Derek Ward
Active Member
Konis get very good feedback on here but they're pricey. Bilsteins also have a good name. Steer clear of anything labelled 'heavy duty' or 'uprated'. They'll destroy the ride whilst doing nothing for the handling. Both the Konis and Bilsteins have increased damping on the rebound whereas the cheaper shocks (or dampers to give them their correct name) do not. They just stiffen up the compression. I'd say if you can't afford the Konis, go for standard.
That should open a bag of worms.
That should open a bag of worms.
Konis get very good feedback on here but they're pricey. Bilsteins also have a good name. Steer clear of anything labelled 'heavy duty' or 'uprated'. They'll destroy the ride whilst doing nothing for the handling. Both the Konis and Bilsteins have increased damping on the rebound whereas the cheaper shocks (or dampers to give them their correct name) do not. They just stiffen up the compression. I'd say if you can't afford the Konis, go for standard.
That should open a bag of worms.
Errmm? Standard shock absorbers only damp on the rebound not on compression. Thats why there easy to push in and hard to pull out. The more expensive gas shocks give some resistance on compression. Which makes the damped rebound a little quicker.
Derek Ward
Active Member
They damp both ways surely. All the shockers I've ever had have been stiff pushing in and pulling out (unless they were knackered). More expensive shockers just do it better.
Below is taken from the RPI website:
''Koni have, over the years, gained a substantial reputation for quality and excellence in the production of suspension units. Instead of supplying a shock absorber to fit a whole range of vehicles, Koni shocks are developed and valved for individual applications. To understand the main advantage of the Koni shocks when used on a Range Rover, it is necessary to understand what is happening when you are cornering. When cornering, the shock absorber on one side is being compressed and is trying to hold the weight forces of the vehicle. Heavily uprating the shock absorber will partially resist this, but when uprating is excessive it causes normal driving to be very harsh. The shock absorber on the other side, however, is being stretched, and standard shocks offer very little resistance to this. The Koni difference is that these shocks are designed to not only resist being pushed down, but are valved to strongly resist the lifting force (stretching), therefore controlling body roll while retaining a very comfortable ride. ''
Below is copied from the Bilstein website:
''Shock absorbers and how they work
The shock absorbers reduce and slow down the vibrations from the springs, which is why technically they are correctly referred to as vibration dampers. Vibration dampers convert kinetic energy into thermal energy through fluid friction. This involves the flow of oil being slowed down by the valve passages inside the damper. The valve passages in the shock absorber are specifically designed to ensure that the vibrations transmitted by the spring are reduced right from the start. The shock absorbers can heat up to between 100 and 120oC in the process.
Interaction between spring and damper
When a car passes over an obstacle, this first has an impact on the spring, which must not be hampered by excessive damping performance on the part of the shock absorber. When a car passes over a bump in the road, for example, the obstacle forces the wheel up into the wheel housing. In the process, the spring is compressed. The shock absorber is now in its compression stage. Once the spring has levelled out the obstacle, the shock absorber has to slow down the movement of the spring as it releases its tension with great force. The shock absorber is now in its rebound stage. Compression stage (compressing of the springs and the damper, e.g. when driving over bumps in the road) = usually approx. 25% of the damping force. Rebound stage (when the spring pulls the damper apart) = usually approx. 75% of the damping force.
Conclusion: A spring with a higher spring rate (sport or lowered spring) will only work at its best in conjunction with the appropriate high-performance or sports shock absorber.''
Not sure I understood what you meant when you said 'Which makes the damped rebound a little quicker'?
We were both nearly right I suppose.
Below is taken from the RPI website:
''Koni have, over the years, gained a substantial reputation for quality and excellence in the production of suspension units. Instead of supplying a shock absorber to fit a whole range of vehicles, Koni shocks are developed and valved for individual applications. To understand the main advantage of the Koni shocks when used on a Range Rover, it is necessary to understand what is happening when you are cornering. When cornering, the shock absorber on one side is being compressed and is trying to hold the weight forces of the vehicle. Heavily uprating the shock absorber will partially resist this, but when uprating is excessive it causes normal driving to be very harsh. The shock absorber on the other side, however, is being stretched, and standard shocks offer very little resistance to this. The Koni difference is that these shocks are designed to not only resist being pushed down, but are valved to strongly resist the lifting force (stretching), therefore controlling body roll while retaining a very comfortable ride. ''
Below is copied from the Bilstein website:
''Shock absorbers and how they work
The shock absorbers reduce and slow down the vibrations from the springs, which is why technically they are correctly referred to as vibration dampers. Vibration dampers convert kinetic energy into thermal energy through fluid friction. This involves the flow of oil being slowed down by the valve passages inside the damper. The valve passages in the shock absorber are specifically designed to ensure that the vibrations transmitted by the spring are reduced right from the start. The shock absorbers can heat up to between 100 and 120oC in the process.
Interaction between spring and damper
When a car passes over an obstacle, this first has an impact on the spring, which must not be hampered by excessive damping performance on the part of the shock absorber. When a car passes over a bump in the road, for example, the obstacle forces the wheel up into the wheel housing. In the process, the spring is compressed. The shock absorber is now in its compression stage. Once the spring has levelled out the obstacle, the shock absorber has to slow down the movement of the spring as it releases its tension with great force. The shock absorber is now in its rebound stage. Compression stage (compressing of the springs and the damper, e.g. when driving over bumps in the road) = usually approx. 25% of the damping force. Rebound stage (when the spring pulls the damper apart) = usually approx. 75% of the damping force.
Conclusion: A spring with a higher spring rate (sport or lowered spring) will only work at its best in conjunction with the appropriate high-performance or sports shock absorber.''
Not sure I understood what you meant when you said 'Which makes the damped rebound a little quicker'?
We were both nearly right I suppose.
kernowdragon
Well-Known Member
I changed mine recently from the tired OEM ones to Terrafirma's. They're a bit more pricey than the OEM ones, but not nearly as much as the Koni''s or Bilstein's. I've found them very good, a hugely improved ride on and off road, and they're capable of an additional 2" of suspension travel if required. I found them on fleabay at what I felt was a sensible price and am very pleased with them.
klf400
Active Member
fit konis it will transform the rangie , you will wish you changed them earlier ,£75 a corner not cheap but i think worth every pennyKonis get very good feedback on here but they're pricey. Bilsteins also have a good name. Steer clear of anything labelled 'heavy duty' or 'uprated'. They'll destroy the ride whilst doing nothing for the handling. Both the Konis and Bilsteins have increased damping on the rebound whereas the cheaper shocks (or dampers to give them their correct name) do not. They just stiffen up the compression. I'd say if you can't afford the Konis, go for standard.
That should open a bag of worms.
if cost comes into it fit oem
They damp both ways surely. All the shockers I've ever had have been stiff pushing in and pulling out (unless they were knackered). More expensive shockers just do it better.
Below is taken from the RPI website:
''Koni have, over the years, gained a substantial reputation for quality and excellence in the production of suspension units. Instead of supplying a shock absorber to fit a whole range of vehicles, Koni shocks are developed and valved for individual applications. To understand the main advantage of the Koni shocks when used on a Range Rover, it is necessary to understand what is happening when you are cornering. When cornering, the shock absorber on one side is being compressed and is trying to hold the weight forces of the vehicle. Heavily uprating the shock absorber will partially resist this, but when uprating is excessive it causes normal driving to be very harsh. The shock absorber on the other side, however, is being stretched, and standard shocks offer very little resistance to this. The Koni difference is that these shocks are designed to not only resist being pushed down, but are valved to strongly resist the lifting force (stretching), therefore controlling body roll while retaining a very comfortable ride. ''
Below is copied from the Bilstein website:
''Shock absorbers and how they work
The shock absorbers reduce and slow down the vibrations from the springs, which is why technically they are correctly referred to as vibration dampers. Vibration dampers convert kinetic energy into thermal energy through fluid friction. This involves the flow of oil being slowed down by the valve passages inside the damper. The valve passages in the shock absorber are specifically designed to ensure that the vibrations transmitted by the spring are reduced right from the start. The shock absorbers can heat up to between 100 and 120oC in the process.
Interaction between spring and damper
When a car passes over an obstacle, this first has an impact on the spring, which must not be hampered by excessive damping performance on the part of the shock absorber. When a car passes over a bump in the road, for example, the obstacle forces the wheel up into the wheel housing. In the process, the spring is compressed. The shock absorber is now in its compression stage. Once the spring has levelled out the obstacle, the shock absorber has to slow down the movement of the spring as it releases its tension with great force. The shock absorber is now in its rebound stage. Compression stage (compressing of the springs and the damper, e.g. when driving over bumps in the road) = usually approx. 25% of the damping force. Rebound stage (when the spring pulls the damper apart) = usually approx. 75% of the damping force.
Conclusion: A spring with a higher spring rate (sport or lowered spring) will only work at its best in conjunction with the appropriate high-performance or sports shock absorber.''
Not sure I understood what you meant when you said 'Which makes the damped rebound a little quicker'?
We were both nearly right I suppose.
On standard oil filled shocker there is little resistance on the compression stroke. There has to be some as the piston is forced through the oil. On the rebound stroke the large valve arrangement which allowed oil to flow past the piston with reasonable ease on compression, closes. As the spring rebounds oil flows through much smaller holes so the rebound is damped. Rebound is controlled by the size of the holes the oil flows through. On a gas shock there is a positive pressure exerted on the piston to push it out. On compression this gas is further compressed. On the rebound this pressure assists the spring rebound, enabling the suspension to return to the ready position quicker whilst still being damped. On lowered suspension were there is little travel the shockers will generally be heavily gas assited and wider than standard because all their damping has to be done with a very short stroke. Which of course leads to a very harse ride. If shock absorbers were damped both ways you would be constantly at the dentist having your teeth replaced. And possibly in traction a substantial part of the year.
Derek Ward
Active Member
Where did you get them at for £75 each? Price seems to be nearer £90 to £120 on fleabay or is that just RPi prices?
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Derek Ward
Active Member
No. The gas has nothing to do with the damping. It's to stop the oil aerating. Also, as quoted above from the Bilstein website as above - compression = 25% of the damping force, rebound = 75%.
from the Bilstein website:
''Hydraulic shock absorbers
Nowadays, hydraulic shock absorbers are rarely used in today's automotive industry. From a technical point of view, this type of damper is a poor solution, because the oil contains approximately 10% air. Under load, the air and oil molecules separate (foaming/cavitation), resulting in a noticeable drop in the damping force - on longer journeys on country roads and motorways, a loss of up to 35% damping force can be measured. That means the wheels provide poorer road holding; only after a break does the damper regain its full force and the vehicle its original driving performance.
Gas pressure shock absorbers
With gas pressure shock absorbers, this loss of damping force does not occur. The use of nitrogen ensures that the shock absorber oil is permanently under pressure, thereby preventing foaming, even under load. As a result, the driving performance of a car fitted with gas pressure shock absorbers can be precisely defined and remains reliably stable, whatever the situation; this constitutes a substantial bonus in terms of safety. Gas pressure shock absorbers are available with either mono- or twin-tube technology. The proven twin-tube system represents top-class technology at an attractive price. The mono-tube system, on the other hand, is the technology of choice in motor sports and on standard sports cars. The comparatively larger effective area of the working piston ensures greater damping force and better handling. Optimum discharge of thermal energy into the atmosphere means consistent high performance can be achieved and the sturdy design provides maximum safety reserves in flexible fitting conditions, e.g. inverted technology.''
SpudH
Well-Known Member
I've Konis fitted all round and found them a substantial improvement.
The ride at motorway setting is firmer than before but the the ride at standard height is very good. Rebound control is so much better you wouldn't believe it with axle tramp over pot holes all but eliminated.
The ride at motorway setting is firmer than before but the the ride at standard height is very good. Rebound control is so much better you wouldn't believe it with axle tramp over pot holes all but eliminated.
Derek Ward
Active Member
The gas only stops the oil aerating - see the previous posts - it doesn't make them harder or softer. The valving inside does that. You'll probably find most shockers these days are gas filled. Ours being 10 years old + aren't. I'm still on the originals but the next big purchase (barring the usual breakdowns....) will be 4 x Konis. Personal choice and how much you want to pay. I bet the originals from Land Rover are pretty horrendous too.
If your suspension is standard at the moment, the Koni Heavy Track dampers may work for you. If you have non-standard (Arnott airspings, low profile rims or polybushes), then the ride will be too harsh.
The best way to get the p38 ride right is go Genuine or at least OEM. There are 2 Genuine Part airsprings available, one made by Dunlop and I think (because I've never seen them except on MicroCat) the others may be a Continental. Both airsprings have different part numbers for the dampers they use.
It is imporant to match the airsprings, and only Genuine Part dampers can do this.
Failing that, you can get hold of the OEM/Armstrong dampers very cheaply. They only last 4 years or so, but you can probably get a set of 4 Armstrongs for the price of one Koni.
The Koni's lack travel as well. They do over-extend to their limit on off road height.
Land Rover did a lot of testing a development before the launch in 1994 to ensure the p38 could deal with the powertrain upgrade. They continued this development as well after the launch. If you try using anything else, you upset the dynamics.
The best way to get the p38 ride right is go Genuine or at least OEM. There are 2 Genuine Part airsprings available, one made by Dunlop and I think (because I've never seen them except on MicroCat) the others may be a Continental. Both airsprings have different part numbers for the dampers they use.
It is imporant to match the airsprings, and only Genuine Part dampers can do this.
Failing that, you can get hold of the OEM/Armstrong dampers very cheaply. They only last 4 years or so, but you can probably get a set of 4 Armstrongs for the price of one Koni.
The Koni's lack travel as well. They do over-extend to their limit on off road height.
Land Rover did a lot of testing a development before the launch in 1994 to ensure the p38 could deal with the powertrain upgrade. They continued this development as well after the launch. If you try using anything else, you upset the dynamics.
I don't think i said the gas did have anything to do with the damping i said it assists rebound. If hydraulic dampers are not used in todays motor industry. Why do they all have oil in them being forced through small holes to give the damping effect? There is bound to be some resistance on the down stroke as the piston moves through the oil as i said before. But the idea is to stop bounce as the spring expands after compression. And not to stop the spring being compressed. Perhaps you could get someone from Bilstein to explain how an oil filled damper that relies on the resistance of oil flowing through a piston full of small holes for it's effect is not a hydraulic damper.
Derek Ward
Active Member
Aahhh you're splitting hairs here. By 'Hydraulic Shock Absorbers', they obviously mean those that aren't gas filled. And they state categorically what the gas is for and it's not to assist rebound. I agree with you that most of the damping on a standard shocker is on the rebound but not all - there is damping in compression. You have it from the horses mouth (Bilstein) above when they say 25% damping force is in compression and 75% on the rebound. In other words, they slow down the compression of the spring. And that is designed in, not just because of the stiction of the oil against the piston. If you don't believe Bilstein, who will you believe?
God, don't you just love a good deep and meaningful discussion
Aahhh you're splitting hairs here. By 'Hydraulic Shock Absorbers', they obviously mean those that aren't gas filled. And they state categorically what the gas is for and it's not to assist rebound. I agree with you that most of the damping on a standard shocker is on the rebound but not all - there is damping in compression. You have it from the horses mouth (Bilstein) above when they say 25% damping force is in compression and 75% on the rebound. In other words, they slow down the compression of the spring. And that is designed in, not just because of the stiction of the oil against the piston. If you don't believe Bilstein, who will you believe?
God, don't you just love a good deep and meaningful discussion
Derek there are shocks that can be adjusted for rebound or spring assistance by increasing the gas pressure. There are shocks that rely on gas pressure alone for springing. But they all use oil for damping and are all hydraulic dampers. No splitting of hairs. A gas filled shocker is still a hydraulic damper whether Blistein like it or not. Early Oleo legs used compressed air for springing and oil for damping. They now use Nitrogen to negate the corrosive properties of compressed air. You may be interested to know that the aircraft you go on your holidays in has no springs in it's undercart, but is suspended on compressed Nitrogen alone. Hydraulicly damped of course.
