Tachometer and Speedometer Repair

[Jeff Miller]

Gene:

Your tach is unfortunately obsolete, and I've found it hard to get
parts. I might have a working used one out of my '77, will have to
look to be sure, if you need parts.

The 90degree tach and sending unit are unusual, the sender is a DC
unit made by Autometer to match that Teleflex tach. The newer FCs
used an AC sender, which is a fairly common cruise-control sender,
easier to find (but doesn't really help you). The angle-drive unit on
my '77 went out twice, last existing of those I believe are at
Holland Motorhomes, and the short drive-tang from the fuel pump to
angle-drive broke once. The drive-tang would be the simple and cheap
problem to fix.

The tach can be replaced with an alternator-driven unit, the sender
wire moved from the old sender to the alternator (if the original
Motorola an AC output wire will have to be added). BlueBird can
probably still supply the 270degree alternator-driven tach for the
later 3208s and it is compatible.

As far as the speedometer, does your cruise-control work? On the '77
the speedometer is cable-driven from the output shaft of the allison
transmission, through a "ratio adapter", a cable to the Dana cruise-
control box under the driver's floor, another cable to the
speedometer. The ratio adapter on the transmission can fail, it is a
relatively cheap (Stewart-Warner) part, can even be rebuilt by some
speedo shops. Disconnect the cable at the transmission, spin it to
see if the speedometer jumps.

Also, if the nut on the yoke of the transmission loosens, the
speedometer drive gear will not spin full-speed and the needle
readings will not be consitent. If this is the case (was once on
my '77), not to be ignored as a loss of this nut can cause
transmission damage. If it is loose, a VERY cheap fix.

I believe that I also have a take-out '77 speedometer, and a new
ratio adapter for 11Rx22.5 tires on 4.63:1 gears, email me if you
need something.

- Jeff Miller
http://www.wanderlodge.net
http://www.millercoachworks.com



--- In WanderlodgeForum@yahoogroups.com, "woodland_builders"
wrote:
> Hello all, it is great to see the new group on track and doing
well. I
> would like to go after the broken Tachometer and Speedometer on my
77
> FC Diesel. Has anyone been down this road? Where is the pick up on
the
> engine for the tach? I do not have a book that covers a test
procedure.
> Does anyone know of one? My tach in the coach is electronic. I had
a
> 3208 in a truck awhile back that was mechanical which makes me
question
> if the current tack is OEM. Are parts still available? The
speedometer
> runs up to about 35 mph and then stays there reguardless of higher
> speed. I think the internal weights may be restricted. Does the
guage
> come apart and has anyone been in there? Thanks Gene
>
> Gene Chaude
> 77 FC33
> Connecticut