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MG MGB Technical - ignition switch / steering lock

The ignition switch on my 75 B roadster has about given up the ghost. First it stopped springing back from the starter position, and now the electrics have started playing up, so I think replacement might be a good idea. Are these still available new, or is it a case of finding a good s/h item? Also, how much of a job is it to swap over?
David Pollard

One of the spring issues of MG World has a good article about it. I just put a new switch in my 70 midget and it was easy. Take the steering column completely out of the vehicle first and follow the article. when we put the steering column back into the Midget, we put the key in so the lock would unlock and allow the steering wheel to turn (it never worked before!) so we could get the wheel lined up straight with the front wheels. Otherwise, it's easy! Moss carries new switches.
Ken Thompson

David,
Just did this on my 74 BGT, think it is the same as yours but I'll check when I get home. may only need the switch. Not the lock and to remove the plastic shield around the steering column not the whole column. I will get back to you. i think the part is about $60 or so if it is the same it is an easy job. I assume price in the UK is the same or less avail from MOSS or MGOC.
ATB,
Tom
Tom

David. I did this job earlier this year and do not remember it as being a problem. I did not have to remove the steering column other than on the first parts car (which I intended to do any way as it is being stripped). There are three basic sub-assemblies which make up the ignition switch (at least on US spec cars). There is the main switch housing. This is composed of two U shaped pieces of aluminum (aluminium) held together by two shear bolts (the heads break off at the required torque). To remove these bolts without removing the steering column, use a cut off wheel in a Dremel tool or die grinder and cut a groove across the top to use with a screw driver. Use of the Dremel "heavy duty" wheel will make a wider slot which is easier to use. You can also use two or three regular wheels at the same time. Thin a spare screwdrive to the thickness of the slot and curve the tip to match the radius of the cutting wheel. This procedure may not be necessary in your case, as you probably do not need to remove the ignition switch assembly. The second sub-assembly is the ignition switch. This is a plastic piece held in with one fine screw at the bottom. Remove the screw and you should be able to remove the switch assembly and replace with a new one. Third sub assembly is the lock cylinder with a rectangular rod running from the lock to the switch. If this is good, there is no need to replace it. I believe that you would need to remove the entire assembly to change this out as it also contains the connections to column lock. As I remember it, the shear bolts on the 1980 donor car were a standard metric and th ones on the 1973 donor car were standard UN thread. Replace the shear bolts with either a "socket head cap screw" or a "button head cap screw" which uses an Allen wrench (hex key) to remove and replace and you are set for the next time. Les
Les Bengtson

You may be able to use a hammer and a small punch. Just back the screw off enough to grab it with your fingers or a pair of pliers. Using an allen head screw as Les advises would be the best method. If none is available you can also run a hack saw across the head and use a flat blade screw driver to reinstall.
Jim Mindy

I just used a small "easy out" to remove the shearbolts. In fact in drilling the hole for these one of the bolts started to back out when I reversed the drill.
I bought a spare switch assembly and for the life of me can not figure out how to get the tumbler out. Anyone with this experience out there?
Thomas Rynne

I am not sure the lock needs to be removed. A typical failure -- that is no spring return to on and electrical problems -- would be to the switch alone not the lock. I have seen the area where the key enters rounded to defeat the switches spring return. I would start by taking off the steering cowl and removing the switch. Just one small screw on the bottom. Look to see if the end is buggered up if so I bet that is your problem. If you want a second check try a screwdriver in the slot the switch has a spring return, if it does not return then replace the switch not the lock therefore the odd bolts to the column should not be bothered. David, I will try to email you a picture from a moss catalog if that helps.
ATB,
Tom
Tom

Thomas. As I remember it, you had to remove the assembly from the steering column, then there was some form of retention system which became visible. It may have been related to the steering wheel lock mechanism. I do not have access to a spare lock right now, but will check this evening and post. I remember removing the cylinder, but do not remember how I got it out off the top of my head. Les
Les Bengtson

My new Key & Lock cylinder are on Back Order from Moss
Ken Knize

Thanks for all the input. I'll try taking the lock apart and see what I can find.
David Pollard

This thread was discussed between 06/09/2001 and 08/09/2001

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