Canon FD 85-300mm f4.5 disassembly

1. Wera 118022 JCIS PH0 screwdriver

1. Loosen 3 grub screws around perimeter for covering ring, the ring will be able to drop down into the cavity left for it

2. Remove 6 screws which hold the FD mount to the lens

Remember the orientation, for me orange aperture mark perfectly aligned with one of the white dots when used with tripod mount

When removing the mount, be careful, aluminum spacer might drop out when lifting the mount

3. Remove the covering right which previously fell into the cavity when loosening the 3 grub screws, remember how it was oriented. In my case groove inside the ring was towards the mount

4. Remove transitional/clamp ring by removing 4 screws around it's perimeter, keeping track of orientation is not important, as all the screw holes line up only in one place

5. Remove decorative ring in around the front element, it unscrews in standard direction, loosening when turning counter clock wise. However if you cant seem to do it, it might be first to remove the front element (step 6), then try again this step by putting fingers from inside the ring and turning it

6. Remove front element retaining ring, for this you will need lens wrench, for me this setup worked well

At first the element ring did not seem to move, by applying some isopropyl around it's perimeter and leaving for couple minutes seemed to help greatly. Be extra careful when using the tool

7. Remove 3 hidden grub screws behind the lens hood, grub crews are spaced equally around the perimeter and the hood must be retracted about 29-30mm from it's base

8. Remove 1st inner element, for this you will need pointy bits of the lens tool

Stick the tool into these holes and turn counter-clock-wise

This will free up element and you will be able to unscrew it by hand

After this element is removed, you can also remove the integrated hood, simply lift if off the body

9. Remove focusing ring rubber

I initially started by applying some alcohol between the metal casing and rubber ring and pushing small film strip by pushing it under the rubber, this created small gap

After the small peace i pushed entire 35mm strip and worked it's way until it hit the other side of the rubber ring, and then thread another film strip from the other side

Pulled the first strip out and used the second one to slowly work around the perimeter of the rubber, it appears to have tiny amount of glue, isopropyl appeared to help a lot

Once you go around the perimeter once, film strip can be andled and used as a ramp to push the rubber ring on to

And then the rubber ring can be removed entirely

10. Remove 3 screws around the perimeter of the focusing element

Unscrew focusing element helicoid

Then remove part which acts as helicoid endstop, by locating flathead screw (it's not a screw) and pinching the ring with your hand, making sure that the endstop screw is a high spot

Apply force with fingers like this

You only need like extra millimeter of clearance, so don't overdo it. Simply try lifting the ring over the helicoid ensuring that the side with the pin has the most space, to avoid damage to the helicoid.