Outer Limits 4x4 Board

Shock adsorbers generally dont work upside down, or sideways unless they are monotube or remote canister.

The gas used to allow for the shaft volume floats around and makes the valving rates go all over the place.

Motorcycle steering dampers get around this by runing the shaft all the way through and out the other end so the volume never changes. Monotube and remote canister shocks islate the gas bahind a piston.

But how does a stock Toyota or my OME damper manage it?

Thanx
Paul

me3@neuralfibre.com wrote:Shock adsorbers generally dont work upside down, or sideways unless they are monotube or remote canister.

The gas used to allow for the shaft volume floats around and makes the valving rates go all over the place.

Motorcycle steering dampers get around this by runing the shaft all the way through and out the other end so the volume never changes. Monotube and remote canister shocks islate the gas bahind a piston.

But how does a stock Toyota or my OME damper manage it?

AFAIK, the gas in shock absorbers, typically nitrogen, usually has one real purpose, and that is to keep the fluid in the shock absorber from frothing up as much during rapid articulation.

It's the movement of fluid that does the damping, the gas just helps the fluid work better and not go foamy.

So, I don't have a specific answer for your question but I think you are on the wrong track in focusing on the gas. I don't really see why it would be technically difficult to ensure that fluid flow through the valving is unaffected by the angle of the damper though. However, I may have missed something in your question.

chimpboy wrote:

me3@neuralfibre.com wrote:Shock adsorbers generally dont work upside down, or sideways unless they are monotube or remote canister.

The gas used to allow for the shaft volume floats around and makes the valving rates go all over the place.

Motorcycle steering dampers get around this by runing the shaft all the way through and out the other end so the volume never changes. Monotube and remote canister shocks islate the gas bahind a piston.

But how does a stock Toyota or my OME damper manage it?

AFAIK, the gas in shock absorbers, typically nitrogen, usually has one real purpose, and that is to keep the fluid in the shock absorber from frothing up as much during rapid articulation.

It's the movement of fluid that does the damping, the gas just helps the fluid work better and not go foamy.

So, I don't have a specific answer for your question but I think you are on the wrong track in focusing on the gas. I don't really see why it would be technically difficult to ensure that fluid flow through the valving is unaffected by the angle of the damper though. However, I may have missed something in your question.

yeh im with chimpboy, its the oil through the valves doin the work not the gas

A shock adsorber works by passing oil thrugh valves in a piston. Pretty simple (variable rates make it more complex). There is no air involved in thie equation whatsoever.

The problem is the shaft. As it enters the shock it has to displace some oil. Oil is like most liquids nearly incompressible. You need some place for the displaced oil to go.

You could solve the problem by running the shaft out the other end like a motorcycle steering damper - this works very well. BUT, it's likely to be in the way and / or get damaged easily.

So they put a gas space in shocks to allow for the change in volume, gas being compressible.

This gas is either in a seperte tube on the outside (twin tube shock) and kept there by gravity,
or in the same tube as the rod/piston (monotube), seperated by a second floating piston.

The gas can cause problems with frothing. Further, seperate to the gas frothing, hot oil can boil, again frothing itself. Pressurising the shock reduces these problems somewhat. Koni makes some of the best shocks around, and they are not pressurised. Their valving and design heats the oil much less, at increased costs. Non pressurised shocks tend to be more predictable in behaviour.

Now - steering dampers.
I know it's not pressurised, as that would force it open all the time, making the car steer to one side.
It could be a monotube, they work fine on their side, but after all the ranting that Rancho does about the evils of monotube - I doubt it. (I like Bilstein, and they are monotube).
The "look" like a twin tube, Outside doesn't seem solid like a bilstein. I also beleive that monotube are more expensive to make, that's why most factory shocks are twin tube.
Finally the floating piston and gas space add to the length of a monotube, making it possibly not have enogh travel for a steering application?

Basically, if the steering damper is a monotube, no worries, makes sense. Suprising though as it would be the only one on the car.
If it's a twin tube, then how does it keep the air out of the oil?

Paul

I think you are overstating the work a steering damper does.

I imagine they are basically a foam cell type shock. They're not very sophisticated, they only run at very low velocity and should never even begin to get warm.

My Gwagen had a monotube steering damper, which is pretty dumb because it doesn't take much of a hit to wipe it out.


Steve.

OK - rang Jamie at GSA Wholesale Suspension as they are about the most knowledgeable suspension guys I have ever met (it's all they do)

Dual tube Steering dampers run the gas in a "plastic bag" in the outher tube to keep it isolated, then have a 100% oil fill. They are non pressurised for obvious reasons. Bag failure is a very low occurance suprisingly. Foam type steering dampers still use the bag as the closed cell foam still "leaks" a little.
Bilstein do make a monotube version that has a very low pressure to make the flaoting piston work.

Interesting side note: they got back a set of Bilstein's from front suspension of Disco where paint had turned brown from heat. Customer wanted warranty on them (and got it). est operating temp in excess of 350deg. Shocks were not seized, but definatley no longer in spec due to internal thermal damage to seals etc.

Paul

me3@neuralfibre.com wrote:Interesting side note: they got back a set of Bilstein's from front suspension of Disco where paint had turned brown from heat. Customer wanted warranty on them (and got it). est operating temp in excess of 350deg. Shocks were not seized, but definatley no longer in spec due to internal thermal damage to seals etc.

What could possibly do that... long-term and continuous shudder in the steering or something?

Corrugations, big ones, at high speed, for long time (hours), with high tyre pressures.

Further, good shocks actually try to control the axle. Monroe's would have spat a valve early and just floated from there. Once cooked they aren't working, hence not getting hotter. The Bilsteins kept on working, hotter and hotter and hotter. I know rallying we never managed to get them to fade, and not much harder on suspension than rallying (cept Off-Road racing buggies etc)

Same thing that snapped 6 wheel studs on a cruiser a mate stopped to help at Cape York.

Paul

Ah, your side note, Paul, referred to the "wheel" shocks, not the steering damper... That might have been the assumption Chimpboy made?

With the new-ish toughdog adjustable dampner that is being advertised...

Anyone ever thought of bolting on two rancho/tough dog 5x or 9x shocks in place (both shocks are bolted in opposite positions of each other, so that together the two shocks are absorbing rebound in both directions). Then adding an adjustable in car kit? So that you can adjust the steering shock absorbtion on the fly in the cabin.

That nearly be a marketable product...

bushy555 wrote:With the new-ish toughdog adjustable dampner that is being advertised...

Anyone ever thought of bolting on two rancho/tough dog 5x or 9x shocks in place (both shocks are bolted in opposite positions of each other, so that together the two shocks are absorbing rebound in both directions). Then adding an adjustable in car kit? So that you can adjust the steering shock absorbtion on the fly in the cabin.

That nearly be a marketable product...

You may want to re-read the very start of the first post that said "Dual Tube shocks don't work on their side".
Rancho are dual tube and spend much time convincing people of the supposed evils of monotube shocks.

Paul

Their biggest "evil of monotube" is just that when you dent one its basically stuffed because you can seize the piston inside.

You would find a steering damper probably isnt doing a whole lot when your driving on the road anyway because the rate of compression/reboud (ie, left and right movement in this application) isnt fast at all. If you have some serious alignment issues that are causing shimmying or wobbling then the damper may be able to suppress it slightly but you need to solve these external problems first before relying on a damper to fix it. Your only going to cook the damper and reduce its working lifespan.

When I wasnt running one, due to massacring my last one on a rock, the biggest difference I noticed was running it offroad when you got one wheel stuck in a rut or on an angled edge and the wheel would just rip right out of your hands. Once I re-fitted a new damper to the steering this never happened again. The damper slowed the "ripping out of my hands" proces right down. This I believe is the biggest effect the damper has on your steering.

To answer the question how does the shock run on its side? Fit a gas bladder (or plastic bag as it was referred to before) of a fixed shape and pressurise it, fill the rest of the shock completely with oil and that gas bladder will allow enough extra space for rod movement. I would draw a picture but i just cant be bothered. Think of it like a Duracell battery on its side. The gold bit up the top end is the bladder with gas that has a relatively fixed shape but allows compression of the gas. The black portion is 100% filled with oil and this is where the piston travels.

Hope that helps.