Front Brake Caliper Rebuild Kit | Honda CB350G / CB360 / CB450 / CB500 / CB550
Does your front brake feel dead, sticking, or locked up? On neglected mid-70s Honda discs, the caliper is usually a rusty ball of corrosion inside a pitted piston and a hardened seal. This kit has every wear part you need to bring a late-style Honda front caliper back to life in one box.
Why You Need This
The front brake provides the majority of a motorcycle's stopping power, and on a 40-to-50-year-old Honda hydraulic disc that power is usually gone. The piston corrodes inside the bore, the rubber seal hardens, pads get soaked in old fluid, and the bleeder screw seizes to the aluminum caliper body. At that point you are not fixing one part — you are rebuilding the whole caliper.
Buying the components separately adds up fast: the piston alone is over $90 from Honda. This kit bundles the piston, seal, pads, bleeder screw, cotter pin, and caliper grease at one price, so you have everything on the bench before you pop the first bolt.
Same late-style caliper was used across Honda's 1973–1978 mid-displacement lineup — CB350G, CB360, CB350F, CB400F, CB450 K5–K7, CB500T, CB500K, and CB550. One kit, one procedure, multiple bikes.
Specifications
| Spec | Detail |
|---|
| Replaces OEM Part Numbers | 45107-323-020, 45107-300-003, 45224-579-013, 45108-300-003, 45105-390-305, 45105-323-023, 45105-323-036, 45105-323-043, 45105-390-003, 45105-390-006, 45106-323-006, 45106-323-013, 45106-390-003, 45106-390-006, 45106-390-305, 94201-16220 |
| Fits Models | CB350G (1973), CB360G (1974), CB360T (1975–1976), CB450 K5 (1972), CB450 K6 (1973), CB450 K7 (1974), CB500T (1975–1976), CB350F (1972–1974), CB400F (1975–1977), CB500K0 (1971), CB500K1 (1972), CB500K2 (1973), CB550K (1974–1978), CB550F (1975–1977) |
| Caliper Style | Late-style (bleeder screw points straight up) |
| Sold As | Single-caliper rebuild kit |
Note: This kit fits late-style calipers only. CB450 K3 / K4 and CB750K use an earlier caliper style (bleeder screw points forward at roughly the 11 o’clock position). Those bikes need our CB450 K3-K4 / CB750K Brake Caliper Rebuild Kit instead. The CB750 also uses a larger-diameter piston, so the standard kit will not seal correctly in a 750 caliper.
Model-Specific Notes
- CB350: Only the CB350G (1973) has a front disc brake. All other CB350 variants (K0–K4, CL350, SL350) use a drum front brake and do not need this kit.
- CB450: Fits K5, K6, and K7 (late-style caliper) only. K3 and K4 use the early-style caliper — different kit.
- CB500K / CB550: The late-style single-disc caliper is shared across the four-cylinder CB500K, CB550K, and CB550F.
- CB750: Does NOT fit. The CB750 caliper uses a larger-diameter piston. Order the CB450 K3-K4 / CB750K kit linked above.
What’s in the Kit
- Caliper piston (1) — chrome-plated iron, replaces factory unit
- Caliper seal (1)
- Front disc brake pads — pad A and pad B
- Bleeder screw (1) — choose Standard or Premium EZ-Style at checkout
- Cotter pin for pad retention
- High-temp caliper grease
Standard vs. Premium EZ-Style bleeder screw: The Premium bleeder has an internal check valve that keeps air from being drawn back into the caliper as you bleed the system. It is a significant quality-of-life upgrade over the factory-style screw, especially if you are bleeding brakes solo. Both options are included in the kit price — pick the one you want before adding to cart.
Installation
Difficulty: Intermediate
Tools needed: 8mm box wrench (for bleeder screw), 10mm wrench, flat screwdriver, penetrating oil, clean catch dish, rags, and a vise for stubborn parts.
A caliper rebuild is one of the most rewarding jobs on a vintage Honda — the brake goes from dead to firm in an afternoon. These bikes were some of the first mass-produced motorcycles with a hydraulic disc brake up front, and the same basic layout (master cylinder, rubber lines, junction block, hard line, single-piston caliper) runs from the CB350G through the CB550 and beyond.
- Break fasteners loose while the caliper is still mounted to the bike so you have something solid to fight against.
- Remove the caliper, disconnect the brake line, and move to the bench.
- Push the stuck piston out using hydraulic pressure — connect a working master cylinder and line, fill with old brake fluid, and slowly pump until the pad and piston pop out. Do not try to pull the piston by hand.
- Clean the caliper body thoroughly. Remove corrosion from the seal groove and pad pocket. Test-fit a new pad — it should drop in cleanly and come out easily.
- Lightly stretch the new seal, install it into the groove, and confirm it is not twisted.
- Lubricate the new piston and seal with DOT 3 brake fluid, then press the piston squarely into the bore with firm, controlled resistance.
- Apply caliper grease only to the metal backing of the pads and metal slide surfaces — never on the friction material.
- Install the pads and secure them with the new cotter pin.
- Apply a small amount of anti-seize to the bleeder screw threads only, then thread it in smoothly.
- Reinstall the caliper, bleed the system, and adjust the caliper swing arm drag so the inner pad just barely touches the rotor.
Reassembly tips: Keep the caliper seal groove clean and free of pits — any corrosion in that groove can distort the seal and cause it to leak. Apply a light coat of caliper grease to the back and metal edges of the pads, but keep it well away from the friction surface. Use DOT 3 brake fluid as the assembly lube for the seal and piston; do not push the piston in dry.
Bleeding tip: The master cylinder on these bikes moves very little fluid per lever pull, so trapped air in a long line acts like a spring and makes traditional caliper-only bleeding miserable. Purge the master cylinder and lines first with the junction block disconnected, then reconnect and do a final bleed at the caliper with an 8mm wrench and a catch bottle. Keep the reservoir topped off — if it runs dry you will pull air back in.
We cover the full front brake rebuild on a CB550 in a two-part video series — Part 1 (embedded above) walks through disassembly, piston removal, and caliper reassembly. Part 2 covers installation, bleeding, and final adjustment.
Frequently Asked Questions
How do I know if my caliper style is late or early?
Look at the bleeder screw on the caliper. On the late-style caliper (the one this kit fits), the bleeder screw points straight up and the brake line enters the side of the caliper. On the early-style caliper used on CB450 K3/K4 and CB750, the bleeder screw points forward at roughly the 11 o’clock position and the caliper body has external ribs. If yours is the early style, order the CB450 K3-K4 / CB750K kit instead.
Will this fit my CB350?
Only if it is a 1973 CB350G, the one-year-only model with a front disc brake. CB350 K0 through K4, CL350, and SL350 all use drum front brakes and do not need this kit. If you are not sure which bike you have, check the front wheel — a disc rotor bolted to the left side of the hub means it is a CB350G.
Does this fit a CB750?
No. The CB750 uses a larger-diameter piston than the CB350G/CB360/CB450/CB500/CB550 family. Order our CB450 K3-K4 / CB750K Brake Caliper Rebuild Kit for the CB750.
Should I replace my caliper piston or try to save the original?
If you can see any pitting or corrosion on the sealing surface of the original piston, replace it. A pitted piston lets brake fluid bypass the seal, which causes leaks and contaminated pads. The included chrome-plated iron piston is a direct replacement for the factory unit.
Can I upgrade to a stainless steel piston instead?
Yes. We also sell a premium solid stainless steel piston separately — see our Front Brake Caliper Piston page for that option. The kit includes the standard chrome-plated piston.
What brake fluid should I use?
DOT 3. That is what the Honda factory manuals specify for this caliper, and it is what we use as the assembly lubricant for the seal and piston during install. Synthetic DOT 3 also works well.
Do I need to replace my rubber brake lines at the same time?
Almost always yes. Original rubber lines are 40 to 50 years old at this point and the internal liner breaks down with age even when the outside looks fine. Plan on new rubber or stainless steel lines along with the caliper rebuild — the hydraulic system is only as good as its weakest sealing surface.
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Last updated: April 2026
