Datsun Roadster Forum-311s.org

Seeking input on resolving inoperable speedometer assembly.

I have pulled the cable out of housing/sheath to inspect and it is fully intact. No broken ends. I seated in side of tranny firmly and tightened retaining nut and even added 2 turns with channel locks.

With the cable disconnected from back of speedo and hanging in footwell, when driving the car, the cable does not rotate inside the sheath.

Is there a part that is inop in that part of the assembly?

Going to pull the speedo and put a drill on it to see if needle moves smoothly.

I did observe under the car that part of the cable got on the exhaust and melted some of the plastic cable covering but the braided wire reinforcement is still there.

1600 or 2L? The 1600 has a right angle gear box @ the trans. Could be the speedometer drive gear, if 1600, link between the trams & the gear box, gear box or cable. Could be the exhaust heat fused the inner cable to the sheath, causing something to shear.

Peace,
Pat

SP3, those two full turns with the channel locks shoud ruin the cable housing end and maybe the housing of the drive gear.

Apologies for not specifying.

‘67.5 1600

I’ll pull everything apart at tranny and see if cable will spin inside housing.

Can the gear be sourced new from Nissan or do I need to find used spare?

Assuming if the speedo drive is removed from tranny visual inspection will reveal damage? 2 turns with pliers were just 1/4 turns each not full rotation.

Lastly, does tranny need to be drained to remove speedo drive to inspect? Does a large amount of fluid come out when undoing?

Thanks

Sounds like a major PIA, sorry to hear. Worst case $$ convert to GPS speedo via Jon Frampton. Chasing this gremlin could amount to plenty although mostly with time.

It's not so bad- really a simple system. The speedo pinion gear is driven by the transmission main shaft. The gear drives the 90degree adapter.
Adapter drives the cable.

Assuming your speedometer works ok, it will be the cable, the pin in the 90 degree drive, or the nylon drive gear. Probably equal chance of each.

Jack the rear of the car up noticeably higher than the front-that way minimal gear oil will dribble in your face. It's usually not a difficult job, just a bit of grime. A good job for Nitrile gloves.

I'm sure we have the correct gear-NLA from Nissan. Also cables and the 90degree drive. Just pm or email if needed!

JT68 wrote: Sat Jul 24, 2021 9:27 pm It's not so bad- really a simple system. The speedo pinion gear is driven by the transmission main shaft. The gear drives the 90degree adapter.
Adapter drives the cable.

Assuming your speedometer works ok, it will be the cable, the pin in the 90 degree drive, or the nylon drive gear. Probably equal chance of each.

It could be that the nut holding the speedo gear in the transmission has backed off. That happened to me. The 90 degree drive is pretty bullet proof.

There should be a short, ~20mm, flanged, drive pin connecting the right angle adapter to the speedometer pinion in the pinion holder/sleeve. Without that pin, which often falls out during disassembly and reassembly, there is no connection between pinion and cable.

maybe somehow the pinion gear has been damaged!