Pneumatic Shocks for a Russian UAZ Simbir

Hi all,

I own a Russian SUV, a consumer version based on their military jeep
series. It has a ton of unsprung weight (solid axles front and back
built pretty heavy). The Russian's use oil-based shocks on their cars
for the most part, this vehicle included.

The large amount of unsprung weight plus the use of oil based shocks
seems to be causing excesive "jiggling" whenever we run across one of
the many bumps here in Armenia. I've had the shocks re-worked recently
(rubber seals replaced, oil replaced), and tried various levels of air
pressure in the tires but am pretty much at a dead end there.

I'm considering trying to get pneumatic shocks instead. They don't
make them for this vehicle, so I'd have to either find a similar
vehicle (not necessarily so hard since they tended to copy a lot from
Toyota) or order some custom shocks.

Questions:
1) Are pneumatic shocks better for a heavy vehicle, specifically one
with significant unsprung weight?
2) How would I go about determining if a another vendor's shocks would
work on my vehicle?
3) If I need to order custom shocks I ned some recommendations on
vendors...

Thanks all,
B. Jetter - without the x's at:

> wrote in message
ups.com...
> Hi all,

My response is not an answer to your post, but a show of interest. Maybe
someone with
a lot more knowledge about this sort of situation can give you better help.
I have earmarked
this thread so I can follow it...

Are you able to purchase a wide selection of shock absorbers in Armenia? If
one could, and the
cost were not exhorbitant, I might be tempted to cobble up some new brackets
and adapt multiple
shock installations where possible. (Although this would be an exercise in
trial and error, and might
not achieve anything at all.)

> wrote:
>
>I own a Russian SUV, a consumer version based on their military jeep
>series. It has a ton of unsprung weight (solid axles front and back
>built pretty heavy). The Russian's use oil-based shocks on their cars
>for the most part, this vehicle included.
>
>The large amount of unsprung weight plus the use of oil based shocks
>seems to be causing excesive "jiggling" whenever we run across one of
>the many bumps here in Armenia. I've had the shocks re-worked recently
>(rubber seals replaced, oil replaced), and tried various levels of air
>pressure in the tires but am pretty much at a dead end there.

The notion here is that the oil shocks are tuned to a particular frequency
and the frame of the vehicle has a natural resonant frequency as well, and
the two points need to be far apart from one another.

>I'm considering trying to get pneumatic shocks instead. They don't
>make them for this vehicle, so I'd have to either find a similar
>vehicle (not necessarily so hard since they tended to copy a lot from
>Toyota) or order some custom shocks.

Or make some adaptors. But first, you probably want to find out what
putting them on is going to do to the system resonance, and if your
effective damping will be getting better or worse.

First thing I'd do is try varying the viscosity of the oil in the oil
shocks and see how the ride changes. That at least will tell you what
direction you need to be going in.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

> wrote:
>
>Are you able to purchase a wide selection of shock absorbers in Armenia? If
>one could, and the
>cost were not exhorbitant, I might be tempted to cobble up some new brackets
>and adapt multiple
>shock installations where possible. (Although this would be an exercise in
>trial and error, and might
>not achieve anything at all.)

I think this IS a good idea, but you need to be careful about the shocks that
you pick. I think if you pick three different sets of shocks that are
far enough apart, you might be able to figure out what basic range you want
to be in.

You might ALSO consider variable gas shocks, which would give you a lot of
options to tweak things.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

wrote in article
. com>...
> Hi all,
>
> I own a Russian SUV, a consumer version based on their military jeep
> series. It has a ton of unsprung weight (solid axles front and back
> built pretty heavy). The Russian's use oil-based shocks on their cars
> for the most part, this vehicle included.
>
> The large amount of unsprung weight plus the use of oil based shocks
> seems to be causing excesive "jiggling" whenever we run across one of
> the many bumps here in Armenia. I've had the shocks re-worked recently
> (rubber seals replaced, oil replaced), and tried various levels of air
> pressure in the tires but am pretty much at a dead end there.
>
> I'm considering trying to get pneumatic shocks instead. They don't
> make them for this vehicle, so I'd have to either find a similar
> vehicle (not necessarily so hard since they tended to copy a lot from
> Toyota) or order some custom shocks.
>
> Questions:
> 1) Are pneumatic shocks better for a heavy vehicle, specifically one
> with significant unsprung weight?

First of all, I suspect you do not understand shock absorber design.

I believe you are referring to "Gas shocks" as "pneumatic."

Fact of the matter is that "Gas shocks" are simply hydraulic shocks in
which the fluid pressurized - usually by nitrogen.

The concept is that the pressure will keep the fluid from foaming.

Picture a bottle of Coca-Cola.

Shake it just a little.

As long as it is capped, it looks okay.

Open the cap and release the pressure, and it foams up.


> 2) How would I go about determining if a another vendor's shocks would
> work on my vehicle?

Most shock catalogs have size and mount information.

You might luck out in choosing a shock from a heavier vehicle that is the
same length and has the same mounts as your vehicle.

You REALLY cannot tell much by "seat-of-the-pants" trial and error.

There MAY be a professional race team in Armenia that owns a shock absorber
dynamometer. THAT is the tool that gives you shock pressure comparison
information.

Without a dyno, it will be difficult - if not impossible - to "tune" your
shocks.


> 3) If I need to order custom shocks I ned some recommendations on
> vendors...

Probably best to go with one of the racing manufacturers such as Penske,
Ohlins and others.

Most of the major shock manufacturers are into Monster Truck shocks -
which, I would guess, might be the best route for you to go - depending on
your OEM shock size.

Surf the web for Monster Truck Shocks, and get in touch with one-or-more of
the manufacturers.

Give them your weights and specs, and they SHOULD be able to design
something that'll work for you.

"*" > wrote in message
news:01c6b033$362123c0$d696c3d8@race...

>
> You REALLY cannot tell much by "seat-of-the-pants" trial and error.
>
> There MAY be a professional race team in Armenia that owns a shock
absorber
> dynamometer. THAT is the tool that gives you shock pressure comparison
> information.
>
> Without a dyno, it will be difficult - if not impossible - to "tune" your
> shocks.


Admittedly, all the bells and whistles equipment and software make this sort
of project
much much easier.

To say that it is impossible to revamp one's shock system without it goes
against the
spirit of the hot rodder. Difficult and time consuming...that is more like
it.

Unfortunately, in many countries, there is a lack of almost every part,
tool, and equipment
except resourcefulness. One works with what one has.

I have never been to Armenia, and have no idea what is available, but wish
you the best
in your project.

>
> To say that it is impossible to revamp one's shock system without it goes
> against the
> spirit of the hot rodder. Difficult and time consuming...that is more like
> it.

Thanks for the encouragement. This is definitely a part of the world
for trial and error.

The current rear shocks come from the Soviet military jeep stock; the
front shocks come from a Volga car - and that's standard from the
factory. Somehow I doubt I can do much worse :-)

>
> Unfortunately, in many countries, there is a lack of almost every part,
> tool, and equipment
> except resourcefulness. One works with what one has.
>
> I have never been to Armenia, and have no idea what is available, but wish
> you the best
> in your project.

wrote:
> >
> > To say that it is impossible to revamp one's shock system without it goes
> > against the
> > spirit of the hot rodder. Difficult and time consuming...that is more like
> > it.
>
> Thanks for the encouragement. This is definitely a part of the world
> for trial and error.
>
> The current rear shocks come from the Soviet military jeep stock; the
> front shocks come from a Volga car - and that's standard from the
> factory. Somehow I doubt I can do much worse :-)

I have to ask if there's a communication barrier here. when you say
this Russian Jeep-like vehicle uses "oil shocks" and then go on to say
that they are rebuildable, does that mean that they are the older type,
lever-arm shocks? and you are considering retrofitting what were
called "aircraft-type" tubular shocks back when they were first
introduced? I have to admit knowing nothing about any Russian vehicle
except that they had a limo that looked scarily like a stretched
version of a '56 Packard

nate

> I have to ask if there's a communication barrier here. when you say
> this Russian Jeep-like vehicle uses "oil shocks" and then go on to say
> that they are rebuildable, does that mean that they are the older type,
> lever-arm shocks? and you are considering retrofitting what were
> called "aircraft-type" tubular shocks back when they were first
> introduced? I have to admit knowing nothing about any Russian vehicle
> except that they had a limo that looked scarily like a stretched
> version of a '56 Packard
>
> nate

Nate,

The shocks are probably better discribed as "liquid" - some type of
oil, but I've never seen the oil, so let's just say it's carbon based.
By rebuilding, I mean the seals replaced, some type of valve inside
adjusted for flow, and the "oil" flushed and refilled.

Afraid I don't know the term "tubular shocks", although the picture at
http://www.vanpeltsales.com/FH_web/F...47-48_Tube.jpg
looks almost exactly like my shocks.

Thanks, Brian

wrote:
> > I have to ask if there's a communication barrier here. when you say
> > this Russian Jeep-like vehicle uses "oil shocks" and then go on to say
> > that they are rebuildable, does that mean that they are the older type,
> > lever-arm shocks? and you are considering retrofitting what were
> > called "aircraft-type" tubular shocks back when they were first
> > introduced? I have to admit knowing nothing about any Russian vehicle
> > except that they had a limo that looked scarily like a stretched
> > version of a '56 Packard
> >
> > nate
>
> Nate,
>
> The shocks are probably better discribed as "liquid" - some type of
> oil, but I've never seen the oil, so let's just say it's carbon based.
> By rebuilding, I mean the seals replaced, some type of valve inside
> adjusted for flow, and the "oil" flushed and refilled.
>
> Afraid I don't know the term "tubular shocks", although the picture at
> http://www.vanpeltsales.com/FH_web/F...47-48_Tube.jpg
> looks almost exactly like my shocks.
>
> Thanks, Brian

OK, those are common modern-style tubular shocks... instead of trying
to buy shocks for your application, perhaps (since you say you have the
"correct" shocks now) measure the compressed and fully extended length
of your shocks and try to buy some by spec instead of by application.
However, I think the idea of using a more viscous oil is a good one,
you might want to check with a motorcycle shop first (as motorcycles
tend to use shocks built into the forks which therefore are by nature
serviceable, as opposed to most tubular-style automotive style shocks
which are sealed and are simply replaced when they're worn out) to see
if you can get an assortment of fluids in various viscosities and try
those and see if one of those makes you happy; if that does not work
perhaps a good off-road shop could match up a heavier-duty shock to
your application if you give them the specs of the shocks you have.
I'm assuming that when you say "almost exactly" that the mounting
method at the top and bottom is the same as well? (bolt through an
eye, with rubber bushings) there are other options (bayonet mount etc.)
but that one is fairly common.

good luck,

nate