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KPR's 84 chromelux discussion


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1 hour ago, kpr said:

the preload needs to be there to push the shock out to full extension when doing jumps etc.  kinda similar to what your staying about the race car stuff.  guessing they are using the dual rate to do similar,  since preload on a high rate single spring  will make droop near non existent

Seems to be a lot of different theories on how to setup the dual rate change over.  seems none of the "suspension tuners"  like to give out there secrets, especially when it comes to shock valving.

Other than the few things above, springs are just there to hold the thing up,  valving is everything on offroad stuff.     shocks need to have fairly low rebound dampening so wheels drop out fast enough, so have max travel to soak up the landing. but too little is also all bad.    the compression valving  needs to be stiff enough to soak up the big stuff,  while using most of the travel to do it  and also not ride rough as shit over the small stuff. 

Yeah, that's another big reason for the dual rate setup - way better over kerbs and big bumps. It helps to make the rear less jumpy and soak up the big hits. 

I've also noticed that most suspension tuners keep their cards close to their chest... It's the same with racecars, speedway, road race bikes, motocross bikes and obviously offroading too. There's a small amount of info on the internet, but it's just enough to get you confused. I'd really like to do an apprenticeship with a switched on suspension Barry to get a better idea of how it all works. 

How low is the rebound damping meant to be? And is there a bump/rebound ration that's ideal? In racecars it seems that 1:2 bump:rebound is the ballpark ratio with a digressive piston that "blows off" in the higher speeds, so you get good low speed feel without flying into the air every time you hit a rut. 

 

Time to buy a shock dyno. 

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pretty much everything offroad seems to be opposite.  shocks are setup very progressive.  bigger hit more dampening, since the shocks are doing most of the work rather than springs

 

rebound is kinda case by case.  but from what i've read most people  end up with less rebound valving than compression when any speed is involved.    my shocks come factory valved at 50/70  compression/rebound. which worked not too bad for out of the box.

Currently have

Front  75/50   comp/rebound
Rear    i have a custom stack on the compression that ramps up the compression with higher shaft speed and 50 on rebound

before the the above changes it was always  way into the bumpstops.  because the wheels didn't drop out fast enough, plus compression was too low to soak up the landing

since it was  then using less of the hydro bumps, i was able to let some pressure of them. so they come in slower and less harsh

 

 

5ae6f6c07b750_radflovalving.png.ad1672c7926ba24190f7626e9c784a2b.png

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1 hour ago, Mof said:

I am a little confused as to what it's doing, is it bodyrolling and not going back to level? 

I'm going to assume you know that if you made the arms from the torsion bar to the link rods shorter, then the sway bar would be stiffer. 

Why not just a normal sway bar with releases?

I did this on the pajero where the sway bar ends could slide up and down the link rods keeping it from flopping about, but insert a couple pins in the rods and it would be back to a normal sway bar.

that was one of the things it was doing.  swaybar solved that issue.  the next issue was the way it bounced back due to lack to shock rebound valving.   pretty sure its near enough now with the last changes. will do more testing next weekend

same deal, want to run it all the time.  and don't want to run too much bar on the road either, since it only has a rear bar,  if go too stiff will make it want to snap oversteer.   only thing i'm loosing out on as it is, is a small bit of flex. otherwise it feels a lot more stable off road as well
 

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seem to be pretty sweet.    guessing can go higher, but would need a heavy truck to need more.      200psi  was way too hard for my truck once got the shocks dialed in .  i only run 65psi in the front and  35psi in rear.    if run them too hard it upsets the truck when you hit them.

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The whole offroad suspension  seems to be portrayed as a bit of a  black  art. guessing there are a lot of suspension tuners out there trying to protect there livelihood /edge.
I found the same thing,  the only good info didnt go into much depth.   was a bit of a steep learning curve. but most of it isn't that hard once you get your head around it.

What shock setup are you running ?

Guess one way at looking how im running my hydro bumps, is a poor mans bypass shock.   the last 3" of travel ramps up the dampening (and spring rate in the hydro bumps case)
Your better off to run a longer hydro bump with less pressure than a shorter one with more pressure.  long as it doesn't interfere with normal suspension travel too much.

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yeah i agree and it seems nz and even aus are far behind what people are doing in the usa so theres pretty much no peer support you could say when it comes to it all down under,

ive just ordered 16" and 18" travel 2.5" king remote coilovers. factory valving (will play around with it once i get it all finished) 

and 200lb over 250lb rates on all 4 corners aiming for 50/50 weight at under 2ton curb weight, 

designed it so 50/50 shock travel from ride height with 2" hydro bumps (probably buy radflo as they are half thr price of kings)

 

 

 

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sweet sounds good.  thats heaps of travel. 
 i'd start with a longer hydro bump if you can.    they are easy  to shorten by adding an internal spacer. if you wanted to shorten them at a later date

how did you work out your spring rates?

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yeah i looked into running longer bumps but im trying to put it through cert, trying to let the shocks do as much work as they can before the bump stops come into the equation, ( filthymotorsports on youtube about shocks had a good way of explaining it) also packaging aswell i havnt got alot of space so 2"×2" stops will be a good fit.

tbh its abit of a educated guess/ stab in the dark ran the numbers in a spring calculator ( on crawlpedia.com)

i should do a build thread on it but super busy

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keen to see a build thread

those spring rate calculators were bit off in my situation. since the shocks have a bit of spring rate built into them; shaft acting on the nitrogen charge.   probably wont be so much of an issue with yours though, since sounds like you will have a bit more weight, especially over the rear.    i'd still err on the light side of the what the calculation spits out 

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flex bro, i stroped it up to the engine crane and pulled up a rear wheel and just keeps flexing till it hits either shocks chassis or rear cage which is heeaps, i had one wheel at like 750mm off the ground and one still on the ground with 200mm+ to go

 

might have to get a custom sway away bar, trophy trucks have same problem and use a hearty stiff sway bar to get around it im fairly sure

20180816_212326-1209x1612.jpg

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