Speedometer rebuild

[collins_dan]

I have replaced the speedometer cable and right angle drive, and still
my speedometer bounces around like crazy. It must be the instrument
itself. Who is the US rebuilder of choice? Thanks. Dan '70 S4 SE

[lotuselan2]

I sent mine to Don Tingle several years ago. He has a guy that does the
work for him. Mine works fine.



Ken

[Frank Howard]

Dan,

I live 5 miles from APT Instruments, but I won't do business with him.
Instead, I send my instruments to:

<A HREF="http://www.nisonger.com/">Nisonger Automotive</A>

My only complaint is they can't convert your tach to work with electronic
ignition. I found my own solution though.

Frank Howard
'71 S4 SE
Minnesota

[dlbarnes1]

I had my speedo done at Palo Alto Speedometer, Inc (SF Bay area).
www.paspeedo.com
Can't say if they would be the US rebuilder of choice, but they did a good
job for me.
Dave 72 Sprint DHC

[elans4dhc]

Frank,

Care to enlighten us on your solution to converting a tach to work with electronic ignition?

Regards,
Andrew King

[Frank Howard]

Andrew,

Considering what the speedometer shops charge to convert a tach to work with
electronic ignition, and the fact that practically every car made in the last
25-30 years came from the factory with electronic ignition and the fact that
many of these cars came with tachs, I thought the way to go was to substitute
one of these tachs for the Smiths one. So I went to the junk yard looking for
a suitable replacement. The Elan tach needle swings approximately 270 degrees
from 0 to 8,000 r.p.m. so I was in search of a tach with a similar set up.
The one I found to be close was the one that comes in 1990-1994 Mazda Proteges.
I yanked one out of a junk yard car and proceeded to replace the guts of my
Smiths tach with those of the Mazda through the use of home made adapter
plates, one for the front of the can and one for the rear. As I happened to own a
Mazda Protege at the time and had a repair manual, I referenced the Mazda
wiring diagram to see how Mazda hooked up their tach and hooked mine up
accordingly. It works great and of course, it looks completely original from the
outside. I even made up a sticker on my label maker and placed it on the bottom of
the can so that a future owner can read it when in the "Lotus Position". It
says "Tach internal parts from 1990-1994 Mazda Protege. Orange - side of coil,
green 12V."

Frank Howard
'71 S4 SE
Minnesota

[denicholls2]

Knowing the internal design, I think the flaw is unlikely to be in the
speedometer. To be so, the internal shaft would either have to be bent
or clogged with something such that the magnetic drive plate contacts
the driven needle plate.



If this is the case, you can easily confirm yourself. If you stick a
screwdriver in the back and turn very slowly, does the needle move and
stick where you stop? If not, or it moves a bit and falls back, look
elsewhere.



If there's a spider web or something like it making a mechanical
connection between the parts where there shouldn't be one, two screws
and a twist of the bezel will get you to where you can see it.



Based on your problem description, you've got a cable issue. Is the
sheath new as well as the cable? If not, don't pay a lot to get a part
that isn't broken fixed. Likewise, did you lubricate the entire cable
well before installing? The parts wear together, and that wear causes
cable bind. The bind is released when the force applied is adequate to
release it, and the needle bounces. Quite simple, really.



While I was writing this, it occurred to me that you can have a cable
issue within the speedometer itself. The ferrule that receives the
cable is brass, but serves as a bushing in a steel fitting. Left to sit
for long periods of time without good lubricant, the dissimilar metals
will interact and bind. You should be able to easily turn the brass
fitting with a screwdriver, feeling little resistance. If not, a
liberal dose of a quality lubricant in the hole should make things much
better.



Other faults in the instrument itself generally result in the needle
pinning itself to maximum speed and staying there.



-- Doug Nicholls, 54/1822 Ma~

[Frank Howard]

Dan,

Don't make the mistake of sending it to APT Instruments.

Send it to:

<A HREF="http://www.nisonger.com/">Nisonger Automotive</A>

They charged $115 to rebuild my speedometer a few years ago.

Frank Howard
'71 S4 SE
Minnesota

[collins_dan]

You've given me a lot to think about. I checked the cable in place
and it seemed to move freely. Also, before the right angle drive
seared off, I used a drill to drive the cable and the needle bounced
around wildly, just as it had with the original cable, so it seemed
like it was the speedometer. Then the right angle drive seared off,
so I thought maybe that was somehow the problem. I found one on ebay
(I also send my original off to Bean to be rebuilt and should have
that one back next week). It seemed a little stiff to turn, but not
too bad. Not sure what it should feel like. After installing it, the
same problem that existed 2 cables and 1 right angle drive earlier.
It sure seems like the speedometer. Maybe its the brass ferrule.
I'll try some of the checks you've suggested this weekend. Thanks.
Dan

[Billmack]

I've seen that problem on other british speedos when the overloaded odometer
drive gear starts to slip off the little shaft that the cable slips into.Since
the end float of the assembly is taken up there ,the two parts described in
other posts can get too close together .The ultimate failure there is when the
needle just spins around and around at cable speed with the obvious internal
carnage to the speedo.
Bill Mack

[collins_dan]

Is there anything short of a rebuild that can be done to get things
back in order? What's causing the odometer gear drive to be overloaded?
Dan

[wgrainge]

This happened to me many years ago. The problem turned out to be that the new cable I
installed protruded too far into the speedometer. I file down the end of it by 1 or 2 mm and
that solved the problem. Might be worth a try.

-Will Grainger
45/9693

[Billmack]

Dan,
Sorry about the lateness of this reply but the f*****g computer went off
line at the worst possible moment the last time and I stomped upstairs and went
to bed.
Yes you can fix your speedo if you are a tinkerer.You can take it apart and
clean and lube the cross shaft driving the odometer.It's eccentric.The
original grease was something organic and over time turns into something blackish
and gluey.
Alternatively call Nisonger in Mamaroneck NY and send it out.I've had a
couple dozen gauges fixed there and am generally happy with them.They ain't cheap
though.
Bill Mack

[collins_dan]

I took the speedometer out this weekend and lots of black particles
fell out as did a small copper triangle (maybe 1/2 inch long by 1/4
wide), does that mean anything to anyone? I'm willing to tinker, but
won't bother if the little copper triangle was important. How do I open
it up to clean/lubricate? The 2 screws on the back? Thanks. Dan

[Billmack]

I can't think of what that triangle is off the top of my head but I would be
looking for a small (speedo sized) box about now.On the other hand,there are
much more common speedos which are 90% compatible with yours as far as parts
swapping goes (MGB,MGMidget, etc) I'm sure you could pick up one of those for 5
or 10 bucks at a flea market somewhere.
Bill Mack