New Bilsteins added a small lift?
- Thread starter Majindan
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PitbullRescuer
New member
Doubtful. Those shocks will compress with your finger. Did you take measurements?
BigFishAllDay
New member
I'd say it's possible, depending on what springs you're running.
Here's the thing about the Bilstein 4600's.... they are LONGER than the stock front shocks. This does two things; one, it allows for more droop, and two, it provides a larger (taller) space for the coil to call home. Note in the picture below that the distance from the bottom of the coil perch to the lower shock eye is the same on the billie and the stocker. However, from the spring perch up, the billie is about 1.5" longer.
Now, say that you have a relatively fresh coil spring in there, with a spring rate that is more than sufficient for the weight of the vehicle. If you give that coil a taller space in which to live, it will see less pre-load than it would in a smaller space. This will make for a softer ride up front, and assuming no change in weight on the vehicle, allow for a potential increase in ride height as the coil can expand further within it's new home. The key factor would be that the coil has excess weight carrying capacity such that it WOULD expand to a length greater than that to which it expanded on the stock shock, while carrying the weight of the vehicle.
I saw a similar effect on my '97, which had some tired '99 tall coils on it when I bought it. I installed fresh '99 tall coils and the Bilstein 4600's and saw a net lift of 2". The '99 talls are only supposed to provide about an inch of lift, and that's compared to the shorter springs on other model years, which I did not have... so where did the extra inch come from? I believe the extra lift was due to the extra length of the bilstein 4600's.
Here's the thing about the Bilstein 4600's.... they are LONGER than the stock front shocks. This does two things; one, it allows for more droop, and two, it provides a larger (taller) space for the coil to call home. Note in the picture below that the distance from the bottom of the coil perch to the lower shock eye is the same on the billie and the stocker. However, from the spring perch up, the billie is about 1.5" longer.
Now, say that you have a relatively fresh coil spring in there, with a spring rate that is more than sufficient for the weight of the vehicle. If you give that coil a taller space in which to live, it will see less pre-load than it would in a smaller space. This will make for a softer ride up front, and assuming no change in weight on the vehicle, allow for a potential increase in ride height as the coil can expand further within it's new home. The key factor would be that the coil has excess weight carrying capacity such that it WOULD expand to a length greater than that to which it expanded on the stock shock, while carrying the weight of the vehicle.
I saw a similar effect on my '97, which had some tired '99 tall coils on it when I bought it. I installed fresh '99 tall coils and the Bilstein 4600's and saw a net lift of 2". The '99 talls are only supposed to provide about an inch of lift, and that's compared to the shorter springs on other model years, which I did not have... so where did the extra inch come from? I believe the extra lift was due to the extra length of the bilstein 4600's.
snivilous
Senior Member
I'd say it's possible, depending on what springs you're running.
Here's the thing about the Bilstein 4600's.... they are LONGER than the stock front shocks. This does two things; one, it allows for more droop, and two, it provides a larger (taller) space for the coil to call home. Note in the picture below that the distance from the bottom of the coil perch to the lower shock eye is the same on the billie and the stocker. However, from the spring perch up, the billie is about 1.5" longer.
Now, say that you have a relatively fresh coil spring in there, with a spring rate that is more than sufficient for the weight of the vehicle. If you give that coil a taller space in which to live, it will see less pre-load than it would in a smaller space. This will make for a softer ride up front, and assuming no change in weight on the vehicle, allow for a potential increase in ride height as the coil can expand further within it's new home. The key factor would be that the coil has excess weight carrying capacity such that it WOULD expand to a length greater than that to which it expanded on the stock shock, while carrying the weight of the vehicle.
I saw a similar effect on my '97, which had some tired '99 tall coils on it when I bought it. I installed fresh '99 tall coils and the Bilstein 4600's and saw a net lift of 2". The '99 talls are only supposed to provide about an inch of lift, and that's compared to the shorter springs on other model years, which I did not have... so where did the extra inch come from? I believe the extra lift was due to the extra length of the bilstein 4600's.
The height of the vehicle will only change with the same spring if the distance from the coil seat to the mount is longer. The picture you show has the same length so the height shouldn't increase, unless the shock is bottomed out. Just because the shock can extend further doesn't mean the loaded spring height changes.
BigFishAllDay
New member
Wrong. It will change if the spring has excess preload on it, and you remove that excess preload.
Edit... just to clarify further for you, sniv.
Imagine you have a simple 12 inch coil spring with a 100lb/inch spring rate.
If you compress that spring to various lengths, secure it with wire so that it cannot de-compress (preload it), and then set a 100lb weight on it, what will happen?
Compressed to 6 inches, the spring will compress very little with the weight set upon it.
Compressed to 9 inches, the spring will compress some.
At free height, the spring will compress about an inch under the 100lb load.
The loaded height of a spring depends not only on the load, but also upon the preload.
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PitbullRescuer
New member
BFAD, you'd have to show both of them fully extended for this to make sense. If the Billy does indeed have a longer extended length, your point makes sense. I still don't agree with it as the shocks are way too easily compressed but we'll say the shock is strong enough to load up the spring more than the stock shock is assuming it is longer fully extended.
snivilous
Senior Member
I kind of agree...my awesome reasoning now
If you relieve some of that preload (because the shock is longer so the coil is closer to it's free length if I'm thinking about this right) the spring will still compress the same amount.
So following your example, if you put some wire around the spring to force it to be 6 inches tall (say the free length is 12 inches, and 100lb/in as you said) then that wire is putting out 600lbs of force. Now you put a 100lb weight on the spring (still preloaded), the spring won't begin to compress any further until you exceed the preload (600lbs).
If the weight compressed the spring any more (so there was a gap between the restraining wire and the spring) then that weight would have to be exerting over 600lbs of force since the spring was already compressed 6 inches.
So even though the shock is preloading the spring, and the longer shock has less preload, the end result is that the coil will compress the same amount regardless because once the preload is exceeded from the weight of the truck that preload goes away and doesn't affect how much the coil is compressed (all that matters is the spring constant).
Please correct me if I'm wrong or my explanation makes no sense
EDIT: You can also think of it this way, you have the example spring stuck between two blocks of concrete that are 6 inches apart. The blocks of concrete are exerting 600lbs of force. To compress that spring further without moving the blocks of concrete, you need enough force to continue exerting 600lbs plus some more to compress it (since the spring is exerting 600lbs of force since it's compressed 6inches at 100lbs/in). Once that is done, one of the blocks isn't contacting the spring anymore and isn't preloading it since the block is static.
Similarly, once the spring starts to compress the shock spindle isn't preloading anymore since it can only preload in tension and once the spring compresses the spindle isn't loaded in tension.
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BigFishAllDay
New member
Both of the shocks in the picture ARE fully extended. I made sure of it before I took the picture because I was specifically trying to illustrate the difference in length.
The force it takes to compress the shocks has nothing to do with my point, it's about the preload on the coil. See below....
I kind of agree...my awesome reasoning now
If you relieve some of that preload (because the shock is longer so the coil is closer to it's free length if I'm thinking about this right) the spring will still compress the same amount.
So following your example, if you put some wire around the spring to force it to be 6 inches tall (say the free length is 12 inches, and 100lb/in as you said) then that wire is putting out 600lbs of force. Now you put a 100lb weight on the spring (still preloaded), the spring won't begin to compress any further until you exceed the preload (600lbs).
If the weight compressed the spring any more (so there was a gap between the restraining wire and the spring) then that weight would have to be exerting over 600lbs of force since the spring was already compressed 6 inches.
So even though the shock is preloading the spring, and the longer shock has less preload, the end result is that the coil will compress the same amount regardless because once the preload is exceeded from the weight of the truck that preload goes away and doesn't affect how much the coil is compressed (all that matters is the spring constant).
Please correct me if I'm wrong or my explanation makes no sense
No, you're on the money, exactly. Now we're on the same page.
What I'm saying is that I think the stock shocks keep the spring pre-loaded to slightly more than the individual front corner weight of a stock 4Runner. Lets just take a guess and say 550 lbs/inch is the stock spring rate. Well, once you clamp those things down with compressors and install them onto the shock, they easily get compressed 2-3". I don't know exactly how much they get compressed from free height to fully assembled, but if it's 3" that's 1650 lbs of pre-load right? (assuming the stock coils are linear)
That's getting pretty close to the front corner weight.
snivilous
Senior Member
sschaefer3
New member
You are correct.
snivilous
Senior Member
[MENTION=44220]BigFishAllDay[/MENTION]
I was thinking about it, and you still shouldn't of seen a height gain. If the coils were already preloaded higher than the truck would load them so they wouldn't compress, then the truck would always be sitting at the equivalent of full droop which obviously it isn't. So I don't know why you were seeing a lift gain, assuming my logic is sound
I was thinking about it, and you still shouldn't of seen a height gain. If the coils were already preloaded higher than the truck would load them so they wouldn't compress, then the truck would always be sitting at the equivalent of full droop which obviously it isn't. So I don't know why you were seeing a lift gain, assuming my logic is sound
sschaefer3
New member
Do you have a 2WD or 4WD 4Runner? Going from a 2WD stock shock to a 4WD Bilstein 4600 will see a slight increase.
BigFishAllDay
New member
[MENTION=44220]BigFishAllDay[/MENTION]
I was thinking about it, and you still shouldn't of seen a height gain. If the coils were already preloaded higher than the truck would load them so they wouldn't compress, then the truck would always be sitting at the equivalent of full droop which obviously it isn't. So I don't know why you were seeing a lift gain, assuming my logic is sound
[MENTION=92884]snivilous[/MENTION]
I've been meaning to come back to this post. Just wanted to shove my foot in my mouth and acknowledge that yes, you are correct.
Steve and I had a talk about this whole thing, and via this thread I had a learning experience. As hard as it is for me to admit, sometimes you youngsters actually know some shit.
sschaefer3
New member
I'm a lot older then you. :wave:
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