Service: 1960s Buren Grand Prix with Buren 1420 Movement

Another Buren Grand Prix on the workbench. I’ve had two close encounters with a Buren Grand Prix before. One of them even had the same movement, the Buren 1420.

This one is from the 1960s and in great condition. The case looks new and it has the original signed crown. That’s the first time I’ve seen a signed crown on a Buren other than a micro-rotor one (Super Slender).

Sadly, it regularly stopped without an apparent reason and it didn’t keep accurate time. The amplitude was also much too low.

Disassembly

Always remove all power from the mainspring before you start working on a movement. This is to prevent damaging the escapement while working on the wheel train.

Move the click away from the ratchet wheel while slowly letting the crown slip between your thumb and index finger. You can move the click with a sharp peg wood or a watchmaker’s pick. You can also use an old oiler or tweezers but you might scratch the movement so it’s not recommended.

Remove the balance and the pallet fork with the pallet cock and store them somewhere safe.

Remove the ratchet wheel and the crown wheel (reverse-fretted screw) and lift the barrel bridge.

Lift the wheel-train bridge and remove the escape wheel, the third wheel, the sweep second pinion, and the barrel.

I opened the barrel to remove the old mainspring because I always order a new one when the amplitude is very low.

Remove the center wheel cock and lift the center wheel.

Flip the movement around and start with the bottom plate.

Remove the motion works and the keyless works.

Pre-clean the pivot holes and bearing jewels with some peg wood.

Clean all the parts in the watch cleaning machine.

Assembly

Fit the center wheel, the center-wheel cock, and the mainspring barrel.

Before I continue I want to confess that I ruined the first new mainspring I ordered. I installed it upside down!

To be clear, almost all Swiss movements have a left-handed mainspring. When you order a new mainspring, it comes inside a cardboard disc with two sides. One side is colored (red or blue) and the other one is blank. USUALLY, the colored side has to be up and you can simply press the new mainspring inside the barrel.

This movement, however, uses a right-handed mainspring so the bridle broke when I tried to wind it for testing. I said some very unpleasant things at the time as you can imagine.

The lesson learned is that you should always pay attention and check the inside of the barrel and the way the barrel arbor hook is shaped. Make sure to fit the mainspring the correct way in this particular movement.

Place the third wheel, the center seconds wheel, and the escape wheel in position.

Install the wheel train bridge.

Install the barrel bridge, the crown wheel, and the ratchet wheel. Don’t forget the bushing for the crown wheel.

This is a good time to test if everything works and if the wheel train rotates freely without any friction.

Turn the movement around and fit the motion works and the keyless works.

Flip the movement to the top plate and reinstall the pallets. Wind the watch a couple of times to check the pallet fork. It should snap to the other side with the lightest touch.

Enjoy watching the movement come alive when you place the balance in position.

Now it’s time to clean and lubricate the shock protection system. Use peg wood to clean the capstone before you clean it with One Dip or something similar. Lubricate the capstones and reassemble the shock protection system on both sides of the movement.

Place the hour wheel and washer in position, fit the dial and continue with casing the movement.

I slightly lubricate the tube with KT-22 grease so the crown winds smoothly. It also adds a little bit of water resistance.

I think it’s a very handsome dress watch with a stainless case, signed crown, and an in-house movement. As far as I’m concerned, this watch has a great bang for the buck.

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What do you think of this Buren? Would you add one to your collection?