Exactly correct.

Is that some weird spacer that lifted both the spring and the shock? How did they do an alignment?

Just crawled under the back end of my 4Runner (the front end is to cramped and complicated to see anything):

There is a pair of elastomer bump stops that keep the axle housing from bumping into the frame rails.

There are two radius rods that keep that enable the torque of the back wheels to push the car frame forward and keep axles aligned.

There are two more inboard short rods that probably limit some of the downward travel of the axle housing.

There is another diagonal rod that is probably called the sway bar.

There is last but not least the OEM shocks that are the final limit to down travel.

- - -

Now then if one were to put in longer springs or spacers on the ends of the springs -> ALL of that above stuff is still there and doing the same jobs. The only thing that has changed is the "resting" center point of the spring.

Now if one were to install a "long travel" suspension system, everything changes.

Now then - I am Not trying to start any arguments - Just a discussion about what a shock is really doing when one has raised a vehicle using a longer spring or a spring with a spacer. Not something more exotic.

Air bags add lift?

One more explanatory document. In Toyota's infinite wisdom they have kept me in the dark as to access to their repair manuals; so here is one page out of my 1600 page Land Rover Repair Manual (on disc):



As you can see I have crossed out a couple of components that Land Rover sells as an option that is probably equivalent to Toyota's X-Reas.

Items 1 and 6 = The coil springs - These will actually fall out of the car if one removes the shocks (dampers0

Items 2 and 7 = The dampers - limits down travel and absorbs shock.

Items 9 and 13 = Radius arms - keeps thing longitudinally aligned and transfers wheel push to trucks frame.

Item 3 = Watts linkage - prevents side to side movement. Does not limit down travel unless the shocks are removed.

ON THE LAND ROVER the ONLY thing I had to do to install longer springs was to temporarily disconnect the shocks so that I could jack the frame up high enough to let the springs fall out.

Also on the Land Rovers for those guys who did install longer shocks in order to increase their 11 inches of articulation to 14 inches; they had to install cones inside the springs so that they wouldn't fall out.

Everyone's OEM shocks lasted longer than the antique Buick V8 did.

FYI - SLS = Self leveling system - Air bags replace coil springs.

On a high level I agree with you but in reference to the OPs question it comes down to bang for your buck.
The OP asked about whether to use spacers with stock shocks/springs, I was only pointing out he wasn't saving much money and that the low end Bilsteins were cost comparable and have both handling and wheel travel benefits over using spacers. Not suggesting he will break something either way.

Longer shocks are not needed but if OP is already spending the money and gets to choose to not lose travel at very little cost... Why not? Out the door for just over $300 using Bilsteins in the front and airbags in the rear. That's actually cheaper than springs all around, is adjustable if needs change, and improves the handling. That's a killer deal!

Yeah they add a little. Esp if you aren't loaded down.

Your springs won't unseat with Bilsteins. The only aftermarket shock that lets your stock springs unseat that I know of is the MT/Icon LT design and they sell the longer spring that avoids this.

Using the rear as an example because it's simpler...
The shocks limit travel and absorb shock. I assume that the OEM springs and shocks are sized so that at full extension (for example, jack up the rear by the frame) there is just enough force exerted by the springs to keep them from falling out, but not so much that they overcome the damping of the shock and you get a harsh impact if it tops out.

If you put in longer springs with the stock shocks, then when the shocks top out the springs will exert more force on the shock, and you might feel the impact or damage the shock when it reaches the limit with more force than expected. You shouldn't top out very often with the stock configuration, but with a longer spring and stock shocks you might be near the limit of shock travel all the time, so it could happen frequently.

If you put longer shocks in and use the stock springs, the springs could fall out if the rear is unweighted since the shock could extend to the point where the spring is completely unloaded. You would probably have to get air or be on a surface that causes articulation for this to happen, but it could be really bad. If the springs fall out while you are in the air, when you land there will be no springs to support the weight and you could damage the shock or something else. I inadvertently hit a bump that turned into a bit of a jump in a 4runner one time, so it can happen. The springs didn't fall out because it was all stock. @Swarty says the springs won't fall out, but I would want to verify that myself if I had different rear shocks. (jacking up the rear frame and checking the springs would be a simple test.)

The front is similar, but there are more parts that might limit travel if the shock/spring is changed from the original design. As far as I know the shock is the primary thing that keeps the wheel from falling down too far. Other things are the upper control arm joint, and the bushings on the control arms which do not move very freely when the alignment cam bolts are tight. There may be no sliding movement there, only the rubber bushing stretching. There's also the sway bar, which links the left and right sides, etc. The shock is designed to limit travel because if it breaks it's not catastrophic. If a control arm ball joint or something like that breaks while driving then you have a problem! A limit strap could work, too, but I've never seen a limit strap in an OEM suspension.

Adding a spring spacer or longer spring has the same effect as a longer spring in the rear, and you need a longer shock to compensate. A longer spring might be equivalent to a spring spacer because the minimum length of the stock spring + a spacer could be the same as the minimum length of a longer spring that has a lot of coils. Adjustable coilovers work the same way as spring spacers, but they are adjustable.

Adding a spacer above the top hat is different since it moves the spring and shock down together, but it doesn't change the relationship between the spring and the shock.

In the front and rear, rubber bump stops limit upward travel. They are not just a hard limit, but they actually make the spring force non-linear as you hit them so that you don't get harsh bottoming out on big bumps. If you add longer springs, spring spacers, or top hat spacers you might bottom out on something solid (metal) before you hit the bump stops, which could make for a harsh impact. If you add lift that limits compression you should probably add spacers to the bump stops, too, so that they can still absorb big hits.

Example of a top hat spacer:
Front Top Plate Spacer (One - 1/4")

Example of a spring spacer:
Front 2" Coil Spacer Lift for 00-06 Tundra

There's a lot to consider, and I still don't understand suspension well enough to change anything. We haven't even considered where the center of gravity is with relation to the roll center. The vehicle rotates around a virtual point called the roll center https://en.wikipedia.org/wiki/Roll_center . And there might be effects on steering or handling if the suspension geometry is changed which might not be noticeable in normal driving. And there's also ride quality, which is difficult to describe accurately and difficult to compare or measure. Could someone test different suspension setups on a controlled course while recording accelerometer data for me? And there's the fact that manufacturers for all this stuff don't give us any parameters that we would need to design or compare suspension setups. For springs I want to know the uncompressed length, spring rate, and minimum (compressed) length. For shocks I want to know max an min length and how much compression damping and rebound it has, and if there are any special damping circuits such as high and low speed circuits (common in mountian bikes), and if the shock has any spring force of its own from a pressure charge. I also want that information for the stock springs and shocks to compare.

[QUOTE=Ron4RNevada;2008273]
There is another diagonal rod that is probably called the sway bar.

QUOTE]

For the sake of clarity I believe what you are referring to is the pan hard bar or track bar depending on where you grew up. If you are indeed referring to the sway bar no worries but the straight bar that runs at a diagonal on the rear suspension of the 4runner is def a pan hard bar and not the sway bar. The two serve very different functions.

I have no idea how they got it aligned, apparently it's 6 inches.

This thread is a bit of a goldmine discussion for technical shock/coil discussion.

Does anyone know what the actual OEM shock travel is for a t4r, front and rear ?
Wondering how significant 1-2" is of the total travel for a mall crawler.

I found this to be a fascinating discussion a year ago and I am now posting my comments.

I put a total of 7,000 miles on lift springs and stock shocks. It was never meant to be a permanent solution so I cannot comment on long term shock wear. Notable trails include Elephant Hill, Kamikaze, Boxcar, Bobby's Hole, Broken Arrow, and a bunch of rough easy-to-moderate desert trails and roads. Also, one upper-end moderate Montana trail. All in all, this setup saw dozens of trails and dirt roads with no issues.

1/ Dobinsons 1.25 front and stock rest:

--On road: much improved handling, improved cornering, much reduced nose dive.

--Off road: the terrible front nose dive over rocks and bottoming out from minor events were gone. Of course, this simply exposed the stock rear.

--Negatives: none. I doubt the shocks would have seen their life reduced.

2/Dobinsons 1.25 front and Eibach 1" rear on stock shocks.

--Off road: SUPREME COMFORT IN ALL SORTS OF TERRAIN. No more bottoming out. Speeds up to 10mph over stock in rough terrain.

--On road: partial reversion to stock feel. Handling still felt improved, but cornering felt like stock again. Nose dive increased somewhat. Resistance to wind on interstate improved. But overall felt less capable on road than just the front Dobs and stock all else.

--Negatives: nothing major in my experience, but I would guess that having weak shocks with strong springs can be a safety issue in emergency situations, not sure. Even without that, there were several tidbits that exposed the setup as a partial solution and something I would not recommend.

1/ while comfort was AMAZING, it was a bit too good. By this I mean that it came at the expense of control in certain, if rare, off road moments where the shocks felt too weak to control the springs.

2/Performance over rough spots and washboard improved in terms of eliminating bottoming out, but not in terms of overall control.

3/ While having front and rear lift springs was great offroad, having only front lift springs was better on road.

My current 6112/Icon 2.0 setup is not quite as plush over rough terrain. But control is superb and comfort is plenty good enough, maybe somewhere north of half way between stock and Dobs/Eibach springs on stock shocks.

NOTE: all comments apply to P265 Wildpeaks at 30-33 psi. I would assume that LTE comfort at 20 would be comparable to P at 30.