Thread: koni vs. bilsteins

The twin tubes shocks fade from airation as the gas and oil are not physically seperated, and gas passes through the shock valving a lot better than the oil. Bilstein is unable to airate as the gas is seperated from the oil by a piston. It makes no difference if the Bilstein is hot or cold apart from any changes in the viscosity of the fluid. I think this also allows the Bilsteins to run a stiffer valving which offers more control without frying. A Rancho on the stiffest setting lasts about 15-20mins on dirt before you throw it away.

I would advise against Konis.

I fitted Konis and heavier Lovells to my 300tdi Discovery to cope with a reasonably heavy load over Talawanna Track and CSR. The Konis lost all damping after less than a day, and did not return until after some hours on bitumen 3 weeks later. Vehicle was left constantly bottoming and unable to grip up sandhills. Soon after return I found 1 front spring broken and the other with stress cracks along coil.

The other vehicle on trip was a standard Defender wagon which carried more load and had no damping or clearance issues.

My previous vehicle was a 110 with Lovells and Konis. It also seemed to lose damping control over corrugations and fast dirt roads.

At this stage my vehicle has the original shocks fitted with raised Kings springs. I still would like better shock performance and am interested in standard Defender Boge units but am keen to hear other drivers experiences.

<span style="color:blue">from what ive heard from different landy owners......

i second what hiline said.....
and will fit some to lurch some time soon......
(hopefully if funds allow...as of monday i am officially unemployed.....)</span>

<div class='quotetop'>QUOTE</div><div class='quotemain'>The twin tubes shocks fade from airation as the gas and oil are not physically seperated, and gas passes through the shock valving a lot better than the oil[/b][/quote]

Its heat that causes the fluid to cavitate and airate. A mono-tube damper will do this as well, it's just that the boiling point of the fluid is raised dramatically by raising the pressure on the system thanks to the gas chamber and floating piston, and a mono-tube damper dissipates heat far better than a twin (or triple tube. Why do Rancho do this ??) Stick a remote can with a floating piston on a twin tube and it will equal a mono-tube in this area (OME LTR anyone )
Generally, the forces generated internally for a given amount of damping are less in a mono-tube damper vs a twin tube due to it's increased piston size (Bilstein 46mm, Koni Heavy track 33mm) but this isn't a problem in the spring rates and motion ratios used in road cars.
Where this first became a noted problem was in the days of Ground Effects F1 and the banning of sliding skirts. To overcome pitch and heave upsetting the underwing, wheel and spring rates went through the roof (the cars effectively becoming karts) and the motion ratios used on the rocker suspensions were so tiny, so the forces that needed to be generated by a 33mm piston to control a 1500+lb/in spring in rebound in a couple of millimetres of shaft movement were becomming excessive. A 46mm piston was able to build the damping force quicker, with less internal pressure, and the dampers weren't fading (as badly) after a 2hr GP.
Of course, the off-road racing blokes had been aware of this for the prior ten years. It's interesting that motion ratios have increased dramatically in the last ten years, and small piston dampers are back in vogue in open wheel race cars (smaller=lighter & less internal friction)

Koni also has an adjustable mono-tube damper (46mm) for 4wds, as well as two larger bore twin tubes, based on their truck shocks. The largest of these uses a 41mm piston, is close to 70mm in diameter (for oil capacity/cooling) and is aimed at 'Raid' type competitors as it can take the knocks (the outer tube is 2mm wall) and resists fade well. It's also stupid expensive, although less than half the price of a proper rally/raid shock like an Ohlins or Reiger. The two Koni importers in Oz tend to push the twin tube shock for 4wd's (I'm guessing they feel it's better suited to rough off road use)

Bubbles, had you bottomed out really badly anywhere ?
What you describe is symptomatic of when they go metal to metal internally. Bits of foot valve and adjuster nut end up getting caught under the valve stack on the piston and in the foot valve, rendering the shock useless. Eventually they sort of flush out, and the damper sort of functions again. If they had just faded from overheating/airated fluid, they are generally ok after a couple of hours cool down.
I've bottomed badly enough to have a couple of Koni's go metal to metal, and the results inside the shock aren't pretty.
I've also heard of Bilsteins failing on a similar type of trip as yours (blowing shaft seals), although I don't believe this is normal, and I have no hesitation in recommending Bilsteins or Konis to anyone.

I had Bilsteins on my old Disco, but now have twin tube Konis on my Defender. I found the Bilsteins to last extremely well, but I thought the damping was much too harsh for the Disco. On a minor point, I also hated the double locknuts on the Bilstein pin ends. They look flimsy and cheap, and needed to be replaced with proper nylocks. Admittedly, that wasn't hard to do.

The Konis so far have been fine, and I do 90% fast (by Tdi standards) dirt driving. The rears still need some kind of stone shield on a Defender. Even though the twin tube Konis aren't as critical in this regard as the Bilsteins, they have still taken a hammering on my vehicle. I've wrapped the lower half of each shocker with 4mm rubber mat to lessen the damage.

Paul

having a rather odd version of the defender that's been raised 2" on series 2000 suspension, then rear springs replaced with stiffer ones that lifted it another 40mm and also running larger tyres 255/85/R16, my shock requirements were anything but off-the-shelf standard.
early last year, the lroc ran a technical day at Ultimate Suspension at minto. i'd had 2 vehicles with ultimate systems on them in the past and both had fantastic handling and off road capabilities.
i was being given the runaround by all the local suspension places where the staff were very good at looking up a spring/shock combo in a guide book but next to useless when it came to anything out of the ordinary.
i ended up going to Ultimate, they measured the spring travel on my vehicle, checked the spring rate and custom built some monotube rear shocks for me, set up for a 500kg load in the tray. i was there on monday of this week, they made them up and posted them to me, i put them on thursday arvo after work....and they are bloody awesome.
they were expensive compared to off the shelf items though, these cost me $245 each.
but you can compare it to buying those pre-set reading glasses at the servo, they might be close to what you need, and allow you to read, but are not exactly set to your eyes and with the right ones, you could see a whole lot better.
i could go on, but the rest is best left for campfire chat and not in writing

they reckon that all shocks are only good for 60,000 to 80,000 km. they lose their ability to perform at their designed parameters. at this age they should be either rebuilt or replaced.

We "did" the old gunbarrell highway a few years ago in my 90 disco V8 with 320 litres of fuel on board, water, fridge and enough supplies for two weeks.

I was the only vehicle out of five with "Billys" fitted as everyone esle had gone with local brands.

When we came to the really badly corrugated stuff I was the only one who could keep going after an hour. All the others would have to stop to let there shockers cool.

The "Billys" were so hot that when I spat on one of them they would sizzle like a hot barbie - BUT THEY STILL WORKED!

I transferred them to my next rover (a Rangie) and they were still perfect when I sold that.

I know what I'll be putting on my Disco!!

Cheers,

Robbie

I am pleased with my Bilsteins.

However, the strength of the bottom rear washer is dubious. It is thinner than the oem washer. In my case they distorted the extent that on one side the rubber split and fell out and the other side was cracked.



And I was wondering why the disco was wollowing and clunking. :roll:

I replaced the rubbers and washers with the ones I had on the old shocks and even now the washer is beginning to distort as I look at this photo:



The only theory I have for this is that the washer takes a lot of strain on maximum articulation of the rear axle.