Suspension help.

Needing some help from the pros.

I bought the truck as is back in December with 16,000 miles on it, sitting at 24,000 today. It’s got some sort of spacer lift and SPC upper control arms but otherwise appears to be stock. I want to ditch the spacers and get 5100’s. Should my plan be that simple or is there something else I should be keep in mind since someone has already gone in and changed it from stock?

 

5100s would be a nice upgrade

 

If you’re going to do the work yourself, might as well treat yourself to some new springs too, have those 5100s set at zero. I believe both headstrong off-road and wheelers off-road will ship them to you assembled for a fee.

 

I do plan on doing it myself. When you say set at zero are you referring to ride height? I forgot to mention in my post that I’m running 285’s and was planning on setting them at 2”.

 

Yes, if you get new springs with your shocks, like OME 88X (whatever number you choose) let that do the lifting for you, set the ride height at zero - it just avoids a stiffer ride rather than compressing your stock springs to achieve the same height.

Also, if you have them assembled for you and shipped that way, just swap em and head out for an alignment and you’re done.

 

I run the 5100's at 4th notch, they dont seem to be too stiff (for me at least).

 

Ok that makes sense. Thank you.

 

Ditch the spacer, Keep the SPC's( Great UCA's, extremely adjustable )

Do what this guy says

 

Those r stock Bilstein shocks with the stock rubber spacer (normal)

If you want to upgrade you may want to do 6112’s, but to answer your question the 5100’s will slap right in

 

It’s a very common misconception that changing ride height with 5100’s changes the spring length and rate.

When mounting the stock 4600’s with the stock springs, the springs need to be compressed between the lower and upper shock mount just as with the 5100’s.

No matter what setting at which you place the clip on the 5100’s, with the tires on the ground and the weight of the vehicle on the stock spring, the stock spring will be the same length.

No matter what setting you use on the 5100’s, the spring length and the ride firmness will be the same.

5100’s have firmer valving and that is what provides a stiffer ride than the stock 4600’s. Even at the 0 setting, they will be firmer than the 4600’s.

When you move the clip upward on the shock body of the 5100, it increases the length of the shock tube below the bottom of the coil spring lower mount and that is what pushes down on the lower control arm giving lift and thereby increasing ride height.

In the picture below, the coil spring which would be to the right of black lower mount of the shock remains at the same length at all settings on the 5100, as it is compressed between the upper and lower spring mount.
Then, as the vehicle weight is placed on the spring, the spring is further compressed. While driving, the coil spring compresses and extends, while the piston of the shock moves in and out of the tube.

Moving the clip and black mount to the right or upwards on the shock tube, lengthens the shock tube below the coil. That increases the ride height.

In the first picture circlip is positioned at second ring for .65 inch of lift.

Coil spring and shock piston on right are constantly changing in length when driving.
Shock tube length at left remains the same, unless clip is moved from 0 to .65, 1.1, 1.55 or 2.0 inch setting.

In the second picture:
Shock tube below coil is longest at position 5. Piston at top of shock moves up to keep coil spring at the same length at all settings.
Because of outward and downward angle of lower control arm, the small changes in clip position can translate into 2 inches of lift at tire.

 

I don't see how that wouldn't compress the spring more. You move the lower mount up say .65 inches towards the top cap and put the same spring in there. Your shock hasn't gotten any longer, so you must compress that spring an additional .65 inches to fit it in between the lower clip and top cap. For these coil springs, they follow the F=kx Hooke's law. K doesn't change since you're using the same spring, but you've added an additional .65 to your x displacement so your F goes up by that factor. Therefore, the force your spring is pushing on your LCA goes up by that factor. That's what generates the lift, and that is why they will generally ride stiffer, because now the force to displace them that 1" is the same as the force to displace the stock spring 1.65".

 

Yes, the initial spring length installed on the shock would be shorter / more compressed. But the space between spring seats (and the load on the spring) will be the same once vehicle weight is loaded onto it. The compressed resting total length of the spring will be the same. It's going to react the same way when bumps are encountered. At 2" ride height increase, the ride quality downside would be decreased suspension down travel. The possible extended length of the shock won't change, but it will be a shorter distance between normal loaded position and the limits of down travel.

Unless that spring is compressed to an extent that putting the vehicle weight on it does not load / compress the spring any additional amount at all, the ride would be the same.

Or what am I missing?

 

You're just extending the shock more. Spring stays same length.

 

Didn’t mean to spark this debate...

The new tacos come with a 700lb spring (at least that’s what I’ve been told) an OME 887/8 will give you a 2~3” lift set at zero on 5100s. The ride will be softer because the spring rate is 590 vs your stock 700lb spring.

 

I can assure you the shock is not extending more. I have those shocks. They only extend to one length irrespective of what the spring length is.

 

Yeah that’s not how springs work. If you compress a spring it exerts a force. In total, the front springs of the truck have to support the front weight of the truck. If you preload your springs, like using a higher clip position, then they are already exerting more force on the suspension and so they don’t compress as much for the given weight of the truck, therefore resulting in a lift. Same way as coilovers generate lift by preload.

 

Maybe you're right. Not sure.

 

Okay, for the sake of discussion, because there are two camps on this, and I have always been in the camp that these shocks and springs (or coilovers) do NOT increase ride roughness if the spring has not been pre-loaded so much when installed on the shock as to not load additionally once a load (the weight of the truck) is placed on them.

Measurements shown below are of spring length (the red outline denotes the spring).



Sorry for the rough sketch.

On the 1st shock (shock A), the spring is installed on the shock without any height adjustment.

On the 2nd shock (shock B), the spring is installed with the bottom spring seat moved 1 1/2" to create lift.

At this point the spring on shock "B" (the "lifted" shock) IS compressed more and IS exerting more force between spring seats than the spring on shock "A" (un-lifted shock) because the shock up travel at full extension is limiting spring extension and unloading.

Now, shock "A" is installed on the vehicle, jackstands removed, and the spring is fully carrying the weight of the vehicle. The spring has compressed to 13 1/2" in length.

On shock "B", it (the "lifted" shock) is also installed on vehicle, jackstands removed, and spring is fully carrying the weight of the vehicle. This spring has also compressed to 13 1/2" length.

In both instances the 13 1/2" is the length the spring naturally wants to compress to once it is carrying the weight of the vehicle. The only difference in length of anything is the length the shock piston is extended, and the overall total length of the shock.

How is shock "B" going to ride any different than shock "A" simply based on the springs off vehicle compressed length when there is no load on it? The length of the spring is exactly the same, and the force it is exerting between spring seats is exactly the same. It will react the same way (compress with the same force and distance) when a bump is encountered (the only limiting factor here being the travel of the shock piston).

Not going for a pissin' match here, BTW. My non-suspension engineer brain tells me the above to be the case, and I've got a pretty damn damn good mechanically inclined brain bucket. But if there's something I'm missing at this point I need it explained, because the alternate does not compute with me looking at this from a distance with tilted head!

 

In your example, if they both compressed to 13.5, why is one longer than the other? These shocks only have one fully extended length. Changing the clip position doesn't add more body to the shock, it just moves the lower spring perch closer to the top cap.

Let's say for the sake of argument that you put 1000lbs of load on that corner, and that it's got a spring rate of 1,000 lbs/in. Ignoring the actual leverage of the suspension on the spring, let's just say it's a 1:1 thing. And let's say that in the stock position there is no load on the spring when the wheels are off the ground. So when you drop your truck on the ground, it settles 1 inch before the spring exerts enough load on the suspension to support that corner of the truck. Now let's say you put a 1/2" of preload on that spring (move the clip up 1/2"). Now the spring is exerting 500 lbs. Now when you drop your truck down, your truck compresses that spring 1/2" to generate the additional 500 lbs, but the overall shock length is the same as before, so the new ride height has to be 1/2" higher.

If you keep going and put a preload on that exerts more force than the weight on that corner, then the only time you'll compress the spring is when you hit a bump, etc. You'll be in for a rough ride.

So I agree - you won't change your spring's stiffness and as long as you don't exceed your corner weight, you won't change the firmness of the ride. But it will also take more force to "stuff" since you'll be higher up in the suspension travel.