| Also known as | E410A |
| Diagram | Fig. 15 — EXHAUST PIPES AND SILENCERS · ref 4 |
| Subsystem | exhaust |
| Listed in parts books | 1960–1962, 1964–1973 |
Hemispherical washer
A domed exhaust washer, PN 70-0410A, used in the exhaust pipe and muffler mounting hardware.
This is the hemispherical washer used in the exhaust pipe mounting hardware, part number 70-0410A, also known by its earlier E410A designation. It shows up again and again in the exhaust pipes and silencer/muffler figures across the parts books, which tells you this is a small but recurring fitting in the system that clamps the header pipes to the cylinder head or holds the exhaust brackets together.
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A hemispherical washer has a domed profile rather than a flat one, which lets it seat properly against a curved or angled surface and take up misalignment where a flat washer would just crack or work loose. On an exhaust system that flexes with heat and vibration, that domed shape matters more than it looks like it should.
This part number turns up across a wide span of catalog years and in exhaust figures for several different frame and engine layouts, so it was clearly a long-running standard fitting rather than a one-off. It has since been superseded by 70-8860, so if you're ordering today that's the current number you'll get, though your parts book may still list the old 70-0410A or E410A.
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