Thought I would share my recent experience with aftermarket speedometer cables with y’all. I had heard that some cables were damaging our speedometers because the instrument end was too long (more than 3/8th" beyond the nylon) but I had not realized that angle drive end could be an issue as well.
Recently I have been trying to calm my jittery/wobbly speedometer, I had Moma rebuild the instrument only to continue to have a jittery needle, especially after the engine compartment warmed up. Then I greased the cable with everything from graphite to superlube all to no avail, it real seemed like the heat must be making the cable expand ‘causing’ some binding but even loosening the fitting on the back of the speedometer didn’t seem to make any difference. Then I decided to clean and grease the angle drive and at this point I noticed that the repro cable seemed to stick out too far beyond the housing, I measured it against my OEM cable and it was fully 7/16" longer than the OEM cable which was only 7/8" compared to the 1 5/16" for the repro cable (both were seated at the instrument end). Thinking this might account for the binding I swapped the freshly lubed old cable back in and this appears to have solved my jittery speedometer. YMMV, I’ve not seen this issued mentioned before but if your having a similar problem you might want to consider this.
Cheers,
LLynn
Interesting: never actually twigged on this being an issue.
Llynn,
My speedo has never worked correctly, I replaced the cable, lubed it and nothing will help it displays low speeds most of the time and occasionally jumps to actual speed. I believe my angle drive is at fault but I don’t want to remove the motor to fix it… 
Hi John,
I think this was the only time I’ve ‘appreciated’ a bodge. A PO had cut an opening in the tunnel covered by a plate allowing me to access the angle drive without doing anything more than removing the carpet on the tunnel.
I would put up with it too if the only other option was to drop the engine but boy is it annoying. 
Cheers,
LLynn
I have the exact same problem as LLynn. I will check the angle drive end for length. the old cable was junk, and long gone. Any experiances with the usual venders and who can supply a proper cable?
Is that what has to happen to service the 3.8 angle drive? Not enough room to unscrew it I guess? I’m glad mine works. I’ve never touched it.
John,
The speedometer in my car was getting jumpy at steady speeds so I pulled the transmission cover to replace the cable. Problem turned out to be the angle drive, and with a 2 x 2 length of wood I was able to lever the transmission slightly to the left and get enough clearance to remove and replace it. There is some lateral flexibility in the transmission mounts so it was tight but doable. Better than cutting holes in the tunnel and a whole lot better than pulling the motor.
No issues with new cable or angle drive both from SNG.
Bob Hodgins
66 FHC
you wouldn’t think there would be enough room between the end and the trans wall for that cute little angle drive to puke it’s guts out the end but, there is.
My old receipts say PO had angle drive replaced so now my car is on at least the third one. I epoxied the end plate of this one…barn/horse/late