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KiwiBacon wrote:$2500 for konis? Yeesh. My last two (gas/hydraulic to fit an 80 series cruiser) cost me just over $200 the pair on clearance. Retail was under $500 the pair..
If you can get Koni 90 series that cheap, You will setup your retirement very very fast.. I'd say you could sell 30 sets on ebay too..
bru21 wrote:$3200 is nothing for shocks. the set I bought when I was going to build the Jimny were over $9.5k I think my new buggy will be close to 20k.
Because generally they are $100-300 ea doesn't mean a good shock should be. Look at the quality of a street bike shock bogged - they would cost 5k easy if they were not part of the bike.
The koni's you mentiond look bigger than I have seen (to be honest) and probably work well for what they are. But they will not hold a candle to fox / king / saw shocks.
Shocks simple turn kinetic energy into heat. Something like a koni will have to have less damping due to their size than a larger fox etc will provide based on sheer size alone - and also due to the remotes (greater surface area for cooling).
A 4" fox saw 600F degrees at one recent event in the US on a fast TT - they turn brown and still survived.
Shocks are the most important part in Off road racing. Look at motocross etc
3" are nice for touring but unless they are bypass or valved soft they will be harsh in the initial stroke for small bumps etc
It has to be said also that the mounts have to be stronger for larger shocks - and 90% of what is getting around is a bit marginal for 2.5 - 3" shocks. The springs are only there to maintain ride height and large jumps etc take a huge toll on shock mounts.
on a tourer it is even more critical as stress cracks are a problem and having a shock pull from the chassis would suck - use similar thickness metals and design well.
Look around for "prerunners" to get ideas - most guys run fox / king on their F150's etc.
There's some absolute junk in this thread. Since when did shock diameter dictate the valving inside?
$2500 for konis? Yeesh. My last two (gas/hydraulic to fit an 80 series cruiser) cost me just over $200 the pair on clearance. Retail was under $500 the pair.
Never have my koni's faded. I did have the head on one unscrew which has been the only issue in over 100,000km.
To get shocks hot you need to work them hard at slow speeds. High speeds provide plenty of forced air cooling and the wheels don't have time to reach the bottom of each hole (natural frequency of unsprung mass and all that).
Its probably not worth my time persisting here but:
Larger diameter is larger oil volume, greater surface area to dissipate heat. Thus You can have more damping for the same shock temp.
You can valve a shock anything from a coil carrier with no damping to a locked rod with no movement with any aftermarket tunable shock. Fox sell shim sets for $230ea for example.
I have never bought koni's, so I have no comments there.
ADHD Racing would like to thank Mrs Bru @ Sunshine Coast Developmental Physiotherapy - www.scdphysio.com.au , Ryano @ Fourbys www.generaltire.com.au Blitzkrieg Motorsport
bru21 wrote:Larger diameter is larger oil volume, greater surface area to dissipate heat. Thus You can have more damping for the same shock temp.
The amount of damping usually isn't the limit of a shock. If you're having problems with shocks heating to fluid fade then there are many other avenues to consider before simply bolting on larger diameter shocks.
For example; increasing airflow.
Besides, running more damping, makes the shock run hotter. It's all energy conversion from fuel to heat.
1MadEngineer wrote:as much as all this shock sizing debate sounds cool, it starts to become a bit of a waste once you really consider what its attached to!
If you are spending $3k or $20k on shocks then bolting it to STD OE chassis geometry then you need f******ng.
Some examples of chassis link force resultants (how much of the bump is absorbed/transmitted by the link/arm rather than the spring):
FRONT
stock GQ GU front rad arm - 3.8%
4/5" GQ GU front rad arm - 15.83%
mitch, its all to do with arm angles and there relation to the chassis. you want your front arms low at the chassis end pointing up towards the diff creating an "up and back" travel radius on bumps. the rear you want as flat as possible, this still wont be zero at the rear but it will be closer than a patrol
chunderlicious wrote:mitch, its all to do with arm angles and there relation to the chassis. you want your front arms low at the chassis end pointing up towards the diff creating an "up and back" travel radius on bumps. the rear you want as flat as possible, this still wont be zero at the rear but it will be closer than a patrol
This has been discussed a lot lately.
The angle of your radius arms means nothing but the height of the pivot above the ground is of prime importance.
That's what I meant as was explained to me in that earlier thread. I wad just explaining it to mich in a way he would easiestly understand... That the factory cassis mount is too high
it means truck all, as a piston is a piston and sure they all might be slightly different but they all do the same thing.
Remote res is always in every way going to out last an emulsion shock. More oil, larger surface area to dissipate heat
if a 2.5" shock isn't creating the resistance you need, up the viscosity of the fluid, simple.
a couple of questions
how long does the average winch challenge stage go for?
how many cycles per minute is the shock doing?
[quote="COOP"] By the way Mr engineering Guru maybe you better get another calculator or learn how to use it![/quote]
www.indurooffroad.com
44mm and 38mm Roll Cage Tube
Eibach Springs SAW Shocks
here is something to think about. a mate of mine who is fairly cluey likes Koni's as they are a oil based shock not gas......one of the reason he likes them becasue they DO faid on corrugations at speed....i didnt undertsand his reasoning as it was over my head....but i will say that he has been driving and building 4x4s for a very long time. and done alot of outback driving, at speed to
There's some absolute junk in this thread. Since when did shock diameter dictate the valving inside?
$2500 for konis? Yeesh. My last two (gas/hydraulic to fit an 80 series cruiser) cost me just over $200 the pair on clearance. Retail was under $500 the pair.
Never have my koni's faded. I did have the head on one unscrew which has been the only issue in over 100,000km.
To get shocks hot you need to work them hard at slow speeds. High speeds provide plenty of forced air cooling and the wheels don't have time to reach the bottom of each hole (natural frequency of unsprung mass and all that).
I was always of the understanding that with any hydraulic cylinder that if you increased the diamater the psi dropped for the same force. And as we all know as you pressurise something it gets hotter so reducing the pressure has a huge effect on heat generated. Also having a greater surface area allows for more heat loss.
And as the same force can be applied with less psi the required valving is different depending upon the clylinder diameter.
So if you generate less heat and loose more heat I would think that would be pretty good. And since it is heat that ultimately kills a shock, having greater dampening with less heat will mean the shock lasts longer and performs better.
Or have I got it all completely wrong????????
93 Nissan Pathfinder / Terrano Turboed VH45, GQ Trans and T-case, coil overs, hydraulic winch and fair bit of other stuff. (Currently a pile of parts in the workshop)
nzdarin wrote:I was always of the understanding that with any hydraulic cylinder that if you increased the diamater the psi dropped for the same force. And as we all know as you pressurise something it gets hotter so reducing the pressure has a huge effect on heat generated. Also having a greater surface area allows for more heat loss.
And as the same force can be applied with less psi the required valving is different depending upon the clylinder diameter.
So if you generate less heat and loose more heat I would think that would be pretty good. And since it is heat that ultimately kills a shock, having greater dampening with less heat will mean the shock lasts longer and performs better.
Or have I got it all completely wrong????????
How much energy goes into warming a shock is the damping force it creates multiplied by the velocity it is compressed/extended at.
Shock diameter doesn't matter at all, neither does the internal pressure generated. Only the stiffness of the valving and the velocity it moves at.
The primary thing cooling a shock is airflow. Which is why working them hard at slow speed is far worse than high speed corrugations.
Hands up all those who have killed a shock through heat (i.e. heated it until a seal failed)? My koni's aren't 3 or 4 inches diameter and the back pair have racked up about 200,000km.
KiwiBacon wrote:
There's some absolute junk in this thread.
You said it!
93 Nissan Pathfinder / Terrano Turboed VH45, GQ Trans and T-case, coil overs, hydraulic winch and fair bit of other stuff. (Currently a pile of parts in the workshop)
