Shock Length

[ckomai]

I have narrowed down the shock length that I need when I get my 4" lift. I checked skyjacker and Bilstein applications and its 11.52" collapsed 18.66" extended for skyjacker and 12.17" and 18.98" for bilstein. I really want to get King 2.5" resevoirs. The King 2.0's measure 13" collapsed and 19" extended which are already bigger numbers and the 2.5's are 14" and 20". My question is can I get away with the 2.5 bigger measurments and if so what effects will it have.

 

[Maniak]

I have narrowed down the shock length that I need when I get my 4" lift. I checked skyjacker and Bilstein applications and its 11.52" collapsed 18.66" extended for skyjacker and 12.17" and 18.98" for bilstein. I really want to get King 2.5" resevoirs. The King 2.0's measure 13" collapsed and 19" extended which are already bigger numbers and the 2.5's are 14" and 20". My question is can I get away with the 2.5 bigger measurments and if so what effects will it have.

Here is how I figured out what to run.

Go to gorancho.com and looked up what the shock they used for the 2.5" lift kit on their online catalog. Now go to the back of the gorancho catalog and look up the specs of that shock. Now that you have the #'s for 2.5" lift add 1.5" to the total length compressed and extended to figure out what it would be for a 4" lift.

For this example I'm going to use 12" compressed and 19 extended.

Now look at all the shocks in the back of the catalog with the right "Mounts" (they are listed with the specs so look at what they use for the 2.5" kit) and write down all the lengths that are anywhere close to what you came up with..

Now comes the hard part.. You need to look at what you wrote down and find a shock that has a compressed length no longer than what you came up with before (12" in this case). Also you need to make sure the extended length is no shorter than what you came up with (19" in this example).

Now, if you have more suspension travel you can get shocks with shorter compressed and longer extended lengths but NOT the other way around.

If your shocks are too long on the compression or too short on the extended length you will top or bottom out the shock which is bad for the shock. You "could" use a limiting strap to limit the droop so you could use a shorter extended length shock but unless you have lots and lots of suspension travel or u-joint/cv-joint/steering issues with the travel you have I would not do that.

~Mark

 

[ckomai]

so I ran the numbers and I came up with 12.5" and 18.5" which is right around all the shocks I mentioned earlier. So at 14" and 20" with the Kings I want, im running the risk of damaging the shock?

 

[Maniak]

The 20" extended is ok. The 14" compressed means you will bottom out the shock and yes, it will hurt the shock. Heck, you can actually break the shock. It depends on how fast your moving when it hits.

There are 2 solutions here (other than a different shock).

One is limit your up travel on your suspension by installing 2" longer bump stops. I don't like this option.

The 2nd is use a different upper shock mount. Look into using an f-250 shock mount. That way you can use a longer shock. I don't remember how much higher is moves the upper mount (I posted it on another thread somewhere) but you need to add that extra length to both the compressed and extended shock lengths.

~Mark

 

[4x4junkie]

I wouldn't go by Rancho's numbers, they were way far off when I had said 2.5" lift on mine (cutting off a good 3" of the available downtravel at the wheel).

Best way to measure for shocks IMO is to remove the coil spring and then jack the suspension all the way up until the axle is against the bump stop, then measure between your mounts for the shock's compressed length, adding 1" or so for bumpstop deflection.
Now reinsert the coil spring and allow the suspension to rest at full hang, then measure again for your shock's extended length. Try to find something as close to these measurements as you can (F-250 extended shock mounts certainly will open up a lot more options for you).
I also would suggest putting a J-clip or other secure attachment for the coil in the upper mount. The small tabs that are there can still allow the coil to pop out under some circumstances.