How to measure for rear shocks after lift

I recently put icon 1.5" AAL on my truck, but the rear still sits about .7" lower then the front of my truck. I purchased the OEM .5" rear blocks but I think I'm just going to get 1" ones instead and have a bit of rake, I'm sure the AAL will settle as well. I wish I would have just gone with a new leaf pack altogether.. but I figured since I already had them installed I'll wait a few years.

I currently have Bilstein 5100s on the rear..how do I go about finding the correct shocks?

Measure from the center of the rear shock bolt hole, to the where the top mates with the truck on jack stands and suspension at full sag without shocks, and again after jacking under differential until the bump stops touch?

Appreciate any input!

 

First part of your question is correct for finding extended length max given your leaf spring setup, however watch your stock rear brake lines as you do it to be sure they don't overextend in the process.
Second part regarding compressed length is more difficult. Compressing leafs to bump stop absolute stop, will require a lot of weight isolated to that corner - like c.t.i/ cross axle ramps or an r.t.i. ramp.
You'll see Tacoma compressed length rear shocks from approximately 13.8 to 15.2, recommended by lift height by manufacturers.

 

If you can find an appropriate obstacle, like a pile of concrete rubble or ramp, you can flex one side at a time with the shock disconnected at the leaf end.

 

Thanks for the input! Glad I asked before having a go at it

 

Compressed length in the stock upper mount is where you need absolute bump stoppage of the frame before max compression. Then whatever length of the grade shock you're willing to pay for, will generally work.

The stock 3rd gen OR bump stop is 2 5/8" and hard. Remove rear shock boots so you can see the shock compression stroke remaining as the bump is engaged, and then the amount of stroke left to account for bump compression to its full stop.
This testing is basically a static weight test, not mass in inertia force, so build in a margin accordingly.

 

I’m not sure what you mean by “correct shocks”, but I can tell you that any OEM replacement shock (same extended and compressed length) will work fine. If you go outside OEM specs, then you have more homework to do.

 

Stock rear on a 3rd gen is 22" from center of hub to fender. If you are at 24" then think about switching to bilstein 5125 rear shocks as they are designed for 2-3.5" of lift, and bumpstops too.

 

I wish more people upon purchase would first jack up their dif pumpkin all the way, place jack stands under the rear end of the frame, unbolt the lower shocks, let the shocks extend, then lower the pumpkin, and see the difference between full leaf droop and shock length for themselves.

In the rear lift scenario, the shock will generally be x" shorter after lifting the rear x". Replacing a stock OR shock with the standard length 5100 @ 23", yields a firmer, stronger shock, but of the same length, of which x" amount of droop is now devoted to up travel for lifted ride height.

The questions become 1. how much downtravel can I give up, does it even affect my daily ride?, or 2. How much longer shocks do I need to regain the downtravel lost or even increase it, and what do I have to do for longer shocks?

The former question goes to usage and the latter goes to limitations of shock builds for the stock mount location, as well as what x" bump stop increase allows x" greater downtravel, or better yet, maximizes total travel usage.

A 2" rear lift would dictate a 25" rear shock length to get back to stock downtravel, right? But to do that you'll find an increased compressed length from manufacturers to about 15.2", which requires a longer than stock bump stop. Next question is how much longer? How long is a stock bump stop (about 2.6" hard)? What is the compressed length of stock OR shocks or standard length Bilstein 5100s (about 14")? How much do stock rear bump stops compress.(not much)? Then, where does my uptravel stop via the bump stop and how much is left? To test this, you need high cross axle ramps or a high ramp with shocks disconnected to measure compression.
Then you can see how much rear shock uptravel is never used in reality. Go test a stock bump on a power press to confirm that the corner weights v. compression were comparable.
Armed with that info, you will find about 3.5" of hard stop rubber and steel on a 1.25" lifted rear, will dead stop compression, allowing 24.8* length rear shocks in stock mounts like I have on mine. Going with Durobumps 3.5" on a flip (3/8" steel plate add) will approximate this.
This will also give you over 7" of up and down, cross axle articulation.

 

I forgot to add that if your lower shock mount with spacers, aal, won't droop to 25" from the upper shock mount location, then every fitting point I discussed above is a moot point.
That is why the rear dif pumpkin has to be jacked up, stands put under the rear frame, suspension dropped, and then measured, to see where you're at.