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Ignition Lock Repair

4K views 4 replies 2 participants last post by  Joey_Twowagons 
#1 ·
I don't know how useful this will be, but maybe some readers might find it interesting.
Unfortunately I didn't get as many pictures as I should have.

The other day my ignition lock / switch failed when I was in a parking lot. Fortunately it failed in the ignition "on" position, so I was able to get the car push started with the help of another fellow.

I took the lock assembly out, fixed the broken part and reassembled it. Here's the details:

Remove lower steering wheel plastic cover by taking out three or four Phillips screws. Lower steering column an inch or two by removing four M8 bolts accessed from underneath, and reinstall one or two approx. 2" long M8 screws, to hold column from dropping and damaging lower parts of steering column.

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If you haven't taken the ignition lock yet, then you will have the original "breakaway" theft proof screws holding the plate and lock to the steering column. Since I had already replaced the lock assembly once, I have already done this and replaced the special screws with M8 x 20mm Allen head cap screws. The originals are removed using a small hammer and ¼" cold chisel tapping around their circumference to unscrew them slightly, until they can be turned with the fingers.

Unclip the two wiring connectors on the left end of the switch and remove it. This is for a manual transmission car, if yours is an automatic there will be another linkage to the shift selector that you will need to disconnect. I don't have one on hand to describe that procedure.

The lock is held in the housing with two 5mm "blind" roll (or spring) pins. They can be drilled out or pulled out with a hardened No. 6 self tapping sheet metal screw. It is important to pull the screw and pin straight out, I used a large pair of linesman's pliers, pulling on the screw with the cutter part of the pliers and prying against a nut set on the lock housing. Be careful when clamping the lock assembly as it is just zinc and easily damaged by clamping too tightly in a vise.

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Then the lock cylinder and a bunch of other parts come out. The intermediate piece has a small tang, about .10" x .20" in cross section. It is made of die cast zinc, so not very strong, and was broken in two, which was the reason for the lock failure.

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#2 ·
This is getting very frustrating, as the post will disappear after I have put in half an hour or so of effort into it. So I will try yet again:

I could not find a source for the broken piece. It would be a rather complex part to machine, so I decided to just make the long thin part with the tang on it. I chose phosphor bronze as it is stronger than brass, and is easy to machine.

I measured up the part carefully, then made the new piece:

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I then trimmed down the damaged zinc part and bored a hole in it a half thousanth of an inch smaller than the bronze part, and pressed them together, making sure that the flats aligned. I had planned to pin them together, but they went together pretty tight, so I didn't bother:

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I carefully tapped the roll pin holes in the housing for M6 threads.

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After a bit of experimentation I decided against the dog point set screws in favour of the regular type. I had planned to use Loctite on them, but they seemed to hold pretty snugly so I didn't bother. It is really easy to over tighten the screws in the small amount of zinc that they are engaged with, so very light torque should be used when assembling.

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Light grease was used on the parts and they were reassembled, and the lock tested. So far so good:

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#3 ·
The protrusion of the flat was checked and tested with the electrical switch and all seems good:

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The steering wheel lock never did work with this lock, and despite fiddling with it for some time I could not get it to work, which is no big deal:

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The lock was reinstalled and tried out. Happily it works perfectly.

If I can find the old, original lock from this car, I may take it apart to use its cylinder in this assembly and once again have all the locks fit by a single key.

Here's the unit back in the car:

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