What is the ZUK mod? Dumb question I know, but I am curious of why its called that and what is the purpose. I KNOW there are threads on this, but I am still a little confused on what and why its done. Just to fix the 4runner saggy rear ends? Thanks, Justin.

 

ZUK mod is when you use a jeep TJ coil in between the frame and leaf springs. I personally would not recommend this for a truck because of the light bed vs a heavy shell on a 4runner.
I would go the block or shackle route for a much better ride.

 

Ok cool. Thank you for the info!

 

If your springs are worn out, a block or shackle wont help your ride, just give you height. As long as you dont get too stiff of a spring, it should pick the back up and help the ride. The ZUK mod (named for ZUK, the guy who brought it to popularity, gearinstalls.com) You can use any springs. Most use black magic springs, but 4runner, jeep tj and zj coils work too.

If you really want to fix the sag, get new springs.

There really are hundreds of threads on this.

 

Not necessarily. He could just find a spring that has less of a spring rate so it's not as stiff. IIRC, those who did this mod on pickups used 100lb. springs instead of the 125lb. springs recommended for 4Runners. I could be wrong. The best thing to do is contact ZUK.


Blocks

Shackles are alright, but you have to worry about changing the pinion angle. I still have a bit of vibration at various speeds after installing my shackles, so at some point, I'll have to add an alignment shim...or do it the right way and just cut the perches and rotate the axle.

With either the block or shackle, the ride quality would be the same because you still retain the same sagging spring.

Literally.

 

The best place to get the black magic springs is eBay. Check out 92 Toy's 4Runner thread for a good install of the springs.

 

Another thing to consider. Streetlancer used factory Celica front springs on his pickup for his No-cut ZUK Mod: https://www.yotatech.com/forums/f199.../#post51515554

Upon little research (since I'm in class right now), it seems as if the stock Celica springs are 135psi, as said in this thread: http://www.newcelica.org/forums/showthread.php?t=232289

So, they're a little stiffer, but it's another option other than black magic springs or TJ springs.