My bad if this has been asked a zillion times but I can't seem to find bang on info.
The BJ Spacer / LC80 Coils lift has been discussed a lot, but unfortunately, your exact questions haven't been explained very well.
I just did this to my '94 and I had to piece together information from many, many different forum discussions. I was planning on doing a write-up to address a few of the un-answered questions that I had, but time just got away from me. I won't answer all of the un-answered questions, but will give a few pieces of information that I picked up as I tried things on my rig.
I'm an ex Jeep XJ guy so this whole IFS suspension BS is completely new to me.
Uh, I won't hold the Jeep thing against you for too long... My first love was an '84 Bronco II. Faithful companion for 15+ years...
Anyway after much reading I'd like to try running FJ80 coils in the rear. However I can't seem to figure out which coils I would use for about a 3.5" lift.
Un-Answered Question: What coils should I get for x amount of lift? (Or my question, What coils should I get for the least amount of lift but still have good flex?)
The amount of lift will vary. If you have a heavy rear bumper, then you'll need a longer coil. I have a {basically} stock 4Runner. Well, that's the way it started! I opted for the least amount of lift and chose the shortest coils I could find. 18.25" 6.25 turns from a 94 LC (coil color code Dbl-Gray, Yellow... or is the Yellow a Tan... Well, it's a yellow or tan color).
This gave me about 4" (but I had a good/bad sag to start with). A little much lift for my taste, but the flex is great!
Another great thread is "Coil Rates":
Coil Rates - Toyota 120 Platforms Forum
The coils come in an un-matched set (18.25" & 18.75"). I ended up buying two sets. I'm thinking about cutting the 18.75" coils down to 17" and see if that would work to lower the rear to my "optimum" lift. If it doesn't work, I'll just put the 18.25" back on. As far as I know, nobody has reported trying this.
I also am unsure on which shocks for both front and rear would work best.
There are a few options for you. I can't find the thread right now, but search around. There is a thread with more shock options than you can imagine.
I basically borrowed/copied my setup from SLOsurfer from YotaTech (with a few tweaks):
slosurfer's profile - YotaTech Forums
Front: Rancho 5167
Rear: Rancho 99009 Adjustable Shocks (had to be modified)
These have given me a really great ride. Washboard is now almost non-existent. But, I guess that's just how I know the shocks are working!
I'm looking to get as much flex as possible outta this thing. I will sacrafice ride quality for flex.
I don't know if this is as much flex as you want, but it's enough for me... (And the ride is great, too.)
For the front I was just going to do BJ spacers and a 1" BL.
Just my personal preference. Don't do the BL. Keep the CG as low as you can.
Un-Answered Question: After installing the BJ spacer do I need to tighten or loosen the t-bars?
The 1.5" BJ Spacer with the 18.25" coils ends up being just about perfect. But, I ended up lowering (loosening) my t-bars about 0.5" to match the front ride to the rear (the LC coil is softer than the stock 4Runner coil). Plus, it helps the little people get into the vehicle easier. The 4Runner looks a little funny if it's sitting on the right (or rather wrong) slope, but it generally looks fine.
End result (33" tires, 1.5" BJ Spacers - 0.5" t-bar {de}crank, LC coils)...
I am by no means an expert on any of this. This is just what I did and I like it a lot. My base principle was to maximize flex with minimal lift.
