| Also known as | 70-4003 |
| Listed in parts books | 1965–1969 |
SMALL END BUSH 500 USA
Small end bush for a Triumph 500, fits the connecting rod's small end around the wrist pin.
This is a small end bush for a Triumph 500, marked in our records as USA-spec. The small end bush sits inside the connecting rod's small end and takes the wrist pin, letting the piston pin rock as the rod moves through its stroke. It's a wear item — over time the bore in the bush opens up and lets the pin knock, so replacing the bush rather than the whole rod is the usual fix.
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Our listing carries the number 70-4003A alongside the older 70-4003 form, and both point to the same physical part. Beyond "500 USA," our catalog record doesn't spell out which 500 models or years this was cataloged against, so if you're matching it to a specific engine, best to confirm the rod and pin dimensions on your bike before ordering.
We don't have further detail on file for this one — no torque specs, no bore dimensions, nothing on material. If you need those confirmed, give us a call and we'll go over fitment with you before you buy.
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