285s on stock Trail Edition Rims

I felt the same way about the 5100's on my Nissan Frontier and my 4Runner. Loved them on a 1997 F150 though.

Eibachs shocks are definitely smoother on the 4Runner.

Just some food for thought. Get what you think you and the wife will like best

 

Bilstein's 5100 are digressive; if you like a smoother ride & better damping and eliminate body roll and nose dive, look at a progressive more linear setup.

 

Like @Roland said, avoid digressive shocks if you're looking for a cushy ride. Eibach is very popular around here.

 

I will mention that Eibach's are also digressive, but not all digressive shocks are created equal.

That bleeder valve early in the travel helps the Eibach shocks act like progressive shocks at lower speeds. That's why they ride smoother than the 5100's.

6112's is another example of a digressive shock that a lot of people love. The only issue with those is I think they are more shock than you actually need......and they are quite a bit more money. No need to spend that much money for a vehicle that spends the vast majority of the time on the street, IMO.

 

I love my 6112's! I just wish they made matching rear shocks. I think the 5100's out back don't have enough damping for my springs and the extra weight. And, 5160's seem to be nothing more than 5100's with reservoirs.

Like you said, not all digressive shocks are equal. Icons are supposed to be fantastic for that month before they start leaking.

 

I don't mind spending a little extra money. I tend go a little overboard when I build things out. Plus I've got her convinced on budget that would be facilitate the 6112s or up to the dobinson IMS. I've done some looking and haven't found very much information. On a couple other forms some people were saying the Dobinsons were progressively valved but I was able to find any exact information.

 

I think because the top isnt moving up…so you are adding compression load to the spring. Motorcycles and mountainbikes often have adjustable spring seats so you can adjust “pre-load” at the turn of a wrench. It’s a rough adjustment, and not the best way to lift something (since you get less comfy ride), but pre-load can effectively lift a vehicle. You are just using up some of the range of motion to get it.

 

It seems like this is debated a few times a year.

I tend to agree with @glwood54 . if the spring perch is moved down, and the truck is raised as a result, the spring should be under the same tension at regular ride height.

The one thing I could see being different is that you can potentially compress the spring more before hitting the bump stops. So, bigger bumps could be harsher.

But, this really shouldn't affect ride quality on the street.

The other part of this is that some shocks, particularly internal or external bypass, can be position sensitive. So, adjusting them to the extreme of their lift range could definitely affect the way they perform.

Shocks are one thing (of many things) that I find extremely fascinating. I would really like to understand them more. It would be truly interesting to me to really understand what is going on inside of them, and how they are custom valved to an application. I definitely have some reading in store for this winter!

 

Dobinsons IMS shocks are progressive, if mated with Dobinsons springs you can choose from the following:

 

The more I learn about Dobinson, the higher they get on my list for the next upgrade. Luckily, I have a few years to figure it out.

 

From what I read and hear, you won't regret the Dobs. If you really want to get nuts, there's always Fox, Elka, King and other 2.5" resi's with adjusters.

 

i dont even know what my springs are! I didnt know they had those options! My head would have exploded if I had to think of that too when I was picking out my dobs.

 

I have to second @glwood54.

A progressive spring, tighter winds are only part of a dual rate spring, the smaller diameter wire is what allows for a secondary spring rate through part of the range. There are three types of coils, linear, progressive and dual rate that are the most common for any of us to be dealing with.

Linear rate springs, have one defined spring rate per inch of deflection throughout most of their range of deflection. For instance, if we have a 300lb/in linear rate spring that is 12 inches long, it will take approximately 300lb to deflect it 1 inch. The next inch of deflection will take another 300lb of load and the next inch of deflection will take an additional 300 number of load and so on until the spring goes solid. At this point there will be 900lb of load on a 12 inch long spring that has now been compressed to a 9” spring height.

The linearity of rate makes it quite easy to calculate a given spring length at ride height and this helps in setting up the ride height of a specific vehicle. If we know that we have 750lbs of sprung mass on a corner and we want to run a 250lb/in linear rate spring; we know the spring will compress 3 inches (750lbs ÷250lb/in = 3 inches). That helps us anticipate the total travel of the spring. Also, by measuring the total travel of the damper, we can easily estimate the total load placed on the spring during an event.

Dobinsons progressive rate suspension springs, the dual-rate spring with two linear rates connected with a rate transition range is a much more sophisticated suspension spring. The design is much more focused on the specific use for the spring. These types of springs are used primarily in road racing and high performance street and GT applications where the vehicle trim package will stay in a very predictable range. These springs are easily identified by having a few closely wound coils at one end and then wider, equal spaced coils at the other end. They have rates described as 200/425lb/in. This means that the spring has an initial rate of 225lb/in through some range of deflection and then the rate transitions to 425lb/in through a deflection range of 1”-1.5.” The big advantage of these springs is that they can provide roll control in addition to roll control provided by sway bars.

 

The difference is that with mountain bikes and motorcycles, you're dealing with adjustable coilovers. At a certain point of adjustment (when you've exceeded the distance the coil would compress from the weight of the vehicle), you start preloading it.

With our standard coil and shock set-up, if you raise the lower spring perch up, you raise the vehicle up. You aren't preloading the coil because you aren't adding any additional weight or tension to the coil like you would be cranking down the coil adjuster on a coilover.

 

Maybe Im not following or Im not envisioning it right in my head then. My Dobs IMS is an adjustable coilover (adjustable for preload anyway). I can move the bottom spring perch up or down. Just like on my motorcycle. Would I not be preloading the spring if I raised the spring seat upwards against the the top of the coilover body (which hasnt moved)? The spring is now forced to occupy less distance between the top and bottom. And on stock 4runner suspension, if you put spacers on the spring side (the only way to preload stock suspension), you would effectively be accomplishing the same thing.

When I used to ride murdercycles, I always kept my preload maxed out. Otherwise with my “husky” build, the back end sat too low. The preload essentially took the sag out from my weight, and effectively kept me at a higher ride height.

Maybe Im not using the word preload correctly? But I could have sworn my manuals called them preload adjusters.

 

I believe the lift spacers sit on top of the whole assembly.

As far as coilovers, the spring is always compressed some when the weight of the vehicle is on it. No matter where the spring perch is, the coil will always be the same length under the weight of the truck. Otherwise, your ride height would not adjust.

At some point, you could potentially compress beyond what the weight of the truck would, but this would be at or beyond the maximum adjustment. The threads might not even go far enough to make this possible.

 

I think there are also spacers (by westcot I think, dont quote me) that go on the spring side, in other words, those spacers take up space that would be taken up by the spring….forcing it to be more compressed (independent of the damper)

Those spacers, the way Im understanding things, would function exactly like an adjustable spring seat, or spring seats you can move up or down (except you cant adjust spacers). As an aside, the term “adjustability” is moot…even though mine are “adjustable”, i have to take my coilovers apart to do so.

That’s where Im thinking anytime you change the distance between the upper and lower spring seats, you are effectively pre-loading/pre-compressing that spring. Because the spring has to be compressed more to fit in a smaller space than before.

Im kinda wondering if maybe we are all getting tripped up by terms lol

 

Exactly.

And that, too.

That's only true if one assumes the 4Runner doesn't go up on top of the now lifted spring. That's like saying the ride height of the truck is fixed, and putting in a higher spring seat or a spacer only compresses the spring without lifting the vehicle. If that were true, no one in their right mind would ever consider using spacers or adjustable spring seat struts to lift or level their 4R.

 

Preload is often a misnomer in the offroading world. I often hear people use the term incorrectly to describe lift.

The "preload spacers" that you're talking about aren't preloading......Wescott was mistaken in naming them that. The coil is not compressing anymore with the spacer on the bottom vs the top......or even by sandwiching the coil with 2 spacers. It's simply increasing the space between the upper and lower spring perches and thereby lifting the truck.

With our stock coil and shock set-up, both sides of the coil are essentially open ended. With an adjustable coilover, the ends of the coils are locked with collars (one side being adjustable). This gives you the ability to crank down on one side and preload the spring.

 

Same here. Put Dobinsons on my wife’s 4runner and quality was amazing. Definitely will go that route on the GX.

 

Well, thanks everybody for trying to make me understand. I’ll have to re-read these posts and try to think about it some more to see how I’m not getting it lol.

Suspensions really are an intriguing thing. We’ve come a long way…I remember reading how some of the early racecars essentially had two planks of wood that slid over each other to function as dampers haha

 

Hmm, a dim light bulb is buzzing in my brain. Maybe Im getting it. So the stock shocks are totally different than my Dobs, from a mechanical standpoint?….

Question, kind of on a tangent. What is the difference between spacers on top of the shock (ala cornfed), vs sandwiched between the perches (on the spring side). (I thought I knew, but maybe I didnt understand it as good as I thought I did.)

And one more…the bilsteins that have perches you can reposition…are those mechanically like the stock shocks (ie open-ended), or more like the “preloadable” Dobs or motorcycle shocks?

edit: as a token attempt to keep the thread on topic, I support 285s on stock trail wheels

 

A Cornfed spacer will just lower the top of the entire assembly in order to raise the vehicle. A spring spacer would function the same as adding "preload" to an adjustable coilover.

I really think the term "preload" causes a lot of confusion. Yes, you are adding "preload" to the assembly. But, once the weight of the vehicle is on it, the spring will compress to the same length, regardless of how much or how little "preload" there is.

6112's are considered coilovers. They just adjust differently than higher end coilovers.

 

Preload is independent of spring free length. An 18″ long, 100 lb/in spring with 1″ of preload will give you the same ride height as a 10″ long, 100 lb/in spring with 1″ of preload.

In both cases you’ve applied 100 lb of force before the vehicle weight collapses the spring. Because spring rates are the same each spring will collapse the same amount under the weight of the vehicle. The result is the same amount of ride height.

 

I actually think the first part of your statement is incorrect. An 18" spring will ride 8" higher than a 10" spring if everything else is equal (obviously not exactly 8" because the strut attaches about midway between the frame and the hub). But, you'd need a longer assembly to accommodate the longer spring.

If spring rates are equal, and one is 8" longer, it will still be 8" longer under the same load.



But, what I'm trying to point out is that the same spring will have the same handling characteristics at different ride heights.

Once the weight of the vehicle is on it, it will compress to the same length regardless of preload. The vehicle is lifted because the spring perch moved, not because the spring has somehow become stiffer.

 

The only time spring length can affect preload is if there aren’t enough threads on the shock to get the desired preload, or if the springs will go to coil bind.

Preload is a measurement of how much a spring is compressed at full extension of the shock. Thread the upper spring adjuster down until it just touches the spring, you are now at 0″ of preload. Every inch you thread it down from there is 1″ of preload. With a 1.0 Motion Ratio that also lifts the vehicle 1″. With a 0.5″ motion ratio that lifts the vehicle 2″.

If you want more lift and have the correct amount of preload then you’ll need stiffer springs. If you want less lift then you need softer springs.

Everyone thinks about what happens when springs compress, but it’s also important to think about what happens when they extend. Spring preload pushes the tire down and makes the suspension work. On big bumps at speed the spring preload pushes the tires down to better follow the terrain and make a smoother, more controlled ride. Under articulation the spring preload increases tire contract pressure improving traction.

 

I understand this. But a longer spring will require a longer assembly, so it won't have the same ride height as a shorter spring. Preload isn't even a part of this equation.

I'm not even sure how different spring rates and lengths have anything to do with what I said.

All I said was that the same spring will have the same ride characteristics regardless of preload. Any difference will be felt towards the end of travel.

Again...

Once the weight of the vehicle is applied, it will compress to the same length regardless of preload. The ride height is increased or decreased because the spring perch moved. Preload cannot make a spring stiffer or weaker.

 

I pointed to your comment "I really think the term "preload" causes a lot of confusion" I try to explain the entire definition of preload.

 

Ok. I just wasn't sure. My only point there was to just say that the spring rate doesn't change due to preload, because preload raises the vehicle.

I also can see how preload would potentially affect ride quality as you approach maximum up or down travel. But, the initial feel should be the same.

 

Well, there is much more to it, nevertheless, we are hijacking OP's thread. Sorry, OP, for the greater good. Lol. James, we should start a preload thread .