Question on Shock Travel
 

Getting ready to replace my worn out shocks. Got it narrowed down to either the Fox 2.0 or the Rancho RS9000XL. I've always liked/wanted the Fox 2.0s, but because I spend 90+% of my time on the pavement I'm leaning towards the Rancho for their 9-way adjustability as well as the cost difference (nearly $200). However, one of the specs on the Rancho has me concerned; on the fronts (RS999307) the Rancho lists the travel at just 1.74" (extended length 15.28"/compressed length 13.54") compared to the stock OEM shocks' 4.1" (ext 15.2"/comp 11.1"). So my question is whether or not that is relevant. Knowing that the shocks are mounted inboard from the tire, how much "travel" is actually needed at the shock on the H3? Is the 1.74" (at the shock) sufficient, or will the shock bottom out before the suspension? Anyone know for sure?

Shocks have a "sweet spot", the further you move from that the harder the ride, not much tolerance with 1.74" travel, so only drive on smooth roads or it will be a stiff ride. I prefer Reflex® Monotube Shock Absorbers
with 2x+ travel & still comfortable on uneven roads.:cool:

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But if the geometry of the H3 only produces 1.75" of travel at the shock, then the Ranchos will work fine. I just don't want a shock that has less travel than the mechanical travel of the suspension (at that location). I find it hard to believe that Rancho would spec a shock that actually limits the mechanical travel of a vehicle; makes no sense. That's why I'd like to know what the actual stats are of the H3 geometry.

H3 has more travel up and down! Get your tape measure and check ride height, then raise the front @ the frame behind the front tires, when the tires come off the ground, recheck ride height. Multiple the difference X2.

What is this geometry you speak of...

In the world of shock absorbers its a linear up and down motion.

Seriously, guys? :rolleyes: I know that the H3 has more than 2" of travel. I also know that shocks only move in a linear motion (I'm actually an engineer). Think about this; My Husqvarna 310 has over 12" of wheel travel, but the shock only has about 4" of travel (yes, there is also a linkage involved, but that's not the point). The point is that because the shock is mounted much closer to the pivot point, it doesn't need as much linear travel (yes, that's called geometry). Same with the H3: wheel travel is NOT the same as shock travel.

With the torsions at stock position, the LCA rests right against the bump stop, so the actual shock compression travel possible at that location is minimal, although I don't know how much droop the H3 will allow. With the torsions cranked up, I have about 3/4" gap at the bump stop. Now the shock is a bit outboard from there, but not much, so realistically, the shock can only compress about 1 1/2". I think this weekend I'll dig into it a bit more and see if I can get a clearer answer, including droop. Also waiting on a response from Rancho.

Here's what's interesting; Rancho's RS9000XL that they spec for the H3 with (their) 4" lift, while being longer (19.4" vs 15.28") to account for that lift STILL only has 2.11" of travel. Again, I find it hard to believe that a shock/suspension company that has been around as long as Rancho has would spec shocks that don't have enough travel for the vehicle they are listed for, including for THEIR OWN 4" lift kit. Anyone here with a Rancho lift want to chime in?

650Hawk "90+% of my time on the pavement"

When a shock or shocks bottom out the spring rate on that end becomes in effect, infinite. For instance the front bottoms out this can induce understeer. If the rears bottom out, sudden oversteer. It's as though you suddenly had ultra stiff springs on whichever end it happens on. What you'll notice is the ride is very harsh + under/oversteer as well. The purpose of a shock is to dampen spring oscillations. If the shock bottoms then it can no longer do what it's meant to and the spring cannot compress any further. The Shock is not designed to be the limiting factor in the suspension's travel. I doubt it would survive the experience.The usual response of the chassis is to throw that corner of the vehicle into the air. The vehicle skips/bounces, which can cause loss of control. I do not recommend reducing shock travel when driving on pavement! :rolleyes:

While all of that is true, it really is irrelevant IF the shock's length is sufficient for the mechanical limits of the suspension components. Even if you removed the shock, there is only a specific amount of travel in that system. If the shock doesn't bottom out or fully extend within it's mounted position throughout that system's range of motion, then your "finite" spring rate never comes into play.

Interestingly, on the H3, the stock shocks ARE indeed the limiting factor in droop. If you allow the suspension to fully droop, the upper stops (frame and UCA) do not hit as long as the shock's are installed. Remove the shock, and the suspension will drop a bit more, and those upper stops actually do come into play. But those stock shocks also have an internal rubber stop to buffer that. The Rancho shocks are about 1/10" longer at full extension than the stock shocks, and while I don't know if they also have that internal bumper, I have now seen several reports/pictures of the shaft being ripped out of the bottom of the shock when full extension/droop was reached (usually in a "tire off the ground" situation). So either they don't have that bumper, or the body's construction is weaker and not designed survive that limit (or both).

What I was interested in originally was whether the compressed length would physically limit the upper (compression) travel of the suspension. After more digging/research, I believe that the 2" of shock travel (at the shock mounts) may actually be enough to provide the full range of H3 suspension travel as designed, but their tendency to fail at full extension has removed the Rancho from my consideration anyway, so it's a moot point.

Wooohooo!:D

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Nice.