Suntour Accushift Derailleur Overhaul

I bought a well used Suntour Alpha 4050 rear derailleur that could use some help. I have this same model on a 1988 Schwinn Letour, and it shifts very nicely.

Time to take it apart. I'll start with the mounting pivot. It's spring loaded, which is unusual for Suntour. There's a small C-clip that can be pried out with a screwdriver:

 

That clip will go flying. After retrieving it from across the room, you can slide out the mounting bolt and spring:

 

To service the pulley knuckle, remove this philips screw:

 

Now let the pulley cage unwind, and find the right position to slide it out. You need to rotate it just right so that it will slide out of the knuckle:

 

There are 3 positions for the spring beneath the plastic cover, I'll just use the middle one for reassembly.

 

The pulley screws are 9 millimeters. A socket works best for the screw on the back of the cage, since it is recessed into the plastic cage plate:

 

Pulleys disassembled:

 

Exploded view:

 

Now I can clean everything.  For reassembly, I added grease to the knuckles and slid the springs into their mounting holes:

 

Next I reinstalled the mounting bracket by rotating it against the spring and pressing it into the knuckle. Then I secured it with the C-clip (I pressed it in with a flat screwdriver, but it's easier to use pliers).

Now I reinserted the pulley cage plate into the pulley knuckle.  First I had to insert the spring into the middle mounting hole, then wiggle it a little bit while pressing it into the knuckle. The toughest part was installing the cage stop screw while holding the knuckle back against spring tension.

 

Next I reassembled the pulleys:

 

 And screwed the cage back together:

 All done. I considered sanding out the scratches and touching up the paint, but I actually like the worn look.

Single Pivot Brake Caliper Overhaul

My new-to-me Miyata has sticky brake calipers that don't move freely.  These Dia-Compe single pivot calipers are very common on older bikes, and I'll show you how to take them apart to clean and grease the moving parts.

Before getting started, grind down a cheap 10mm wrench so that the open end is thin enough to fit the inner locknut without touching the outer nut. Alternately, you can buy Park Tool CBW-1, which is rather inexpensive. You won't be able to retighten the locknuts afterwards without a thin 10mm wrench, so don't try to do this without that special tool.

First I loosen the two locknuts with my thin 10mm wrench on the inner nut, and a normal 10mm wrench on the outer nut:

A thin washer will be next. Slide that off, and you can remove the brake arms after you unhook the spring from the back side:

 

Keep everything in order. There should also be a plastic washer between the two brake arms, and another washer on the back.

Here's the order for reassembly (left to right):
Acorn nut
Small locknut
Washer
Long brake arm
Plastic washer
Short brake arm
Washer
Spring








Clean all of these parts, and add grease to the washers and the pivot bolt before reassembly:

  

The reassembled brake pivot needs to be adjusted like a wheel bearing. You want the brake arms to pivot freely, but you also don't want them to wobble around because the brake will feel sloppy. I will screw the small locknut on until it is snug, then back off a little bit and check. Then I will screw the outer acorn nut back on:

 

The most important step is to tighten the locknuts against each other to secure the caliper. Again, you'll need that special thin 10mm wrench for this step. Put the thin 10mm on the inner locknut, and tighten the outer acorn nut against it to secure the adjustment (like a wheel bearing, but less torque).

Finally, you can hook the spring back into the nubs behind the brake arms, and then you're done: