5100's at 2.5" advice

Bingo. If you address the rear ride height so that it's level at 1.75" and again at 2.5" the difference in ride quality that everyone talks about doesn't exist. The spring rate will not change if you did this and therefore any change in ride quality would not be due to this simple adjustment like people keep parroting.

 

Oh yeah.......

 

OK. Picture yourself installing some coils on a 5100 purely by hand, i.e. no tools (improbable I know, but bear with me for a second). Say the 5100 set @ 0" spring mount surface to spring mount surface is exactly the same as the coil it self. Easy right? 0 preload. Put it on your truck and the fender sits 20" off the ground(hypothetically)
Now take that same spring and adjust your coil bucket to 2.5". Put it in by hand. Now it may sit @ 22.5" +or- because you guessed it, you preloaded the spring. Was the installation of your preloaded spring onto the shock more difficult or was it just as easy as 0 preload?

 

Too many variables. Of course your ride height isn't 1:1 because your rear suspension stayed the same which means you introduced a rake from front to back. There is now more weight over the front wheels due to this fact. More weight equals more stored energy which equals a higher rate spring and a 'stiffer' ride. If you increase the rear suspension effectively keeping the rake of the truck the same as it was on the 0 setting your springs would be the same. The same apples to a fully adjustable suspension on a sports car. To adjust you put all four wheels on scales and then adjust until all the weights are the same for perfectly level adjustment. Same here. You increased the front of the truck which will put MORE weight over the front. If you increased the height of the truck of the rear it would balance this weight out more and the spring compression would return to where it was at 0.

Take the tower out of the truck. Increase the height adjustment to 2.5" and the top moves 2.5", right? 1:1 The reason there is more compression on them when you put them back in has more to do with the rear suspension and it's height than the difference between 1.75" and 2.5" on the front 5100.

 

I give up lol. OP you'll have a stiffer ride if you go with 2.5"

 

YES!

 

I'm with you, but I believe the above to be incorrect. The spring gets shorter, but the assembly stays the same.

The truck's weight is preloading the coil all the time. A given coil will be compressed by the weight of the truck a certain distance either way. Say a coil in an assembly set at 0" shortens a distance of 3 inches from when it's in your hands to when you have the truck's weight on it. Now 'preload' it to 1.75" and now the truck's weight will just compress it 1.25" to have 3" overall compression still with the same available 'potential' for further compression. Same with 2.5" preload, the truck will still settle down 0.5" to 3" overall putting the truck statically at the same 'potential' on the spring. Now the problem I can see that can arise is if the trucks weight can only compress a given spring less than how much the preloading is compressing it. That crossover point is where you will start getting a 'harsh' ride.

The figures I used are purely hypothetical to prove a concept.

 

Lets take the rear out of the equation.

Take the tower out of the truck. Increase the height adjustment to 2.5" and the top moves 2.5", right?

Wrong. Not trying to be a smart ass, but have you actually installed coils on 5100's? I would assume that if you had, you would realize that you are thinking about this incorrectly. When the coil is installed on the shock body there is pressure on it, and the shock length is maxed out. When you move the coil mount further up the 5100, it increases pressure and does not increase overall shock length. With the increased pressure from preloading the coil, you get more height and a slightly stiffer ride.

 

^Lol This.

 

And there is the opposite statement of absolution I was looking for. In math, to check your work you work backwards with the answer to get the question. Your statement (one I've heard everywhere) is an absolution that is simply not correct because there are more variables than just the front 5100 setting. If you set the front to 2.5" and then add an equal amount of rear lift you will NOT have a stiffer ride. That's my point. People now think that there is some sort of a change in spring compression due simply to the difference in 1.75" and 2.5" and that's simply not true. Sure, if you eave the rear stock and go to 2.5" on the front 5100's and do nothing else it will ride harsher but who's going to do that? Who wants their front to sit 2.5" higher than their rear? If they do, it's going to ride harsher anyway unless you go with an aftermarket spring that has a different rate of progression.

It's pretty simple actually. If you go to 5100's and leave it at sock height it will ride close to stock. A little bit better but for sake of this discussion we'll say that's the baseline. Now, if you increase the front to 1.75" and make no other modifications it will ride slightly harsher due to all the things we've discussed. Now if you raise the back to 1.75" you will get a ride quality more like the baseline because your weight distribution front to back is back to what it was stock. Say you then go to 2.5" up front while leaving the back at the previous increase of 1.75"... guess what? It will feel exactly like it would had you gone to 1.75" from 0" due to the front to back weight distribution. So that 2.5" setting has nothing to do with the harshness. If you plan your rear suspension on whatever you plan to do up front the spring compression will remain unchanged. If you do a 2.5" AAL in the back and set the front 5100 to 2.5" your front to rear weight distribution will be the same as the stock setting and your spring compression will be the same as well. Easy as that.

 

Once again lets leave the rear out of this please.
We are talking spring rate, not weight distribution. The spring rate does not change when you are working on the rear end of the truck.

 

Hey. Have fun with your 5100's. I'm done here. Apparently preload doesn't exist.

 

I'm gonna stick this out for another couple of posts or until I actually say ermagherd.

 

The top of the spring doesn't move, just the lower spring perch. The shock length stays the same, spring rate goes up, that's your lift. Any lift from a spring comes from more arch, length, or spring rate. If some one thinks that they are ending up with a longer coil over after raising that lower spring perch, that is wrong. The higher the spring rate the less it's going to compress under the same load, that's the lift.

 

This. Only thing that is adjusted is the spring perch.

 

Wrong. What are you even talking about the rear having anything to do with front compression. Here it is straight from Bilstein. Preload of the spring.

http://www.youtube.com/watch?v=PG1GynQEAPc&sns=em

 

Yeah, I installed my 5100's on my truck set at 1.75" after having the rear TSB done. I'm trying to explain this in terms of apples to apples by saying that the truck goes up 1:1 regardless of if it's the top of the spring that goes up or the bottom. That's irrelevant to the conversation. I'm not sure I was the first one to say it that way but I was trying to keep the discussion as straight as possible by not bringing up the fact that the bottom goes down. This doesn't change the fact that whatever amount you put on the front 5100 that's how tall the truck goes at a rate of 1:1. Even if this isn't 1:1 it's pretty darn close so as long as you increase your rear ride height to match the front the spring compression changes would be negligible.

 

I am desperately waiting for that "Oh, now I see. Sorry guys" moment, but I'm not sure I'll live to see it.

 

I was like 20 posts ago lol.

dude, the top of the coil perch DOES NOT MOVE

 

Another question just out of curiosity. Do you ever do any suspension work on that Suzuki of yours? Rear being what is in question.