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1978 Honda CB400A Master-cylinder Parts

The front master cylinder on a 1978 Honda CB400A may still be original or may have been replaced. Identify the assembly before selecting a rebuild kit. Reservoir caps, diaphragms and internal service parts are different purchases with different compatibility checks.

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Currently viewing Master Cylinder & Rebuild Parts

Honda motorcycle parts

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Honda CB750 CB550 CB500 master cylinder rubber boot 45522-300-010

Honda CB Master Cylinder Rubber Boot ~ Replaces 45522-300-010

$9.95 USD
33-0003
Replace your master cylinder rubber boot with this Master Cylinder Rubber Boot, which attaches where the brake hose joins the master cylinder. Replaces OEM...
Honda CB750 CB550 CB400F master cylinder diaphragm 45520-300-000

Honda CB Master Cylinder Reservoir Diaphragm ~ Replaces 45520-300-000

$10.95 USD
08-0282
Replace a hardened or torn master cylinder diaphragm with this Master Cylinder Reservoir Diaphragm, replacing OEM #45520-300-000. Exceptional range of applications, fits FRONT master...
Honda CB750 CB550 CB400 front master cylinder kit 45530-404-315

Honda CB Front Master Cylinder Rebuild Kit ~ Replaces 45530-404-315

$59.95 USD
08-0281
Service your late-'70s CB750K/A, CB550, or CB400 front master cylinder with this Front Brake Master Cylinder Rebuild Kit, replacing OEM #45530-404-315. Made in Japan.Key...
Honda CB1000 CB900 master cylinder reservoir cap plastic o-ring 45521-MJ6-006

Honda CB Master Cylinder Reservoir Cap Plastic O-Ring ~ Replaces 45521-MJ6-006

$4.95 USD
29-0062
Replace your master cylinder cap O-ring with this Master Cylinder Reservoir Cap Plastic O-Ring, replacing OEM #45521-MJ6-006.Key Features• Master cylinder reservoir cap O-ring• Plastic•...
Honda CB1100 CB1000 CB900 master cylinder reservoir cap 45513-341-771

Honda CB Master Cylinder Reservoir Cap ~ Replaces 45513-341-771

$39.95 USD
29-0054
Restore your master cylinder cap with this Master Cylinder Cap with Plastic O-Ring, replacing OEM #45513-341-771. This original style was discontinued long ago by...
Universal Honda-type front master cylinder assembly 13mm

Universal Honda-Type Front Master Cylinder Assembly ~ 13mm

$84.95 USD
08-0262
Upgrade to a universal front master cylinder assembly with this Honda-type unit. Complete with lever, banjo bolt, banjo bolt washers, and brake light switch,...
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Honda CB750 CB650 CB550 replacement brake lever for master cylinder

Honda CB Replacement Brake Lever for Master Cylinder 08-0262

$9.95 USD
08-0430
Replace the brake lever on the #08-0262 Master Cylinder Assembly specifically with this Brake Lever. Designed for this particular master cylinder.Key Features• Replacement brake...
Honda CB1100 CB1000 CB900 master cylinder reservoir cap 43513-MJ6-006

Honda CB Master Cylinder Reservoir Cap ~ Replaces 43513-MJ6-006

$23.45 USD
29-0080
Replace your master cylinder reservoir cap with this Master Cylinder Reservoir Cap with Diaphragm, round OEM thread-on type. Cap replaces OEM #43513-MJ6-006, diaphragm replaces...
Magura universal front master cylinder assembly 13mm

Magura Universal Front Master Cylinder Assembly ~ 13mm

$259.00 USD
08-0250
Build a custom front brake setup with this Magura Universal Front Brake Master Cylinder. Features a 13mm piston diameter, 12mm stroke, and a threaded...
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1978 Honda CB400A · Front Master-cylinder Parts Buying guide

Identify the master cylinder before buying its parts

A rebuild kit suits internal service, while reservoir-cap products offer different included pieces. Use the fitted assembly’s identity and the condition of each part to decide whether you need a kit, a cap or a diaphragm.

Parts to consider

Honda CB Front Master Cylinder Rebuild Kit ~ Replaces 45530-404-315 Front master-cylinder rebuild kitJapanese-made rebuild kit for the 1978 CB400A, replacing reference 45530-404-315.View part Honda CB Master Cylinder Reservoir Cap ~ Replaces 43513-MJ6-006 Reservoir cap with diaphragmRound thread-on cap supplied with a diaphragm; cap reference 43513-MJ6-006 and diaphragm reference 45520-300-000.View part Honda CB Master Cylinder Reservoir Cap ~ Replaces 45513-341-771 Reproduction cap with plastic O-ringReproduction cap replacing reference 45513-341-771, supplied with a plastic O-ring.View part

Related parts: Separate reservoir diaphragm · Separate cap plastic O-ring

Compare the two cap packages

The round thread-on cap includes a diaphragm, while the reproduction cap includes a plastic O-ring. Choose according to the reservoir and which pieces need replacement. If retaining a sound cap, the related diaphragm is a separate option for the original-type application.

Universal assemblies need their own service parts

A universal master cylinder may appear in the same shopping grid, but that does not make its internals or lever interchangeable with the stock unit. Identify its maker and assembly number before buying a rebuild kit. Have hydraulic compatibility assessed before selecting a replacement assembly.

Front Master-cylinder Parts questions

Which cap option includes the diaphragm?

The round thread-on cap with reference 43513-MJ6-006 includes a diaphragm replacing 45520-300-000. The reproduction cap is instead specified with a plastic O-ring; compare the packages before choosing.

Can I replace just the reservoir diaphragm?

Yes. The related diaphragm is separately listed for the CB400A front master cylinder. Compare the existing reservoir and diaphragm before ordering, especially if the assembly is no longer original.

Will the stock rebuild kit service an aftermarket master cylinder?

Do not assume that. The kit is listed for the CB400A application and reference 45530-404-315. Use the aftermarket assembly’s own identity to find its correct internal parts.

Not sure which part you need?

Send your model and year, plus photos of your existing part and any changes to the original setup.

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