If you own a 4Runner, chances are it came with a trailer hitch installed at the factory. But if you have a V6, the factory hitch is not suitable for use with a Weight Distributing Hitch, which you will want to have if you're towing regularly. So many owners upgrade by mounting a new trailer hitch which is compatible with a Weight Distributing Hitch (WDH) system, such as the Curt 13445 or Hidden Hitch 70779.
Below are my lessons learned in installing my own hitch, which may be useful for anyone else upgrading or simply installing their first hitch onto the 4Runner.
Get the hitch. I ordered from eTrailer and it arrived quickly, in good shape, with free shipping. I went with the Curt 13445 because the install looked slightly simpler (the Hidden Hitch requires you to trim some tabs on your bumper cover). Overall the price I paid ended up being over $100 less than the same hitch installed at U-Haul. A professional installer will be faster for sure, but the cost savings were worth it to me.
You need a torque wrench. I ordered the Pro Quality 3/8 Torque Wrench from Amazon, and it served me well. Or, if you know somone that might have one, just borrow it for the day. For the Curt I only needed to create 65 ft-lbs of torque (780 inch-lbs), so a heavy-duty one was not required. Torque wrenches can also be rented from equipment rental places, but for the cost of the one on Amazon I chose instead to add it to my toolbox.
Other tools: you'll need some WD-40, the right size socket to torque the bolts with, and a wire pipe cleaner. Get these things in advance if you don't already have them.
If you have a factory installed hitch that you are removing, you'll need to remove the bumper. There are some bolts accessible without, but there are four bolts holding the factory hitch to the frame that need to be removed are are not accessible any other way. See my write up on how to remove the rear bumper cover on the 4Runner for my experiences with that part of the project.
Remove the tow cable hook. For this you'll need to generate a lot of torque, as the factory tends to put this on particularly tight. However, with the mechanical advantage from the torque wrench, I was able to remove them without
too much trouble. If you're stuck, get a breaker bar at your local hardware store, or just use a bit of old metal pipe to extend the length of the handle on your wrench (which increases the mechanical advantage and torque).
Remove the bracket for the 9 way connector. This depends on the hitch you're installing, but I think most will require it. Without this, the cable will just kind of hang down-- probably not the most secure, but not a pressing need either. You can get replacement mounts online or a place like U-Haul, or just rig up your own solution. You may need to extend your cable, these parts can also be found online.
Lower the exhaust. I read some accounts of people not having to lower their exhaust, but after wasting an hour or more trying this, I went ahead and lowered the exhaust in a matter of minutes. It was a lot easier than I had anticipated, and immensely helpful. To do this, just lube up the rubber hanger with WD-40. The instructions for the hitch made reference to some way to use a crowbar to remove it, but I found nothing to leverage it against. In the end, with enough WD-40, I was able to just kind of shove it off the hanger using the blunt end of a screwdriver. There is a cone-shaped end on one of the hangers, so you need to get the rubber hanger over that-- but rest assured it will fit over and can be slid back on when you're done. Note, I had prepared to support and suspend the exhaust if it sagged enough once lowered, but as it turned out the exhaust didn't need it. When lowered it was firm enough to suspend its own weight, but the three or four inches it lowered made all the difference in accessing the rear weldnuts in the frame.
Prep the smaller sockets by removing rust and corrosion. I wasted some time before doing this, and it's as if the bolts are simply too small to fit. If it feels like you're forcing it, you should clean a little more. Of course you need it tight, but not so tight that you're worried the bolt might break. So to clean them, just lube it up with WD-40, wait a minute, then scrub it out with a wire pipe cleaner. Even without a pipe cleaner, the WD-40 will help. Then thread the bolt to get it started, and see if you can get it in a bit of the way. If not, remove the bolt and try again.
Now you're ready to mount the hitch receiver. The hitch will be heavy, so you'll need a way to suspend it up against the frame of the vehicle. I propped up the driver side of the hitch with an old toolbox which got it close to the frame, then held up the passenger side myself as I attached the first bolt.
Thread all bolts before tightening any of them! I learned this lesson the hard way, as the last bolt would not go on because the hitch was not perfectly aligned with the remaining weldnut. If I had simply threaded all the bolts first, there would be more wiggle room to slide it around. in the end, I was able to get it aligned by loosening the bolts so that the washers could spin freely, and then taking a long clamp in between the hitch and the frame (or spare tire) to move it in the direction I needed. The clamp did a good job moving the hitch just enough to start the last bolt.
Tighten to the hitch manufacturer's instructions. In the case of the Curt, I went to 65 foot-lbs on the larger bolts. With the torque wrench, it just clicks and gives a bit when it reaches the right amount of tension so I knew I was there. It required most of my weight on the wrench to get to that amount, but it was not all the way-- I felt I could've applied more torque if needed, but take comfort in knowing that the bolt is to spec and that I haven't over-torqued which might risk breaking the bolt-head off.
Once torqued, you're almost done. Just reattach the bumper if you haven't already. One suggestion here, is that you might consider reattaching the bumper cover before installing the hitch itself. I waited until after the new hitch was installed, and that resulted in making some of the bumper bolts hard to access since the new hitch is in the way.
from Amazon, and it served me well. Or, if you know somone that might have one, just borrow it for the day. For the Curt I only needed to create 65 ft-lbs of torque (780 inch-lbs), so a heavy-duty one was not required. Torque wrenches can also be rented from equipment rental places, but for the cost of the one on Amazon I chose instead to add it to my toolbox.