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TR6 Speedo Angle Drive

Gerry M

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My speedo stopped working. I think my angle drive is the problem. I disconnected the speedo cable at the tranny and tested the cable with my electric drill. The cable is OK (speedo needle moves). I then took out the angle drive (see pic). Not sure what the end that connects to tranny is supposed to look like but mine has what looks to be a short twisted off cable end. What should this look like - does anyone have a pic of what it should look like? Is it possible that the rest of this twisted cable is still stuck in the threaded piece that goes into the tranny? How do I get the tranny piece out to check it - just loosen bolt on top? Thanks.
speedo.jpgangle drive.jpg
 
Mine broke in a similar fashion:

AngleDrive_zpse62e1409.jpg


I was able to extract the missing bit from the gearbox fitting without disassembling any further (there was some sticking out I could get hold of).

SpeedoDrive_zps7e384b44.jpg


I was also able to pick out the remains of that piece from the angle drive and make a replacement piece from the end of an old speedo cable I had.

That piece is just a short length of speedo cable with a square end (looks like the end of you long speedo cable). I stuck that short piece is with JBWeld.

AngleDriveCO25547_zpsee5c4e70.jpg


Hmmm - that may be a new angle drive in that picture, no photo of the one I repaired but it looks the same.

On mine there was a special rubber or plastic washer/grommet that fit over that short cable before it is offered to the drive on the gearbox. If yours has that is may still be in there or may have fallen to the ground when you removed the angle drive.

Unknown_zps042d3b5e.jpg


It seems the system is designed so that, if the speedo head binds, the $90 angle drive breaks to save your $18 cable.
 
It seems the system is designed so that, if the speedo head binds, the $90 angle drive breaks to save your $18 cable.
Just to emphasize Geo's point, the speedo head may be the real problem even though it moved when you spun it with the drill. When the bushing gets dry, friction causes it to heat up and bind after some time of continuous operation. Once it cools, it turns fairly easily again.

When I bought Stag #2, the previous owner had just replaced the angle drive. Less than 100 miles later, it broke again. The speedo head turned fairly easy when I got home, only a tiny bit of drag, but it was the problem.
 
On my MGB, when the angle drive went bad (just like the pictures above) rather than replacing the $$$$ angle drive I bought a slightly longer speedometer cable and eliminated the angle drive completely. Never another problem. On the MGB there was plenty of room to make the angle drive unnecessary.
 
Geo when you say "I was also able to pick out the remains of that piece from the angle drive ..." does that mean that it will pull out (e.g. not permanently attached inside the angle drive). I've given mine a light pull it didn't budge much. Should I just apply more 'pull power'?
 
...Should I just apply more 'pull power'?

That's what I did. I really thought I'd have to do something mechanical (perhaps a drill) to clean it out but there was enough to get ahold of with needle nose pliers and I just yanked for all I was worth.

It is just twisted wire and I'm thinking I pulled it out one strand at a time. Done that way, no single strand has very much holding it in there.
 
Just for clarity, the broken stub that pulls out is inside the transmission drive gear, not in the angle drive. I got ahold of one strand with a pair of hemostats, and the whole thing slid out. But it no doubt depends on how badly chewed up it is.
 
Actually, I had a broken stub in both pieces. The one in the gearbox end came out easily as it just slip in there when the drive is mounted to it. The remains in the drive itself (shown in first photo above) was what I had to yank out strand by strand.

I do not know what was holding them in there but whatever it was could be over come with force without damaging the rest of the unit. The hole left was clean and I used an angle grinder to slice off a length from the end of an old speedo cable to use as a replacement. Measured carefully to be sure I would have the right amount of cable projecting when it was done.
 
...I have now a really good way to fix these.
There will be a new topic shortly showing how I do this.

It's bound to be better that cutting off a piece of a nail (which is how one person I know 'fixed' it).

Interesting photos of one disassembled - don't think I had seen that before.
 
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