I have a 2004 4.0 Sport. The vehicle is equipped with the stock hitch and 7 terminal wiring. My question is whether or not I should upgrade the hitch to a frame mount style. The boat and trailer is well under the max of 5,000 lbs, coming in at 2,225lbs. I have not been able to find a tongue weight yet but would estimate 150-165lbs.

My only real concern is that the stock hitch and rear frame section do have some rust. I have been descaling the entire frame and treating it section by section.

I imagine tapping the holes and mounting the frame mount hitch will surely have it's headaches with a vehicle this age from New England. But, at the end of the day if its going to be much safer I will definitely do it. Am I being paranoid or should I upgrade? Thanks in advance.

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If it were me, I'd go with the bigger hitch.

Is it overkill for the boat? Absolutely.

Will it be safer and is it worth doing? Absolutely.

My $0.02, I'd rather have the bigger hitch because There's no telling what I'll end up towing. Most of the time it's a small 5x10.utility trailer, but I've pulled some pretty big stuff previously and it was nice not having to worry if the hitch would be sufficient.

Ignoring the rust for a moment, I would trust the factory hitch receiver over anything else up to and including the limits of rated tow capacity. Taking the rust into consideration, it's a judgment call. If you have any reason to believe the receiver is compromised you are better off replacing it. I can't really advise beyond that without looking at it myself.

On another note; if the total trailer weight is 2,225# and your tongue weight is only ~165# the trailer is going to sway like hell and be extremely unstable. Tongue weight should be no less then 10% of the trailer weight, with a target of ~15%. Generally heavier is better as long as you don't exceed the maximum rating of the hitch and receiver. It's usually pretty hard to adjust tongue weight on a boat trailer because the load is "fixed", but they are usually designed to have the appropriate weight distribution. If the tongue weight is significantly low it's a sign the boat isn't loaded properly. If it's close, but you wan't to improve it a little you can add a cooler, or some other boat-y type accessories to the bow.

A trailer with poor weight distribution is, at best, a chore to drive and, at worst extremely dangerous.

I have driven the trailer before with a Cadillac Escalade and its fine. I do not know the actual tongue weight. I took a calculation from a website online that used 7% of the total weight. I did not come up with that formula but saw 5%-10% for single axle trailers listed on multiple sites. I may try the bathroom scale method mentioned on E-trailer to calculate the actual tongue weight when I get a chance.

I do not think the hitch it compromised beyond safe using. I'm just more of a better safe than sorry type person. I have been an ASE cert. tech for 16 years and am definitely capable of the work. It was more of a "is this really worth it" type things.

My opinion, if the stock hitch seems solid it's probably not worth replacing.

I have an 05 v6 as well and have use the stock hitch to tow a 6x12 uhaul trailer about 300mi without issue. Mine was kind of rusty when I first got it, but I have since wire wheeled it and shot some spray paint on there to slow it down. I have no idea how much it weighed, had everything for a 1 bedroom apartment in it, including couch, table, desk, etc. My guess was maybe 4,000lbs ish?

Another note: Not sure how the torque converter would behave with that weight of trailer, but I towed all of my trip with it capped in 4th gear to lower the possibility of the torque converter clutch staying unlocked for a long time and overheating your transmission. If you're not sure with how torque converter lockup works, check out some youtube videos. Without the trailer, if you make a few 3-4k rpm accelerations then let off the pedal smoothly around 50mph, you should be able to tell the difference in the transmission downshifting once or twice and the torque converter clutch locking up at the end. You can feel the unlock while going smoothly at 45mph, press the gas to accelerate and watch tach. rpms will probably go from around 1.5k to 2.5kish without your speed changing. Its kind of hard to describe how the lockup and unlock feels, but its a good thing to keep and eye on this while towing. If you already knew this, then that's awesome! Hopefully others will also stumble upon this and find it helpful

Definitely good advice. I'll be installing a hayden trans cooler (I already bought) before I start towing this summer. I also plan on gettong a gauge for the trans temp.

This thread pushed me to pull my rear bumper cover off and look at the frame as I do use my truck to pull things. After a bunch of hours scaling, cleaning, cutting and welding it is now in better shape than it was. You can see some pics in the thread below.

Who had their 4runner frame replaced?

Looks great. I need to pull my bumper too. I've poked and tapped with a hanmer to descale everything I can get at. Rear seems pretty solid. I did have to weld in a section uo front by the radiator support and body mount.

Thanks. It seems odd how they rust differently, my nose sections are fine. I had a hole just under where the drivers door is, up where the rear tank strap attaches to the frame and one of the frame brackets a rear control arm attaches to. I'm just amazed at how much dirt I have removed from the inside of the frame in all locations. Maybe the prior owner lived on a dirt road.

It is weird! Mine has weird patterns of rust on different sides of the vehicle too. Usually the passenger side of vehicles are worse off... my theory being the road salt accumulates on the right side of the road due to road crown. In keeping with that train of thought the salty water travels to the passenger side as well. But, this vehicle has some on the front right and some on the back left.

I really don't want to pull my rear bumper off to look. But the curiosity is killing me.

Yeah, usually the ditch side is worse but not on my truck. On the bumper cover, it is pretty easy to get off, I had mine off in 15 mins. Gotta be careful to not break the bolts under the hatch and the plastic upper retainer clips on the side but the rest was easy. Only clips and screw type fasteners besides those.