My beloved XJR passed its MOT yesterday, a source of deep joy and satisfaction, compounded by the fact it only had one advisory to the effect that the coil springs were "rusty". The examiner is a very experienced and reasonable chap I have been using for years, so during our customary post event chat, I enquired whether it was a new requirement of some sort, as my springs had been "rusty" for some time. He indicated that testers were paying more attention to this area given the rate at which coil springs snap in use.
While I have encountered broken springs on more modern designs, has anyone encountered a broken spring on an X300?

 

According to an article I read a few years ago, modern springs break more often because the tops are not flattened.

When I had my suspension over hauled earlier in the year, David Marks (JEC Tech advisor) advised me to have my original springs powered coated instead of replaced for this very reason.



New springs (Not for Jag, just first that came up when looking for pic)

Original XJR6 springs after powder coat

 

I've never heard of or seen a broken spring on an x300 or virtually the same XJ40. Reason for this is they are very thick and even when super rusty they are still much thicker than majority of springs on new cars. Powder coating on these is purely cosmetic and doesn't rly affect them, if your MOT tester is telling you otherwise it just means he doesn't know much about these cars.
Springs on these cars do get worn out, but this is evident in the rear end height and bottoming out while driving over level crossing. For this reason I do not recommend powder coating your existing springs unless you can confirm that they are correct height when out of the car and they feel ok on the road. I've replaced a number of them on my cars and they were always worn out to a degree, some lost all of the powder coating but you could still drive the car on them to the moon and back and they would still be structurally fine, just flatter, compared to new ones.
I've always used the thicker KYB springs at the back, cant remember what I've used for the fronts but there was always around ~10cm difference in length, between old worn out springs and new ones.

 

Thanks Katar,
As I understand it, the advisory he gave me re the rusty springs comes from a DVLA database of advisories from which testers can select. He suggested that there were increasing levels of spring breakages generally, hence the increased focus. I have certainly experienced spring breakages in recent years, but only on much more "modern" designs of springs, which even a cursory glance would suggest are much more fragile than the X300 design. (As an aside, I think it is metal fatigue which causes springs to break, and I dont believe that the type of metal they are made of is susceptible to other than surface rusting) .
I would have preferred not to have the advisory, but am not losing sleep over the risk of breakage. The hare which has been set running is the one you mention about ride height, and I may need to get the measuring tape out, as she could be a shade low at the front....