The speedometer gears in the transmission may be bad. If you are lucky its
the one that can be replaced from the outside, if not, it may be the one
inside the transmission.
Missouri City, Texas
> -----Original Message-----
> From: Rich Kosiba [SMTP:email@example.com]
> Sent: Sunday, May 13, 2001 11:45 PM
> To: OleTruck Mail List
> Subject: [oletrucks] Strange speedometer problems...
> I have "finished" my truck, just making some adjustments and little
> additions. One of those adjustments is the speedometer...
> If I go take the truck out right now and go down the road at 45, the
> speedometer will read 50. No big deal, I can live with that.
> If I drive for about 10 to 15 minutes, and I'm still doing 45, it will
> read about 40.
> A few more minutes and it will read 35... if I'm out for 20 minutes or so,
> it will start to bounce between 25 and 30, or just hover somewhere between
> If I'm driving for 45 minutes or more, it will just read 0 while the truck
> is still doing about 45 down the road.
> Now, if I let off the gas, it will immediately pop up to 50, then go down
> as the truck slows down. If I push in the clutch, it will go back down,
> sometimes between 15 and 20, and just sit there until I am almost stopped,
> then go down all the way. This is very well defined and happens every
> time, there does seem to be some direct connection.
> At first I thought maybe the pedals were hitting on the speedometer cable,
> so I tried moving it around to various different places, clipping it to
> things, etc. Nothing helps.
> I pulled the cable out and looked at it, it's lubed good, pulls out and
> turns very easily, and fits snug into the back of the speedometer. There
> doesn't seem to be any frey on it. It *has* been replaced, it's not the
> original cable. Seems to be long enough, though.
> I tried unhooking the cable and just letting it hang while I drive down
> the road with somebody to watch the cable. It doesn't seem to pull in or
> push out or anything.
> I tried another speedometer and it does exactly the same thing, but this
> doesn't sound like the speedometer itself. Nor does the cable seem to be
> such an obvious thing, since it reads 0 after a while. If the gear is
> turning, the cable has to be turning, it would seem. Unless something on
> the cable gets hot and prevents it from turning properly. I know the end
> that goes into the speedometer is plastic. That makes me wonder...
> By the way, there don't seem to be any noises involved. No grinding,
> rubbing, nothing.
> I'm not sure what else to do or what it can be. Anybody have any ideas?
> By the way, if you want to see the truck, I have a picture up:
> Rich Kosiba
> 1950 Chevy 3100
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959