I think this is probably the best place to post this brief article.
I was going to post it in the TR forum as it was TR suspension that prompted me to write, but really its something to watch out for on all triumphs.Unfortunately I don't own a TR but I have just bought a Reliant Scimitar SE5a which uses the TR6 front suspension, I've also been running my spitfire for 3years as an everyday driver.
Coming home from work yesterday (luckily at low speed on a roundabout) the front right hand side of the Scimitar made a lunge for the tarmac, and stayed there! grinding a neat groove in the road surface until I managed to get off the roundabout and into a handy BusStop.
As soon as it happened I knew that this was my first experience of the dreaded front trunnion failure. The front right wheel was tucked right up into the arch and the car was resting on the remains of the trunnion and anti-roll bar link. Luckily the wheel had been able to rotate on its bearings and the rest of the suspension had prevented it moving violently and damaging the bodywork.
A short while later, after a ride on a recovery truck, closer inspection revealed a surprise - the trunnion wasn't in too bad condition (not good! but not that bad) but there was an almost complete lack of thread on the bottom of the suspension vertical link. No wonder it popped out!
But aren't we usually told that its the trunnion that fails?
Hmmmm
The trunnion itself was rigid on its bolt with absolutly no available movement to allow it to rotate as the wheel moves up and down. Four hours later and after copious use of big levers and WD40, I managed to make it rotate......... but not correctly as the bolt was rotating in the wishbone rather than the trunnion rotating around the bolt.
I've seen this before on my spitfire, but I replaced the components before they failed. In fact I replaced trunnion after trunnion before realising that I wasn't really managing to signifcantly reduce the play in the joint, then I started to wonder about the condition of the thread on the vertical link.
When the trunnion is seized onto its bolt and the bolt is tight in the end of the wishbone the trunnion cannot rotate and stays rigid with the wishbone. Any movement of the suspension transfers stress directly into twisting the trunnion/vertical-link joint causing extreme conditions in which wear will be accelerated. Imagine trying to screw a bolt into a threaded tube that is forcibly being twisted out of alignment first one way then the other. If you keep on trying then eventually you will wear away the thread at the top and bottom of the tube and also the top and bottom of the bolt - the points where they are forcibly made to contact each other. Continuous movement of the suspension in normal driving obviously implement much higher forces and 30 years of wear result in the thread being worn away.
My experiences lead me to believe that advice on trunnion and front suspension maintenance probably needs to be updated and to direct more attention to the condition of the trunnion bushes and the thread on the vertical link as well as lubricating inside the trunnion itself. These components are getting pretty old now and whereas in the past play in the joint would have been due to a worn trunnion (its made of brass not steel after all) now we will start to find that the thread on the steel vertical link can be worn to a dangerous degree.
Be warned.! 
if this had happened to me on the motorway at high speed - the damage, not to mention personal injury!!! could have been very severe.
David
1972 Spitfire
1974 Reliant Scimitar Se5a GTE
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