Shock valving for dummies

Can we revive this old thread?!? lol I have some questions on how to relay my issues to the tech. I currently have issues where I think I have too much rebound. It seems like its "Topping Out" over speed bumps, really slamming down on certain bumps. Is this a rebound issues? Is it too much or not enough, what do I tell the tech I would like? I feel most revalving is trial and error, who has that kinda cash to just try it and do it over!

 

It would be an issue of insufficient rebound, but more likely, it is a ride height issue. The ride height may not be allowing enough droop travel to catch the truck before the shock tops out - resulting in the truck dropping down creating a top out feeling - then trying to catch the whole truck on the way down.

 

hmm that’s interesting. Haven’t thought about that. Any suggestions on narrowing that down and solutions? I haven’t adjusted these other than leveling it out which was about a 1/2 inch of preload.

 

Thoughts on drilling bleed holes on the old factory low flow pistons? Thinking of bringing out the drill next time I tear down the coilovers

 

Depends on what you are trying to change. Drilling bleed holes does not convert a low flow piston to a high flow. Bleed holes go around the shim stack. This opens up more fluid to flow through the piston without hitting the rebound or compression stacks.

 

First step would be to figure out how much downtravel you have at ride height. Basically measure from top of tire to the fender. Then start jacking up the truck until the wheels just loose contact with the ground, then measure again and subtract the first number. That will tell you how much downtravel you have.

If that number is, lets just say 2", then that means that if you drive over a 3" dip/hole the wheel will only be able to extend down 2" and you'll hear a bang as it tops out because it can't extend as far as it needs to. Knowing how much downtravel you have will let you know how big of a dip you can handle without topping out. Note that "dips" can also occur after bumps like speedbumps because your shock will compress over the bump but then needs to extend back down to the ground after. However if your suspension isn't dialed in (too stiff either from spring or compression) then the truck body/chasis will move upwards on that bump, making the amount it needs to extend down after more than it is currently compressed. If you don't have extra downtravel, you will top out. This isn't really a shock tuning problem though. It's likely just too much lift resulting in too little downtravel.

If you discover you have plenty of downtravel, it could just be that you are oversprung and the shocks don't have enough rebound dampening to overcome the force of the spring. That makes the wheel rebound very fast which makes it feel like it's topping out. But really it's just the tire firing into the ground too fast. You can tune for this but it's kinda a double edge sword, cause at slow speeds you want slow rebound, but too slow of rebound means the shock will "pack down" on high speed stuff like washboard.

I don't know what the right answer for you, just providing some context. This video also does a great job of explaining the symptoms of improper valving and what to kinda look for to help explain what changes you need to make with the valving. https://www.youtube.com/watch?v=e8AgCvlgGsY

 

Will this smooth out some harshness I'm experiencing on washboard/manhole covers?

 

I'm thinking of going back so a lighter stack (55/70) Currently at 75/90 with .08 flutter. It takes slow speed shaft moment excellent but the high speed is rough and it isn't pleasant on washboard, or over sunken manhole covers. I typically run my DSC fully open on both high and low speed.

If I change to a lighter stack I've pondered that if it's too soft I could tear down the DSC and put a heavier stack in there to compensate. Sounds like an easy workaround that may be to be too good to be true.
It's really hard to tell a difference with the DSC adjustment when it comes to high speed. Low speed is obvious when its adjusted relative to body roll and brake dive.
Curious as to what people's thought are on this.

 

As far as washboard goes… our truck frames are wet noodles. IMO you are not going to get rid of the chatter no matter what valving you do because of the amount of flex in the frame. I’ve been in it with stock travel, mid travel and long travel and the chatter was always there. But finally got rid of all of it with one simple thing. A cage…..literally don’t even feel washboard chatter at all. Short of that you will always have issues in washboard.

 

Didn't think I'd be going from, "I should do another re-valve" to caging the truck lol!
my wife's going to be asking a lot of questions when all the pipe shows up..
All jokes aside you've gotta show off some pictures of your truck now. Haha

 

Nvm just hit the link to your build in your name

 

@Airdog super nice build dude!
I wish I had the time and money to attempt what you've completed here. I think I may be able to a frame boxing kit but the cage likely a dream

 

I had a similar ride with my Elka's before I had them revalved for softer compression. Any amount of DSC adjustment just made them feel more harsh, didn't really matter if it was low or high speed. So I just ran them wide open all the time. Washboard and potholes were harsh af. They really only shined with harder hits like brutal railroad crossings or large g-outs.

After getting the compression stack reduced it made a huge difference. Wide open on the DSC was finally too soft and I would get too much chassis movement, which actually made the ride feel more harsh. Now I can actually feel the difference both adjustments make. More high speed compression actually helps smooth over washboard and bumps, whereas before it would just make things even more stiff and cause the wheels the skip around.

I actually agree with @Airdog kinda, the frame 100% needs more rigidity. But I don't know if a full cage is necessary. Those shitty factory shackle hangers aren't doing anyone any favors. They basically just act like a second spring but without a shock to dampen the bounce. I found that Hammer Hangers with the cross tube made a massive difference in that regard, and would highly recommend you look into those before re-tuning anything. Getting as much of the energy into the shock as possible is important for ride quality. And taming the rear of these trucks is basically the key to a better ride.

 

Ya its a crazy stupid mid life crisis build. But fun as hell. Its just funny that the most noticable thing after putting in the cage is the lack of washboard chatter making it into the cab. TE designs has made cages cheap. Especially if you can do it yourself. My buddy is a welder and I did my cage for about 3k out the door. But ya...hers a few recent pics.

 

Appreciate your in depth response!
I'll just start with a lighter compression stack and play with the dsc. If need be I can always open the dsc after I make those changes to try and isolate my adjustments.

 

Wow the more I look the more mods I see haha. Very nice rig!

 

Do you recall what the original Valving was to what you switched it to? I know fox has a chart that I will use as a starting point. I'm thinking of going to a 55/70 from a 75/90. If it ends up being too soft I can just make a custom pack from what I already have. Thanks

 

No idea, sorry. I had Elka do everything. And it likely would be different anyway since Fox use different pistons and internals.

 

All good.