Bilstein 6112 Question

Perhaps somebody can educate me.

What is meant by preload in the context of this thread?

For the same front end weight supported, the spring will compress to the same length, regardless of the perch used, right. Perch will change where the length of the spring/shock assembly at vehicle static loading.

I ASSUME that the piston and valving behavior are not dependent on stroke location.

The available up and down travel from vehicle static will change, depending on the perch location.

So nothing is being 'preloaded', correct. The loss of down or up stroke, depending on perch location could have a huge impact on felt behavior.

Am I missing something? Or by preload are we describing something other than the spring compression?

 

Two different ways to think about it using the options mentioned in this thread thus far.

One, by moving the spring perch up further on the shock body, you are correct in that the the spring is “under more load” in static state. Now, usually the spring manufacturer takes this into consideration while designing the springs that are meant to work with these “adjustable” shocks but the bottom line is you’re changing the dynamics of how the spring reacts by compressing (shortening) it and thus, the ride quality is affected.

Two, by adding a top plate spacer, you’re moving the entire shock and spring down. This adds additional “preload” to the entire coilover, both the spring and the shock. Adding more preload to an already compressed spring (moved further up on the shock body) distorts the dynamics of the spring even more and in conjunction with the preloaded shock (because you’ve moved it down from its intended mounting point) this results in an even more impacted ride quality.

Now, some people will claim they can’t feel any difference in ride between say notch three and four, while others will say the ride is “softer” the lower down the shock body the spring perch is. Others will claim top plate spacers don’t impact the feel of the ride at all. Obviously there’s a lot more science to all of the above and there are plenty of threads on TW about both topics. A quick search will yield several days worth of reading on the pros and cons of both. From a scientific aspect and from a real world, ride quality insight point of view.

I don’t have any experience with “preloading” a spring by moving it further up the shock body (I have OME 885 springs on the lowest notch of the 5100s) but I do have a top plate spacer on both sides and I can tell you that my ride quality has suffered over time. As the shocks wear, the preload caused by pushing them down exaggerates the already stiff feel from the digressive valving. And that’s exactly what I’m trying to move away from with my next suspension.

 

The problem is, I cannot see that there is any additional spring load at static condition caused by either a spacer, or higher spring perch. (assuming that all 4 corners are changed similarly, and assuming that the lift or lower isn't so much that the truck hits an up stop or down stop statically).

The freebody of the suspension combo indicates same load in the spring/shock regardless of its length, within reasonable bounds. So therefore spring compression would be the same, within reasonable bounds.

I must be missing something, but I don't see it.

 

Need to get a professional in here to explain the science behind it better.

Tagging in @AccuTune Offroad

 

Are Tacoma springs linear or progressive?

 

I'm running 2nd gen Tacomas 6112s on clip 5 (2nd gens only go up to 5) w a 1/4" spacer on the driver side. Drives great, not stiff at all.

 

Depends on the model, at least I know they were different on the 2nd Gens. TRD Sport models had one and Off Road the other.

 

OP- Don’t overthink it. There is a big difference between a 5100 jamming a progressive stock spring in on the top clip and a 6112.

I ran mine on clip 3 w/ lean spacer for a year. Just added a 1/2” top plate spacer (above the top hat) and moved the driver side up to clip 4. I literally noticed no change in how it rides or drives.

I also run 2nd gen 6112s so add one to any clip settings I say.

 

Pretty sure these have linear springs. I haven't looked but I don't remember seeing a tighter coil in one end. Does anyone know?

 

Would you recommend installing an AAL and UCA? I just want to clear the rubbing issues and have everything ride smoothly in the long run. Also mind posting a picture? It's hard to see a tiny profile picture.

 

I would definitely recommend the AAL for the lift, firmer ride, and also for handling weight in the bed without bottoming out on the highway. (Some will recommend a full leaf pack, but I have had no issue with AAL on two trucks now.) UCA is recommended for correct caster which does help steering feel on the highway. But, you may or may not notice a difference, so use your own judgment.

Pics of lift: (running 275/70/17 tires)

 

Sick

 

Looks great! Where did you buy your full suspension?

 

I legit can’t make a decision for my second gen...

On one hand, I want to save ~$600 and go with the 6112/5160 setup but on the other I’m afraid the truck will sit lower than it does on my current setup and it’ll still be too stiff for my liking. I know the Fox suspension will be “softer” and give me the flexibility to adjust the lift as I see fit, but I almost can’t justify spending $2000+ right now.

It sure would be nice to ride in a truck with a 6112 on the 4th or 5th notch before making the final decision...

 

I bought from Wheelers Offroad. They are knowledgeable if you want to call and discuss ideas too.

 

Nice bike! I have the 501 (Same year)
Tacoma and Husqvarna guy, I like you

 

Yeah, I've been happy with the Husky. 350 because I enjoy mostly technical single track type riding. Came off a 250 Honda. The bike is more agile and more powerful. Fun!

 

I ride enduro/single track as well, actually strickly ride/race the slower stuff that where the real riding is in my opinion. The 501 does a fine job but I would love a 350 just as much!