Rear Suspension

     For several years I made no changes to the ProComp Stage I lift kit I had installed on my truck.  The kit had come with some 3.5" tapered lift blocks for the rear, and these had survived so far.  In the fall of 1998, I was on a trail ride where I managed to snap a front CV joint and crush a rear shock on one obstacle.  I managed to fix the CV, but I was forced to finish the trail with the damaged shock.  After several years of riding on blocks, the stock rear springs had been stressed, and one dead shock was too much to take.  Within a week the spring on the side with the damaged shock had *died*, and was almost 2" lower than the other side.  

    This prompted me to consider some other options.   For quite a while I had considered the Mazda spring swap, but was reluctant to weld new perches to the frame.  Thinking along the same lines, I started playing the swap game.  This is a game where you get all the springs you can & mix and match leaves until you get the results you want.  Needless to say, this took a little time, but the result is a setup that I am pretty pleased with so far. 

In the two pictures below, you can see the travel I was achieving with the stock rear springs and the blocks.

Trailflex1.jpg (24244 bytes)     Trailflex2.jpg (24180 bytes)

    My custom packs that replaced this setup consist of the following:

Stock Toyota top main leaf
Stock Toyota military wrap second leaf
Stock Isuzu 2wd Pup rear 3rd leaf, center pin drilled 2" forward
Stock Isuzu 2wd Pup rear 4th leaf, center pin drilled 2" forward
Rough Country 2" add-a-leaf

This combination gives me a pack that has 5 leaves, evenly spaced ends, and very flexible.  The main reason for the Isuzu leaves is that they are from a pack that was intended to be under the axle, meaning they have more arch.  although they do have more arch, they are thinner that the stock Toyota leaves they replaced.  The add-a-leaf is used in place of the stock Toyota "Diving board", and serves to give a little lift and control axle wrap somewhat.

    In addition to these custom packs, I need some extra help to level the truck out with the front 4" IFS lift.  To do this, I purchased some braced 1" lift shackles, as well as some 1" lift blocks from J.C. Whitney.  With the bed loaded with normal trail gear including the spare tire, the truck sits level.

    Here are some pictures I took while testing the new suspension in a ditch in a friend's yard.  Compare them to the ones from above and you should notice a dramatic increase in travel, especially compression travel. 

Yardflex2.jpg (23332 bytes)    Yardflex1.jpg (83010 bytes)

    As you can see, the rear suspension has much more flex (much to my delight!).  From my measurements, I am getting around 19" of articulation at the tires.

There are some concerns though...

Yardflex4.jpg (23108 bytes)    Yardflex3.jpg (22332 bytes)

    I am a little concerned with the springs compressing into a negative arch.  Although they are managing to compress the rather stiff add-a-leaf, it seems that over time this will eventually destroy the springs.

    Also, I am still using the shocks that came with the ProComp lift kit, as well as the stock shock mounting locations.  I still have roughly 1" before the compressed side in the above pictures let the bumpstop hit the frame.  At this point the shock is bottoming out.  I plan to make some changes soon when I do my axle swap to get more lift, so shock relocation will be in order to take advantage of even more travel (20" or more?).  I have yet to check the shocks to see if they are limiting droop, but I would assume they are.

UPDATE (4/27/99)

    After swapping in a solid axle to the front of my truck, I found that the rear spring packs I had built were not up to the job.   Besides the fact that they did not give enough lift, they were too soft.  The stiffness of the IFS allowed me to use springs this soft and never notice it, but the addition of a solid axle with soft front springs made the road ride pretty scary :)

    I was looking to get about 6" of lift from the rear.  With the 1" blocks and longer shackles, I was needing a spring pack that would give me close to 4" of lift on it's own.  The choices for rear springs for my year model truck are limited, and I was not about o purchase a set of $400 Alcan springs.

    Luckily a friend had a set of 4" rear SkyJacker springs for an 88 & older truck or 4Runner.  He had kinked the main leaf, on their first outing, but the reast of the pack was in good shape and practically new.   Since my rear springs are longer than the 88 & older springs, I could not use the main leaf anyway. 

    For a quick fix, I use the top 2 stock rear main leaves already on my Toy with all of the SkyJacker leaves except the kinked main leaf.  This gave me the height I wanted and a pretty good pack.

     Of course, there are some down sides.  By using the stock main leaves with so much arch, the shackle is near vertical and gives a less than perfect ride quality.  I have plans to either find a longer main leaf to lay the shackle back some, or mount another shackle hanger eye a few inches forward of the stock one.  This should give a better ride and increase the droop.

    Another small problem is that the longest leaf from the SkyJacker pack is too close to the eye of the stock second (mil-wrap) leaf.  I think this is also limiting compression some since the leaf cannot slide anough forward as the spring compresses.  I may pull the packs apart soon and shorten this leaf by about 1" to see if that helps.

    As with just about any spring change like this, I am experiencing some axle wrap.  I am unsure what I will do to fight this, as there are several ways to go about controlling axle wrap and not limit travel.  I will be sure to post back soon with the method that works for me.   

UPDATE (6/25/99)

    At the Rosser event at the end of May I managed to crack & destroy both of my 1" aluminum rear lift blocks into very small pieces while on the trail.  I am presently running the same spring pack as above, just without the 1" blocks.  This has actually worked out well, since the front has settled almost the same amount & now the truck sits level.  I still have room for full suspension travel, so the extra lift was not necessary after all.


This page last modified 07/10/03

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