Project Lucas, Tailgate Locking

As part of my continuous programme to improve Lucas, I wanted to get the tailgate lock working. The latch and release worked, but the key wouldn’t turn.

I don’t know if the central locking worked on the tailgate yet, I tend to lock the car after the battery is disconnected and it’s not a major for me if it isn’t working (for now at least), but since I park the car nose down in my driveway, it’d be nice to have the peace of mind that someone can’t just open the tailgate up.

The key goes into the lock fine but doesn’t turn in either direction and makes no attempt to lock. Looking at the lock, I suspect someone has tried to screwdriver it open at some point. Dicks.

With the car in the garage for other work, it was the perfect time to strip the end off the tailgate and investigate the issue. First the outer trim has to be removed, this is held in place with about 6 screws, two of which are under the number plate lamp lenses.

The parcel shelf makes an excellent workbench.

With the plastic trim off you have access to the lock assembly

Found some surface rust, which I later treated

The handle assembly is secured to the lid with two nyloc nuts and washers recessed into the inside of the lid

With those two removed, the whole lock assembly can be pulled free of the tailgate. If you have central locking, you will need to disconnect the actuator rod, which is a bit of a pain, but release the metal clip and wiggle and jiggle until the lever twists free. A tip for refitting is to slip the locking tab onto the rod at the same time as you slide it through the hole on the handle,

It’s no real surprise the locking mechanism doesn’t work, the whole thing is gummed up with dirt

The lock doesn’t look so great

After a quick clean with just some household cleaner and water

Interestingly, after a clean, the lock started to work, albeit it was really stiff and hard to operate. The act of turning the key in the barrel moves this C shaped tab left or right to lock and unlock

It’s quite interesting (to me) how the lock disables the handle. The yellow/white plastic in the photo above is the cam that uses the curved edge to press against a lever on the catch to release it (the cam would rotate downwards in that photo when the handle is pulled).

Turning the key in the lock physically moves part of the mechanism (orange arrow) so that the exterior handle is disengaged from the rest of the mechanism. The C shape tab on the end of the barrel pushes and pulls the plate attached to it, sliding the mechanism across.

The central locking would have been simpler in its operation if it had just acted on the same mechanism as the key, but no, that would’ve been too easy. Instead, the central locking actuator pulls on the rod on the other end of the handle assembly, in the opposite direction to the key mech

Pulling on that rod disengages the handle from the mechanism, by moving another part of it away from the actuating cam (orange arrow again).

Annoyingly I never tested what happens if you lock or unlock with the other means (ie. lock with key, unlock with central locking); I might have to see if I have a spare to play with.

Anyway, with everything working as it should, I wanted to refurbish the lock barrel. I sourced a better condition barrel from a local SD1 supplier and planned to rekey this to suit my keys.

The barrel is held in place by one small screw on the rear

Do take care when you remove it as there is a ball bearing and spring under the actuating plate

The barrel can then be removed

The donor barrel was in good, used, condition

Whilst my original one was covered in old grease which resembled a grinding paste with all the dirt in it

This isn’t my first rodeo with rekeying a barrel; I did the same job with Project Rolla, where the ignition barrel had been damaged.

I carefully removed all the wafers and springs from the donor lock

I cleaned the inside of the lock barrel up, and refit the cleaned springs

The old lock was pretty grim. The wafers were sticky and the first one is completely jammed down.

You can see how bad the face was damaged

I removed, cleaned and transferred all the wafers over from the old lock to the replacement, one by one. I tried all of the wafers from the donor lock in the number one spot to see if I could replace the one that is jammed in the original lock, but none of them were quite right. You can see the number one wafer is sticking out on the underside, all of them stuck out to some degree, which would stop the lock from operating.

It also sits low on the top side too. They should all sit flush

I could have filed one of the wafers down to make it work, but in the end, I removed the number one wafer and just left it. There are still 5 more, and it’s probably easier to break a window than to try and pick it (please don’t).

A light coating of white lithium grease will keep the barrel lubricated, whilst all the other moving parts got lubricated too. Now everything works very smoothly indeed.

Before reassembly, I also removed and cleaned the catch. It was disgustingly filthy

A quick clean-up and grease and it was ready to be refitted

I’m yet to refit the tailgate trim, but the catch and lock mech have been reinstalled and work perfectly. I wanted to treat the tailgate surface rust before refitting the trim, so I have done that and it’s currently curing.

That’s one more thing fixed on Lucas, and I’ll be glad to finally lock the tailgate.