TR2/3/3A TR3A OD speedometer drive

[fogdot]

Is a 90 degree drive required on a TR3A with overdrive?
I have a new cable, but no 90 at the OD. My speedometer is anything but steady.

 

[Don Elliott]

My TR3A (TS 27489 LO) never had a 90 deg. drive. I have overdrive and the cable comes straight out and down at an angle from the RHS of the overdrive. It is protected from above by a black rubber boot which in held with sheetmetal screws to to floor and the tunnel wall.

 

[Geo Hahn]

The OD I added to my TR4 came with the right angle drive so I used it (with a non-OD cable), but the 4, like the TR3 originally used longer cable connected directly to the drive on the tailshaft.

Perhaps the right angle drives are troublesome (they certainly aren't cheap) so I will use mine while it lasts and if it fails get the longer cable.

I think (not sure) that changes in later cars (e.g. the 6) precluded connecting the cable directly and thus the right angle drive was introduced.

 

[TR3driver]

No, TR2-4 didn't use the angle adaptor even with OD.

Make sure all the bends in the speedo cable are as gradual as possible; it should loop all the way over against the RH frame rail as it turns to run forward, then up the firewall and across in front of the battery box.

Odds are good that your wavering needle is a problem in the speedo head. The speedo on TS39781LO always wavered, but it still did so even when I temporarily removed the OD and installed a new non-OD cable.

One thing you can try, is loosening the clamp where the cable enters the speedo head. Apparently some replacement cables are too long, and put pressure on the mechanism, leading to binding (wavering) and rapid wear. But if it's already worn, there isn't much you can do besides rebuild it.

 

[Geo Hahn]

...Apparently some replacement cables are too long, and put pressure on the mechanism, leading to binding (wavering) and rapid wear...

If that proves to be the case you can make a washer that fits inside the knurled connector that will allow you to tighten it down w/o jamming that cable tip in too far.

One has to start with a washer with the correct size hole then trim the outer diameter (mount it to a bolt and chuck it in a drill to file/grind it down) to fit in the knurled cap.