| Diagram | Fig. 23 — FRONT BRAKE · ref 8 |
| Subsystem | brakes |
| Listed in parts books | 1976–1980, 1983 |
Diaphragm
Rubber diaphragm that seals a Triumph front or rear brake fluid reservoir cap, current part number 06-6032.
This is the diaphragm that seals the top of a brake fluid reservoir on Triumphs from the mid-to-late OIF era. It sits inside the reservoir cap and flexes as fluid level changes, keeping air away from the fluid surface while still letting the system breathe as the pads wear and the level drops. It shows up in the parts books under the front brake and rear brake sections, which fits since both master cylinders on these bikes use the same kind of sealed cap arrangement.
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Catalog records show this part appearing across front and rear brake listings from 1976 into the early 1980s. Ed's counter has this one crossed to a later Triumph number, 06-6032, so if your parts book or an older reservoir cap shows the 60-4366 designation, that's the same physical piece under the current number.
A reservoir diaphragm is a wear item worth checking any time you're into the master cylinder or topping off fluid. If it's torn, hardened, or won't seat flat against the underside of the cap, air and moisture get where they shouldn't, and that's no good for a hydraulic system.
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