Monday, July 11, 2011


Read everything here first and understand what you are about to do – Take Pictures – Make Diagrams – Don’t trust your memory... You will forget

1) Clean everything after disassembly or before installing. I use denatured alcohol (methyl alcohol – Home Depot sells it as a paint thinner). Grease or oil anything that can’t be reached after part is installed. For example: Motor gears located on the bottom or outside of motor. Once installed, these gears cannot be seen or greased. Do before installing. You can oil other parts after motor is reinstalled. I use a hypodermic syringe and a blunt (flat) needle as an “oiler”. It is easy to control, and gets into tight places.

Use the smallest amount of oil possible. I use “NYOIL”. It's inexpensive and a synthetic alternate to real "clock oil". Real "clock oil", the kind used for watches etc, is about $30-$50.00 per ounce.


NYOIL is available from:

It doesn’t dry out fast or gum up. DO NOT over-oil otherwise the oil may find its way into the film path and contaminate the film. Don't get any oil on the speed regulator pad or into the leather coverings. Sometimes previous owners will have oiled the wind mechanism from the outside. The result is the leather coverings now come loose. This is because the oil acts as a solvent to the glue holding the covering.

2) Take pictures (digital) or video, or make sketches or drawings of the camera before disassembly. This will help you when reassemble the camera. Refer to the Bolex Camera Parts Manual (PDF) on CD-ROM when assembling. Manual is available from

All Bolex repair personnel are trained by the factory, or are other experienced camera repairmen and can rebuild a camera from diagrams without the assistance of “step-by-step” method. This paper is a “step-by step” method outlining how a trained repairman would replace a motor. I have made important warnings and cautions as CAPITAL letters.

3) Before installing motor, grease all items that are not accessible after assembly, such as: motor regulator bushings, bottom of motor (override clutch) etc. Don’t forget or you will have to do the job over again.

4) Oil everything else after assembly. Don’t forget or you will have to do the job over again.

5) It is very easy to damage some parts such as the “shutter angle selector arm” during disassembly and reassembly. You MUST work slowly and carefully check each step by making sure the parts or assemble are installed correctly before proceeding to the next step.

6) Place “like screws” and related parts as a group as you disassemble. Clean as a group. Screws, springs and other small parts are easy to loose. You can use a “donor camera” if you loose screws or need to replace damaged parts. has a complete supply of used parts for sale.

7) This is only an overview on how I replace a motor. I’ve tried to give all the steps necessary as well as some of the problems that arise. I usually disassemble the camera completely down to the last part and remove all the coverings before rebuilding. I clean, polish, inspect and replace all damaged or worn parts before reassembly. This tutorial does NOT give these exact instructions for everything I do. If it did this tutorial would be many, many times longer :)


1) Open camera door.

Remove pressure plate.

Remove pressure plate plastic housing (claw cover). It has (1) long screw.

Remove claw spring.

Remove claw’s (1) short hold down screw. Use a small screwdriver (Wiha #260 / 2,5 x 50mm Made in Germany. Available from Or do a web search. This screwdriver will work on almost every screw, but not all. Use a slightly larger screwdriver to hold the claw from turning when removing screw. I use a Wiha 260 / 4.0 x 60. There is a slot on the side of the claw eccentric. Insert 2nd screwdriver here to hold shaft from turning.

Take out the claw.

Remove film footage counter cover. Two screws. Use the Wiha #260 / 2,5 x 50mm.

Remove top plate. Use the Wiha #260 / 2,5 x 50mm. There are (5) screws. All are the same length and thread pitch on the D8L and D8LA and P1 will have plastic film guide. The screws will be longer on these models. Some models will be missing the long screws and guides. Some cameras will have had them added by enterprising repair people.

Place all the screws and plate / cover as a group to keep separate each from the other. Makes assembly easier.

Set the frame speed (FPS) to 12. This will press the regulator’s friction pad against the regulator and prevent it from falling out when removing motor.

2) Press the RUN button camera to until the motor is completely wound down. MAKE SURE the motor is run down. It may SEEM that its run down, especially if the camera has not been serviced. The motor may actually be wound and its gummed up and won’t move. This is common.

If the motor is “sticking”, you can hold the run button while helping the regulator (brass shaft with weights) to turn with your fingers. If necessary, put a few drops of oil on the intermediate gear and shutter assembly gears. Anything that looks like it turns. Do not oil the speed regulator (gold colored brass).

Remove shutter screws (4) each. DO NOT REMOVE THE SHUTTER ASSEMBLY! If you remove it now, or the shutter assembly comes loose, and the spring motor is wound, the motor will immediately unwind and the intermediate drive gear will be damaged (stripped) and the motor’s spring will most likely be damaged!

3) Holding the camera in your left hand, press your left hand thumb against motor’s top. This is to prevent the motor from turning in case if the motor spring is NOT fully wound down. Always assume the motor is NOT wound down and that it MAY turn when the shutter plate assembly is removed.

The other 4 fingers of your hand should be against the side of the camera with the winding key. If you hear a “Zzzzip – kerchunk”. The intermediate gear’s teeth are probably now stripped and the motor is most likely damaged :(

Very gently release the pressure of your thumb. If the spring motor was NOT fully wound down, the motor will want to turn. If fully wound, there will be a very large twisting force exerted on you thumb and fingers. If the motor is only partially would, the pressure will be less. Allow the motor to turn slowly while keeping firm pressure on the motor so that the motor does NOT turn too fast! Use both hands.

If the motor releases all the spring pressure at once, the motor’s internal flat spring will be damaged beyond repair and the intermediate gear’s teeth will be stripped.

3) Remove and place the shutter assembly on the workspace or table. Be careful not to touch or disturb the run button (on the side of the shutter assembly) or the lightmeter engage lever located on the top of the shutter assembly. If these are disturbed, or fall out, you will have to disassemble the entire shutter assembly to fix.

4) The motor is now wound down and the shutter assembly has been removed and placed aside. Remove the by setting the speed dial to 64 FPS. Remove the 3 small screws from the winding key hold down plate. Place these aside as a group so the screws do not become lost or mixed with other screws. All screws MUST be returned to their original locations upon reassembly. Some thread sizes (pitch) are the same, but the lengths and different. Sometimes only by a fraction of millimeter.

5) Remove the large slotted screw holding the motor shaft to the winding clutch. I use a ¼” screwdriver blade. It fits snugly into the screw slot. Loosen by turning counter-clockwise. “Righty tighty – lefty loosy”. The screwdriver will want to turn the motor. You can prevent this, again, by using you fingers to apply pressure to the motors flat surface, while gripping the case with your other fingers of the same hand.

After removing the large holddown screw, use a smaller screwdriver and insert it into the hole where you removed the large slotted screw. Push firmly and the motor will move away and become disengaged from the winding clutch assembly. Remove the motor from the open case top.

You will have to tilt the motor at an angle slightly to remove it. The ring gear on the motor fits underneath a lip on the back of the camera case. When re-installing the motor, the gear slips under the lip first.

6) Carefully remove the winding clutch assembly from the case. It has an outer ring, an inner ring where the large screw goes, (3) very small springs, (3) clutch rollers and a circular flat spring. If you can remove the assembly intact, you will not have to reassemble the clutch later. If the parts separate from each other, simply place them all in a single location (area) so you can reassemble later. This part gets lightly greased before or after reassembly.


1) Clean everything first. Inspect for damage. Repair or replace parts as necessary. After this, lightly grease the motors outer ring gear, override clutch (2 gears), and the lower spindle drive gear (other aside - opposite the 2 gears). Use Moly grease. You can get this at any auto parts store. It's called "High temperature wheel bearing grease". Unfortunately, you'll have to buy a 1 pound can - minimum.

2) Reassemble reverse order. Insert good motor, lubricate and insert the winding clutch. If winding was “crunchy” or the key is hard to turn, the grease in the one-way winding clutch assembly is dried out. There are 3 small screws hold the clutch in the camera’s case. Remove these screws. Remove the tops circular plate. The winding plate and clutch assembly will come out.

Take pictures and note how the coil spring is wound onto the drum part of the plate. Remove the coil spring. Remove the extremely thin thrust washer. DO NOT DAMAGE OR BEND IT. Note which way it came out. When you reassemble the assembly, the flat spring should go back in the same way it came out.

This spring wears different from top or bottom. One side rubs the wire spring. The other rubs the machined surface of the plate. Use a magic marker to mark the top. After cleaning, reassemble the winding clutch in this order: 1) grease the machined surface of plate where the thin washer rests, 2) Replace washer onto plate, correctly,  3) Grease thin washer now in place on plate, 4) Wind the spring onto the plates edge, starting with the spring end with the small bend in it.

This “bend” in the wire indexes into a small slot on the camera’s case and the bottom of the camera. The spring winds onto the plate clockwise (looking from spring side of assembly) with the end that has the bend going on first. Use you thumb to hold the springs “bent end”.

This spring acts as a one-way clutch when winding. When done winding on spring (may be difficult), put assembly aside. Clean and then grease the inside of winding assembly where it insert into the case.  Wherever you took off old grease, re-grease that area.

Insert the assembly into the camera. The small bend tip of the spring wire indexes into the cameras case at the bottom. Put the large circular plate with the 3 holes back on from the inside of the camera. Insert 3 screws – leave them a little loose.  Double check to see that the index spring tip is still in place. If so, screw the assembly down tight.

Place a dab of clear fingernail polish over the screws to hold them from coming loose. Install the motor after greasing the 2 gears on outside of motor. Lightly grease edge gear. Slip into case with motor close to back of camera. Align the square drive. Push into place.

3) Insert cleaned and greased clutch. Replace large screw and tighten. Again, use finger to keep motor from turning. You cannot overtighten the large screw as you fingers will slip before the screw threads can strip out. Be careful the screwdriver does not jump out of the slot and puncture you hand while tightening the screw.

4) Replace the flat spring and winding key. The spring indexes into (2) small holes on the clutch. The key tangs rest over the slots in the housing and touch the spring. Grease the tip of the key where the key touches the spring. Use a small amount of grease to hold the spring in place if necessary. Insert key into two slots. Doesn’t matter which way.

5) Put winding clutch cover on and insert one of the (3) screws. Tighten snug and back the screw out about 1/2 turn to leave the cover slightly loose. Replace the other (2) screws. Tighten all (3) screws snug. Check to see that winding key works as normal. If not, disassemble and reassemble. Then tighten all (3) screws tight.  Sometimes the spring will shift and the key will bind.

6) After the motor is installed, you can check for operation by rotating the winding key. Motor should turn smoothly in one direction, only. If key does NOT turn, spring has slipped off its index point at the bottom of the case and is binding. Remove the motor, loosen the 3 small screws and re-align spring into index slot. Check operation, again. At this point, the motor will turn, but NOT wind as the speed regulator is not installed.

7) Double check that the motor idler gear is not damaged. The one-piece gear is made from plastic (bakelite) and a small brass gear in its center. Clean and oil the support shaft. Clean the grease from the idler gear’s brass gear (inside part of idler gear) with a dental pick or toothpick. Inspect the gear for missing or “ground down” teeth. Then replace the idler gear onto its shaft.  Tighten screw securely. This gear couples the motor’s ring gear to the shutter assembly drive gear.

8) Rotate the shutter angle selector dial so it's pointer is pointing forward. This is full counter-clockwise rotation looking down at the dial. Full half-moon position or half shutter. There is a “lock” on the dial (sliding chrome button). Leave the lock OPEN (allows rotation of dial).

9) Turn over the camera and look inside the camera’s case. The shutter angle selector arm has a short pin (6-8mm tall or so) sticking out of it. This pin engages a slot in a brass gear at the bottom of the shutter assembly. When the selector arm is turned, the pin moves the brass gear’s assembly and that changes the relative angle of the (2) shutter blades which are located inside the shutter assembly.

10) Make sure the pin is NOT bent. If it is bent, it is possible to straighten it. Usually only once. The 2nd time the pin usually breaks. It MUST be fully straight up (perpendicular) to the case. If it is bent, use a needle nose pliers to straighten it. If it breaks off, replace this part or you will NOT be able to adjust shutter angle. About half the time I straighten a pin, it will break off :(

11) Rotate the speed control to 64 FPS. Remove the regulator if it is still installed. Clean it thoroughly. Remove any oil or grease. Grease the hole where the regulator end pin goes in the back or the camera’s case with a very small amount of grease. Use the tip of a small screwdriver.

Re-install the regulator. Turn the Speed Control to 12 FPS. This will push the regulator pad against the regulator keep the regulator from falling out of the case while you replace the shutter assembly. DO NOT get any oil or grease on the small leather friction speed regulator pad or the flanged part of the regulator located closest to the camera’s back.

12) Note the position of the brass gear of the shutter assembly. It will slide front-to-back (lens-to-back of camera). Using your finger, position it so that it is full back or away from the lens mount side. The gear’s slot or groove, matches up to the shutter angle selector arm’s pin.

13) The pin MUST go into the grove of the brass gear when assembling the shutter assembly into the case. If you install it incorrectly, or the pin is not engaged in the gear’s slot, you may damage (bend) the pin upon re-assembly. DON'T FORCE ANYTHING!

14) Insert the shutter into the case carefully, keeping an eye on the pin and gear to make sure they are engaged. The regulator end pin fits into a small brass oilite bushing located on the side of the shutter gear housing. With the pin still in the slot, place the end of the regulator into the bushing. It is easy to do after you have done several camera overhauls. But not so easy this first time.

The gear and pin is a tight fit with not much room to allow the regulator end to be placed in the bushing, but it can be done :)  I use a small dental tool with a hook shaped end to lift the regulator into position or use a small hemostat to grip the regulator shaft. Once the regulator is in place, the shutter housing can be pushed LIGHTLY against the cameras case. The (4) attach screws can be installed - loosely (finger tight) . DO NOT TIGHTEN YET!

15) After the screws are in place, BUT NOT TIGHTENED, rotate the shutter dial and at the same time watch the brass gear and pin. The pin should be moving the gear back and forth from front to back smoothly. If NOT, remove the shutter assembly and check to see if the pin is bent. Repeat until shutter assembly is installed correctly. Check and make sure the regulator end is in the shutter housing bushing. Rotate the shutter knob and visually confirm that the lever pin is operating the brass slider.

16) If pin and gear are ok, and the regulator ends are in place correctly, tighten the (4) screws that held the shutter assembly to the cameras case. If for any reason you cannot insert the screws, this is a “hint” that the shutter plate in NOT lined up with the holes in the camera body. Usually, it's the brass slider and the pin that are not in the correct position.

17) Turn the camera over and set the Frames Per Second (FPS) indicator to 24. Set the shutter dial to open (full CCW).

18) Wind the motor a few turns. Press the run button.

19) The motor should turn smoothly. If not, double check work or do over. Once the motor turns smoothly, proceed.

20) Double check that all screws are tight and reinstall the top plate after oiling. Oil any part the goes into a front shutter assembly bushing. DO NOT oil regulator flange or the leather pad that rubs against it. DO NOT OIL the other end (camera case) of the speed regulator. You already greased a bushing (bronze oilite) earlier. The greased end will NOT toss lubricant it into the regulator pad. Oil could be thrown. And its next to the regulator pad. So, no oil!

If you are not sure what to oil – do NOT oil it. Parts that get oil are: shutter assembly end pin of the speed regulator (towards the front of the camera), brass sliding gears inside shutter assembly, claw rotating shaft top bushing, and lower bushing.

21) Check top plate’s lower spindle. This is the spindle the rotates the take-up reel. Hold onto the top side of the spindle and press a thumb against the bottom side gear of the spindle. This gear is attached to an over-riding clutch. The gear MUST not turn when the spindle is turned. If both are stuck together, the film registration will skip after few frames or the film will tear.

If the two parts appear to be "fused" or “stuck”, you can lightly oil the edge of the brown plastic wafer between the gear and to bottom plate. This will soak in and “rejuvenate” the grease. The proper procedure is to disassemble it and clean everything and re-grease the assembly.

22) The clutch is stacked as follows: bottom plate, thin rotation plate, plastic (brown) friction disc, circular flat spring, and last, a small gear held by a short screw. The parts are “indexed” to each other. If you disassemble to clean off grease, pay particular attention to the order in which they camera apart. It is possible to assemble the over-riding clutch incorrectly. Lubrication is a very thin coat of grease on the brown friction plate. The drag from the grease provides the friction clutch drag.

23) Lightly grease the cross shaft for the footage counter on both ends and lightly grease the top plate gear that the cross shaft engages. Lightly grease the gear on the motor's top and the gears teeth on the underside of the top plate. On D8LA models, grease and then install the backwind gear. Grease the end that goes into the bushing installed in the camera case. The grease will hold it from moving or falling out.

24) Inserting plate into camera case: insert the shaft into top plate pilot hole. It will engage an idler gear on the top plate. Now insert the top plate/shaft, as an assembly, putting the back side of plate in first. Align the cross shaft with the hole in the back case. Use the tip of a small screwdriver or dental pick to move it around..

25) Make sure the shaft is fully install into the case opening (counter assembly interface). You will have to wiggle the top plate until it engages the motor small gear to the lower spindles small gear. On the D8LA models, the backwind shaft will move into the hole. Shift and wiggle the plate until is does. Once in place, the lid will fit flush. Double check that the cross shaft is in place.

26) Insert the top plate screw closest to the claw. Screw it down but leave it loose. Insert the other 4 screws. DO NOT TIGHTEN ANY SCREWS. If you do, you may damage parts.

27) After the (5) top plate screws are in place are in place, and top place is still a little loose,  wind the motor a few turns set on 12-16 FPS. Run the motor and move the top plate with your finger until the lower spindle engages the motors gear. Double check that the cross shaft is in place (hole).

28) Press the run button again. Grab the lower spindle. It should be turning freely. It will stop when you grab it. If it does not stop when grabbed, the spindle clutch needs repair or replacing. Remove, fix and try again. When the top plate is correctly in place, the spindle gears will mesh. You may hear a loud click when it happen. If the spindle is rotating, the gears are engaging. Tighten the 5 screws.

29) Wind the motor and press the run button. Look at the footage counter. If the counter is turning, the cross shaft is installed correctly and is engaged the counter assembly. If the counter is NOT incrementing, remove the 5 screws, move the plate, and use a small screwdriver or other tools to push against the fluted splines on the cross shaft. Go back to 26 and try again.

You may be able to do this without fully removing the top plate. There is a gap at the counter side if the case (rear) when the screws are removed. Place the tool between the gap and gently push on the fluted splines of the gear shaft. The two will engage each other. Replace screws. Repeat this step until the counter is incrementing (going higher in footage count).

30) When the counter is incrementing, tighten all screws. Run the motor to see if all is running smoothly. Check the counter again.

31) Replace the claw after oiling its shaft lightly. Place a very small amount of grease on the brass bushing the lower end of the claw where it touches the small steel post (rubbing block).

32) Add the claw return spring. Replace the top cover (claw cover) by first pushing the lever forward. This is the same position the lever would be in if it were installed and the pressure plate is against the gate. There is a index rod that must be forward to align itself. Pushing the lever forward with set it right.

Be sure the spring roller (at top of film path) is still operating. It's purpose is to take up slack from the feed reel. If it has come out, you will have to roll the spring top end (about a turn) with your thumb and forefinger. The assemble by inserting the pin into the hole in the cover while holding the spring. When done correctly, there is tension against the roller pushing it toward the shutter assembly (forward). Done wrong, it will just flop back and forth or pushes toward the center of the case’s case.

33) Check tensioner for operation. Spring tensioner should be pushing the film towards the case edges – not towards the inside of the case. The tensioner regulated the drag of the film through the gate.

34) While holding down the cover, insert the screw/button into the cover and then into housings hole. Screw down finger tight. Make sure that tension roller is still in the right end of the cover. If not reset the tension roller spring and place into the top cover. Move the cover right side and slide the tension roller’s bottom (part that touches the top plate)  around until the lower part of tension roller engages a hole in top plate.

After the tensioner is in place, line up the screw hole and screw down the cover. Check that the tensioner is still working properly by pulling the tensioner away towards the center of the camera. Let it go. It should snap back into place. If not, disassemble and start over. This cover assemble is one of the most difficult procedures to do. You probably wish you had two for hands :)

35) If all is ok, Give it a full wind, which is about 22 half turns (or 11 full turns) of the winding key. Run the motor. Check different speeds. It should run at 12 FPS and at 64 FPS and all speeds in between. Check single frame operation. Check to see of claw is operating. Check the counter to see if its incrementing.

Pull back pressure plate lever. It should pull the pressure plate back (towards the center of the camera) when the lever is operated. Pressure plate should “spring back” on its own. If you cannot move the lever or the pressure plate does not move back on its own, the cover or the pressure plate is installed incorrectly. Remove and reinstall.

Push lever forward. Fully wind and run down the motor. Run it until the counter reads 25’. You’ll have to rewind the motor several times. Then listen for a “clicking sound”. This is the end of reel indicator at 25’. A click every few second when the motor runs to indicate the reel has gone 25’. If no click, or the counter click before reaching 25’, repair the counter assembly. Pull back the pressure plate lever. You will hear a click. This is the counter resetting itself. The counter should read 0 feet.

36) If all is ok, put in test roll of film and check film travel. Look to make sure that lower take-up spindle is working properly. With the camera run button depressed and film passing through the gate, place a finger on the top of the take-up reel. The Reel will stop. Wait 2 seconds or so and release finger pressure. The reel should then take up the film slack. If not, suspect the spindle clutch is assembled wrong or needs an overhaul (cleaning and greasing).

37) If all appears ok, replace counter cover (inside the case) using 2 very short screws.

38) Motor overhaul is done. Any problems, retrace your steps. If it overwhelms you, send me the camera and all the parts. I will fix it all for you. Normal rates apply.

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1 comment:

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