4x4 Action Group

KurtG wrote:It would be interesting to weigh yours, Henri, just before you depart for a trip like NKZN.

Not disputing all the other comments of pendulum action etc. which caused the failure but as you said the caravan’s balance is probably out of spec for most of the tow bars made in SA.

Also, your tow bar doesn’t look like the one I had on both my Pajero’s which in my useless opinion is a stronger design to yours.

It probably went wrong in the beginning when I had the dealership supply a Mitsu approved towbar.

I never inspected it before fitment, because, it was, after all, Mitsu approved......

If insurance pays out I will make sure she is VERY STRONG!

KurtG wrote:It would be interesting to weigh yours, Henri, just before you depart for a trip like NKZN.

Not disputing all the other comments of pendulum action etc. which caused the failure but as you said the caravan’s balance is probably out of spec for most of the tow bars made in SA.

Also, your tow bar doesn’t look like the one I had on both my Pajero’s which in my useless opinion is a stronger design to yours.

To take some nose weight off I always try to travel with a full water tank. The tank sits behind the axle and takes 90 litres.

Then I pack as much heavy stuff like solar panels tables tent bits and pieces on the bed or under the bed.

To weigh, well most domestic scales only go to 120kg. I think. I need to go look.

Bottom line is not much more can be done other than use on moerse strong towbar.

Seen many Pajeros towing Xplorers so never thought of having a problem.

Always a first time....

BushWacker wrote:... the tow-bar is at the end
of a long-necked beam from the chassis
and there is a consequently too big a moment
imho ... ( in my humble opinion ... )

Hows this one Chaz!

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Strange that it broke before the weld. Is that an area where the heat of the weld caused the metal hardness to change? It broke because of metal fatigue caused by the flexing of the long extended arm. But I don't know much about these things.......

HenriSteyn wrote:Hows this one Chaz!

Depends on the quality of the welding

Chris Stoffel wrote:Strange that it broke before the weld. Is that an area where the heat of the weld caused the metal hardness to change? It broke because of metal fatigue caused by the flexing of the long extended arm. But I don't know much about these things.......

If you applied an aftermarket lubricant to the metal resulting in the said lubricant penetrating the metal, it may have resulted in no failure. I think.

The gusset shouldn't have been in the middle of the tube as that is the weakest area for stress flexing. Two gusset plates, one on either side will be much stronger and have a dual path for the stress/loads to travel. That is definitely not a heavy duty design.

Chris Stoffel wrote:Strange that it broke before the weld. Is that an area where the heat of the weld caused the metal hardness to change? It broke because of metal fatigue caused by the flexing of the long extended arm. But I don't know much about these things.......

Looks like it had fatigued over a period as there was rust on the weld around the gusset. The final straw is the clean metal tear.

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HenriSteyn wrote: ↑

Thu May 06, 2021 9:45 pm

BushWacker wrote:... the tow-bar is at the end
of a long-necked beam from the chassis
and there is a consequently too big a moment
imho ... ( in my humble opinion ... )

Hows this one Chaz!

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One cannot just go and bolt on extensions to a tow bar. That is looking for trouble. Everything must be strengthened on that tow bar.
It is like fitting a 1800cc Toyota engine into a 1300 Samurai. From the gearbox to the rear wheels everything is compromised.

This is a Towbar rated to tow 3.5t with a vertical load of 150kg. It mounts to the chassis with 6 m12 and 4 m16 bolts. The plate is 10mm thickness. You will also see there are no sharp corners in the design to prevent stress raisers.
It's a pity you can't fit something similar to your vehicle Henri.

HenriSteyn wrote: ↑

Thu May 06, 2021 9:45 pm

BushWacker wrote:... the tow-bar is at the end
of a long-necked beam from the chassis
and there is a consequently too big a moment
imho ... ( in my humble opinion ... )

Hows this one Chaz!

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Chief Engineer of Bosal, lives next door to me,
... said something to effect that in case of caravan/trailer
towed over, say speed bump etc , at any excessive speed
has to sustain huge ' whip lash' type forces as vehicle tow ball jerks down as momentum of trailer hitch is nosing up etc ...

It does this 3 times per speed bump!

Chaz please go speak with your neighbor.

I want a Bosal replacement tow bar!

HenriSteyn wrote: ↑

Thu May 06, 2021 7:35 pm

This picture shows the crap design. Absolutely no strength behind the square tubing. Those 2 gussets at 45 degrees do absolutely nothing.

Is that a factory towbar?

It’s not that the gusset does nothing in that position , it actually makes it more susceptible to cracking .

If it wasn’t there at all , it wouldn’t have broken.

Properly positioned it would have made it stronger .

... long knecked towbar also considerably compromises
departure angle ... and I would venture that
it has probably previously experienced
a few hefty grazing cracks & bangs ?
Was it Archimedes who said:
' ... give me a lever & I will move the world ... ' ?

BushWacker wrote:... long knecked towbar also considerably compromises
departure angle ... and I would venture that
it has probably previously experienced
a few hefty grazing cracks & bangs ?
Was it Archimedes who said:
' ... give me a lever & I will move the world ... ' ?

Makes me think of my swottings.
Lasarm en kragarm

There must be serious forces added with the length of that towbar.

Think an aftermarket rear bumper will be the best solution.

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