushing and pulling, so I presume it's doing its job.

Brian

[reachme]

Our host sells them (911-375-175-00-OEM) for $87.75, the cost of unobtanium is coming down. But do I
1. Buy one because it will save my engine from a certain catastrophe
2. Buy one because it is black and shiny, highly visible and cheap insurance
3. Take the wife out to dinner and forget about it

[aoncurly]

I would advise to buy one to save your engine/engine mounts from POSSIBLE catastrophe. The addition of the damper is to "tune" out the resonance - basically, shift the vibration frequency of the components so they are not within the same range.

Failures due to fatigue depend on a number of things - stress risers (sharp changes, reentrant corners, and such), stress levels (it takes a certain stress level to propagate a crack), material characteristics, and number of cycles. Not sure if the resonance is at all engine RPM or speed or suspension ranges, but better safe than sorry.

[A horse with no name]

Originally Posted by 1982911SCTarga

I could be wrong, but I thought the small shock absorber for the cab engine dampener mount was unobtainium. I checked mine when I rebuilt my engine and it showed similar resistance when pushing and pulling, so I presume it's doing its job.

Brian

Hi...When I hear the word 'dilithium', I immediately think Star Trek. When I hear the word 'adamantium', I immediately think Wolverine. However, when I hear the word 'unobtainium', I think Engineer's Joke...Kryptonite though is a 'real' element

[BE911SC]

Thank you for not calling it a dampner.

[frannyB]

I guess it is really a vibration energy converter and dissipator. A loss device like a resistor in an electrical circuit.

f

[A horse with no name]

Originally Posted by frannyB

I guess it is really a vibration energy converter and dissipator. A loss device like a resistor in an electrical circuit.

f

It in reality is just a torque dampener due to the cars structural rigidity aka - 'A brace'. With out a roof the body looses its lateral support. The torsion of the motor twists the body due to the applied torque.-->GT RS2 That is why the newer VW Cabs have a 'built in roll bar'...Most owners will think that it is a safety item in case of 'rolling over' - true...But this was not the main reason of the VW engineering department.

Trivia: On most convertible's, if top is up when it goes on a hoist frame type hoist they suggest to undue the roofs clamps as the bending of the body can/will rip/break the roof...On a 911 I don't think so because they are so short. In a 3 series Beemer for example, their manual advises to undue them.

If you have ever seen any full size N/American convertibles with their top down on a hoist...They bend so much that it just about springs their doors open.
You will see a large gap between the door and the 'b' pillar due the body bending.

Note* Kryptonite though is still the real thing....Its from the planet of Krypton

[JJ 911SC]

The Damper is easy to replace, still available for less then $100.

It's the Engine Mount with the soft center that is the key part...

NLA, so if you see one for sale, get it. I got one Powder Coated for $250 delivered.