I have yet to see this topic covered anywhere on the internet and to me at least, this needs significantly more coverage. I do not believe I am overthinking, but let's see where this goes.

Situation: leveling struts vs strut spacers and their relationship to suspension down travel. (For simplicity, remove UCAs and LCAs from the equation because that just adds unnecessary complexity for the sake of discussion.)

For example, if you max out a set of Bilstein 6112s on a truck by putting them at their tallest setting, you'll be installing a slightly extended strut onto the truck and therefore will retain less down travel compared to stock. This is what I have. Conversely, if you install high quality strut spacers (AutoSpring for example), you will have less up travel than the Bilstein leveled setup, but will retain the stock down travel value.

I have read innumerable articles on why strut spacers are bad, but I'm not buying. I see absolutely no issue with a 2" or shorter AutoSpring strut spacer. In fact, and in addition to drop brackets and other lift components, strut spacers are required for any sort of actual lift on trucks which utilize struts. So my question is why not run a 1.5" or 2" AutoSping so that the truck is leveled, but then also run Bilstein 6112s at their stock height setting so that I may retain that oh-so nice and necessary down travel while also enjoying the benefits of a 2.5" piston strut?

 

I don't have enough knowledge to participate in a conversation, but part of me says that if you don't want to discuss the control arms then you will never know why you can't stack the 2 level kits.
Travel is altered because you have changed the radius of the arc the control arms swing by. The control arms no longer articulate with their counterpart.

You are welcome to stack a leveling puck on top of your coilover but you'll quickly find that your axles are prone to damage due to the centerline distance of the hub vs transfer case.
Travel will be reduced and the ride quality will diminish from the upper/lower control arm arguing about which way to move. It's like arm wrestling with your equal, one will take the advantage and the other will counter pulling in the opposite direction.

That's all I know but yes, when you don't want to consider the role the control arms play, there isn't a way to say numerous stacked level options will work.

Or I am completely wrong (which is totally possible) but that is how I know it.

 

I still don't know how to do all of the fancy stuff on forums yet so bear with me.

"Travel is altered because you have changed the radius of the arc the control arms swing by."
Please don't focus on this. The arc of the control arms is not altered by installing a shock, strut, or spacer. The pivot point (mounting points on the chassis) stays the same and so does the point of articulation at the spindle. Neither of those change so therefore the radius arc does not either. What I was trying to avoid was debating aftermarket control arms (which do change radius arc). But to solve this problem, discussion of control arms is not necessary. This is very difficult to elaborate upon through text versus having a white board in the garage or a truck to show components on, so I hope this makes sense.

You are welcome to stack a leveling puck on top of your coilover but you'll quickly find that your axles are prone to damage due to the centerline distance of the hub vs transfer case.
This is true in large amounts of lift. Proneness to damage is near stock on a 2017 F150 with ≤ 2.25" of lift and is completely safe. Remember that the 6112s in this hypothetical scenario would be installed at their lowest setting, therefore offering no additional lift in addition to the spacers.

 

I really dont think strut spacers are bad. The shocks on these trucks are the bumpstops so you don't risk messing anything up in the sense of bottoming out early or anything. But, depending on how far you go with the spacer, I could see it over extending the suspension/CV's. There seems to be some 3-3.5" spacer kits out there.

Combining spacers with 6112 would really come down to whether or not the 6112's is longer than the stock coilover. IDK, I have never seen them side-by-side nor did I check my 5100's before installing. I do know the 6112's I just put on my Lexus are about 1" longer than the stock shock side by side. So I gained about 2" of lift but also gained 2" of downtravel at the wheel.

I do know a guy that put a small spacer over 5100's like you said. I think it was the faction fab 1.5". But say the shock is 1" longer as well, now you are letting the wheel drop 3.5" total more than stock with the spacer.

I forget where it was now but some guy went over all the coilover options with a fine tooth comb and figured out the specs on most of the big name ones. Total length, compressed length and travel.

Edit, found it:





So the fox's are .5" longer extended than the Kings so the would allow for some more downtravel

 

I also noticed Elka makes two coilovers, one is for 0-2" lift and then they have a second for 2-3". I suspect they are different lengths because of exactly what you are talking about.

 

The icon 2.5’s are 23.5 fully extended and the halolifts aluma 2.0’s are 23.75. I have had both on my truck.

 

Aluma's are made by Elka arnt they?

 

Yes, I think the build quality is better then the icons, they also have a smoother ride.

 

Take look at my build thread and you will find everything you are looking for. I run the Bilstein 6112s set at 1" of lift, with a 2.25" Ready Lift Strut Spacer.
Sure the CV Axle angles are more severe than most because of the overall lift height, but its nothing thats going to destroy them. I have used the stock CV axles the entire time without issues. The only CV issues I ran into were aftermarket axles tearing the boot with normal driving, where as the Ford OE and Motorcraft have stretchy-er boots. I have built many high end suspension set ups that range of rock crawler to desert runner. There is no issue running a strut spacer with an adjustable strut. Stacking the two up to 4" will be too much, but keeping it to 3ish inches and below results in no issues. Using both the strut spacer, and an adjustable level strut is going to net you the most down travel, as well as the most comfortable ride. When you max a lift strut, you are leaving maybe .5" of strut rod downtravel, meaning you bottom the strut out very easily and quickly, creating that harsh ride that comes with most leveling struts.

Oh and for the uptravel to downtravel... Couldn't find the original pics on my new phone, but here are some crappy pics to show.

 

This post has certainly delivered! Thank y'all, I have some suspension homework to do now!