Understanding Shock Dynamics

[kcb58h]

Dear Abby,

My front shock has 5.06" travel. I have a 3" lift spacer and stiffer springs that add .76" static lift.
When my truck is at rest, is 3.76" is drawn out of the shock. Or is that 3.76"/1.50=2.50" drawn out of shock?
So at the wheel, how much (downward, I assume) travel am I losing?
Does it gain anything in upward travel?
Does this mean hitting a deep pothole with this setup make it more likely to top the shock out?
Do I have the whole thing reversed?

Signed,
Curiously Confused

[bartonmd]

The "lift" amounts advertised are at the wheel, so 1.5x what is happening at the shock.

Mike

[Trail X]

You had it just about right KC. Not sure where you got the 5.06" of travel, shock mfg website? Lets roll with it.

Lets assume that at 5.06" of travel, you've got half up and half down from stock stance, giving us around 2.5" of up and down travel.

There are three types of lift blocks: Inside, outside, and combination.

Outside blocks take nothing from your travel, and only offset the whole strut down. This may be fine for 2WD trucks, but for 4WD trucks they can allow the suspension to droop down too far and damage the CV shaft.

Inside blocks take directly from your down travel. So if you get a 1" thick inside block, your up travel would become 3.5", and your down travel would become 1.5".

Combo is what most one-piece blocks are on the market today that replace the upper shock mount. They tend to balance their lift between inside and outside strut amounts to achieve the maximum amount of lift without overextending components of the suspension and drivetrain.

Lets assume that your lift is balanced half and half. A 3" lift block equates to a block thickness of about 2" due to the lever arm (3 / 1.5 = 2). Assuming it is balanced between inside and outside lift, you are losing 1" of strut extension. With the spring in your post also contributing .75" of lift (.5" at the strut), you lose 1.5" of extension in total. This is taken away from your 2.5" of original suspension extension travel, giving you 1" of downward travel from the resting point.

Yes, it basically gains the equivalent in compression travel, now giving you 4" of compression travel (its possibly a little more limited due to the fact that the spring will eventually compress into itself and form a solid, which you want to avoid because it can prematurely damage a spring).

Yes, the setup will be more likely to top out. Its a price we have to pay for IFS where you can't reposition the front diff.

[kcb58h]

JD - Thanks for the detailed response. I understand about half of it. I'll re-read it later. 5.06" is what Monroe (don't laugh) states.
I put Mark's 3" on and swapped 83 springs for 87s (+.75"). Too harsh for my likes.
Mark sent me a pair of .75" spacers to account for the 87s and go back to 83s. I'm having doubts about how much that'll improve ride, but before I had the 2"RC level kit and 83s and it rode like a dream. Really - more than one passenger commented on the smooth ride. Now I feel every tar strip. But eating up another 1.75"?

Should I take my sorry-assed 2wd b*****t to one of those sites where they discuss led underlighting?

2" RC kit + 3" LM kit + Monroes + 87 springs + labor = $150 less than Radflos!
Spend and learn.

Happy Trails

[Anthony Hernandez]

Where'd you find 87's @?

[Trail X]

Anthony, have you installed your 89s yet?!?

KC, I'm curious when you say the 87s were too harsh. I wonder if you were merely topping out a lot? or if you really thought it was too stiff. For us that go offroad, the stiffer springs are very nice because they keep your suspended body and frame from smacking into the ground as much when your tires are coming down off of objects.

[Anthony Hernandez]

Nope....no balls....

[KingBird]

I, too, like a softer springrate. I rarely get to climb trails and I take every chance I get, but my softer springs work great on caliche roads and washboards.

Plus, it's a lot better having the wife enjoy riding in the thing and if it jarred her around too much, she wouldn't. You just have to be extremely careful about carrying momentum coming down off rocks or you'll damage your rig.

Once it becomes my dedicated rig I may change the springs.

[djthumper]

Should I take my sorry-assed 2wd b*****t to one of those sites where they discuss led underlighting?

GMTN will talk to you about under lighting as well