Topic: cb750 speedo gearbox and broken cable

[Big Cobra]

I just got my 74 cb750 up and running-- on the maiden voyage my the speedometer gearbox moved counter clockwise and broke the speedo cable-- I'm not sure..is the gearbox supposed to sit tight in one position? and if so, how can I make sure that I have it set in that tight position so it won't brake another cable?

[Terry in Australia]

G'Day Mate, why would the speedo gearbox moving counter-clockwise break your speedo cable? Was it a new cable, or maybe a rusty old cable that was siezed in it's outer sheath?

Lets face it, the gearbox has to run backwards occasionally (rolling into a car park, backing out of your garage, rolling off a trailer or pickup etc) and that doesn't break speedo cables in 99.999% of cases, so I'm guessing it was a faulty cable.

Your speedo gearbox itself can be positioned at just about any angle, just make sure that the cable run from your speedo to the gearbox is a nice gradual curve. Cheers, Terry.

[Big Cobra]

I'm tellin ya man it moves about a half turn counter clockwise, bends the cable so the speedo stops working or breaks.  Once the gearbox moves the half turn down, it sits there.....in order the reconnect the speedo cable I have to use a rubber mallet to knock it back into a position where I can reconnect.

[mystic_1]

Sounds like your front axle nut is loose. 

Normally the speedo gearbox is pinched between the axle and the bearing on that side and cannot rotate relative to the axle, so when the axle is installed in the pinch clamps the gearbox cannot rotate relative to the forks.

mystic_1

[Johnie]

Correct...that speedo gear box should not turn at all once the axle nut is tight.

[Terry in Australia]

Yeah, sorry mate, I assumed that you at least had your axle tightened up, go and do that and try again!