Thread: More on Shocks ???

Hi Roscow

I run Bilsteins in my Defender and I pretty much hate them. Way too firm in my opinion.
Am also looking at other options if I cant revalve the existing units to ride softer.

Have you looked at any of the Tough Dog products?
Daz

<div class='quotetop'>QUOTE(Rosco &#064; May 16 2006, 02&#58;27 PM) Quoted post</div><div class='quotemain'>

What’s the general consensus of opinion on:
(1) Expected lifespan of OEM shocks
(2) Opinions on “EFS” shocks
(3) It is easy to tell it shocks are on the way out, but not yet stuffed (which would make it real easy)

Cheers

Rosco
[/b][/quote]

Hi Rosco,

Have you got a 90? I have a pair of rears (new from showroom) you could have. Is it the rears only?

I now run Tough Dogs in the rear only.

Trev.

<div class='quotetop'>QUOTE(disconut &#064; May 16 2006, 08&#58;08 PM) Quoted post</div><div class='quotemain'>
Hi Rosco,

Have you got a 90?
Trev.
[/b][/quote]


Thanks for the offer Trev, but the beast&#39;s a 110

Cheers cobber

Rosco

<div class='quotetop'>QUOTE(Rosco &#064; May 16 2006, 02&#58;27 PM) Quoted post</div><div class='quotemain'>

What’s the general consensus of opinion on:
(1) Expected lifespan of OEM shocks
(2) Opinions on “EFS” shocks
(3) It is easy to tell it shocks are on the way out, but not yet stuffed (which would make it real easy)

Cheers

Rosco
[/b][/quote]

Hi Rosco,

Have you got a 90? I have a pair of rears (new from showroom) you could have. Is it the rears only?

I now run Tough Dogs in the rear only.

Trev.

Hi Rosco
Ive been poking around on a few suspension posts as I need to upgrade my Disco2 as the shocks are shot.
From what Ive read the Bilsteins are the "ducks nuts" on a Landy,perhaps the firmer ones mentioned arent quite the right spec valving for what the owner wants.
From what Ive come to understand,(PLEASE CORRECT ME IF IM WRONG GUYS) the Bilsteins are a mono tube design compared to every one elses twin tube design.As I have read here and in mags many shocks fade quickly on rough ground,but the Bilsteins dont.In the previous 4WD Monthly mag they did a makeover on a brand new Pathhopefullyfinder and fitted Bilsteins.Their explanation of the benefit of the monotube design was the shock has a greater oil volume which is actually in contact with the outside layer compared to a twin tube having a lot less oil and being insulated to the outside area of the shock for cooling by the gas.Bilsteins still have gas but are different in design.
I guess this explaind why most love their Bilstiens,which are rebuildable as far as I know???? Im lookink at the Kings Springs +60mm and Bilstiens for BlackBetty,but waiting to see what the taxman is returning to me.Plus if anybody can go better on the springs,with others backing I will change that idea.
I hope Ive got my head around this finally guys,if you feel Ive got the wrong idea please say so.I want to get mine right first time around.
Andrew

<div class='quotetop'>QUOTE</div><div class='quotemain'>.Their explanation of the benefit of the monotube design was the shock has a greater oil volume which is actually in contact with the outside layer compared to a twin tube having a lot less oil and being insulated to the outside area of the shock for cooling by the gas.Bilsteins still have gas but are different in design.[/b][/quote]

Nope. A mono tube does dissipate heat more quickly compared to a basic twin tube, but not because the outer tube is insulated by gas. The outer tube also has oil in it, as well as air or nitrogen.

A mono tube is simply that. One working cylinder in which the piston (on which the valve shims are situated) plus the shaft move in. In a twin tube design, the working or pressure tube is a smaller tube inside of the outer body. When the damper shaft is compressed in both types, fluid is displaced by the volume of the shaft. In a twin tube type, this displaced fluid is forced through the foot (compression damping) valve into the outer tube which acts as a reservoir. In a mono-tube, the displaced fluid forces a floating piston that separates the high pressure nitrogen gas from the hydraulic fluid to further compress the gas to compensate for the volume taken by the shaft.
To dampen the energy released by the springs, the hydraulic fluid is forced through ports in the piston (and in the foot valve in a twin tube) and through shim and/or coil spring loaded valves which restrict the fluids flow which converts the energy from the spring into heat. In a mono-tube this heat in the oil is conducted through the wall and is disipated into the ambient air, wheras our twin tube damper has to pass the heat
through two cylinder walls, as well as the oil in the outer tube, taking longer.
In a mono-tube with the hydraulic fluid under high pressure from the nitrogen gas (Bilstein use up around 300psi) cavitation of the oil is less likely to occur, or at least happen at much higher fluid temperatures.
In a Bilstein, with a body OD of approx 51mm, the piston diameter is 46mm, whereas in say an OME Nitrocharger, the piston diameter inside the pressure tube is 35mm to allow for sufficient oil volume in the outer tube. In very simple terms, a (relatively) larger piston diameter results in a lower internal pressure (and temperature) for a given amount of damping. It also means that a mono-tube may be made more sensitive to very small shaft displacements.
A Bilstein can still cavitate and fade, it just takes longer than a comparable twin tube.

A twin tube can be made much more efficient at tolerating higher temperatures and less liable to incur cavitation by several means.
1. using a larger or expanded outer tube containing more oil.
2. using low pressure nitogen gas in the outer tube with the oil.
3. using a remote canister (eg. an OME LTR) which greatly increases the oil volume and uses a floating piston to seperate the nitrogen gas from the hydraulic fluid, eliminating, or at least dramatically reducing cavitation
4. Increasing the piston size and outer cylinder size to equal and exceed the size/volumes used in a standard type mon-tube. eg Koni Raid (42mm piston, 70mm outer body and Tough Dog Ralph, 53mm piston, 70mm outer body.)

A twin tube has these advantages over a mono-tube.
1. A big hit by a rock, etc on the outer tube is far less likely to render it inoperable as the piston isn&#39;t travelling inside the outer tube.
2. Superior bump (compression) damping due to the compression valving being seperate to the piston and not being influenced by large gas (nose) pressures.
3. Stronger/larger diameter piston rod as the piston rod in a mono-tube (generally 14mm) is made to displace the least amount of fluid and incur the least disturbance on the floating piston. (This can be overcome by using a remote canister to house the floating piston. Pure race mono-tubes can use 22mm shafts, but big &#036;&#036;&#036;&#036;.)
4. Superior open to closed length for a given application. A twin tube will extend further for a given compressed length, giving more wheel travel for a stock application.

These are the reasons why Koni tend to push their twin tube range over their mono-tubes (yes, they make both types) for off road use. The Koni Raid damper and OME LTR were aimed originally at the off road race market, however the vast majority of specialist off road race dampers are mono-tubes, but they are also a lot of money. Both designs have their pros and cons, you just have to weigh up what suits you and your type of driving best.

Thanks Rick130. That was very interesting and informative.

i have a s1 disco that i did a fair bit of reasearch on what shocks and springs to upgrade too (some of you will remember iwas thinking of rancho&#39;s) all i can say is i looked at all the options and weighed up everyones thoughts and experiances and went with King Springs +40mm and a full set of Tough dog Ralphs 53mm and i can honestly say the disco has never been so good to drive both on and off road, with or with out a load. I also replaced the steering damper with the 4way return to centre unit and would recomend that upgrade to all aswell Brilliant.