Coilover valving

[Eddie315]

Would like to get schooled on shock valving. I am running King 2.5 12" fronts and 14" rears. Front springs are 175/175 and rear are 150/150 with 0 preload on all 4. Ride height is perfect and I have 6" shaft showing in front and 7" rear. I am running leading and trailing arms but the shocks are mounted pretty far out on the links.

Edit: Front is .015 Compression .012 Rebound.
Rear is .012 Compression .010 Rebound

It rides way too stiff. Couldn't bottom them out if I tried. Any bump that the tires don't soak up is felt in your spine. I was going to go with 8/10 shims on all 4. I would like to hear what someone with experience recommends.

 

[Yotota]

Short answer: you need fewer shims.

Less short answer: I'm not a shock tuner, and I have no idea what your shim stacks are (thickness, qty, arrangement), so you need to talk to someone reputable who can build you shim stacks. You'll need to know the weight of the rig on each axle, unsprung weight, leading/trailing arm dimensions, driving style, terrain, and probably more that I'm forgetting. Then they can put together what you need.

The upside is that your spring rates sound perfect.

 

[Bebop]

Start by lowering spring rate to add preload, then open them to see what's inside.

Also, it looks like you have no bumpstops of any kind. When the shocks are gonna start moving after you revalve them you'll quickly figure out why it's not a great idea.

 

[Yotota]

Start by lowering spring rate to add preload, then open them to see what's inside.

The perfect amount of preload is none. Well just slightly enough to keep the springs from rattling, but as little as possible.

If his ride height is where he wants it, and it sounds like it is, the springs are perfect.

 

[Eddie315]

Start by lowering spring rate to add preload, then open them to see what's inside.

Also, it looks like you have no bumpstops of any kind. When the shocks are gonna start moving after you revalve them you'll quickly figure out why it's not a great idea.

You're right I don't have any bump stops. I have fox bump stops sitting on the shelf if I need them. It's a fairly new build. I don't know much, but I know that preload is not what I want. I really should open them up to see whats in there.

 

[Ghetto Fab.]

I would shoot for 1-2" of preload, but if your light enough that can sometimes be hard to do.

You really need to pull your shocks off and open them up. Once you figure out what valving you have you can figure out a direction to go in.

 

[Eddie315]

Pulled the shocks apart and edited original post with current valving.

F: 15/12
R: 12/10

 

[Bebop]

Why don't you want any preload ?

 

[Yotota]

Pulled the rear apart. Currently at .012 compression and .010 rebound.

Pyramid stack? How many shims on each side?

 

[bdkw1]

How many bleed holes open? Most ride complaints can be solved with less low speed damping.

Your spring rate sounds good.

Reb might be too stiff. 8's are usually the way to go with that light of spring rate.

Where are your cross over rings set?

 

[Yotota]

Why don't you want any preload ?

Why would you want any preload in this case? Or more specifically, why would one advise to run a softer spring with more preload?

This is a crawler. He's at 50/50 up/down travel right now. When fully articulated, the full weight of the truck will be held up by two of the four shocks. With his current spring rates the shocks would just bottom under full articulation but would be controlled until that point. With softer springs, the two compressed shocks would bottom out before the truck was fully articulated.

I guess if he installs air bumps this would mitigate my concern and allow more travel to be used with softer spring rates.

 

[RPS1030]

Why would you want any preload in this case? Or more specifically, why would one advise to run a softer spring with more preload?

This is a crawler. He's at 50/50 up/down travel right now. When fully articulated, the full weight of the truck will be held up by two of the four shocks. With his current spring rates the shocks would just bottom under full articulation but would be controlled until that point. With softer springs, the two compressed shocks would bottom out before the truck was fully articulated.

I guess if he installs air bumps this would mitigate my concern and allow more travel to be used with softer spring rates.

My understanding of preload.

Right now, the rears are compressed 7”, with a 75 lb/in combined rate. So 75 more pounds of force will compress it 1”. With a lighter combined rate with some preload, the ride height can be the same; but that same force will compress further, or less force to move the same 1”.

Therefore, the lighter preloaded springs allow easier movement at a given shock position. Putting the work and control and adjustment on the valving.

I’m not sure I was fully following your flex theory. Lighter rate within the constraints of no coil bind, and lengths that allow the dual rate stop to be functional and admirable thru full travel.

 

[Eddie315]

Pyramid stack? How many shims on each side?

Standard pyramid stacks with 6 shims. Each shock has 3 bleed holes and they are all open. I am new to shock tuning so I'm not sure what a closed bleed hole looks like. But the 3 little holes you can see in the picture are open all the way through.

 

[Eddie315]

Where are your cross over rings set?

Right now they are all the way up and don't do anything. Because it was so stiff I raised them up so it doesn't get any stiffer through the cycle. At full compression there's no coil bind either.

 

[bdkw1]

Ok, time to eliminate the stupid. Piston in the right way? That should be nut side up in the pic.

Is the comp stack sitting directly on the top out washer or is there a spacer shim in there?

 

[Yotota]

My understanding of preload.

Right now, the rears are compressed 7”, with a 75 lb/in combined rate. So 75 more pounds of force will compress it 1”. With a lighter combined rate with some preload, the ride height can be the same; but that same force will compress further, or less force to move the same 1”.

Therefore, the lighter preloaded springs allow easier movement at a given shock position. Putting the work and control and adjustment on the valving.

I’m not sure I was fully following your flex theory. Lighter rate within the constraints of no coil bind, and lengths that allow the dual rate stop to be functional and admirable thru full travel.

There are a lot of ways to accomplish the outcome of a stable truck that rides well. Dual rates are another, but to get back to his desired ride height he would end up even stiffer from ride height (depending on the stop ring setting).

On pretty much any vehicle I'm a fan of the most spring possible to achieve the desired sag/ride height and travel, and the least damping needed to control stability. Soft springs and stiffer damping is rarely a good combination.

 

[Eddie315]

How many bleed holes open? Most ride complaints can be solved with less low speed damping.

Your spring rate sounds good.

Reb might be too stiff. 8's are usually the way to go with that light of spring rate.

Where are your cross over rings set?

Sounds like you've done this before. So 8 rebound would probably be good. What about compression? 8 as well? If it's just a little too soft I can compensate with the crossover rings to a point.

 

[bdkw1]

Sounds like you've done this before. So 8 rebound would probably be good. What about compression? 8 as well? If it's just a little too soft I can compensate with the crossover rings to a point.

8's on comp is really soft unless you do a second small stack on top for high speed control similar to what MX bikes use.

Go down to 8/10 combo, take the largest 12 shim and put it on top of the comp stack. Make sure you have at least .060 of spacing between the comp stack and the top out washer. When you run thin stacks, the lack of spacing to the top out washer turns it into a rate plate and will make the high speed damping go balistic.

 

[Eddie315]

Ok, time to eliminate the stupid. Piston in the right way? That should be nut side up in the pic.

Is the comp stack sitting directly on the top out washer or is there a spacer shim in there?

No spacer shims. And I believe piston is in correctly. All 4 shocks look exactly like this. Dont be afraid to talk to me like im an idiot. I learn better that way lol.

 

[bdkw1]

Ok, that all looks correct. You have the small diameter top out washer which is good. Also looks like you have the .090 spacer between the comp stack and top out washer. Also good.

Get an 8 stack for reb and swap the 10's to comp with a single 12 high speed shim.

 

[Eddie315]

Ok, that all looks correct. You have the small diameter top out washer which is good. Also looks like you have the .090 spacer between the comp stack and top out washer. Also good.

Get an 8 stack for reb and swap the 10's to comp with a single 12 high speed shim.

So replace that largest shim with a .012 shim and leave the rest as 10's? Total of 6 shims with the largest being a 12. What exactly will that do differently than all of them being 10?

 

[bdkw1]

No, you take the largest shim from the 12 stack and put it on top if the pyramid (new 10 stack).

This let's the stack flex like normal to a certain point, then it gets stiffer. It allows for a better ride while retaining bottom out control.

 

[Bebop]

On pretty much any vehicle I'm a fan of the most spring possible to achieve the desired sag/ride height and travel, and the least damping needed to control stability. Soft springs and stiffer damping is rarely a good combination.

I'm a believer in the opposite

Eddie315 try what bdkw1 is telling you. I would have been more aggressive with it but let's see how you like what he's offering.

 

[Yotota]

I'm a believer in the opposite

Eddie315 try what bdkw1 is telling you. I would have been more aggressive with it but let's see how you like what he's offering.

Interesting, one of these days we should dive into the topic a bit more. Sounds like you have different experiences than I have with suspension.

I definitely agree that that bdkw1 has the best specific advice here. Play with the valving to get the damping in a better place, then figure out if spring rates are still good.

 

[bdkw1]

My spring preference are more go fast based, the rock crawler stuff seems really backwards to me. Almost everything I work on ends up being technically negative preload, I.E. main and a tender.

But valving works pretty much the same, you just need to know what area you need to work on.

Usually making more than 1 change at a time is a good way to confuse what the real issue is. Going lighter on something with a close to 1-1 MR is a pretty safe bet though. Video of the suspension working makes it way easiet to target issues.

 

[Bebop]

Interesting, one of these days we should dive into the topic a bit more. Sounds like you have different experiences than I have with suspension.

Light springs induce little extra loads during suspension motion, so your valving ends up mainly controlling the loads from the terrain.
Heavy springs induce a lot of extra loads which means you have your shocks controlling the springs on top of the loads from the terrain.

There is a point of diminishing return where you can't get the rebound low enough but that's when you're really going fast and need a quick(er) reacting suspension that what you'd see on a standard rock donkey.

That's why my suggestion would have been lighter springs and a lot more aggressive valving.


On the other hand, OP already has these springs on an could start playing with that.

 

[Treefrog]

I know that in threads on springs and tuning on other offroad forums, the experienced tuners would switch springs to get preload before they started messing with valving. They did that for crawlers, trail rigs, and race rigs.

 

[mobil1syn]

I know that in threads on springs and tuning on other offroad forums, the experienced tuners would switch springs to get preload before they started messing with valving. They did that for crawlers, trail rigs, and race rigs.

if he is happy with his ride height and has zero preload, his spring rates are acceptable. perfect world he would have rate split between the upper and lower, with 1-2" and 2-3" preload.

as its been mentioned his main issue is rebound, .008 stack min. the .015 on the front is a little much, but the rebound change will make a world of difference.

 

[Eddie315]

If a local place has the shims in stock I will make the changes today.

 

[Eddie315]

Not in stock. Ordered from Poly Performance. So I'll get back to this in a few days. Once the new shims are in I'll set up a gopro to film the shocks in the bumps.