| Also known as | E4158 |
| Diagram | Fig. 11 — ENGINE FITTINGS AND EXHAUST SYSTEM · ref 33 |
| Subsystem | exhaust |
| Listed in parts books | 1966–1970 |
Right silencer (muffler)
Right-hand exhaust silencer (muffler) for Triumph twins, cataloged 1966–1970, later superseded by 71-2018W.
70-4158 is the right-hand silencer, or muffler, that appears in the catalog under Engine Fittings and Exhaust System / Motor Fittings and Exhaust System. It's the tailpipe end of the exhaust run on the right side of the bike, bolted up behind the head pipe to quiet the exhaust note and carry the gases out the back.
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This number shows up across catalog entries spanning 1966 to 1970, and it also appears under the older E4158 form if that's what's printed in your parts book. Later on, the factory replaced this part number with 71-2018W, so if you're chasing this down from a newer reference or a parts diagram, that's the number you may run into instead.
Silencers get replaced for the usual reasons: rust-through, dents, packing gone soft, or just swapping over from an old restoration project. Since this is the right-side unit specifically, don't mix it up with the left silencer when you're ordering — call the shop if you want us to confirm which side you need before it ships.
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