Lift height calculations (Bilstein 5100s)

[Bluestreak4thgen]

So I've been on a long journey to replace my spacer lift. Started with wanting a zone 4" kit, decided against it, then decided to drop the money on an icon kit, then decided I wouldn't use it to it's potential and be a waste of money, then went to the Bilstein 6112 kit and was told by a Bilstein rep that they haven't tested them on the 3.6l v6 yet and wouldn't recommend them.

So now I'm back to everyone's favorites, the 5100s. My current spacers are 3" front and 2" rear. I'd like to not lose any height than what I have now.

So if I went to the 5100s set at 2.8 with a 1" rear spacer (talked with some 4x4 shops near by and ruled out the Bilstein or icon coils) and stepped up to a 35x12.5r17 from my 285/70r17s then I should come out with more lift right?

I'm thinking the 5100s may settle down to 2.5" and then the sidewall of the tire should give me at least another .75" over what my tires are now, which should put me at about 3.25" over stock. Am I correct in this thinking?



Also if anyone has 5100s and running 35s feel free to post some pictures for me!

 

[crazykid1994]

This was at 2.5” lift front and 1.25” lift rear. I’m running bilsteins with eibach replacement coils and eibach coils rear as well. I did however add a 1/2” top hat spacer to my struts last night and am sitting at 3” lift as of last night. No pics of that yet. My truck is a hemi quad cab. tire specs 305/70r18 Mickey Thompson atz p3 on 18x9 -12 wheels. I only received 2.5” lift from the eibach springs but they’re claiming that’s due to manufacturing tolerances and vehicle weights. I’d imagine you’d be at 2.75 being a v6

 

[Bluelights11]

This was at 2.5” lift front and 1.25” lift rear. I’m running bilsteins with eibach replacement coils and eibach coils rear as well. I did however add a 1/2” top hat spacer to my struts last night and am sitting at 3” lift as of last night. No pics of that yet. My truck is a hemi quad cab. tire specs 305/70r18 Mickey Thompson atz p3 on 18x9 -12 wheels. I only received 2.5” lift from the eibach springs but they’re claiming that’s due to manufacturing tolerances and vehicle weights. I’d imagine you’d be at 2.75 being a v6

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Any reason you're running the eibach springs over the stock springs? How much did they run you? I was thinking of just going bils on stock springs for now

 

[crazykid1994]

Any reason you're running the eibach springs over the stock springs? How much did they run you? I was thinking of just going bils on stock springs for now

Reason is more lift with less preload. Makes for a softer ride. I purchased them through @Nick@GotExhaust just message him for a price. I ran stock springs on the 4th notch for 2” lift till I decided I wanted 35s and wanted to go higher for that.

 

[kurek]

The front Bilsteins won't settle if you are reusing your existing springs, the heights are pretty consistent since the only flexible component is the spring itself and it's already under the same load with or without bilsteins

 

[kurek]

Reason is more lift with less preload. Makes for a softer ride.

Preload doesn't affect rate on linear springs.

 

[crazykid1994]

Preload doesn't affect rate on linear springs.

What causes the harsher stiffer ride on bils set to 2.8 vs stock? I understand linear rate springs stay linear but the more you preload the spring the less give it will have until you hit that weight that it’s being compressed to. I’m not exactly a suspension guru but I noticed a softer ride swapping out to the eibach springs

 

[Bluelights11]

What causes the harsher stiffer ride on bils set to 2.8 vs stock? I understand linear rate springs stay linear but the more you preload the spring the less give it will have until you hit that weight that it’s being compressed to. I’m not exactly a suspension guru but I noticed a softer ride swapping out to the eibach springs

Maybe they let the shock compress less over all? I've always been told the stiffer ride comes from the bils bring a digressive valved shock.

 

[Bluelights11]

The front Bilsteins won't settle if you are reusing your existing springs, the heights are pretty consistent since the only flexible component is the spring itself and it's already under the same load with or without bilsteins

Ok so, with 35s, I should be around 3.5-3.75" over stock then?

 

[crazykid1994]

Ok so, with 35s, I should be around 3.5-3.75" over stock then?

Ground to fender? Roughly 3.5-3.75” taller yes. I’m at 3.5-3.75” taller than stock ground to fender with my current setup. Sorry for the sidetrack.

 

[Bluelights11]

Ground to fender? Roughly 3.5-3.75” taller yes. I’m at 3.5-3.75” taller than stock ground to fender with my current setup. Sorry for the sidetrack.

Sweet. Yeah ground to fender. I'm currently at 39.5 front and a hair under 42 in the rear. I'm not too worried about losing rear height but I want the front to be at least 3 inches over stock

 

[Bluestreak4thgen]

Ground to fender? Roughly 3.5-3.75” taller yes. I’m at 3.5-3.75” taller than stock ground to fender with my current setup. Sorry for the sidetrack.

That's exactly what I'm going for. Thanks for the tip

 

[Bluestreak4thgen]

Sweet. Yeah ground to fender. I'm currently at 39.5 front and a hair under 42 in the rear. I'm not too worried about losing rear height but I want the front to be at least 3 inches over stock

Lol looks like we are going for similar builds!

 

[crazykid1994]

Sweet. Yeah ground to fender. I'm currently at 39.5 front and a hair under 42 in the rear. I'm not too worried about losing rear height but I want the front to be at least 3 inches over stock

My stock ground to fender was 36.75 with the wrangler sra and 37 when I switched to at tires.

 

[ram1500rsm]

What causes the harsher stiffer ride on bils set to 2.8 vs stock? I understand linear rate springs stay linear but the more you preload the spring the less give it will have until you hit that weight that it’s being compressed to. I’m not exactly a suspension guru but I noticed a softer ride swapping out to the eibach springs

From my conversations with a shock tuner couple of days ago, adjusting 5100's for example using it's different perches is not changing the preload on the springs nor compressing the spring any further like i thought it was happening. Only thing compressing the spring is the weight of the truck so preload on 1st notch should be the same preload on the last notch assuming the truck weight is not changing AND your strut shaft can still extend as your going up in the notches, What you're doing with the perches is effectively changing the position the spring is sitting at in relation to the lower seat so as you move the seat up, the strut shaft is extending and the top goes up pushing the truck up. (the spring is supporting the weight of the truck). Same thing happens with a coilover at the top when you adjust them to go up. You can turn the adjusters all the way up which is basically moving the spring down and extending the shock down which in turn by the force of the spring cause the truck to go up, but the preload on the spring is not changing as the adjuster is turned unless the shock is maxed out on extension or you are adding things that will increase the weight supported by the springs: fenders, winch etc. In other words the spring is compressed the same amount under the truck weight until the shock can't extend anymore.

With that said i don't think is the stock springs preload giving people the harsh ride, it must be the shock absorber inability to operate at the top of it's rebound cycle because the generic valving they use on them. Move the shaft down (going down on the perches so the shock doesn't run at its max allowed extension) and life gets better.

The other thing is the assumption than your stock UCA's can operate with 2.5"-2.8" of lift, they're not at an optimal angle past 2", your suspension won't operate as designed past 2" and it wasn't designed to live at 2" either. The arms were designed to live on a more neutral position which we call 0" lift and BJ's can reach proper operating angles that way. Hence the reason for the need to offset the upper arms with 2-3" of lift. In most forums it seems aftermarket UCA's are made by the boogyman .. but it's mostly because they're an extra $500-$700 to add your lift they're well worth their price.

 

[crazykid1994]

From my conversations with a shock tuner couple of days ago, adjusting 5100's for example using it's different perches is not changing the preload on the springs nor compressing the spring any further like i thought it was happening. Only thing compressing the spring is the weight of the truck so preload on 1st notch should be the same preload on the last notch assuming the truck weight is not changing AND your strut shaft can still extend as your going up in the notches, What you're doing with the perches is effectively changing the position the spring is sitting at in relation to the lower seat so as you move the seat up, the strut shaft is extending and the top goes up. Same thing happens with a coilover when at the top when you adjust them to go up. You can turn the adjuster all the way up until the shock can't extend anymore, at that point the spring will then begin to compress more because the shock has been maxed on extension and there is no way to further extend it.

With that said i don't think is the stock springs preload giving people the harsh ride, it must be the shock absorber inability to operate at the top of it's rebound cycle because the generic valving they use on them. Move the shaft down (going down on the perches so the shock doesn't run at its max allowed extension) and life gets better.

The other thing is the assumption than your stock UCA's can operate with 2.5-2.8' of lift, they're not at optimal angle past 2", your suspension won't operate as designed past 2" and it wasn't designed to live at 2" either, the arms were designed to live on a more neutral position which we call 0" lift and BJ's can reach proper operating angles that way.

I learned something today. No kidding. Always glad to learn new info