WARNING: this update will be long, boring, and technical. Proceed with caution.
When I originally bought the 4runner it was in surprisingly great shape for a 30 year old 4WD. It was garage kept and the previous 2 owners truly babied it. The suspension on the other hand was in a sorry state.
THE PROBLEM
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 bad that there was less than 1-inch between the bump stops while sitting on flat pavement. Not only does this make for terrible ride quality, but it also makes for pathetic ground clearance, poor handling and minimal articulation. The tiniest bump on well paved roads would send me into a spine jarring shock as the suspension bottomed out. Considering the notoriously poor quality of roads along our route between the US and Argentina, we consider it a priority to address our 30 year old suspension before we head south.
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| "saggy bottom" blues |
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| Apparently the CV boot is ready for TLC also |
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| Less than 1" between bump stops |
THE TEMPORARY HALF-ASSED FIX ($17 ZUK MOD)
One solution for these older Toyotas is what's called the "Zuk mod". Basically you use a coil spring to compensate for the weak leaf springs. The general idea of the "weldless Zuk mod" 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 locking it into place using the bump stops and compression forces between the frame and the axle. 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 next to nothing.
While planning a permanent solution for our 4Runner, I decided to temporarily give it a shot. 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 4Runner was empty, the rear suspension was way too stiff and it was a rough ride. The other negative was that there was very little articulation of the rear axle in off-camber situations. Luckily it only takes about an hour to remove. I spent $17 for front coils from a 1997-2006 Jeep TJ Wrangler that I found at a Pick 'N Pull yard. These worked great because the tapered end seats perfectly around the lower bumpstop and u-bolts, while the wide end fits snug over the upper bumpstop. They were originally a little too long at slightly higher than the front. 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.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.
While planning a permanent solution for our 4Runner, I decided to temporarily give it a shot. 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 4Runner was empty, the rear suspension was way too stiff and it was a rough ride. The other negative was that there was very little articulation of the rear axle in off-camber situations. Luckily it only takes about an hour to remove. I spent $17 for front coils from a 1997-2006 Jeep TJ Wrangler that I found at a Pick 'N Pull yard. These worked great because the tapered end seats perfectly around the lower bumpstop and u-bolts, while the wide end fits snug over the upper bumpstop. They were originally a little too long at slightly higher than the front. 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.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.
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| Zuk mod with Wrangler/TJ coils |
This "band-aid" for the rear suspension held up very well actually but it still left a lot to be desired. The more we contemplated our travels across the globe, we realized that our suspension will be pushed beyond its limits. Overland vehicle = overloaded vehicle most of the time…combine that with Latin American topes, tumulos and derrumbes, we decided our 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.
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| After trying the "Zuk mod" |
A MORE PERMANENT SOLUTION
While hunting for the proper replacement parts, one name kept popping up: Old Man Emu (ARB). Made in Australia, Old Man Emu (OME) has been world renown for reliability and performance in the offroad world for decades. All of their components were originally designed for the harsh demands of the outback.
The choice you have to make is if you want a light/medium application or the HD (heavy duty) kit. The light/medium kit is designed for vehicles not expecting to exceed GVW (Gross Vehicle Weight) and adds 2" of lift. The heavy duty application is designed for vehicles carrying up to 440 lbs over GVW and adds up to 2.5" lift. Keep in mind, if you're expecting to exceed your GVW you will need to upgrade your steering components, braking ability and you should consider reinforcing the frame where applicable.
I decided that the heavy application seemed overkill and would provide too stiff of a ride since we had no plans to exceed GVW. IN HINDSIGHT: we should have gone with the HD option for our PanAmerican journey, although we made due with additional overload springs. Keep in mind though, even with the light duty/medium kit we have found that even with a bone stock 4Runner and no cargo or passengers the rear suspension feels too stiff. Over time it will soften up, but not a lot.
The choice you have to make is if you want a light/medium application or the HD (heavy duty) kit. The light/medium kit is designed for vehicles not expecting to exceed GVW (Gross Vehicle Weight) and adds 2" of lift. The heavy duty application is designed for vehicles carrying up to 440 lbs over GVW and adds up to 2.5" lift. Keep in mind, if you're expecting to exceed your GVW you will need to upgrade your steering components, braking ability and you should consider reinforcing the frame where applicable.
I decided that the heavy application seemed overkill and would provide too stiff of a ride since we had no plans to exceed GVW. IN HINDSIGHT: we should have gone with the HD option for our PanAmerican journey, although we made due with additional overload springs. Keep in mind though, even with the light duty/medium kit we have found that even with a bone stock 4Runner and no cargo or passengers the rear suspension feels too stiff. Over time it will soften up, but not a lot.
We found that Toyota of Dallas (TRDparts4u) had the most reasonable prices at the time for what we wanted 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. While we were beginning to stress about our backordered parts, they arrived stateside. TRDparts4u was kind enough to overnight them to us once they arrived from Oz, at no extra cost to us.
PARTS LIST:
N94 shocks
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. I asked my buddy Zack Johnson of Zack's Customs if we could use the lift at his shop and he was happy to help. Zack is a talented mechanic and he's taken a real interest in our trip since he's been to Honduras and Belize recently. 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 lend a hand here and there. I originally planned on taking video and tons of pictures of my install, but honestly who has time for that when you've got work to do!
First of all, before you start wrenching on anything I highly recommend spraying down any nuts or bolts beforehand with PB Blaster or whatever snake oil of your choice. Depending on the rust or condition on your 4x4, you might wanna do this a couple times in the days leading up to the job.
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| the easy button |
It's a good idea to hit everything with penetrating oil a day or two prior, to make sure everything comes loose without too much headache. If that's not enough, you can always heat with a torch. Using an impact will make life easier obviously but if you don't have one you can always go crazy with a big f'n hammer.
I started with the rear leaf springs, which was easy peasy. Lift the vehicle by the frame, letting the suspension droop all the way.
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 has been a rust free Texas truck all it's life, so these bolts were all easy to break loose.
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.
I started with the rear leaf springs, which was easy peasy. Lift the vehicle by the frame, letting the suspension droop all the way.
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 has been a rust free Texas truck all it's life, so these bolts were all easy to break loose.
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 a hammer (do not lose this bolt, there is no replacement in the OME 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.
Assemble the greasable shackles. 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, round prybar or skinny pipe 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…
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, round prybar or skinny pipe 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 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 a lot easier if you use a vise to place equal pressure on the bushing face and the opposite side of the shock mount.
ANOTHER NOTE: installing new bushings on a shock can be a lot easier 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. 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.
The other side is done exactly the same as the other.
The other side is done exactly the same as the other.
REMOVAL OF TORSION BARS
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 honestly because of the torsion bars. We skimmed over 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. We lifted the 4runner completely so that we could stand underneath and gave it a go. No problem at all. I was surprised nothing was seized up and I don’t know if it didn’t because this is a clean Texas truck or because I soaked it in penetrating oil prior.
Measure the threads remaining on the protruding bolt and make note of it for later reference.
Loosen and completely remove the adjusting nut, then move forward to the other side of the t-bars.
Remove the torque arm mounting nuts and the torsion bar will be 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. It only took 15 minutes to remove the T-bars, but again this is a rust-free 4Runner that's been babied all it's life!
Measure the threads remaining on the protruding bolt and make note of it for later reference.
Loosen and completely remove the adjusting nut, then move forward to the other side of the t-bars.
Remove the torque arm mounting nuts and the torsion bar will be 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. It only took 15 minutes to remove the T-bars, but again this is a rust-free 4Runner that's been babied all it's life!
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)
INSTALL THE NEW TORSION BARS
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 very 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 simply a few nuts and bolts so I won't go into detail on that. The kit did not have the larger bottom bolts for the front shocks, but it did 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 with fewer beers.
FIRST IMPRESSIONS ON PERFORMANCE:
POSITIVE: I love the way this suspension handles. The handling is much more responsive and tighter all around. When "soft-roading" down dirt and gravel, I can actually rally it with some speed and it feels much tighter all around. In off camber situations it articulates much better than it used to, though I haven't taken the time to measure travel yet. Obviously disconnecting the sway bar will make a big improvement too. The ride has never been so quiet on and off the pavement. Cornering even feels a little improved with much less body roll, 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 a little 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 too stiff, It was even worse obviously when I gutted the rear seats, cargo panels, and spare tire. This is completely expected of course, but I have found that with all the factory equipment installed the ride quality seems best with 100lbs or more of cargo (and a passenger or two). My biggest complaint with the OME shocks? Other than price, I can't stand the obnoxious yellow color! It makes the undercarriage look like it belongs of the Fast & Furious set.
Do I regret my decision to spend $1000 on the OME kit instead of sticking with my $17 Zuk coil springs? Absolutely not. The Zuk coils were great visually and rode well on dirt, gravel and pavement but I still worried about the longevity and reliability of 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 because frankly articulation is so limited. 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 leafs to worry about carrying us and all our gear to South America.
After I replaced the rear shocks with the N92 shocks, the ride in the rear does feel much better than with the Zuk mod.
After I replaced the rear shocks with the N92 shocks, the ride in the rear does feel much better than with the Zuk mod.
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| ride height with Zuk mod |
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| ride height with OME suspension |
PRE-TRIP PANAM UPDATE:
While driving from Austin to Seattle we rushed to get out of town and ended up pretty overloaded, which settled out the new leaf springs pretty quickly. We also received word from our friends James and Lauren of Home On The Highway that they had an issue with their OME leaf pack. The passenger side leaf pack has a bolt that's poorly placed and when that side is compressed the hardware can make contact with the fuel tank lip, causing the tank to leak.
After looking closely at our setup, I could see this easily happening to us down the road so I tried to source an OME D5XL Add-a-leaf (adds 200lbs capacity) to hopefully address this situation, but we could not find any in stock stateside and we were itching to finally head southbound.
We ultimately decided to add the Zuk mod once again as overload protection until we could thin out our gear cache and lose some weight down the road. See the install and more notes here..
After looking closely at our setup, I could see this easily happening to us down the road so I tried to source an OME D5XL Add-a-leaf (adds 200lbs capacity) to hopefully address this situation, but we could not find any in stock stateside and we were itching to finally head southbound.
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| Easy to see how that nut could contact the fuel tank lip! |
We ultimately decided to add the Zuk mod once again as overload protection until we could thin out our gear cache and lose some weight down the road. 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 had no issues, even the ZUK mod survived while we had it installed. I lost count how many times a topé (massive speed bump) would sneak up on us and I'd launch it at 50mph and actually catch air. Between that and all the shitty roads and corrugated 4x4 tracks we found, we never had a problem with our suspension. To my complete surprise, we have found no damage to our suspension. Now that the Zuk mod is long removed and I use the 4Runner for daily driving, I find the OME medium kit perfect unless I'm completely unloaded in the back.
