| Diagram | Fig. 19 — REAR WHEEL · ref 40 |
| Subsystem | wheels |
| Listed in parts books | 1969–1970 |
BSA Speedometer gearbox, m.p.h. (1.25 to 1)
Rear wheel speedometer gearbox, m.p.h. type, 1.25 to 1 ratio, drives the speedo cable off the hub.
This is the speedometer gearbox that lives at the rear wheel, taking drive off the hub and turning it into the rotation that spins the speedo cable up to the instrument. The catalog lists it as an m.p.h. type with a 1.25 to 1 ratio, which is the specific gearing this housing carries inside it.
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It shows up in the rear wheel section of the parts books, so this is the drive unit mounted at the wheel end of the speedo cable run, not anything at the headlamp or instrument end. Our catalog record ties it to appearances from 1969 to 1970, but we don't have more detail beyond that on exact model fitment, so check it against what's on your bike before ordering.
If your speedo is reading off, or the cable drive feels rough or noisy at the wheel, this gearbox is one of the usual suspects to inspect. Worth confirming the ratio marked on your current unit matches before you swap it in.
We've never carried this one. Tell us what you're after and we'll go looking — you'll get a price and photos before you commit to anything.
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