Dec 25, 2011

Suspension Rebuild

WARNING: this update will be long, boring, and technical…This is for the nerds out there that enjoy working on their own vehicles of trip.  Proceed with caution.

When I originally bought the 4runner it was in surprisingly great shape for a 4WD just a couple years younger than me.  It was garage kept and the previous 2 owners were meticulous about maintenance. The suspension on the other hand was in a sorry state.

If you talk to anyone who owns a Toyota of this vintage they'll tell you the rear suspension is weak.  The pickups, motor homes and 4x4’s all tend to have flat leaf springs unless they’ve been replaced.  The Chicken Tax which affected the way the 1st generation 4Runners were imported from Japan, meant they used the same weak leafs that were never designed for the extra weight of the removable fiberglass hardtop that these original 4Runner’s were famous for.  The Border Runner's suspension was so tired that there was less than 1-inch between the bump stops!  This is makes for poor ride quality, terrible handling and pathetic ground clearance.  The tiniest speed bump would send me into a spine jarring shock as the suspension bottomed out and considering the notoriously poor quality of roads we’re planning on traveling in Central and South America, we consider it a priority to address our 30 year old factory suspension before we head south.

"saggy bottom" blues

ignore the CV boot, I took care of it!
a little bump n' grind

One solution that is popular on some online forums is the "Zuk mod" using coil springs to compensate for the weak leaf springs.  The general idea is to spread the leaf springs as far from the frame as reasonable, then compress a coil spring small enough to fit between the frame and lower u-bolt mount, theoretically locked into place by the bump stops.  There are several different variations of this modification out there, but this is the simplest form because it requires no welding, it's easy to undo, and costs less than $50.  This being "Southern Engineering" at its finest, I decided to temporarily give it a go on our 4runner.  It lifted the rear end of the 4runner and performed like a set of "helper/overload springs", riding great when the 4runner was loaded down with camping gear.  When the Border Runner was empty, it was a rough ride but if you weren't a fan of that you could just remove them in an hour.  You can read more about the Zuk mod, or see many of the different versions that have been done at the bottom of Zuk's website.

Zuk mod with Wrangler/TJ coils
This "band-aid" for the rear suspension held up surprisingly great.  However, the more we contemplated our travels across the globe, we realized that our suspension will be pushed beyond its limits.  Overland vehicle = overloaded…combine that with Latin American topes and corrugated roads in Baja, we decided our 24 year old suspension could use an overhaul.  We will sleep much better at night knowing that our leaf springs won't experience a catastrophic failure in the middle of the Chilean highlands, leaving us unable to drive, push, or tow our vehicle 250 miles back to civilization.

After "Zuk" 

While hunting for the proper replacement parts, one name kept popping up: Old Man Emu.  Made in Australia by ARB, Old Man Emu (OME) is world renown for reliability and performance.  All of their components are designed for the harsh demands of the outback.  Since they have a complete kit designed specifically for our vehicle, it took a lot of the guesswork out of choosing individual pieces.  The only choice you have to make is if you want a light/medium application or heavy duty.  From all of my research I gathered that the heavy application is overkill and provides too stiff of a ride.  We want to keep our vehicle's loads under GVW (Gross Vehicle Weight), which is what the light/medium kit is designed for.  If we decide that we'd like to stiffen the rear suspension even more, we can actually order an add-a-leaf to the rear end which would be similar to the Heavy kit.

We found that the Toyota of Dallas (TRDparts4u) had the most reasonable prices for our kit (OME-4RUN-1GC-IFS), and we had heard good things about their customer service.  We ordered our kit in September and opted to pick the parts up directly from their store in Dallas.  Unfortunately the rear shackles and u-bolts were on backorder from ARB, so we had to wait until they arrived all the way from Australia!  So lesson #1, order foreign parts FAR in advance just to be sure you're not waiting until the last minute!  We have good friends who live in Dallas that were kind enough to pick up our parts for us and drop them off in Austin while they were in town.  Thanks to Megan and Zach because they saved us over $150 in shipping and handling.  While we were starting to stress about our backordered parts, they finally arrived to our door.  TRDparts4u was kind enough to overnight them to us once they arrived from Oz, at no extra cost to us.  

The only instructions that came with the kit were for the assembly of the rear shackles and a general rundown of torsion bars.  It didn't help that the 4runner's Service Manual (FSM) gave very few details about the removal/installation of these torsion bars.  Feeling a little intimidated by the T-bars, I asked my buddy Zack Johnson of Zack's Customs if he would be able to help me.  Zack is a talented mechanic and he's taken a real interest in our trip since he's been to Honduras and Belize recently.  He had luckily just moved into a larger shop and was kind enough to let me use his car-lift to install the suspension.  Let me tell you, I forgot how nice it was to use a lift and pneumatic tools!  This made the process 10x easier.  Even though Zack was busy working on other cars for the holidays, he took the time to check on me and make sure I wasn't killing myself.  He was kind enough to avoid the "you're doing it wrong" comments, but offered me tips on how to do it right and kept me on the right track.  I originally planned on taking video and tons of pictures of my install but unfortunately I forgot to charge my cameras and they quickly died after a few shots.

the easy button
I started with the rear leaf springs.  This was very simple.  Lift the vehicle by the frame, letting the suspension droop.   Put a floor jack under the axle tube and raise it to take the load off the side you're removing.  Undo the top nut/bolt of the rear shackle (leave the bottom nut/bolt alone) then tap the top bolt out with a rubber mallet, freeing the shackle from the frame.  Luckily our 4runner hasn't been attacked by cancer, so these bolts were all easy to break loose.  Not everyone is so lucky, so you may have to use penetrating oil, a pry-bar and fulcrum, or even a torch to get some of these ancient bolts free.  Next, remove the bottom bolt of the shock to give your axle some free play to articulate.  Lower the floor jack and the axle will pivot on the front leaf spring bolt.

NOTE: since I had the Zuk coil springs still installed, this was the best way to slowly remove pressure from the compressed coil.  Even though it was no longer compressed at this point, I had to give it a few taps with the rubber mallet to free the ends from the bump stops.  Skeptics of the Zuk mod speculate that the coils can "pop out" under serious articulation, but this should give an idea as to how well the Zuk coils stay in place.  The Wrangler/Tj coils had a tight grip on the upper bump spot and I even had to pry it a little.  

Now you can remove the front bolt for the leaf spring and tap it out with the hammer (do not lose this bolt, there is no replacement in your kit).  With the leaf pack free of the frame, you can jack the axle back up to get to the nuts underneath that hold the u-bolts secure.  Remove the 4 u-bolts and the leaf packs are now completely free.  If you're careful enough, you can slide the leafs out, taking care to avoid the brake lines.  If you haven't assembled the greasable shackles yet, now would be the time. See instructions below.  

Grease the yellow OME bushings and slip them into the front and rear leaf spring mounts on the frame.  Install the new shackle to the OME leaf pack, on the side opposite of the yellow "+" (the yellow + goes toward the front of the vehicle).  Slide the leaf pack into place, using caution around the brake lines, and secure them to the axle using the longer u-bolts provided.  Start by bolting up the front of the leaf ("+" side) to the frame.  NOTE: a beefy screwdriver or round prybar will make lining up the mounting holes much easier.  Jack up the axle again until the rear shackle bolts line up with the hole in the frame.  Are your new bushings still there?  Good.  Install the shackle nuts.  Now you can completely remove the old rear shock to install the new one…

This is when I realized I was given the wrong rear shocks (N92).  As a matter of fact they were front shocks for another vehicle.  No biggie, I called TRDparts4u and talked to Barbara King who was extremely helpful…this is where you'll thank yourself for ordering from a dealer with reputable customer service.  I re-installed the old shock and they sent me the correct one overnight.  Once I had the correct N92 shocks, it only took me 15 minutes and one wrench to swap them out.  LESSON #2: check your parts and make sure they appear to be the correct parts when they first arrive!

ANOTHER NOTE: installing new bushings on a shock can be tricky, but it can be very simple if you use a vise to place equal pressure on the bushing face and the opposite side of the shock mount.

If you didn't tighten all of the nuts & bolts for this side, now is the time to go back and torque them all down.  Be sure to grease the installed shackle while you're at it.  Now crack open a beer and drink it slowly as you revel in the fact that you're halfway done…with the rear.  Now get back to work you bum!  The other side is exactly the same as the other, only you'll probably get it knocked out a little quicker…keep it up you're getting closer!

Back to the vague instructions…this is where a lift and a buddy who knows what he's doing can come in handy.  We weren't looking forward to this part because Zack had not-so-fond memories of previous torsion bar jobs on different vehicles.  We read the generalized instructions and the Factory Service Manual's removal/installation steps.  

Could it really be that simple?  No way, surely there's something that the FSM is leaving out.  With our luck Newton's Law will kick in and we'll spend the next 3 hours cussing and destroying the old t-bars with a hammer and prybar.  With hesitation we lifted the 4runner completely so that we could stand underneath and Zack gave it a go.  No problem at all.  We measured the threads remaining on the protruding bolt and made note of it for later reference.  We then loosened and completely removed the adjusting nut then moved forward to the other side of the t-bars.  After removing the torque arm mounting nuts the torsion bar was theoretically ready to come out.  The passenger side was a little stubborn and we had to knock it out of the rearward "cradle" using an air hammer.  Other than that, the t-bars just pop up then you wiggle it rearward until the splines are free of the front mounting.  This whole time Zack was doing all the work and I was anxiously waiting to take over so he could get back to his other projects…fortunately it went so fast, that he was able to get it done in 15 minutes and I just held the flashlight!  

Once the old t-bars are out you can swap out all of the attached pieces to the new torsion bars (OME303003).  (Torque arm, anchor arm, and dust boots)

The key to installing the new torsion bars is to be sure and clean the splines well with a wire brush and then apply a little grease.  The t-bar was designed for a snug fit on the splines, so it takes some gentle wiggling to get it in place.  Remember the threads that you measured on the adjusting bolt?  That's the other key to proper installation.  As long as that measurement matches up at the end, you should be good to go.  Replace the front N98 shocks and steering stabilizer, which is very simple so I won't go into that.  The kit does not have the larger bottom bolts for the front shocks, but it does include new hardware for the upper shock mount.  The steering stabilizer (OMESD33) comes with a new nylon lock nut to replace the castle nut & cotter pin.  Now you're ready to get an alignment!  Total installation time was 6 hours, but I could easily see this being done in 4 hours.


PROS: I love the way this suspension handles.  Everything feels much tighter all around and my ride has never been so quiet.  Cornering even feels a little improved, but I never expect the 4runner to handle like a corvette.  The suspension feels very responsive and does a great job of absorbing bumps with some weight in the back.

CONS: Although it's stupid to classify this as a negative remark…I completely unloaded the 4runner to have it weighed and the suspension was pretty rough (completely empty, with the rear seats, cargo panels, and spare tire removed).  This is completely expected when a vehicle is underweight but I just wanted to make note of it so nobody spends $1000 on suspension, expecting to drive an empty 4runner and end up disappointed.  However with a little gear in the back this kit really does perform well so take that poor note with a grain of salt!  My biggest complaint with the OME shocks?  The obnoxious yellow color!  Okay now I'm just splitting hairs, but I feel like it gives the 4runner that "ricer" look... 

I will honestly say that so far the OME rear feels very similar to the ZUK coil spring mod.  All around (front and back) it's definitely an improvement but the rear is comparable.  The difference with the Zuk coil mod depends on the load rating of the coil spring used.  I used the front coils from a '97-2006 Jeep Wrangler/TJ and I honestly don't know the spring rating.  These coils are nice because one end is wide enough to fit over the upper bump stop perfectly while the other end is a little tapered so it fits snug around the bottom bump stop.  They were originally a little too long, around 17" I think, so I cut the widest end short so that they ended 14" long which made the rear sit level again (approx. 3" of lift in the rear).  Immediately after I installed the Zuk coils I noticed a few popping sounds (which is common) as the springs settled onto the bump stops.  After that I never heard another sound from them.

Do I regret my decision to spend $1000 on the OME kit instead of sticking with my $17 Zuk coil springs?  Absolutely not, even though it looks pretty much the same.  The Zuk coils were great but I still worried about the longevity and reliability of slightly used coils supporting VERY worn-out leaf springs.  There's always the paranoia of the coils popping out on an extreme articulation, but honestly I don't think that would happen.  I COULD have replaced all 4 shocks, steering stabilizer, and suspension bushings and MAYBE it would feel the same as the OME kit for 1/2 the price…but I'd still have 24 year old t-bars and leaf springs ready to fail at any moment.

After I replaced the rear shocks with the N92 shocks, the ride in the rear does feel much better than with the Zuk mod.  Would it have felt the same if I had N92 shocks and Zuk coils?  I guess we'll never know.  I would be fine driving with that if it were just cruising around town or hitting local trails, but since we're driving to the other side of the world on terrible roads, I feel the extra $500 was worth the price.

ride height with Zuk mod

ride height with OME suspension
I hope this information helps others who find themselves in my situation, whether they're trying to fix the "saggy butt" on their daily driver or driving their mini Toyota to South America and beyond.  I will do my best to update my impressions of the Old Man Emu suspension as our travels progress and please feel free to ask any questions.

While driving from Austin to Seattle, slightly overloaded, the leaf springs have settled quite a bit.  I tried to source the OME Add-a-leaf to address this, but we were out of time and would have had to wait months to receive the part.  We ultimately decided to add the Zuk mod once again, just to level it out and provide overload protection on serious bumps.  See the install and more notes here..

Well, we made it all the way to Tierra Del Fuego and the suspension performed flawlessly.  The OME suspension along with the ZUK coil mod had no issues whatsoever, even after countless encounters with speed bumps of all shapes and sizes, thousands of miles of washboards, and the worst roads I've ever encountered in my life.  To be completely honest, there were a few times where I didn't see a speed bump in time and we hit it so hard that the 4Runner actually got launched into the air.  To my complete surprise, we have found no damage.  We are now due for a new set of shocks, which is totally reasonable at this point.  Once the 4Runner is back in the states, I will report on what I choose and why.