Loose tow hitch; how to fix the rattle
We’ve had our Isuzu Dmax for nearly 6 years now, and its done fairly well. If you read through our Common Dmax problems post you’ll see that its not been trouble free, and I’ve made a point of noting down every significant issue we’ve had, and how its played out for us.
One thing I haven’t mentioned though, is the loose tow hitch, and its only been recently that I’ve ‘resolved’ it. We have a factory tow bar, tow hitch and are running a DO35 hitch, which we love.
However, right from the get go I noticed that the tow hitch and receiver didn’t mate together very well, and were actually quite sloppy.
Asides from a bit of extra noise when you’d stop, or take off, or on slow but quiet off-road tracks you never really noticed, but it was still a bug bear of mine. However, a few months into using it for towing and I started to notice that the actual tow bar was getting damaged due to the loose tow hitch, and I was pretty annoyed about it.
The hitch was not only loose in the up and down orientation, but in the left to right and also the in and out, which meant every time the hitch moved it was causing wear. I could see that the hole in the tow bar where the hitch pin goes through was starting to get mushroomed over, and was no longer the round shape it should be, and was quickly becoming an oval.
I never raised it with Isuzu, but the fact that it was wearing and making the problem even worse was pretty poor, in my opinion.
Why not use the anti rattle bolt?
Now, I can already hear some of you; why not tighten the anti rattle bolt? If you don’t know what this is, most tow bars have a nut welded onto the bottom (or sometimes the side) of the tow bar, which allows you to screw a bolt in, which pushes the tow hitch across and locks it in place.
It’s called an anti rattle bolt as it stops the hitch from rattling when you are driving around, and its fantastic, except for two things. The first, is that its actually ‘illegal’ to drive around with a tow hitch in if you aren’t towing anything. I’ve never seen this policed, but it is a thing.
The second, and more prevalent fact is that anti rattle bolts are meant to be used when you aren’t towing, and that is it. The moment you are towing, you should be undoing the anti rattle bolt (according to the owners manual), and allowing it to rattle around. Strange, right?
Yep, except that there is some merit to it; leaving it in place will eventually end up with the bolt, or the nut thread damaged, and then its completely useless to everyone. You can’t put 300kg of tow ball weight onto a little M8 thread and expect it to maintain good health. Something is going to break, or strip.
Fixing the loose tow hitch
So, you’ve got a hitch that’s loose, and you want to fix it. I’ve seen all sorts of ways of doing this over the years, with some being pretty good, and others being, well, lets just say rather backyard.
Weld and grind
A lot of people will take a tow hitch, and weld a few runs down the length of it, wherever its loose. If its loose up and down, you do it on the top. From there, it’s a matter of just grinding the weld down until it fits snugly, and bobs your uncle.
I’ve also seen people do the same thing to their tow bar. Both ways work, but I’m not going to recommend either, as welding creates a lot of heat, and that’s not always good for things that are designed to take heavy loads, outside of the OEM build process.
Shims
Toyota actually sell shims to take the play out of a tow hitch, and you just slide them in and choose the right thicknesses that will keep it snug, and not flopping around in the breeze.
This makes a lot more sense, as its removable, doesn’t weaken or alter anything and is easy to do for anyone.
A lot of trailer shops, and auto places also sell these generic kits, which can work quite well. Of course, you can also DIY; see below.
Anti rattle fixture
You can actually buy fixtures that you bolt onto your hitch, which comprise of a plate, U bolt and two nylock nuts. These force the two parts together, and take the rattle out, and work quite well.
How did we fix it?
On a quiet afternoon at Walkers Rock, I walked past my tow hitch and decided I’d had enough of it flopping around. I could hear it thump when we pulled up to a stop, and the hitch and trailer slide forward another 2mm, and then crack as you took off again, and the mushrooming was getting worse.
With a fairly comprehensive bush mechanic fix-it kit, I dug through the treasure chest to see what I could use as shims. I came across a roll of building strapping, roughly 30mm wide, and 1.5mm thick, and wondered if that would fit in nice and snug.
After a couple of cuts and trials, I found I could make a full U shape, and as long as it was tight around the tow hitch it would work really well. After one attempt that still left a bit of rocking (as the outer end was tight but the inner was loose, I succumbed to making two of these up, and carefully knocking them in with the hitch.
This is locked in place by a lockable tow hitch, and rarely comes out anyway, so its not a major concern. It’s tight enough to not rock anymore in any direction, and the pieces used are big enough that they can’t physically come out without the hitch coming out, so I’m happy.
Given they are steel (and I’ve since proven this), it can’t deform too much, and the slop is completely gone. This means my tow bar won’t need replacing in another 100,000km because the holes flogged out, and the noise is gone.
In my mind it’s a bit of a shortcoming on Isuzu’s behalf, but its fixed now and its one less thing to annoy me!
If you’ve got a loose tow hitch, consider getting some ‘shims’ and fixing it!
