Make it handle

[robnolimit]

Originally Posted by Hop

Not sure if this has been addressed. looking to add coil overs. Are new upper and lower control arms required or will the current setup met my needs. 64 Step Side 2 1/2 spindle w/3 in drop spring in front, 4 in drop spring in rear. I want to lower the vehicle another inch all around without changing much.

Before I say what I feel I need to, remember that I am really trying to help. OK. So, my first question is, "What are you trying to accomplish?" I.E. - What are your goals for the suspension and/or the truck? This information has a lot to do with the right answer. Here's why.

IMHO (or, my opinion being fairly well educated on this subject) Adapting to a coil-over is seldom the best choice. (this is different that using a coil-over from a fresh design standpoint) What could you gain from a coil-over. 1. Compact design. uses less space and weight than a conventional coil/shock. 2. Easy mounting, - from a fresh design standpoint. 3. Adjust-ability of spring height via the threaded spring collar. 4. Typically built with high quality shocks, and/or with some valving adjustment.
And for the down side, LENGTH. To get 5" of travel from a coil-over, the open and closed measurements would be around 12" closed and 17" open. (eye to eye of mounts) Travel = ride quality. The shorter the travel available, the higher the spring rate needs to be to stop the vehicle from bottoming out on compression (bump/dip). The worst offender in the ride quality game are the 'Hy-brid' or 'direct fit' coil-overs. The ones that bolt to the LCA and the spring tapers out to fit the OE upper spring cup, with the upper shock mounting into the OE hole. These typically have 3" to 3 1/2" total travel, and I will now ask anyone, "If you, or anyone you have ever known, or heard of, has ever swapped in a pair of these, on any vehicle, and been happy with the ride quality, please let us know. As they may be the Unicorn, the only one.
Now, if ride quality isn't an issue, and you just want it lower, and maybe some adjustment to fix other problems, OK, they will work.

On to real Coil-overs shocks. The video shown is the best way to fit in a pair. By raising the upper shock mount they have created room for a longer shock to get back to the OE travel range. (lets say 4" to 4 1/2" of shock travel) that shock would be 11" to 15" long (closed vs open). But, this is a fair amount of work. There are kits avail, like the one from RideTech, and if this is your goal, that may be the best bet.

Now, on to your desire for 1" more of drop. If you do a coil-over swap in 'kit' form, and then back off of the spring collar 1/2" to drop the truck 1", you are loosing potential compression travel. And you didn't have a lot to start with. If the shocks and springs - or - coil-overs are installed correctly, then they are NOT the limiting factor of the suspension, the actual suspension design is, say, bump stops. Again, you need a very stiff spring to stop the vehicle from bottoming out.

You could get the same from a 4" drop spring and installing a high quality adjustable shock, BUT, the OE C10 shock mounts don't allow for a shock when the suspension is that low. Porterbuilt has a raised upper shock mount for that. BUT, the suspension itself is still almost bottomed out. You can trim down the bump stops (please don't just take them out) But by now, I'm sure you have noticed the front crossmember smacking the ground from time to time as it is now, and dropping another 1" will make that even worse.

Sorry for the heart-braking. But I want to be honest, and to give you the knowledge you need to make a good plan. If you want a coil-over because of the cool factor, then great. If you want another 1" drop, just trim the spring that you have, but know you will loose clearance and ride quality. Please stay away from the direct fit type coil-over swap kits. OR, you can go farther. Raise the crossmember up, or consider an aftermarket IFS with more travel and clearance. Sorry again for going on, and being a bit harsh, but I hate seeing people spend money and get a lot less than they were sold. Keep Truckin!