Tom,
The fact that you bench tested the unit and got it to 20 mph indicated that you
ought to see AT LEAST that register when you are driving. Any idea how fast
the drill was turning when you got the pointer to 20 mph? I'd guess about
400 rpm... It really sounds like the speedo is OK now. That leaves
the angle drive (again), the cable itself, or the speedometer drive in the
transmission. I guess you inspected the angle drive by eye. The drive in
the transmission is pretty tough steel (in the TR4A at least), so that is
unlikely to have failed. That leaves the speedometer cable.
If the angle drive failed, you might not be able to turn the cable by hand. The
angle drive's short flex cable on mine exploded in a mop head of strands. They
might
bind enough to prevent you from turning the cable. Did you see and feel the
cable turning when you drove?
To rule out the speedometer, you can remove the angle drive and attach a short
(tach)
cable to the transmision and have it lead directly into the passenger
compartment.
THen hook the speedo directly on the cable and see what happens when you drive.
IF it
works then the speedo is OK. If the angle drive is perfect then it must be the
speedo cable....
Remember, if the speedo would not move due to the bound screw, something
between the speedo and the transmission HAD to break. In my case it was the
angle drive twice. If the angle drive is really fine, then it must be the
speedo cable..... I think.....
-Tony
Message text written by Tom Snabl
>Tony
Fantastic, what a quick reply, thanks. So to answer your questions.
1- Is the new angle broken - NO
2- Does the [inner] cable turn - YES, both directions, moving the TR forward
and in reverse. Also I can not turn the cable with the car stopped. All of
this tells me that the cable and the angle are OK.
3- The input shaft is easy to turn. I can spin it with a 2 inch long
Robertson head screwdriver bit.
4- The magnet spins smoothly.
5- The cup follows smoothly as does needle.
6- The return spring is OK
7- The needle is free since it returns to the peg and if I gently move the
Speedo by hand (disconnected of course) the needle bounces.
8- I checked the unit using an electric drill (bench test) it works
normally. Mind you all I pushed it to was about 20 MPH. However I assume
if it works to 20 it will as well to 120. The odometer also drives forward
so there is no bizarre binding here.
Is it possible that the magnet has lost some of its magnetism and will not
drive the cup under some peculiar circumstances. The bezel goes on with
finger pressure only as do the mounting nuts, so there is no deformation
when installed in the dash. None of this makes sense, or have I forgotten a
step somewhere.
I really appreciate your help. If you need some time with this, I'm in the
office now and will be out tomorrow. Looking forward to your thoughts
Thursday.
Tom<
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