Suspension Rebuild on 5th Gen 4Runner

Front Suspension

In this post I would like to cover unique challenges that I faced while rebuilding suspension on my 2010 Toyota 4Runner. It’s focus is to address the challenges that one may face while rebuilding suspension on a car that spent most of its life in an area where snow, moisture, and salt destroyed undercarriage, and every component they could get to. There are plenty of tutorials out there that cover installation of suspension components on new cars that do not have these problems.

After getting back from a recent 3k mile road trip that involved extensive off-road sections, a spring on one of the front struts broke. I am not sure if it happened while I was off-roading or when I was in the city. All I heard was a loud clunk coming from one of the suspension components as I was coming down a driveway.



It has been a year since I got this car, and I really didn’t want to deal with any of the suspension components, knowing for a fact that I will inevitably stumble upon many rusted bolts. Several months before this, I was strategizing how I may make it happen, and every time I thought about it, I convinced myself that I could not do it without help from a suspension shop.

To do complete front suspension rebuild with 3 inch lift, you have to take off swaybar brackets. I already had experience with bolts that were bolted directly to the frame, and knew exactly what to expect after 10 years of East coast winters. When I was installing new skid plate and catalytic converter protection plate, I had to rethread some bolt threads and install rivets in place of others. I really had to be mentally pushed to the edge, where I was ready to loose everything to get this job done. This happened in a very unexpected way.

I was planning a trip to the North in the summer of 2023. By that time, I have already saved up enough money for new suspension components and installation, which was around $5,000. This is the price I was quoted in Colorado by a reputable suspension shop. Those guys didn’t care about rust, and had a solution for every problem I threw at them. When I arrived to California, the story was different. There was no question about necessity of suspension rebuild at this time, so I called a few shops to inquire about the rates.

Being a fairly straight forward guy, I told them that my car spent 10 years in New York, it is a 2010 model, and it needs it’s front suspension rebuilt. One shop told me that they will not take the job because of how old the car is and the time it spent on the East coast. They wanted the car on the lift, bolts taken off in seconds, parts installed, and car out of the the shop. They didn’t want the car to sit in their shop for weeks because of rusted components. When I asked the other shop to do the job, they agreed. Although, I wasn’t happy with their responses to the way they will approach the job. The shop in Colorado gave them straight forward solution to the problem I told them about. This is what we will do, and this is how much it will cost. The guys in California didn’t have a clue what they were going to do once they face a similar problem.

From this point I knew for a fact that I will either have to take the car to a state where people are used to rust on car, or I will have to take care of this job myself. I wasn’t worried much about the extent of the suspension rebuild job. It was rusted bolts that made me tremble.

I found solution to this problem fairly quickly, which inspired me to keep on moving forward.

Bolt Extraction

I attempted to remove one of the M10 bolts from the bumper, which sheared. This meant that the rest of the bolts had the face the same destiny. From this point, I decided that I will do the job even if I have to drill them all out one by one, and retap the holes. I then suddenly remembered that there is a method of bolt extraction that uses heat and PB blaster. The bolt is heated first, and then cooled down with PB blaster. This allows PB blaster to penetrate deeper, which eventually releases corroded fastener. It worked like a charm.

M8 bolts were pretty much sized in. I tried heating them up and applying PB blaster. They would still shear off. Extraction of the bolt itself with extraction tool was also hopeless. The bit was too thin, and the tip broke after a few attempts.

M10 bolts were thick and strong enough to be removed. I first heated them up until red hot, soaked them with PB blaster, and then used impact wrench to remove them. If they were a little stubborn, I would remove them with hand tools using back and forth method.

Bolts larger than M10 could be removed just with impact wrench except a few stubborn ones.

Extraction Bits and Extraction Sockets

• The only extraction bit that I really needed was for M8 bolts, and that one broke.
• The only extraction socket that I needed was 14 mm. The rest could easily be removed with 8 point socket of appropriate size.

Taps



M8, M10, & M12 are a must to clean up the threads.

At the beginning I drilled out and retaped skid plate bolt threads to M10. Catalytic converter protection plate bolt threads were drilled out and replaced with rivets.



Now, looking at this, I could have saved myself a few days of work by using this method and possibly limiting the number of rivets and taps needed.

Bolts



For this project I mainly needed M10 and M12 bolts. Overall M8, M10, and M12 bolts are the only one that need to be replaced. I purchased Class 10.9 bolts of the right size from AutoZone along with washers, and lock washers. If larger bolts needed replacement, they were purchased directly from Toyota.

Suspension Upgrade: Big Question and Choice of Parts

Big question that often gets asked on forums is, “Do I need a lift?” After several lengthy overlanding trips that involved large off-road segments, I can say for a fact that lift is not necessary. 4Runner with it’s stock suspension can get you pretty much anywhere. Things just become much easier when you have a lift. You don’t have to be as cautions and careful, as when you did not have one. The biggest problem for overlanding is inappropriately chosen coils for the weight that you are planning to carry. Stock coils are not capable of carrying a lot of weight, which results in a car that is consistently sagging and dragging its belly over every obstacle it encounters.

This is before getting the lift.



This is after getting the lift.



After some research, I decided to go with Toytec 3 inch Lift Kit and SPC UCA. I decided to keep stock tire size. As I have mentioned earlier, the car was already very capable off-road with stock tires. Getting 285/75/R17 tires would only increase ground clearance by about an inch, which wouldn’t make much difference for the type of off-roading I do.

 

Front Suspension: Rusted Shock Removal

Up until this time, I thought I would only need to deal with rusted fasteners. All the other suspension components would just come out on their own, once the fasteners were loosened. This was wishful thinking.

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The shock is held in place by 3 bolts on top (Shock Absorber > Frame), and 1 bolt on the bottom (Shock Absorber > LCA). The bottom one came off without any problems. To remove the top ones, I had to come up with a unique solution.

The front two bolts can easily be removed using the method describe earlier. Heat, PB Blaster, and extraction socket work like a charm.





The problem is with the rear bolt. There is no way for you to access the rear bolt unless you drill a large hole in the body of the car, and drop down a socket extension through it.

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This is just first half of the problem. After removal of these 3 bolts I discovered that the shock itself was seized. All the rust and rot, literally, super glued the shock in place. It was impossible to remove it by hand.

These are the steps I took to remove the shock.

First, I had to find a way to get the tension off the spring. To do this, I cut the spring into pieces with angle grinder. I used hose clamps to compress the spring a little, so when I cut it, it doesn’t explode.



Once the spring was cut, I used chisel to create an opening between the frame and top of the shock bearing plate.



Once the opening was created, I stuck a screwdriver in that opening and kept on hammering it in until the wedge released the bearing plate, and the bolts. Yes, the bolts! The real problem is that the plate that was glued in place by the rust, was also held in place by 3 spline bolts. The splines prevented the bolts from coming out, so they had to be knocked out. The front two ones can be knocked out by this method.



On one of the front bolts, screwdriver was not enough, so I used chisel to remove spline bolt.



The rear spline bolts had to knocked out by sliding socket extension down the hole that I created earlier, placing 10mm socket over it, and hitting the other end of socket extension with a hammer.





In the end, it finally came loose!

 

Installation of New Shock Absorbers

I would like to add that I kept the holes that I made in the body earlier. I used them to install the shocks and torque upper, rear bolt to specs.





Front Suspension: LCA Removal

Another thing that kept me from upgrading my suspension earlier is the cost of parts and labor. The shop in Colorado explained to me that on an older car that came from the East costs, cams in the LCA will be seized. This meant that I had to invest in a new set of LCA and pay for the installation.

This part of the job is fairly common. Older LCA cam bolts have to be cut off either by a reciprocating saw with diamond tooth blade, or by an angle grinder with a large size cut off wheel. I used both, and had better success with angle grinder. To get better access to cam bolts, I cut off control arms with large cut off wheel. I then used the space created to cut off the cam bolts.





New LCA and cam bolts were installed in their place. I went with OEM parts, and decided to adapt a practice of taking cam bolts out once a year and covering them with anti-size.



Front Suspension: Other Parts
Other parts of the fronts suspension were dealt with in a similar fashion.

• It was fairly easy to cut off UCA bolt, and remove UCA.
• Swaybar bracket bolts were removed by heating and PB blasting them.
• Swaybar link bolts were cut off.
• Outer tie rod end bolts were removed with impact wrench. I used ball joint separator to free them up.

Before and After

This is what was left of front end suspension once removal of old parts was complete.



This is picture after installation of the new parts.

 

Rear Suspension

I did not have to struggle much with removal of the bolts while working on rear suspension components. All of the bolts were bigger than M10. There was no way they would sheer off. I still had to use PB blaster and impact wrench on all of them, but application of heat prior to this was not required. I was able to salvage most of the older bolts except a few. Bushings, on the other hand, were in pretty bad condition on all of the parts.



Parts

Compared to front suspensions components, aftermarket rear suspension parts were fairly inexpensive. On 5th gen 4Runner you don’t have an option to buy bushings separately and have them pressed in, so I decided to purchase Moog control arms to offset the cost of already expensive repair.

Item Quantity Price Total
MOOG RK643534 Lateral Arm 1 $91.25 $91.25

$42 MOOG RK643320 Suspension Control Arm rear left upper forward, rear upper

MOOG RK643320 Upper Control Arm 2 $30.29 $60.58
MOOG RK643256 Lower Control Arm 2 $49.17 $98.34

Rear Coils Installation

It took me a while to figure out how to install new rear coils. I ordered RCC2.0-P – Toytec Superflex Rear Coils, which were taller than the stock ones. I tried bottle jack method, and jacking up rear axle from another side with a floor jack. There still was not enough space to get the coils in place.



The last thing that I could do was to compress the spring with spring compressors that I loaned from AutoZone. This final step made insertion of the spring possible. I will say that this was the most stressful part of the suspension rebuild.



Rear UCA Removal

Manual Page: 3029




The biggest problem with removing rear UCA on the driver’s side is that access to the nut is restricted by the fuel tank and the wing of the mount. On a car that doesn’t have much corrosion, removal process is pretty straight forward. In my case, I had to go to extremes.



At first, I tried cutting of the head of the bolt, hoping that as the tension of the fastener on the mount is released, I would be able to wiggle the bolt out somehow. That did not work. The bolt was seized in place. I then cut off the arm of the UCA, as seen in the picture above, and went to work with reciprocating saw and diamond tooth blade.



To get the tool in there, I had to disconnect rear shock, and drop rear axle quite a bit. Stock rear brake lines were to short for this manipulation, so I had to be take them out of the mounting plate.



The bolt had to be cut on both sides for the head of the UCA to come out of the mount. It is important to be aware of the blade at all times, because the tank is made out of plastic. It is probably wise to put cover the tank with some kind of hard material that the blade cannot go through in case it slips.



Geometry

The hardest part of the installation of rear suspension components is aligning everything in line with the bolt holes. The easiest way to do this is to use a ratchet strap. It allow you to push the component that you are installing in the direction you want it to go. Jacks are also useful to fine tune alignment.




Extended Brake Lines

According to the information that is available on forums, you don’t have to change rear break lines. In my own experience, I felt like I have no choice. To install the springs, I had to take them out of mounting plate. There simply was not enough slack to install new springs.



I went ahead with Metal Tech FJ Cruiser/4Runner Extended Rear Brake Lines. They are heavy duty braided steel brake lines that give plenty of slack for rear suspension.



Final Result

This is the image of new rear suspension components installed, undercarriage cleaned out from rust and rot, and new fasteners in place.

 

Torque Chart

Additional Safety Measures

In addition to tightening the fasteners to specified torque specs, I added several safety measures to prevent them from loosening.

• blue loctite
• lock washer
• lock nut
• cotter pin

I also applied Torque Tamper Detection Marker to each of the fasteners. This way I can routinely check nuts and bolts by visually inspecting them.


This is a list of all the fasteners, along with manual page numbers, and torque values. Socket size may be slightly off, since most of the parts that I installed were aftermarket parts.

 

Dude you're awesome for documenting all of this. I will definitely need and use some of this info in the near future.

 

Regarding drilling a hole to reach the rear bolt on the front shock install, you probably are more willing to drill a hole than many. I just did my Bilsten 8112/5160 install and I had to hand-torque the 3rd bolt with a 14mm wrench by hand. The torque specs are, 52 ft/lbs. How I approached that last bolt was, I made sure to pay attention to how much effort it took me to unbolt it with the same wrench by hand (the only way to do it). Then I test-bolted it, and unbolted it again to see if I was in the ballpark, and I was. So, I wound up hand-torquing them, and now I'm keeping an eye on them to see if they'll losen up. If they will, I'll need to have a more creative way, maybe adding a lock-nut on top of the existing nut for safety, it would fit perfectly fine.

I'm surprised that Toyota didn't bother to give us room, in this car they're very thoughtful about allowing modifications on the car, except for this bolt apparently.

The same problem exists in the rear shock upper nut install, there's literally no room for anything other than a wrench.

I plan to buy a torque wrench adapter set and that'll probably allow to torque them with ease. You'd need to calculate equivalent torque difference with extensions:
https://belknaptools.com/extensions-calculator/