Front coil springs on our cars to fail from time to time in fact in the three cars that I run I have replaced a coilspring on each one in under three years so that’s three springs in three years, so I would suggest that the fail rate is reasonable, when compared to other makes and models, however with our cars we can put tyre protectors on to protect the tyre from the coil spring snapping and popping the tyre, protectors are quite important as you don’t want a coilspring going through the car tire whilst you’re driving
I’d always recommend to replace suspension and braking components on both sides of the same axle at the same time, wherever possible. (Well that’s what I do)
Both will currently be the same age - if one has failed, it is likely that the other is in a similar condition and so could easily fail soon. In the case of springs, the constant flexing of the metal can eventually lead to fatigue, which is presumably the cause of the first failure - the other spring will be similarly fatigued. Similar arguments apply to other components such as shocks and bushes, which all wear out over time.
Additionally I suspect that the spring rate will change over time and use, so a new spring would be slightly harder than the old one - if that is the case then it would or could result in uneven handling, which would be very dangerous. This is certainly the case with shock absorbers, which lose their damping ability as they wear.
Oh and top mounts, don’t even get me started on them.. little rock side to side with the steering wheel and once they are past their best you’ll be getting knock knock who’s there? oh it’s me the top mount and I need changing
These are only my opinions based on my experience as a user of these vehicles and as a dismantler.
People are free to make their own decisions, however I would always recommend doing a job right first time rather than doing a job over and over
Mick
