Tow Bar bolts

[Muzz On Line]

Thanks OT

I always appreciate your input.

When I see the nuts and bolts place, they should be able to determine if the holes are out of round.  Could look at next size bolt and have the hole drilled accordingly if they are too far gone for there current original size.  I do have "free" access to a heavy engineering company but I have to travel to get to them.

The whiteout suggestion is certainly worth doing, buy I think I will use a lick of white enamel on the gloss black as it will last a bit longer.  I have used whiteout on some other nuts but the pressure cleaner took it off in no time.

Cheers

[Old Techo]

Jul 6, 2019 19:19:21 GMT 10 Muzz On Line said:

When I see the nuts and bolts place, they should be able to determine if the holes are out of round.  Could look at next size bolt and have the hole drilled accordingly if they are too far gone for there current original size.

Muzz,

I was only thinking about bolt thread damage.  If there is a bit of wear in the holes I wouldn't be too worried.  Those bolts are only in shear load and if correctly torqued the 2 metal plates are clamped together entirely by friction so a bit of hole slack won't matter - except when loose.

[Muzz On Line]

I agree, the clunking I am experiencing at the moment does not happen everytime I take off or accelerate.  I can take off slowly without a single noise or clunk.  Take off hard and yes it is there.

I think I will be lucky as I have caught it early.

When I was in Tassie and until I had tightened the bolts, I basically heard it at the bottom of every hill because the bright road engineers down there have put a 30 kph hairpin bend at the bottom of every hill and just after every 100 kph sign.

To quote you - The Bar Stewards

[KeithB]

Muzz, maybe replace the bolts with a finer thread and fit with anti-vibration washers (much better than spring washers), Nyloc nuts and Loctite. There will be a table on the net somewhere to give you the correct torque.

You can order the anti-vibration washers and other gear over the phone from the Newcastle Hi Tensile bolt company. You can also get things called Conelock nuts which have a distorted thread and will never come loose; but I found them too hard to do up.

Keith

[Old Techo]

Keith,

Do you think it is a vibration issue rather than just constant flexing?

My Prado towbar bolts use that type of washer but they are not in shear, only tension.

[KeithB]

Old Techo, I don't think a joint can flex if it's torqued up tight enough, or can it?  Things can come loose whether the bolts are loaded in shear or tension. With the exception of bolts through suspension bushes, the clamping force supplied by the bolts should mean that there is no shear loading on the bolts themselves as the joint should be held fast by friction.

On my crappy Chinese camper trailer, we had all the suspension bolted on with spring washers and Nyloc nuts ex factory. That's the bolts through the trailing arm bushes and the ones that held the removable stub axles on.  After a week on outback roads and a run over the Simpson, most of them came loose and one trailing arm bolt actually fell out.

They were 12mm metric coarse threads and a bit of Loctite and some new nuts fixed the problem. I am guessing that the level of vibration transmitted to the towbar would be no less severe.

I notice that all of the threads on my Landcruiser are much finer and locking agents are not necessary. But coarse metric threads seem to need a bit of  a hand. Out on a remote road is the last place you want anything to come loose. So I reckon that overkill is definitely in order. Every suspension bolt and coupling bolt on my build has anti-vibration washers and Loctite. But I'll still put an indicator stripe on them just in case and do regular inspections.

On many critical applications the vehicle manufacturers don't trust threads either and put through-wires, tabs washers or pins on them to guarantee no movement. A thread locking agent is also called for in a lot of locations. The guys at Coventry Fasteners told me that the off road racers use anti-vibration washers, conelock nuts and Loctite in the suspension to keep body and soul together.

So I like to go over the top to avoid losing my nuts.

Keith

[loub]

I have the same bar as muzz and check but never been able to move them,been to tassie as well.I wunder if mine has lock tight on it or some other type

[KeithB]

Loctite, Araldite and Sikaflex made a tradesman out of me.
Keith

[Mick Themungrel]

Keith, I would take a lot of notice of the guys at Coventry, I dealt with them a lot in a past life in Adelaide and they do know their stuff.

[Muzz On Line]

Hi Loub,

My caravan weighs in at 3100 kgs.  How does that compare to yours?

The weight could be the difference, then again my tow bar may have been originally fitted on a Monday morning or a Friday afternoon.

[Scotty]

Muzz I've got the same towbar and tow approx 3000kg and have been on some real nasty roads and have never had an issue with the bolts coming loose.

[loub]

Hi muzz We tow at 2.5 ton,so a bit lighter then you but i am going to have a closer look to see if there is anything that stands out

[Muzz On Line]

Thanks for the replies fellas.

Maybe my tow bar was originally fitted on a Monday morning or a Friday afternoon.

Anyway it is a good thing that we have got people checking their tow bars.

The alternative may have been being overtaken by your own van.

[collyn]

As Kieth says, use one of the thread filling compounds (like Loctite) made for this very purpose. They preclude the sideways movement that causes screwed fastenings to unwind. It works with jack-hammers!!

That clunk can also be caused by movement in that absurd horizontal pin used to locate the tow hitch into it's receiver. Replace it by a tight fitting nut and bolt.


Collyn

[Muzz On Line]

Thanks everyone for the advice,  I will definitely find a nuts and bolts place nearby and replace the nuts and bolts before my next trip.  I have recently purchased a torque wrench and will set them (the new nuts and bolts) as advised by the experts, with the appropriate thread glue ( for lack of a better term), using the appropriate washers and nuts.

 Cheers