Many vintage bike enthusiasts are aware of the "Schwinn Approved" brakes, often the ones made in West Germany. However, fewer are familiar with the "Schwinn Built" flat arm calipers that say "Made in USA" and are on the early postwar bikes.
The Schwinn New World I worked on this weekend is just such a bike. This weekend I had a little time and spent some of it cleaning grease and rust off of the calipers, while re-lubricating them for use when the bike is finally ready to go.
The above brake is the assembled item off the bike. It is basically dirty, though a little surface rust was present. The system used in these early Schwinn Built calipers is a guide and pinch bolt system with a side pull. A central wire spring and axle system binds the whole thing together.
Above we see the caliper taken apart to a level that allows cleaning.
2. Slide the the axle (A) out of the unit. You may separate the spacer on the axle to clean the surfaces of the axle and the spacer. Be sure to keep the spacer and axle together so you don't lose the spacer.
3. Squeeze the wire spring attached to the spring guide (C and D). This releases some tension on the arms (H and I) and allows you slide the spring off of the arms to separate it. Remove the spring from the assembly. Clean the spring of gunk/grease/rust.
4. Separate the two caliper arms (H and I) by sliding out the axle holder (E). Beware of the rubber washer (F). The rubber washer may have petrified and be easily broken. If broken, replace with a similar O-ring. I do not recommend using a metal spacer in lieu of the rubber washer (F), but rather a similar plastic or rubber ring. Clean the axle holder (E) of any junk or debris.You should also be able to separate the arms.
5. Clean the caliper arms. If you wish to disassmble the cable hosing holder (G) and pinch bolt (J) assemblies, you can do so. Again, remove debris and rust. I suggest reassembling G and J because it's easy to lose the parts. After cleaning them, I put them right back on to their respective caliper arms.
6. Once cleaned, apply grease to moving/sliding joints and quality light oil to pivoting joints and screw threads. You may also apply anti-seize like shotgun choke tube lube to screw threads. Then reassemble the caliper in the opposite order you took it apart, as outlined above.
Note- the brake pads can be refreshed by sliding the rubber blocks out of the holders and replacing with similar new pads. Take a pad with you to the shop, or measure the rubber pad to make sure you get a suitable substitute that will fit. Once cleaned and reassembled, re-attach to the bike.