Speedo and odometer not working...
Thread Starter
Cruising
Joined: Jul 2002
Posts: 10
Likes: 0
From: derby ct
Speedo and odometer not working...
My dad had his 79 Vette store for about 12 years - now it's back on the road again, but the speedometer and odometer don't work. What should I have him check specifically?
Thanks a lot,
Bill
Thanks a lot,
Bill
Melting Slicks
Joined: Apr 2001
Posts: 2,280
Likes: 0
From: colorado springs CO
Re: Speedo and odometer not working... (MustangWTC)
it could be several things...
1. speedo cable
2. tranny gear
3. drive gear in speedometer
you have to narrow em down.
yank the end of the speedocable off the tranny. hook it upto a drill and see if a speed regiusters on the speedometer... (should be like 30 mph depending on your drill...). if it registers then your tranny gear is bye bye and you gotta swap it out.
after u do that and it doesnt register a speed, then yank the other end of the cable andlook at it while spinning the other end with a drill. if its spinning then your cable is ok. this means the bottom drive gear is bad in your speedometer... if the cable dont spin then swap out the cable.
if you find the speedometer drive gear is bad, i wrote a paper on how to swap em out...it has LOTS of pictures.... it is on http://www.corvettefaq.com or get it here....
in word XP format
http://grove.ufl.edu/~dreksler/odometer.doc
or in pdf format
http://grove.ufl.edu/~dreksler/odometer.pdf
good luck with it!
:)
1. speedo cable
2. tranny gear
3. drive gear in speedometer
you have to narrow em down.
yank the end of the speedocable off the tranny. hook it upto a drill and see if a speed regiusters on the speedometer... (should be like 30 mph depending on your drill...). if it registers then your tranny gear is bye bye and you gotta swap it out.
after u do that and it doesnt register a speed, then yank the other end of the cable andlook at it while spinning the other end with a drill. if its spinning then your cable is ok. this means the bottom drive gear is bad in your speedometer... if the cable dont spin then swap out the cable.
if you find the speedometer drive gear is bad, i wrote a paper on how to swap em out...it has LOTS of pictures.... it is on http://www.corvettefaq.com or get it here....
in word XP format
http://grove.ufl.edu/~dreksler/odometer.doc
or in pdf format
http://grove.ufl.edu/~dreksler/odometer.pdf
good luck with it!
:)
Melting Slicks
Joined: Apr 2001
Posts: 2,280
Likes: 0
From: colorado springs CO
Re: Speedo and odometer not working... (daily_driver)
btw: the speedo drive gears (in speedometer) can be purchased for $10 from corvette america and corvette central....although i advise against using corvette central cuase their inventory is always @#@#!@ up.
Drifting
Joined: Mar 2001
Posts: 1,411
Likes: 2
From: St. Louis, Missouri
Re: Speedo and odometer not working... (MustangWTC)
To add to what was posted already:
If you have cruise control and both the speedometer and cruise control are dead, chances are it's the lower cable that's bad. I believe that if the upper cable is bad, cruise control will work but the speedometer will not.
Speedometer cable failures with cruise control are usually caused by the cruise control transducer. Even if your cable is broke and you replace it, the bad transducer can still eat a new cable.
The transducer is common to other GM vehicles and is not just specific to Corvettes. $25 - $35 from a salvage yard, $60 - $100 for a remanufactured unit.
If you have cruise control and both the speedometer and cruise control are dead, chances are it's the lower cable that's bad. I believe that if the upper cable is bad, cruise control will work but the speedometer will not.
Speedometer cable failures with cruise control are usually caused by the cruise control transducer. Even if your cable is broke and you replace it, the bad transducer can still eat a new cable.
The transducer is common to other GM vehicles and is not just specific to Corvettes. $25 - $35 from a salvage yard, $60 - $100 for a remanufactured unit.
Instructor
Joined: May 2001
Posts: 186
Likes: 0
From: CT, USA
Re: Speedo and odometer not working... (MustangWTC)
That's great info on the speedo drive gear ... I'm wondering if you (or anyone else) can offer some detail on the tranny end. I pulled the cable off and the speedo holds smooth with the drill attached. What's the process for swapping out the drive gear in the transmission. Any help would be appreciated, I'd love to know how fast I'm going!!!
(TTT please)
(TTT please)
Drifting
Joined: Feb 2001
Posts: 1,603
Likes: 0
From: San Francisco, CA
Re: Speedo and odometer not working... (rafox77)
The speedo DRIVEN gear is the one in the housing that pulls out of the tranny. Simply loosen the bolt that holds that housing in and pull the whole housing out. The gears are color coded so be sure to order the correct color (also count # of teeth.) To add to what others have said, if replacement of the driven gear does not work (which it did not on mine) then it is the speedo DRIVE gear (use a flashlight and you can see this gear inside the tranny when you pull out the housing). Put your finger in there and you may be able to feel that it is worn down. This gear meshes with driven gear and may also be plastic. If it is worn, guess what major driveline item you have to pull? I will be pulling my tranny this winter!!! :smash: Let us know what you find out. :cheers:
Melting Slicks
Joined: Apr 2001
Posts: 2,280
Likes: 0
From: colorado springs CO
Re: Speedo and odometer not working... (R. Bruno)
id put my money on the driven gear....... made of plastiiiic
its the easiest to replace anyways!! ROTFL :lol: :lol:
u asked me to look at this thread but r bruno already covered it...
:cheers:
its the easiest to replace anyways!! ROTFL :lol: :lol:
u asked me to look at this thread but r bruno already covered it...
:cheers:
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