Speedo Cable replacement.

[mention1]

I have a '79 C3 with a manual gearbox and cruise control. I verified with ZIP corvette that I needed an upper and a lower speedo cable, which I now have.

Trouble is I have no idea what they attach to. The cable from the gearbox goes into a box behind the dash board. I don't want to disassemble the whole instrument panel for no reason. Any suggestions?

[gtc]

Some discussion here:

https://www.corvetteforum.com/forums/c3-general/2549389-1979-speedo-cable-location.html

https://www.corvetteforum.com/forums/c3-general/3656124-79-manual-speedo-cable-routing.html

https://www.corvetteforum.com/forums/c3-tech-performance/579747-replacing-speedo-cable-in-79-a.html

https://www.corvetteforum.com/forums/c3-tech-performance/1436174-speedometer-cable-removal-installation.html

https://www.corvetteforum.com/forums/c3-general/3923146-79-attaching-speedometer-cable-do-i-have-to-take-the-dash-apart.html

https://www.corvetteforum.com/forums/c3-tech-performance/1783089-79-speedometer-cable.html

[Vettech]

The picture throws you a bit, but it is the same as on 78.

The lower cable is from gear drive on the gearbox.

Goes up into engine bay and SHOULD attach to the transducer fitted to LH side guard near booster and cruise vac unit. (As per your pic)
Of course if yours is RH Drive then the booster will be on other side (mirror)

Pic shows cable passes thru fire wall onto speedo, on my 78, it is a custom cable across fire wall to RH side, thru fire wall and onto the back of speedo.
Custom cable from a guy at St Mary's - also does clocks and instruments.

The box is the pedal box for pedals and power booster.

You need the required multi-jointed hands and arms to get in, to undo the cables, once removed, dont drive the car, I find the square drive (cable inner) is impossible to re-allign and go in. Im slowly evolving  suction pads on my finger tips, to cope with such jobs.

Hopefully a pic is attached.     Regards.

[sirfixalot]

Obvious question is LHD /RHD if LHD you can remove cable from rear of speedo by removing footwell courtesy lite & AC duct. There is a  spring clip around cable which you have to push toward speedo & then pull cable to ward engine all with one hand . Run hand up cable till it gets larger you will feel the clip. You should then be able to remove grommet next from firewall & pull it into engine bay. Removed cable on one the other day

[sirfixalot]

If you look at 2nd article GTC put up there is a pic of cable the clip is under writing at top of  pic