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Cleaning Weld Nuts for Trailer Hitch Installation

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Demonstration of Removing Corrosion

Okay as you can see here on the drivers side, our weld nut has a lot of corrosion built up in there. And when we try to install our 10 millimeter bolt is not wanting to start at all, in fact it almost seems like the bolt is too big for the weld nut. It is a common misconception, again when the weld nuts got a lot of build up in there.

To go ahead and clean that out we are going to use a spray lubricant like a WD-40. Go ahead and soak that up, let it sit for a second. Then you can take a wire brush, I am actually using the top of a battery terminal cleaner here. And just run that in there a few times, what that is going to do is help loosen up all that debris and road grim that is in there. Then repeat that process a few times until you have that all nice and loosened up. Then you can go ahead and take our bolt now, we just need to get it started, see I just got the thread started there now, and just take our ratchet and run it in and out a few times. That will help further clean it out. That is going to make our installation much easier.

Erik P.


I’m trying to do this on a 2006 Toyota Sienna. And, it’s not cleaning up very well. What do I do? Drill and tap it? I would think that would lessen the strength of the weld nut. I am considering dropping down from the existing 10.9 grade M12 - 1.25 to a 12.9 grade M11 - 1.5 bolt. I’m hoping the smaller bolt will slide up into the existing nut and I can just crank another nut down on top of the existing weld nut. The strength is slightly less, unfortunately. How bad and/or dangerous of a cob job does that sound like to you?

David B.


Just hit it with a tap, if you use a smaller bolt you're floating into dangerous waters. Just chase the threads, if you use a smaller bolt the threads won't be biting into metal they will be hitting build up and corrosion and once any real pressure is on them it will fail and strip out.

Erik P.


@DavidB Thanks! So use the same size tap as the current bolt size of M12- 1.25? Or go bigger for fresh metal?

David B.


You need to use the M12X1.25mm tap. If you use a larger tap you will be in the same boat and not have enough material for the bolt to hold onto and it will be unsafe.

Bill S.


Very helpful. Wish that I saw this earlier in process. Excellent description- I thought bolts were wrong size, tried long enough to get them started, but could only get them halfway in….then did an internet search and found this which solved it. Thank you! I wasn’t sure what I was going to do

David B.


Glad it helped Bill!

David L.


Very helpfull on cleaning rusted nuts. You .might also include tapping as a last resort.

Ken P.


I should have looked at this before I started installation. A great tip and I will know to look here first.

Info for this part was:

Employee Zack K
Video Edited:
Zack K
Employee Joshua S
Video Edited:
Joshua S
Employee Matthew S
Installed by:
Matthew S

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