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According to the Bilstein web site the 5100 perches are spaced 5/8" or .625" apart. So using the OE coils bottom #1 = 0 lift, #2=.625 lift, #3= 1.25" lift and #4=1.85 lift.
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So does this sound right? :infidel:
Bilstein 5100 shock perches are 0", .85", 1.75" and 2.5" of lift. FJ coils give 1/2 - 1" of lift depending on 2wd, 4wd and V6 or V8. Also depends on how much your stock coils are sagging as to how much lift you'll actually see. I got over an inch of lift in the rear with fj coils because my stock springs were toast!
[MENTION=101553]t-man[/MENTION] is correct about the lift.
[MENTION=2262227]jrm[/MENTION], you're right that the actual perches are spaced 5/8" inches apart on the front 5100's, but because of the geometry of the suspension, the lift experienced
at the front wheels starting with the bottom setting on the 5100's is :
- setting #1 = 0" lift
- setting #2 =0.85" lift
- setting #3 = 1.75 lift
- setting #4 = 2.5" lift
Below is my attempt to explain why.
The shocks don't mount directly to the tires. They mount to the lower control arms several inches inboard of the tires, and the lower control arms themselves can pivot from where they are attached to the truck's frame. Thus you have a dynamic system that includes a "lever" effect.
Also, when you move the spacer on the front shocks, you are only
INDIRECTLY making the shock longer. Technically, what you are doing is moving a collar up by 5/8", and this collar supports the bottom of front coil springs.
So, what you are really doing is
raising the attachment point of the bottom of the front springs to the front shocks in 5/8" increments, which will increase the effective length of the shock some amount and also may also increase the pre-compression of the front springs by some amount So, when the truck is still on level ground, the change in the anchor point of the front spring, and amount of pre-compression on the front springs work together to determine the effective increase in the length of the front shock.
Thus, when you add an additional 5/8" inches of height to where the front springs attach to the front shocks, you increase the effective length of the front shocks by some amount that may be more or less than 5/8" (I suspect less... but I'm not sure).
However, the height to the top of the wheel well increases by more than 5/8", and this "extra" increase is primarily due to the geometry (meaning the shock is NOT attached AT the wheel, it's attached several inches inboard from the wheel, and is attached to the lower control arm which can pivot... so you have a lever effect that gives you more than a 5/8" increase at the wheel). However, the springs and their compression rates, along with the slight change in weight distribution that comes from the height changes... and that impact on the compression of all four springs might also play a small role in the final outcome.
This is probably why all the predicted changes in height are approximate or average... there are several different factors that affect your exact outcome, and these
factors are probably slightly different for each truck depending on equipment and the particular types and condition of your truck's components.
On the 5100's, for each 5/8" inch increase in the attachment point of the front springs, you gain between 0.75 and 0.9 inches of extra clearance at the wheel.
I suspect the non-linear gain in height has to do with how the weight distribution shifts, and slight changes in the compression from all four springs when you change the effective length of the front shocks by raising the anchor points for the front springs.
What I mean by non-linear is that for each 5/8" increment on the shocks you go from 0" of front lift, to 0.85" of lift, to 1.75" of lift, to 2.5 in lift", so the gain is 0.85", 0.9" and 0.75 in lift. I also don't know if these gains are approximate or exact. If they are only approximate, then it is probably the impact of the spring compression and slight changes in weight distribution that causes the differences.
Make sense? If I've confused anyone, just remember the bulleted list above. That's correct, and it's most important.
One last thing... which is more of a fine-tuning issue.
FOR THE FJ FRONT SPRINGS, THE LEFT AND RIGHT SPRINGS ARE DIFFERENT. THEY ARE COLOR CODED TO TELL YOU WHICH IS LEFT SIDE AND WHICH IS RIGHT SIDE
On the FJ cruiser, the left side (driver's side in the US) would tend to sit a little lower because of the the gas tank being off-center and the weight of the driver. As a result, the FRONT FJ springs are color coded to tell you which side they go on.
The left front FJ spring is has one extra coil in it, so that it doesn't compress as much as the right spring, and this helps the truck sit more level, instead of leaning towards the driver's side.
In the photo above, notice that the coil with the purple and green paint marks has eight coils (if you count them). This purple / green marked spring goes on the left (driver's in the USA) side.
The other coil, marked with purple and orange (or purple and red) only has seven coils if you count them. This coil goes on the right (passenger's side in the USA) side of the truck. If you have FJ cruiser coils with different color codes, use google to find out which is the left and which is the right front spring... or count the number of coils.
The one with more coils goes on the left side (driver's side in the USA).
You may have noticed that some posters have mentioned putting a small spacer (maybe 1/4" spacer") above the left front shock, or using only a single 1.5" spacer on the only ONE of the rear shocks. These are all attempts to make the truck sit level from side-side, meaning to have the right front be the same height as the left front, and have the right rear be the same height as the left rear.
The FJ springs help with this side-to-side difference by making a different spring for the left front than for the right front.
I haven't played around with any further leveling adjustments. On my setup, (FJ springs, Bilstein 5100's set at 0.85" lift, 1.5" daystar spacers on both sides in the rear), my left REAR is 0.5" lower then my right REAR.
Some have suggested the removing the right rear daystar spacer will level out the rear height. I haven't tried it yet... but I might some day. More importantly, if I try it, and it's still not level, based on the measurements with and without the 1.5 rear right spacer, I should be able to figure out how much to cut down the rear right spacer to make the truck level from left to right.
Of course, the truck does sit on 4 tires, each with springs, so messing with just one tire's height, MIGHT have an impact on the height of other tires. I'd assume that lowering the right rear, might also impact the height of the front let tire to some degree, but I haven't played with it to be sure.
Just more info and and FYI. I'll either update this post or post a new thread if I do mess around with the rear spacers on one side, and I'll let people know what impact, if any I observed.
P.S. -- I also have air-ride rear air boosters inside my rear coil springs, but I have the pressure equal in each of the air bags, and it is low, so I don't think that they really impact my height much if at all. Their real purpose it to allow me add air to boost the rear height if/when I attach a boat and load up the rear cargo area.
Then I can add more air to the rear air bags so that I can offset any rear sag. The air adjustment is manual. It has a Schrader valve, and takes regular air. I have a good compressor which I plan to mount on-board, but I'll still manually use an air hose to inflate the rear air bags, or I might even buy and use a portable, small bicycle hand pump, since the air bags don't hold much air and it seems that they can easily be over-filled.