Gas vs Oil Dampers
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  1. #1
    Sense Pug307's Avatar
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    Gas vs Oil Dampers

    I was just wondering, noting that the latest Peugeots are using gas dampers - what are the differences between the gas & oil dampers, in particular, what the the pros and cons of them?

    For instance, when the 406 was updated, one of the updates was the introduction of gas dampers, replacing the oil dampers. Is this a bean counter led drive, or an engineer's one?

    Regards,

    Justin

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    Peugeot 307 XS 1.6
    Aussiefrogged in MEL, PER, SYD, BNE & ADL.
    Rendezvous Adelaide 2005

  2. #2
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    The gas simply keeps pressure on the oil (there's still oil in the gas ones) so the oil doesn't froth as much. This in turn stops 'fade' caused by the air bubbles in the oil passing through the damper ports/valves in the piston, reducing damping effectiveness. So, it's a engineering decision for sure.

    Stuey


    2003 PEUGEOT 206 GTi

  3. #3
    Gone Fishin' Ray Bell's Avatar
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    You're right there, the gas pressure... well, it reduces frothing, in that frothing might not have occurred anyway.

    If there were frothing, there would naturally be a residue of air in the working chamber when you come to rest. That froth would ultimately become one large bubble of air and the damper would no longer be effective.

    Thinking about it, frothing can't be all that prevalent, or no dampers would work properly after the first long run!

    Teleflo had a better system than gas... nothing inside the damper other than the oil. A rubber sac allowed the oil level to rise and fall without any contact with any air. No gas pressure to cause other potential reliability problems.

    In Spax (not sure if this is current) they used a system devised by Delco, I think, where the gas only expanded to produce pressure when it was heated. It was contained in a kind of sac wrapped around the outside of the working chamber and also precluded the gas pressure reliability risk.

    But the main thing to bear in mind is this: All dampers work in oil.

  4. #4
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    Whether there's frothing or not, that's the manufacturer's theory. I'm just the messenger. Same reason you leave the shockie upright for an hour or two before installation, I believe.

    Stuey

    <small>[ 03 March 2003, 12:10 PM: Message edited by: Stuey ]</small>


    2003 PEUGEOT 206 GTi

  5. #5
    Real cars have hydraulics DoubleChevron's Avatar
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    Gee's guys,

    all this shocker/spring crap was solved in about 1955 in production cars roll_lau roll_lau mallet mallet dance dance tongue

    seeya,
    Shane L.
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    Yay ... No Slugomatics


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  6. #6
    Gone Fishin' Ray Bell's Avatar
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    Leave it upright for an hour before installation?

    No, not necessary... all you have to do is operate it in an upright position until there is no dead spot in the damping and keep it upright as you instal it... even the latter isn't always necessary.

  7. #7
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    I didn't say it was necessary. I said it was for the same reason. When we had a country service station, my Dad used to install about fifty pairs a year. The mfr's instructions always recommended leaving the shock for the hour or so, then three or four complete pumps, then install. He'd only leave them upright for the time it took to remove the old ones, though. Your turn...

    Stuey


    2003 PEUGEOT 206 GTi

  8. #8
    Gone Fishin' Ray Bell's Avatar
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    Well, the quick way, if you really want to know, is to invert them to close them, then reopen them the right way up... This allows the air in the working chamber to float to the foot valve and be quickly expelled as you close it down.

    That's the whole purpose of the bleeding process.

  9. #9
    Sense Pug307's Avatar
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    Thanks for your replies - I don't really know much about how dampers work, so I was interested to see what the differences were.

    Peugeot 307 XS 1.6
    Aussiefrogged in MEL, PER, SYD, BNE & ADL.
    Rendezvous Adelaide 2005

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