The introduction of the advice in the IM regarding the EXTREME END will not or should not make a great deal of difference with the way we look at coil springs and make a decision on there condition,but we will be pass/advising a few more that's for sure as for a long time now;coil springs with the extreme end being an issue were in my opinion did not really need replacement as few will also agree.
Referring back to the picture it is clear that a substantial amount of the coil spring is missing;!! not just the extreme end
.SO ITS A FAIL
The coil spring is also located in its seats at either end,however the missing part of the spring is more then the extreme end, ;)SO ITS A FAIL.
The coil spring did not require me to assist it back into its location,however the missing part of the spring is more then the extreme end ;)SO ITS A FAIL.
The missing part of the coil spring was in fact 3 coils of varying sizes.
The question was asked on the thread to how much of the coil spring would an extreme end be with regards to a size in length.
MY answer to that would be ultimately,it will depend on that person using there knowledge,skill and experience when making that decision,me personally could not be definitive as to what length would constitute a fail but it would only be a small amount, but staying within the regulations.
Coil springs usually have tangs which sit in the seat in a stop on the spring mounts.
This stops the spring rotating(independently)and the raised lip keeps it in the seat when in operation.
I think most of us have seen that it is not unusual for these tangs to break off.
Weather the end (tang) of the coil spring is fractured or incomplete,in reality this small piece has little effect on the spring as its still perfectly capable of performing its function and remaining seated,
This is in direct contrast to a spring in the photos were more then one coil has broken off and clearly affects the springs function and meets the rfr descriptions.
What will need to be taken into account is on some coil springs such as Renault Megan,which has a small pin on the side of the spring seat to prevent the coil from dislodging off the seat,the extreme end on one of these springs is critical to the spring remaining seated.
Whilst the location of coil springs in there seats is important; but its not on all designs; the issue of the spring having to "but up against its stop" is not a requirement for the purpose of the test,as long as its seated top and bottom and is not" askew"then its met the standard.
If it was a requirement,VOSA would not be allowing the standard were the coil spring extreme end is fractured or incomplete as without this extreme end the coil spring will not be able to" but up "against its stop on the spring seat.
The problem with coil springs these days is that there lighter,thinner and cant cope as well with salt and rust.
Most often coil spring failure seems to be caused by corrosion accelerated by salt applied to the roads during winter.
The corrosion exposes the micro structure of the material to the atmosphere and makes it susceptible to a process known as hydrogen embrittlement. ;D
Electrolytic action between the salt solution,formed by road salting and the iron in the spring generates free hydrogen atoms which enter the steel and cause microscopic cracking.
The cracks propagate and combine,ultimately leading to failure of the spring.