Rear door latch button not always locking door when open

[GrahamFountain]

The button on one of the rear door latches won't always go down properly to pre-lock the door. Well, it will always go down, but sometimes it feels like the wire rod is bending, and it won't stay down, so the door does not lock. Usually, if I jiggle it up and down for a bit, it works. But if it's been left a while, I have to take the panel off the inside of the door and try and grease the mechanism. Trouble is, I have never been able to see where it is that the problem lies, i.e. which part of the mechanism is jammed. So the greasing is only hit-and-miss and rarely last long.

I can always lock the door when it's shut.

Anybody got any idea where the mechanism might be jamming to have this effect?

Graham

[new to this]

I would have thought one off the clips that hold the rod to lock mech may have split

Dave

[GrahamFountain]

All the ones I can see are in place and the same as the other side, which always works. Plus, I wouldn't have expected that slapping grease everywhere reasonable, and as far beyond as possible, would fix a split clip, even temporarily.

Graham

[Carledo]

The jamming point is always the same, near as I can tell, front or rear they are almost identical.

It seems to centered on where the locking mechanism transits the latch at the top of the assembly. On front doors the lock comes in from the outer barrel and the inner rod on opposite sides and it's the bit of the latch/lock in the middle that sticks. on rear doors it's only one side actuated but the transit within the lock is still made and it's this bit that sticks. I found that sometimes you get lucky with repeated operation of the lock button till eventually it works. More often the door card needs to come off as the spring in the lock rods defeats the distance they work over, so I douse everything in WD40 and work the latch bars at the lock, or as close as i can get.

I've never had much luck with grease, it goes hard and eventually makes things worse. WD40 isn't really permanent so I'm between a rock and a hard place. But it seems to me they stick more in winter when the grease is thicker (and cars are used less often)

Steve

[GrahamFountain]

Sounds like the same boat as I'm in Steve.

It seems to me to be a bit odd that it's just the one door lock, just that one function of it, and not on the least used door neither - driver's side rear, which I use to chuck some shopping in the back and then lock it and the driver's front, while I get me pound back. So I'm wondering if there's a specific wear-point or pattern that make it prone to the problem.

I've tried lubricating that upper part of the mechanism, where the bar from the button applies, and working the mechanism direct; but I still haven't found an obvious point where it sticks before it's lubed and don't stick after.

Graham

[xvivalve]

I’ve marked the above photographs where the lock mechanism sticks; the small washer and rivet needs to be able to have lateral movement so that the locus of travel around the right angled slot can be achieved. Unfortunately the second of the photographs I’ve used is from an angle very difficult to achieve when the lock is attached to the door!

Graphite powder would be a better lubricant or a ptfe based one.

[xvivalve]

…and think yourself lucky, it can occur when the door is locked and won’t unlock, which can make getting the door card off to access it difficult!!

[GrahamFountain]

I’ve marked the above photographs where the lock mechanism sticks; the small washer and rivet needs to be able to have lateral movement so that the locus of travel around the right angled slot can be achieved. Unfortunately the second of the photographs I’ve used is from an angle very difficult to achieve when the lock is attached to the door!

Graphite powder would be a better lubricant or a ptfe based one.

Thanks Alun, I'll whip the card off when the sun goes over the yardarm and have a look at the state of that rivet and washer. It's working intermittently at the moment, so I've a good chance to see what happens differently when it works and when it doesn't, now I have a clue where to look.

In this context, lucky is remembering to check the keys aren't still in the ignition when you lock the car. That, or knowing how to open it with no key. Easiest with the DHC TR7s, where Triumph, in their immeasurable wisdom, fitted door locks that are entirely decorative.

Graham

[GrahamFountain]

Didn't get to look at the lock. Had a business meeting tomorrow that I didn't want to go to, so I threw myself at the bin I was putting out and dislocated my shoulder instead. That smarted a bit. I'm told it will be a day or two before I can use a screwdriver again.

Graham