Damper Arm Pivot Bolt

[fosterfamily]

We had an unsettling experience yesterday evening, whilst out on a driving lesson with my daughter.
Initially I thought we'd ran over a stone, and heard something hit the floor pan and saw it bounce down the road behind us.
Something told me to turn around and double check what it was.
As we reversed around a corner there was a scraping noise from the front o/s wheel; so we parked up immediately.
I could see that the nut and washers that secure the back of the damper arm pivot bolt to the trunnion were missing.
(Parts 36,37 & 38 in picture)
Sure enough; after a walk back down the road I found the big washer, tab washer and nut (no sign of bush).
The car had been re-bushed recently; by a good friend and experienced amateur mechanic.
My first thoughts are that he didn't fold back the washer's locking tab far enough - hard to tell from the part now as it may have been run over by the cars behind us.
Does that sound the most likely explanation or are these parts prone to stripping or failure in any other way?
(The car's a 1969 Minor 1000, 2 door)[frame][/frame]

[bmcecosse]

" experienced amateur mechanic. " - obviously - NOT! There are no forces that could cause this to 'undo' - it has obviously not been tightened.......... If you didn't before - take the chance to fit polyurethane bushes now.

[DAVIDMCCULLOUGH]

There are lots of stories about minors suspension falling out and in fact I have been asked many times 'do the wheels still fall of those cars?' They are not prone to striping or failure at the top, its probably been a simple oversight when being reassembled. I would suggest you check all the other nuts and bolts on the suspension just to be sure.

[minor_hickup]

This isn't as uncommon as you may think. It has happened to me once and I know of two other cars apart from this it has happened to. In all cases the top trunnion has not come off the pivot but the rear most bush has escaped as well and the trunnion has been able to move around.

I think the large washer is not snug enough fit to the flats on the thread and jiggles about undoing the nut. There must be something causing movement as its obviously defeating the locknut. Either way I always use locktite on this nut and fold the lack washer in two places to secure it. I have wondered if poly bushes were to blame but cannot think of a reason why they would be!

[bmcecosse]

Never had the slightest problem here - it does need to be tightened good and well - and then the lock tab used as designed.

[minor_hickup]

Unfortunately the one that let go on my car was on a car I'd recently bought so I can't say how well it was attached as the nut and lock washer went AWOL. I think its safe to assume these need to be properly secured and not by a frail lock tab that's been straightened out a 100 times! A bit of locktite always adds security on non torque critical fastenings!