Thread: Murphy's Law, catastrophic failure in a very bad place

I wonder what action would be taken if the electronics detected overheating - put the engine into limp mode (the usual action) or not be so pedantic about making the ride so good by increasing the oil flow through the soft valve? I've already established that I can set a user-selectable minimum open time (eg 20%, 40%) for the bypass valve that has the potential to reduce heat build-up in such circumstances.

Originally Posted by Graeme

I wonder what action would be taken if the electronics detected overheating - put the engine into limp mode (the usual action) or not be so pedantic about making the ride so good by increasing the oil flow through the soft valve? I've already established that I can set a user-selectable minimum open time (eg 20%, 40%) for the bypass valve that has the potential to reduce heat build-up in such circumstances.

Bleeds only work at low shaft speeds and the overheating will be caused by medium/high shaft speeds and high displacements. (depending on bleed size)

So less soft valve open time could be an improvement on the basis that not all the oil can get though the firm valve before its time to change direction. I expected more heat to be generated by the higher volume of high pressure oil but if less total volume passes through then I can see the possibility of a reduction in heat generated.

The RR is advertised as one of the best if not the best off road passenger vehicle in the world. However I believe that people confuse this to mean that they are the best remote area tourer.
Being able to cross ruts with ease and go up and down the steepest of hills without breaking a sweat is not the same thing as being able to traverse 1000kms of corrugations in the middle of nowhere and be able to be fixed with fencing wire.
Generally driving in the outback doesn't require a 4wd. It just requires a tough simple vehicle and enough available time for you to drive to the prevailing conditions.

This is not directed at the OP. Just my observations of what appears to be a common misconception.

Originally Posted by Graeme

So less soft valve open time could be an improvement on the basis that not all the oil can get though the firm valve before its time to change direction. I expected more heat to be generated by the higher volume of high pressure oil but if less total volume passes through then I can see the possibility of a reduction in heat generated.

You miss how the flow works.

At low shaft speeds the fluid has the time to flow through the low speed valving, in most dampers this is a simple orifice, hence the term 'bleed' as that's precisely what happens with the fluid.

In very simple terms, as the shaft speed rises the fluid can't continue to flow through the bleed fast enough to balance the forces and so packs up in front of the piston (or foot valve in a twin tube when in bump) and then starts to force open the stack, shim or poppet valve.

You won't reduce heat buildup by playing with the valving, and most valving adjustments usually only work on the bleed as low shaft speeds is where most 'comfort' is felt. (low shaft speeds can be thought of as body roll, pitch and squat)


IMO if we could reduce the valving on the main stack it will only lead to more uncontrolled movement (both the chassis and unsprung mass) which means greater displacement and shaft speeds that the damper is experiencing which leads to more heat generated, and on it goes.
You generate the damping equivalent of a thermal runaway.

Originally Posted by isuzurover

True, but some shocks are built better than others. Some on here have overheated bilsteins so badly that the paint cooks off, yet they keep working...

Not that they are immune from failure though:
Bilstein Fail

True , I have a set of Bilseins on the '56 S1 that I burnt brown on a fully loaded trip to Dalhousie about 20 years ago. They are still fitted and working today.
Terry

Just received notification that not only has LRA picked up the tab for our expensive recovery, they're sending me a cheque (more than $4,000) to reimburse us for out-of-pocket expenses (charter flight, accommodation etc) we incurred after the shockie failure. (Or rather, as the experts in this thread have gently identified, driver failure:-)
Can't imagine another manufacturer ever going to those lengths.

If LRA don't use me in their marketing, they'd be mad. I'd willingly shout their praises from the rooftops.

Running 7100 Billies on the D2. We past the grader about 15km north of Drysdale (he was heading north so the road was as bad as it was going to get) and managed the whole way to the Mitchell falls camp ground in 3hrs.

For those that have just come back from there will know how hard we went.

Shocks were only warm to touch.

My only failure was I popped a fog/indicator out of the rear bar when I went bush turning around to go and help a mate change a cooper tyre he blew. A stick poked up and just popped it out. It was still hanging from the wires but I lost the metal clip so I couldn't refit it.

Happy Days.