I’m still waiting for the exhaust to be re-chromed on my 1972 GT750 project, and so rather than just stand around, I’ve decided to do a but more fiddling with the next project, which is a 1975 GT380.
One of the (many) little jobs to be done is to assemble a working set of locks and latches and for them to all be keyed alike. For the GT380 I have collected together a set of latches to be worked on as seen in the photo to the left (just click on the image for a larger version). Re-keying these locks is not difficult if you have a spare one or two to provide you with a decent selection of tumbler parts to choose from. Over the years, I have at various times described lock re-keying elsewhere on this web site, but I thought it time to gather all the information into one place for ease of reference. Note that normally, on the 1974 through 1977 models at least having the flip up fuel cap, you do not have to re-key fuel cap locks as any Suzuki key from that era should open them. The 1976/1977 GT750 is a different case and I may cover that later, but right now the focus is on the GT380.
The Suzuki locks of this era having the double sided key blanks, used a 4 different leaves (possibly 5 but 4 for certain) for their key combinations in the tumbler that the key is inserted into. These leaves are set into channels and in their normal state, are lifted into the ‘lock’ position by a tiny little spring under the ear of the leaf which is very easy to loose if you are not very careful. The act of inserting the key, just pulls the leaves down into a position that allows the tumbler that the leaves are fitted into to turn in the barrel. So to re-key a lock, all that is needed is to alter the leaves so that which ever key you wish to use will, when inserted, allow all the leaves to sit flush with the tumbler. The first thing though is to get the tumbler out, without damaging the mechanism.
We will start with the steering lock first. Each tumbler regardless of whether it is for the seat latch, ignition switch or steering lock is held in the barrel with a locking blade at the rear of the tumbler. In the case of the steering lock, this locking blade is in a recess that Suzuki pinched shut as seen in the photo. To release the locking blade, you need to open up the slot, either by using a Dremel, or some means of prying the slot open. Having done so the locking blade may be lifted out and the tumbler will drop out of the barrel. There is a photo showing the disassembled steering lock near by. I use a bit of white grease on the locking bolt when putting the cleaned assembly back together and a bit of light oil on the tumbler. After testing to be certain the lock works properly, I reseal the locking blade either by pinching the slot closed again, or using a small dab of sealant just to hold it in place. Once installed in the steering head, it can’t fall out, so something like epoxy is not required.
For the seat latch, you need to first disassemble the rear of the latch housing by removing the two screws securing the backing plate. Having done so, the spring loaded latch arm may be lifted off its post. Under the latch arm you will see a pawl the slides the helmet strap retaining bar back and forth, There is a small brass spring blade recessed into a slot on this bar, so when pulling the bar out of its slot be sure to not loose this. Take a look at the photo nearby to see the spring preparing to escape. With the pawl out of the way, the spring loaded locking tab can be seen in its recess, and it just needs to be depressed using the blade of a small screw driver such that the lock tumbler can then be slid out of the front of the lock barrel. A photo of the whole assembly in pieces is somewhere near here. I know a fellow in the UK who makes some excellent quality stainless steel components for these seat latches, plus a few other items. If you wish to add some bling to your latch, then his contact information is located here.
For the ignition switch, there is a hole at the rear of the lock barrel (indicated in the photo) into which you insert a pin to depress the locking blade, and then the tumbler will fall out of the front of the lock. Corrosion and the passage of time may make it reluctant to leave, so just work slowly and don’t force anything. Note that this release only works if the switch is in the ‘Off’ position. Give everything a good clean, lightly oil the tumbler and put it back together again once you are happy with the key operation. While you are at it, it may not be a bad idea to open the rear of the ignition switch to give the contacts a good cleaning and some dielectric grease. It could also be a very bad idea. Just be aware that there is a load of spring loaded contact plates and ball bearings all waiting to make a dash for freedom under that contact plate, so if you do decide to do this, be very careful.
For the re-keying, I usually do these one lock at a time and with the tumbler removed, I just insert the key I want to use and see which leaves are not being retracted into the tumbler. These I then pull out (or in some cases push out from the under side) and substitute a different leaf having either more or less lift as required, such that all the leaves sit flush with the top and bottom of the tumbler when the key is inserted.I then give it all a good cleaning, lube with some light oil and put each assembly back together.
When doing these leaf swaps, there are just a three things to be aware of:
- There are two styles of leaves. The older style has ‘pips’ on the side that lock the leaf into the tumbler, and the newer style of leaves do not have these. You can mix and match the different types of leaves, and if you have leaves with pips and are modifying a newer assembly, then just file off the pips. The leaves with pips normally have to be pushed out of their slots from the bottom of the tumbler.
- Note that the newer style of tumbler that uses leaves without the pips has the annoying tendency to have all the leaves escape the tumbler if you turn it upside down which can result in loosing the tiny little springs. You have been warned !
- The most important thing is to not loose the springs. If in doubt, do the disassembly inside a clear plastic bag so that if something does escape you at least have a reasonable chance of finding it. Disassembling the rear of the ignition switch inside a plastic bag is also not a bad idea, for the reasons noted earlier.
The last thing to note is that if you re-key the lock, then the key number stamped into the stainless steel cap on the face of the tumbler (later locks are not stamped – earlier ones are) won’t match the key that you are using. Because of this, where possible, I try to buy a key (there are several sources on eBay) that matches an available ignition switch, as that is really the only one that can easily be seen. The other locks (steering and seat), I just polish up and don’t worry about the number mismatch.
If all of this seems like a more work than you wish to take on, then there is a fellow I know in the UK who does offer this as a service (and no – I do not get a commission). You can do an internet search for Mike Yeadon to find him, or check the Kettle Clinic board in the UK (which is the second best source for free information after this web site 🙂 ), or contact me directly via email and I will forward your contact information to him.