Door Lock Repairs

Two decades of having something slotted in you and wiggled about will take its toll, or so my mum says. So it is with your E30 door locks. Over the years they tend to stiffen up and jam, rendering the lock on that side of the car inoperable. If that happens to both locks, then you're in serious trouble, so avert disaster by learning how to strip down and rebuild your door locks.

This guide can also be followed to recode your door locks. Recoding means re-organising the sequence of tumblers within the lock to match a new or original key.

Procedure

First off, we need to remove the door card. Follow those steps then come back here.

With the door card off, you'll see the inner skin of the door is covered in a plastic membrane which needs to be carefully removed. Mine was already missing so I replaced when I refitted everything.

Now this is where you needed a hole in the door, which some E30s have and some haven't - there isn't yet a consensus as to BMW's logic on this. At the back of the door, if you have this hole, you will see the microswitch, lever and a horseshoe clip retaining the lock. In the way is a black plastic shield, which prevents the lock mechanism being lifted by a coat hanger/other implements.

The bodge tape around the hole is to prevent me repainting the door in arterial red...

The horseshoe is sat on its side, on a UK drivers side like a 'C' To pop it off, a long screwdriver levering it to the front of the car will see it ping off into the recesses of the lower door. Fish it out, you will reuse it.

The lock and the microswitch plate will now be free, the lock will twist and turn out the door side. The microswitch plate will stay more or less in place.

Once the lock is out, you will need to pull it apart, to find out what went wrong and to rebuild it.

From all the locks I have seen, if they go wrong its not worth a repair job, as the parts fail properly. Small components are very difficult to repair and, more importantly, the lock repair set is currently £21.47 inc VAT direct from the stealers.

Soper of Lincoln got me one in two days, delivered to my door. Part no: 51219061344 (note this is for my 316i saloon, check yours in OEM part catalogue before ordering)

The kit:

You need to spilt down the old lock to determine your key combination. Do this by tapping out the rear dowel with a nail of correct size.

The lock will now slide apart. Its worth keeping your key engaged in the slot, to prevent any tumblers falling out of place. If this happens you will be unable to rebuild your lock to your key without a lengthy process of trial and error.

When you have your lock to this stage:

you will note there are 11 tumblers: 6 on one side and 5 on another. Open your bags and note there are different tumblers too:

Then lay some paper out, to disassemble the main barrel.

I noted down the numbers on each key (not complete here as I don't want you lot knowing my key configuration, its my scrap...) but you get the idea. The guides do not ping out in all directions as the springs are pretty shagged.

Note from this picture that the two innermost followers to the car (2 and 3, and the ones opposite un-numbered in the pic) are a certain type, with a different profile to the others. With this laid out, you will be able to start to rebuild a new barrel, with correct pins/followers in place. Grease as you go using the stuff supplied. Insert a new spring into each hole (11 in total).

You should end up with something resembling this:

Then rebuild the rest of the lock using new parts from the bag. First:

Then:

Note orientation of overall lock and bits fitted- you will get it when you do it as it falls into place when its lined up correctly.

Next:

Again, note spring location. This part above the spring fits only one way, into a U shaped groove.

Insert the main barrel, with key in place. The new followers will take some time and wiggling to get the key in, especially on the last two 'different' followers. Don't worry about this. ensure you grease everything again and slide it on in.

Armature next- note the new ball bearing replacement. Grease this well and it will sit in the right place. The armature then slips into place, with the bearing moving down a channel in the middle of the spindle.

Then the final fiddly bit, the last remaining spring and armature. Mine did need a little tap to sit well. Refit the dowel pin then use some needle-nosed pliers to fit the spring. See pictures:

The only snag on this bit is getting the final stage to engage with the spring fitted in the early stages. Arrowed for clarity.

Reassembly is then completed by popping the pin back in:

It's prudent to test movement/key operation.

To refit the lock, its a reverse of removal, however a damn sight more fiddly. You need to coordinate the microswitch plate, the new lock, the actual locking forks inside the door AND get the horseshoe back on. Its possible but you may benefit from a second pair of hands, if only to keep fishing it out of the bottom recess of the door. If you need more space to move, consider unbolting some of the window winder mechanisms to give yourself more arm space.

Refit all trim and stand back, and be amazed that you don't have to use the central locking from the boot to open the car up any more!

Original E30 Zone article by bigwinn