Tight Bushings

Sometimes the bushings can fit so tight that the links have trouble rotating freely. A small amount of friction is OK and normal, but the links should not have too much friction for the servo or return spring to move the links easily.

The bushings should be a super light press fit into the links, but the pins should rotate freely inside the bushings. The tolerances of several parts need to match up just right to take the slop out of the linkage, yet still rotate. Because of this, if a few factors conspire in the wrong way, they can be too tight...

The factors are:

1. We have 2 types of bushing fit: A "close" fit, and a "loose" fit. If the close fit ones are too tight, the loose fitting ones will improve the situation. If you are in the US, we can mail you a set of loose fitting bushings. Please email us at support@madronecycles.com for this. 
2. Check the pin fit on the bushings right after you slide bushings into the links, and before they go on the derailleur. This way you can change anything easily before you get further.
3. If the friction is borderline (noticeable but you are not sure if its too tight) when you do a rebuild, you can usually tell when the derailleur is off the bike. The servo will move the linkage a bit sluggishly compared to a free moving one. Make sure you have a well charged battery of course. Ones like this will also hesitate on shifts on the cassette, especially at 1 end of the cassette, kind of like the symptoms like a bent hangar. If they are like this, its best to use one of the other tips to free up the linkage before installing the derailleur.
4. Avoid putting a lot of force on the bushings when installing the pins. Always try to push the pins in by hand as far as possible, then use the punch tools only when required and use them as light as possible.
5. The Madrone pins fit just a tiny bit looser than the SRAM ones, but not too loose to function correctly. So, you can revert to Madrone pins if the SRAM pins are fitting too tight and you've tried all other options.
6. Check that your pins are not bent. You can do this by rolling the pins on a flat surface, or spinning them in a drill.
7. You can reduce the OD of the pins. Use a drill and fine grit sandpaper, followed by an abrasive pad (such as Scotch Brite). Chuck the pin in a drill, and spin it while using the sandpaper to remove material from the bushing surface. When doing this, make sure to check the the fit frequently to make sure you don't remove too much material from the diameter of the pins. After you reach the right diameter, polish the surface with the abrasive pad so it is extremely smooth for the bushing.
8. Some bushings have flashing (an extra ribbon of material) on the inside edges of the hole. See the next note.
9. You can increase the ID of the bushing and remove flashing. Use a drill bit that is just a little bit smaller than the ID of the bushing. For example, for the 5mm hole, you can use a 3/16" (4.8mm) drill bit. Or for the 4mm hole, you can use a 1/8" (3.2mm) drill bit. With the bushing pressed into the link, spin the drill bit with a drill to gently shave material off the ID of the bushing. With the drill bit spinning, move it in circular motion parallel to the axis of the bushing to evenly take material off all ares of the ID of the bushing. When doing this, make sure to check the the fit frequently to make sure you don't remove too much material from the ID of the bushings.
10. Sometimes a few passes through the range loosens it up enough though. And the bushings do wear in with use.
11. In general, we do not recommend using a lubricant because it will attract grit and ultimately wear the bushings faster. Do not use a wet lube or grease. However, one trick is to add tiny drop of wax chain lube (like Squirt) on the bushing or pin surface that is in contact. Then work the wax lube in by rotating the link. Make sure to wipe off all of the excess.