5100's at 2.5" advice

I'm getting 5100's on my 2006 prerunner this week and I want to go with the 2.5" setting. Is this gonna ruin my ride or will it be ok. I don't mind if its a little stiffer. Anybody have any problems with this setting. Thanks

 

Some people have issues with it being too stiff. I for one like the front end a little more firm with the Billies @ 2.5". It seemed kind of squishy to me when it was stock.

 

ruin? no. there's only a few things I would consider could RUIN the ride. these trucks are not Cadillacs to begin with, so expect the ride to be harsh and a bit jarring over potholes.

if you first accept that you're driving a truck, the ride improves tremendously

 

Too high you gonna have to lif the back end. I just put my 5100's at stock setting and left the rear end alone. I don't offroad or put any mods in my truck though. Mine rides good and no issues so far since I put those 5100's this past December.

 

Mine is currently at the 1.75" setting up front with the TSB rear leafs and the stance is visually level and looks good. I'm considering doing an AAL and setting the fronts to the 2.5" up front for a more aggressive look and because I'm considering doing some 33's w/a wheel offset that should get most of the clearance I need (from what I've read). I keep seeing people say that on 2.5" you're changing your spring rate and I still don't get that. You're simply changing the location of the spring and no how much or little it's compressed so I don't see how you're changing the spring rate. A truck that rides a little bit higher is just going to handle a little bit different which is the nature of the beast. I don't get all this discussion of spring rate change from 1.75" to 2.5" though.

 

It's just a matter of preload.With linear springs:
When you put the weight of a corner of a vehicle(probably around 700lbs) over your spring it compresses to absorb that weight. With 400lb spring, it will compress about 1 3/4". So, if you start with the lower collar so that it is just tight enough to hold the top of the spring against the upper perch this would be 0 preload. Raise the collar 1 3/4", and you now have 700lb's of preload. (arbitrary #'s for the sake of illustration.) Since you have preloaded the spring, the same weight as the car's corner, when you put the car on that spring, it will not compress at all, and will simply sit on top of the spring. If you were to hit a bump, the force would still compress the spring the same amount it normally would if you had set the spring to 0 preload. Now if you set the spring to say 900lbs of preload, when you hit the bump (say its a bump that generates around 250lbs of upward force), the spring will compress much less b/c the spring is already beyond the load specified to absorb the bump. Since there is only 50lbs beyond the preload, the spring will only compress about 1/8th inch, and the truck will likely be launched over the bump.

Generally.

 

In english, ^ This means, if you jack your truck up to the 2.5" setting on those billies, expect every bump to be pretty harsh compared to if you left them at a lower or stock setting.

 

Thanks for that. I was trying to help explain preload to Ostrichsak. His comment was more direct than just a "it's stiffer @ 2.5" answer".

 

Hahah I know . We both know what preload means...some people just don't want to think about physics and such.

 

I get how springs work but your description isn't accurate to what is actually happening. When you adjust from 1.75" to 2.5" your moving the LOCATION of the spring, not changing the tension that is present. In other words, the top and the bottom move upward at the same rate. Now, if changing the bottom up to the 2.5" setting compressed the spring any then I could see your scenario applying. I've done a LOT of suspension mods over the years on many different vehicles and when I installed my 5100's I planned on 1.75" based on everything I read having not seen them myself. I assumed that the shock tower was a static unit and increasing ride height on 5100's meant you increased compression of the spring which would change the spring rate or put it in the more compression state which would indeed change the ride ergonomics since there wouldn't be as much 'cushion' built into the rate. When I swapped out my suspension however I noticed something entirely different and that was that the 5100 shock tube would keep the SAME spring tension regardless of what setting you chose. From stock to 1.75" to 2.5" the spring TOP would move upward within the assembly the same amount. You're effectively relocating the location of the spring upward within the shock tower assembly so I don't see the physics behind the spring linearity as it applies to this specific setup. You're explanation doesn't apply unless the shock itself or something within the setup keeps the top of the spring in place and the bottom goes up but that isn't the case here. I'll admit I'm wrong if someone can explain how the top of the spring tower is being held in place when the lower is raised but it's not. Hence why you get a 1:1 ratio of truck height to spring height because the truck (along with the top of the spring) is being raised along with the bottom at a 1:1 rate. How does spring rate change?

 

I assure you I'm not afraid of physics. Quite the contrary in fact and as such the physics don't support a spring rate change based on ride height change on the 5100. For there to be a spring rate change there would have to be a ride height change that is different than 1:1 ratio compared to the spring height change. That's how physics work. See my previous post.

 

This makes no sense.

You are using the coil bucket on the truck to hold the coil in place. A bilstien 5100 is basically an upside down coilover that only has 4 adjustment points on it, as opposed to a threaded body . When you move the coil clip up or down, you are changing the preload on the coil. So leaving the clip at the bottom setting is supposedly the same load that the OEM shocks/coils have...moving the clip up, just puts more preload on the coil...

 

I ran 5100's with OME 885x for almost two years. When they were installed, the dumbass I paid to do it put them at the 1.75" setting and my truck had a 4"+ lift up front and bounced if I touched the gas....PRELOAD.

 

But that coil bucket on the top increases height the same amount that you raise the bottom. Hence, lift. It rises at 1:1 so mathematically there can be no increase in spring rate based on this change alone. In order for their to be an increase in spring rate the rate at which the truck raised would have to be different than the bottom of the spring. In other words, for an increased spring rate, every inch you raised the spring the truck would go up in height less than one inch. This additional height difference would have to be made up in the form of spring rate progression storing the additional energy which means a stiffer ride. It doesn't. When you increase the 5100 (assuming all other variables remain the same) 1" your truck goes up 1" which means a perfect 1:1 increase. The spring remains unchanged. Even if it only went up 0.95" the difference in rate would be negligible and likely would never be felt by someone driving their truck. So, you set your 5100 at 1.75" and your truck goes up 1.75". You set your 5100 at 2.5" and your truck goes up 2.5". Neither of these would indicate a spring rate progression change since it's 1:1.

Bingo! You're bringing in another variable entirely and I have a feeling this is why a LOT of people talk about the 5100's having a different spring progression on the 2.5" setting. When you change the pitch of the truck front to back you introduce something entirely different that is independent of the right height itself. The rear was lower so the front compresses and takes more of the truck's overall weight. This would be the same if you left the 5100 at the stock height and then put in a 2.5" AAL in the rear. The 'feel' would be the same and there is a spring rate change but it has NOTHING to do with the 1.75" or 2.5" setting other than their relative relation to the rear ride height overall. So, to replicate this supposed harsh spring 'feel' of the 2.5" setting all you would need to do is leave the front 5100 at 1.75" and then lower the rear the 0.75" difference and the front would ride literally the exact same as it would if you left the rear end the same and went to 2.5". So in essence what people are parroting is misinformation based on something they 'heard' which was likely someone with stock rear suspension 'testing' the various ride differences of the front 5100. The 1.75" wouldn't be much of a departure to make the difference noticeable though i assure you the rate had indeed changed. Then, when they went to the 2.5" setting (still stock rear ride height) OMG it drove like shit! Well duh. But you're taking the difference in rake front to back which has ZERO bearing on where the spring rides in the front shock tower. If you took that same truck and put an equal AAL in the rear to level it out more it would ride the same as the stock setting because less weight would be over the front wheels.

This is COMPLETELY separate from the difference in the 1.75" and 2.5" settings on the 5100 though.

 

You're picture actually proves my point... the spring is the exact same length in that picture and will remain the same regardless of which setting you set the bottom on. In other words 1:1 increase in height and the spring never changes length. If the spring doesn't change length how can there be a difference in linearity? For what you say to be true that bottom spring would be shorter than the top spring but what is holding that top in place when you do? The truck. The truck then goes up an equal amount and you get lift. If you increase that setting 0.75" (regardless of from stock or 1.75") the truck goes up 0.75" which is a 1:1 ratio so the spring would also remain the same length.

Again, this is taking all of this in a vacuum w/o the rear suspension taken into account since I have a strong suspicion this is where this internet 'fact' began. I'm fully willing to admit being wrong if someone can present factual information that indeed proves me wrong. I've seen this suspension first hand and changed it myself and I don't see where the physics lend to this and it's something I questioned before I ever did my suspension. In hind sight, I wish I had ordered the proper AAL and gone 2.5" to begin with and I have zero doubt in my mind that my ride quality would be the same as it pertains to bump absorption and things most often attributed to 'ride quality' while some other aspects of suspension would be affected due to an increased center of gravity but that's more lateral stuff and doesn't affect what we're talking about in this conversation.

 

OP, It's a harsh ride. I would suggest going with OME 884's and set the 5100's at '0' it will give you the same amount of lift. You could set them at 2.5 with the stock coils and see how it rides. You will have to address the rear height...

 

Keep face palming Mr "I Had A Shop Install My Suspension".

I've been doing vehicle mods for decades including numerous suspension modifications in every direction. I speak from personal, hands on experience and applied theory. Other than parroting what you heard on an internet forum as claimed fact you haven't said a damn thing that contradicts what I've stated. I've presented simple math that would have to be found to inaccurate for my stance to be wrong and have yet to see anyone debunk that very simple math. If you don't have any first hand knowledge to add then by all means, have at it. I'm fully ready to be proved wrong since I keep hearing this same information all over the forum.