Load leveling T&C shocks ?

Discussion in 'General Motoring' started by Zork, Jan 27, 2005.

  1. Zork

    Zork Guest

    Have the standard shocks on
    my '03 T&C. Nivomats can't be installed in this situation
    without changing springs. Not a good option.
    So....are there ANY shocks in the market that will assist
    when the van is heavily loaded and a trailer attached ?
    The rear end sag at this point is not drastic, but would be
    nice to eliminate it if possible.
    Thanks all ! !
    Zork, Jan 27, 2005
  2. Surely -- air shocks. They can be inflated from any tire pump.
    Daniel J. Stern, Jan 27, 2005
  3. Zork

    jdoe Guest

    If you do anything like this it may upset brake pressure balance and cause
    issues ranging from excessive front brake wear to who knows.
    jdoe, Jan 27, 2005
  4. Zork

    Geoff Guest

    No. No. No.

    Never use the shocks, air or otherwise, to level a vehicle in this
    situation. "Nivomats" are a system -- not just shocks.

    Standard shocks aren't meant to carry the weight of the vehicle, they're
    intended to dampen suspension movement. Their mounting points were never
    intended for this purpose. It's a really *bad* idea to raise a vehicle
    with air shocks. This idea was commonly employed in the 70s and 80s
    when the 'raised rear' look was popular on RWD vehicles. It resulted
    in a lot of broken shock mounts and broken shocks. Some were more
    successful than others, to be certain. Those folks are known as

    If the van sags dramatically under the tongue weight of the trailer,
    it's overloaded, plain and simple. You're asking too much of it. If
    on the other hand, it merely rides a bit lower, than determine the
    tongue weight of the trailer, and compare this value to the published
    maximum trailer tongue weight rating for the vehicle. If the actual
    tongue weight is "within spec" -- then the sag needs no further
    attention. Don't alter the vehicle.

    The springs are supposed to carry the weight of the vehicle, and suspend
    it at ride height. I would recommend against changing your vehicle -- a
    vehicle's suspension, braking and handling dynamics are the product of a *system*
    that's designed to work with components of known properties. That said, the
    proper way to raise the ride height is to increase the spring rate in
    the rear. This can be accomplished in a variety of ways -- changing the
    springs, adding 'helper springs', adding air bag suspension 'helpers',
    etc. If you go this route, you will undoubtedly be adversely affecting
    your brake proportioning, which can be a deadly serious issue when
    towing a load (think about the words 'jackknife' and 'brake failure').

    The words "heavily loaded and trailer attached" combined with "'03 T&C"
    worry me, quite frankly. For occasional, light duty towing, a T&C is
    adequate. For packing the family up and towing a camping trailer, it
    ain't up to the job, and could be hazardous to you, your family, and
    anybody else on the road.

    /soapbox mode off

    Geoff, Jan 27, 2005
  5. Zork

    Joe Pfeiffer Guest

    Note that he's not proposing Nivomats.
    I've heard this claim before, but never quite understood it. The
    problem is, the loads that the shocks transmit to their mount points
    are greater than the ones the springs transmit: while the springs are
    transmitting the weight of the vehicle as you point out, it's the
    shocks that are transmitting all the high-amplitude transients. So it
    would seem like the shock mounts would have to be at least as strong
    as the spring mounts. Also, of course, the factory load-levelling
    system in the '70s used air shocks (at least, on my Newport).
    Here you've got an undoubtedly valid point.
    Joe Pfeiffer, Jan 27, 2005
  6. Er...OK. I'll take your word for it, though I've certainly seen it done
    often enough to have concluded it was a standard and acceptable practice.
    Perhaps as you say those who got away with it were just lucky, or perhaps
    the ability to do this (regardless of official sanction) was contingent
    upon overly-engineered shock mounts that are no longer commonly found.
    ....except to aim the headlamps downward so they're not pointing up in the
    sky (and other drivers' eyes).
    Now, this is overstating the case rather severely. People have been
    successfully installing different springs, different shocks, etc. for
    *years*. As long as the components are thoughtfully selected, there's
    seldom a problem and often an improvement.
    C'mon, now you're *really* laying it on thickly.
    Me too, if for no other reason than the ability of the transaxle to
    withstand such service.
    Daniel J. Stern, Jan 27, 2005
  7. Zork

    Steve Guest

    Because its bogus.
    I love it when reality intrudes on silly statements :)

    My '73 Satellite manual mentions both dealer-installed air-shocks and
    dealer-installed coil-over load levellers. All of the big-3 had similar
    "towing packages" with coil-overs or leveller. In fact my car has run
    most of its 400,000 miles with coil-overs since it used to do trailer
    towing duty and still gets called on to act like a pickup truck
    sometimes. I can truthfully say that my Satellite is slower with a 440
    in it than just a 318... of course the 440 (bare block) was riding in
    the trunk on the way to the machine shop :)
    Steve, Jan 27, 2005
  8. Zork

    Geoff Guest

    Steve, I'll defer to your greater engineering knowledge 'most every
    time. I do know what I've been taught, but sometimes the actual physics
    behind it is a bit murky.

    That said, why not just use air shocks to suspend the vehicle? Why use
    leafs or coils at all? (My guess: it's too much to ask of a shock
    absorber to both suspend *and* dampen suspension movement. But it's a
    guess. I know that I've seen many air shocks bent nearly in half.)

    (Notwithstanding Lincoln's air bag suspensions, which can frequently be
    seen in complete failure around here.)

    Again, a guess: in the typical situation, the transient load is shared
    between the springs and shocks. Perhaps raising a vehicle with the
    shock absorbers affects the amount of the load that is shared, placing a
    much larger proportion on the shock absorber mounting points. And
    remember, we're talking about a minivan, not a Satellite, which may well
    have been engineered with the idea that the load on the shock absorbers
    could increase dramatically beyond normal in towing situations.

    Geoff, Jan 28, 2005
  9. Zork

    Geoff Guest

    Daniel J. Stern wrote:

    I believe the key words here are 'thoughtfully selected'. I question
    the extent to which this is possible, but I'll agree that you make a
    good point.
    There's tolerance in every design for foreseeable abuse, as I understand
    it. Start changing the design significantly, and it's easy to imagine
    secondary and tertiary effects that aren't easily predicted.

    Perhaps the OP is a mechanical engineer. Maybe he's been
    professionally installing trailer hitches for half a lifetime. I dunno.
    My own father-in-law drove a pickup truck for years with 1-ton overload
    springs installed on his half-ton Chevy pickup, and used it to tow a
    10,000 pound camper all over hell's half-acre. With a homebrew
    drivetrain, to boot. I wouldn't describe him as an engineer, or even
    particularly well educated, for that matter. It worked...but I'll be
    damned if I'd call it a safe design. Thankfully, he apparently never
    got into a serious accident-avoidance situation.

    Another relative...another camper, this time being pulled behind a
    half-ton Chevy G-series van. Came over the hill doing about 45MPH,
    discovered that a.) the road curved and b.) had a stopsign about 200
    yards away from the crest. One thing lead to another, the remote
    control for the trailer brakes was out of reach, and before she knew
    what was happening, the thing was sideways, then ass-over-teakettle.
    Destroyed the van, the camper, and nearly killed everyone inside the
    van. The van was overloaded, the trailer brakes were thought to be
    adequate compensation. They weren't.

    I take the towing safety stuff seriously as a result.

    Geoff, Jan 28, 2005
  10. Zork

    Steve Guest

    I will 100% agree that in a conventional spring/shock combination, the
    shock mount points should not REPLACE the springs. But adding a set of
    300-lb "load levellers" is very different than suspending the whole back
    half of the car on the shock mount points. And I never said that it
    wasn't stupid to "jack up" a car with air shocks. Again, that is very
    different than simply levelling a load with them.

    I can't speak directly to minivans, never having owned one. But I
    *thought* that load-levelling shocks were still a factory option with
    them. If not, then I wouldn't try it for exactly the reason you mention.
    Steve, Jan 28, 2005
  11. Zork

    KaWallski Guest

    Dang it Stern, Shock absorbers are just that, shock absorbers. LOL

    If you have a trailer towing package your rear leafs or coils are going to
    be designed for increased load.
    Incrementally heavier loads. that is why the arcs of the springs are

    If you overwhelm the stock springs with too much load then your vehicle is
    not going to be suddenly "all better" when you add air-shocks. If anything
    your vehicles rear end will bounce around due to the lack of shock
    absorbtion if you install air shocks.

    Joe P. wuz correct - shock mounts are NOT meant to bear the weight and
    forces induced by loads. That is because SHOCK are not meant to bear the
    weight - only to reduce rebound and harmonic bounce.

    Airshocks never were designed for anything less than trouble. BECAUSE - they
    are solving the symptom and NOT the cause.

    The only way to fix heavy hitch problems are to reduce or reload
    (redistribute the load) of your trailer so tongue weight is not exceeding
    capacity or to respring your vehicle to accomodate heavier hitch weights.

    To correct vehicle level problems you have to install a airbag system ot
    other adjustable system such as that used in the newer Lincoln Navigators,
    (self leveling)

    Zork asked for a simple fix for a problem that is not easily fixable unless
    he was within capacity, and can learn to live with high beam flashes..

    Are you suggesting longer shakle assemblies and airshocks? lol.
    KaWallski, Jan 29, 2005
  12. Actually, no. They're nothing of the sort. They are oscillation dampers.
    The term "shock absorber" is quite a misnomer.
    Daniel J. Stern, Jan 29, 2005
  13. Zork

    Joe Pfeiffer Guest

    Assuming you mean me, there was a mis-attribution somewhere (and my
    server seems to have missed a good part of this thread). What I said
    was that I've never understood that claim: since the shocks have to
    handle the high-force transients, I would expect their mounts to be *at*
    *least* as sturdy as the spring mounts. I also pointed out that the
    factory load-leveller system of the 1970s (in particular, the one on
    my Newport) used air shocks.
    Joe Pfeiffer, Jan 29, 2005
  14. Zork

    KaWallski Guest


    OKAY, then redefining is what you want?

    They (Shocks) are either or both of Shock absorbers or Oscillation dampers.
    They are STILL NOT SPRINGS or LOAD-BEARING devices.


    Install or order springs for the load and shocks for the bounce.

    DO NOT ORDER AIR-SHOCKS to counter improper loading of trailer. ( as you had
    so casually suggested )
    KaWallski, Jan 29, 2005
  15. Zork

    Matt Whiting Guest

    I'd call them motion dampers. The motion doesn't have to be oscillatory
    in nature.

    Matt Whiting, Jan 29, 2005
  16. Zork

    Bill Putney Guest

    I much prefer the more technical term "bump stopping thingies".

    Geez - you'd think a complex formula could be summed up in an
    approximate two-word name for something!! At least my attempt uses
    three words - 1/3 again as much ability to define complex equations.

    Bill Putney
    (To reply by e-mail, replace the last letter of the alphabet in my
    adddress with the letter 'x')
    Bill Putney, Jan 29, 2005
  17. Zork

    Bob Hewitt Guest

    There has been no mention of the "Torsion Bars" being used on the
    trailer. These must be adjusted to the proper level.

    Another point is, We would never pull a trailer heavier than the tow
    vehicle. Bob
    Bob Hewitt, Feb 10, 2005
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