Broken front torsion bar mount in OZ, anyone heard of this?
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Busted Torsion Bar Mount
Excellent photograph clearly showing the root cause of failure.
All these parts are highly stressed when in 'rough' driving conditions. Highly stressed cast steel and rolled steel are both weakened by pitting type corrosion (rust). What might appear to be insignificant in terms of metal loss, a pit can greatly increase the local stress to the point a crack begins and then propagates through the balance of the part that is not tough enough for the service. (toughness being a measure of high stress ductility--the ability to yield but not brittle fracture like that part did)
The photo shows a lot of rust under all the suspension fittings and fasteners,which is NOT good. I suggest you disassemble all the parts, clean up all the surfaces with a wire brush, then spray with a zinc rich cold galvanizing paint, then reassemble. replace any bolts that have pitting deep enough to catch a pencil point.
Excellent photograph clearly showing the root cause of failure.
All these parts are highly stressed when in 'rough' driving conditions. Highly stressed cast steel and rolled steel are both weakened by pitting type corrosion (rust). What might appear to be insignificant in terms of metal loss, a pit can greatly increase the local stress to the point a crack begins and then propagates through the balance of the part that is not tough enough for the service. (toughness being a measure of high stress ductility--the ability to yield but not brittle fracture like that part did)
The photo shows a lot of rust under all the suspension fittings and fasteners,which is NOT good. I suggest you disassemble all the parts, clean up all the surfaces with a wire brush, then spray with a zinc rich cold galvanizing paint, then reassemble. replace any bolts that have pitting deep enough to catch a pencil point.
Follow-up-- I owned several '126' series MBZ sedans--and the front 'torsion bar' was also the 'strut rod' to which the front top control arm attached, controlling the fore-aft movement as the inboard rubber bushing was huge and would not restrain fore-aft movement at all. That torsion arm developed pitting corrosion under the rubber bushings where it attached to the control arm. I found myself measuring and estimating the amount of good metal remaining and calculating its loading capacity remaining (R&R of the torsion bar was a 22 hour book time job!) I suddenly realized the stupidity of my approach--loss of that attachment in a sharp turn (when it would be most stressed) could easily cause loss of directional control--leading to an unplanned exit from the top of a freeway interchange followed shortly by an abrupt stop as the car (and occupants) impacted the ground maybe some 80 feet below. On this realization, I went inside and drank a 6 pack , accepting the fact the corroded torsion bar had to be replaced. When in doubt, change it out is my firm mantra now with ANY component that is needed to steer, brake, or otherwise control the direction and location of the vehicle. Not quite to aircraft standards, because failure to 'go' is not life threatening like in airplanes. (Landings are mandatory, take-offs are OPTIONAL)
Torsion bar mount all fixed.
Thanks all for your replies. (from the owner)
The jury is probably still out on the root cause of this problem. However, the group consensus, and I'm speaking experts in this field, that amongst them, have litterally converted thousands of LC100 IFS. They agree that the bolt (as per in the photo) was more than likely loose exacerbating the problem. In addition, when I had the torsion bar mount replaced, the front control arm LHS was also replaced due to severe cracking and twisting of metal. This was un-expected news, as well as cost, and was not discovered until the car was on the hoist and covers were taken off exposing said problem. At a later stage with the vehicle on the hoist again, the mechanic and myself spent over an hour with LED lights and mirrors into hard to see spots checking all other vital components, hoses and pipes for possible gremlins that may be awaiting me. Good news is that the underside of the vehicle appeared okay which makes me feel better.
So what next; the car is booked in for a much needed upgrade to the suspension. (currently the suspensiion stuff on there is about 120,000 kilometres, so best to start on a fresh clean slate). Surprisingly my wife has not objected to spending these additional funds.
I'll be looking at Bilsteins long travel with specific valving and stone shields, Ridepro torsion bars and Ridepro springs on rear, new Toyota/Lexus bushes and a Slee off-road Diff drop X member + the all important strengthening mod, stitch welding a bracket to the lower front control arms.
All of this will not be happening until 21st December, which is when the car is booked in.
The aim of this is to transform this cruiser into a very capable heavy duty touring vehicle, ready for those huge around Australia expeditions.
I'll post another report in the New Year on the mods and will also do a before and after measurements of the height difference front and rear.
cheers all
Kym
Thanks all for your replies. (from the owner)
The jury is probably still out on the root cause of this problem. However, the group consensus, and I'm speaking experts in this field, that amongst them, have litterally converted thousands of LC100 IFS. They agree that the bolt (as per in the photo) was more than likely loose exacerbating the problem. In addition, when I had the torsion bar mount replaced, the front control arm LHS was also replaced due to severe cracking and twisting of metal. This was un-expected news, as well as cost, and was not discovered until the car was on the hoist and covers were taken off exposing said problem. At a later stage with the vehicle on the hoist again, the mechanic and myself spent over an hour with LED lights and mirrors into hard to see spots checking all other vital components, hoses and pipes for possible gremlins that may be awaiting me. Good news is that the underside of the vehicle appeared okay which makes me feel better.
So what next; the car is booked in for a much needed upgrade to the suspension. (currently the suspensiion stuff on there is about 120,000 kilometres, so best to start on a fresh clean slate). Surprisingly my wife has not objected to spending these additional funds.
I'll be looking at Bilsteins long travel with specific valving and stone shields, Ridepro torsion bars and Ridepro springs on rear, new Toyota/Lexus bushes and a Slee off-road Diff drop X member + the all important strengthening mod, stitch welding a bracket to the lower front control arms.
All of this will not be happening until 21st December, which is when the car is booked in.
The aim of this is to transform this cruiser into a very capable heavy duty touring vehicle, ready for those huge around Australia expeditions.
I'll post another report in the New Year on the mods and will also do a before and after measurements of the height difference front and rear.
cheers all
Kym
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