mid-travel suspension tuning

I was going to put this into our favorite thread of all time but figured that there would probably be some good information coming so, why not let it have it's own home?

The only thing I know about suspension tuning is on the trail and DH bikes. With the MT upgrades on their way, I figured it might be good to try and get my head around it a little. Right now, my questions are really focused on the front end.

Just like the bikes, I get that I'll need to head out and run a section of trail over and over with a notebook and pen. That's not a big deal. I actually kind of like that. Reminds me of when I first started in a darkroom developing and printing my own film. Lots and lots of trials and notes.

Currently, the Kings on the truck have the compression adjusters. When the bypasses go on, how do the two compression adjusters work together? I get that the secondaries are there to increase the dampening but what else is going on? Does the adjuster on the coilover affect the bypass and vice versa? Should they be treated as separate? Is there a baseline?

 

This is for Fox but the concept is the same. Pretty good read

http://accutuneoffroad.com/articles/how-fox-dsc-dual-speed-compression-adjusters-work/

 

I think for tuning shocks, best is not to have clickers from my past discussion with @jberry813. So you can tune it the way you want for your truck.

 

Run the coilovers wide open (softest setting). Have the bypasses be the primary adjustment on the truck.

 

okay but why? how and why does that work?

 

in for the knowledge.

 

Everyone sets them up differently. A friend who tuned my FJ shocks also does shock tuning for race teams. His choice is to run the coil over as soft as possible and adjust the bypass.

The coilover's main job is to dampen at low speed, the compression adjuster works well at high speed, and the bypass is both high speed and position sensitive. The compression adjuster compounds the bypass and gives you a harsh feel. Running the coil over at it's softest setting avoids this. The bypass covers any tuning necessary for the front end.

 

• BYPASS SHOCKS OFFER THE ULTIMATE IN ADJUSTABLE DAMPENING. BYPASS TUBES ARE INSTALLED AT VARIOUS POINTS ON THE SHOCK BODY AND ALLOW FLUID TO BYPASS THE SHOCK PISTON. USERS CAN ADJUST THE BYPASS TUBES SO THAT ALL THE FLUID CAN BYPASS THE PISTON RESULTING IN A VERY SOFT RIDE OR THEY CAN CLOSE THE BYPASS TUBE RESULTING IN A VERY FIRM RIDE. HAVING MULTIPLE TUBES ALLOWS USERS TO SET THE SHOCK UP TO PROGRESSIVELY MOVE FROM SOFT TO FIRM. BYPASS SHOCKS ARE NOT DESIGNED TO SUPPORT THE WEIGHT OF THE VEHICLE AND AS SUCH ARE COMMONLY USED WITH A COIL CARRIER. A COIL CARRIER IS A COILOVER SHOCK WITH NO INTERNAL DAMPENING FEATURES.

 

∆∆∆from the ADS website

 

Tagging along...

 

that's exactly the kind of info i was hoping for.

 

I revalved my coilover shock really soft. Now the shock is just mainly a carrier for the spring. My bypass is now doing all the work up front and I make the adjustments from there.

 

This is not the best way to run your set up. A coilover needs to have compression. You want to split the heat load between a bypass and a coilover. If you run the coilover soft and put a monster stack in the bypass, then your bypass will soak up all the heat and your coilover will stay cool.

The job of shocks is to control chassis movement. They do this by converting kinetic energy into thermal energy. Shock oil can olny get so hot before it starts to break down. On an MT set up its even more critical to keep the heat in check.

Clickers are not the best way to adjust dampening. The are not progressive. They flow the same rate regardless of shaft speed. A shim stack is the best way to control flow. As the shaft speed increases, the dampening increases, which controls hard hits, but still allows it to be soft over the chop.

On an MT setup, don't over think shock tuning. You have to get the spring rate correct, thats WAY more important. Typically 600# coils are best on a truck with no armor. If you add bumper and skids step up to 700#. As for shim stacks in the bypasses, King 20 stacks are a good start, or Fox 120 stacks. Not sure about other brands. You basically want a very heavy stack and then adjust the tubes. For the coilovers, you want an aggressive flutter stack. I would just call down south and buy one from them. Tell him what you have a and tell him to send you an aggressive flutter. I could give you the actual shim recipe, but it would only be for Fox and I would have to dig through my notes.

As for tuning bypasses, there is such a thing as too much compression. but first I would open them up all the way and adjust your rebound. Go over some pretty good sized whoops (for MT truck like 1' to 1.5' whoops) and increase the rebound until the front end stops feeling like its bucking or bouncing too much as you come off the top. Its much easier to show someone than it is to explain by text. Then go back to compression and increase the transition zone until it feels progressive going into the bump zone. After it feels like you have something there, then increase the ride zone until its bumpy over the chop and then back it off a little.

Every thing depends on personal preference and different terrain can require different valving. But generally speaking, if you can get over whoops well, then it will preform well over other types of terrain.

 

Thats a bad way to run your setup. See my post above

 

Rad. I was hoping you'd chime in here.

I'm on 700# springs so I'll check on the stacks this week.

As for the tuning, your description sounds exactly like the process I go through with the DH bike except that I'm trying to limit the bucking in the rear. Totally get it.

Thanks for the input.

 

It's what ADS recommended. The front shocks don't get nearly as hot as the rears.

 

Yes I'm sure that the fronts are not over heating. and I'm not saying that your valving sucks or it rides bad.

I'm just saying that its not the best way to set up your shocks. And I don't care what ADS says. They only said that because they wanted to make it easy for you to tune. In other words, they treated you like a n00b. Its better to spread the heat load and put a flutter stack in your coilover.

 

It makes sense to spread the load, they said to just flip the shim stacks. I questioned it when I was given the info.

 

"flip the shim stacks" ??? I dont understand

 

Good thread here, king will revalve/rebuild your shocks if you catch them with their truck out testing other customer’s vehicles, I think that’s what they said. They come out to Barstow a lot which is 45min from me. Eventually going bypasses front and rear in the near fewcher.

 

because this is way more fun and interesting to me than actual day job stuffs, i'm wrapping my head around this. when you say King 20, are you referring to the thickness of the shim? for example .020"?

 

Fox does the same at Plaster city

yeah.

 

Correct. A 20 stack means the whole stack would be .020 thick. 15 stack would be .015 thick. Then you have in betweens which are mixed stacks.

 

To reverse them or put upside down

 

lol well I dont understand what that would accomplish

 

maybe he wants to roll over his truck but doesnt know how... i can certainly give some advice if needed.

 

Hopefully they mean put the rebound on the compression side and the compression on the rebound side. Not literally flip them upside down because then you wouldn't have any dampening.