C3 Vette Registry - The Best Resource on the Net for C3 Vettes! C3 Vette
Forums -> C3 Driveline Components
Not Logged In! Login or Register!  Users Online: 23 / Help 
Features  Find C3 Parts on ebay in only 2 or 3 clicks!  | Add YOUR C3 to the Registry

Supporting Vendors
Bair's Corvettes
Mid America Motorworks
VetteBookStore.com
Volunteer Vette Products
CorvetteClothing.com

C3 of the Month
None Current
Enter Yours Today!
Online C3 Show
13
C3s are Registered

Vanity Plates
ILRUNYA
bradjarmstrong
Featured Links

Buy Now
Corvette Fuel Injection & Electronic Engine Control: 1982 through 2001
Corvette Fuel Injection & Electronic Engine Control: 1982 through 2001


GM Corvette 1963-82 (Chilton's Total Car Care Repair Manuals) (Paperback)
GM Corvette 1963-82 (Chilton's Total Car Care Repair Manuals) (Paperback)


Corvette: America's Sports Car Yesterday, Today, Tomorrow (Hardcover)
Corvette: America's Sports Car Yesterday, Today, Tomorrow (Hardcover)


Motor Trend - $5 for 12 issues.
Motor Trend
Only $5 for 12 issues.



| Hide Signatures and Profile Pics

 New Topic New Topic Post Reply Reply New Poll New Poll Search     Search Page [1]  
6/19/17 6:14pm - Original Message: 'Speedometer gear'
dainc96
Limited Member
- Send Private Message


Stanwood, WA - USA

Vette(s):
1978 black on black 350

Joined: 6/15/2017
Posts: 2
Hi all. I just purchase my new baby - 1978 w/ 3spd auto. The speedo isn't working so I disconnected the cable at the tranny and did the drill test. Speedo worked perfect that way, so I removed the transmission driven gear and sleeve, then spun it that way. Again works perfectly. The gear itself looks to be in perfect condition- no mangles or broken teeth. I had no way to look inside the hole, so I just felt around with with my finger. I couldn't actually feel anything that felt like threads or teeth that the gear would be driven by. Of course, when I put it back together it still didn't work. I'm thinking the speedo gear internal to the tranny may have broken off or ??? Should I be able to feel or see it through the hole? Do these things break? (I still can't believe these kinds of parts are made of plastic.). Is there some other way to inspect that piece? Also, if I do have to replace it, does anyone know how much ch of a project it will be? I've never actually opened up a transmission before. Thanks!
 Reply Reply  Quote Reply w/Quote
 
Support C3VR!
Suport our advertisers
6/19/17 7:21pm - Reply: 'Re: Speedometer gear'
stingrayjim jr Lifetime Member
Lifetime Member
- Send Private Message


SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
Well, this is a Joel(adam's apple) question,but i'll try to fill in till he can give a proper response(he rebuilds these things).. the speedometer gear that you are trying to feel for is on the output shaft, i have a picture, and the gear you are feeling for is the gear that is colored teal-ish.  I think(dont hold me to it) that this gear is metal,  and the driven gear as you found out is plastic. Probably in the event something happens with the cable it would strip that gear(which is easier to replace) than the gear on the output shaft...  

Related image


____________________________________
StingrayJim
NCM Lifetime Member #1936

Stingray's '76                             StingrayJr's '78                           Lil Red '94

(click each one to see a bigger version)
 Reply Reply  Quote Reply w/Quote
6/19/17 10:53pm - Reply: 'Re: Speedometer gear'
73shark
Standard Member
- Send Private Message


Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.

Joined: 7/9/2003
Posts: 382
IIRC, the gear on the output shaft is pressed on.

|UPDATED|6/19/2017 7:53:46 PM (AZT)|/UPDATED|


____________________________________

1973 L-82 4 spd

 Reply Reply  Quote Reply w/Quote
6/20/17 2:51am - Reply: 'Re: Speedometer gear'
stingrayjim jr Lifetime Member
Lifetime Member
- Send Private Message


SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
basically  it is pressed/slid onto the output shaft.... and held in place with a retaining clip

youtube video shows how.... even i learned something looking this up :)  

https://www.youtube.com/watch?v=vh16skyeK8k

may have to copy and paste to see this



|UPDATED|6/19/2017 11:51:37 PM (AZT)|/UPDATED|


____________________________________
StingrayJim
NCM Lifetime Member #1936

Stingray's '76                             StingrayJr's '78                           Lil Red '94

(click each one to see a bigger version)
 Reply Reply  Quote Reply w/Quote
6/20/17 3:14pm - Reply: 'Re: Speedometer gear'
dainc96
Limited Member
- Send Private Message


Stanwood, WA - USA

Vette(s):
1978 black on black 350

Joined: 6/15/2017
Posts: 2
Thanks for the video reference StingrayJimJr!  Doesn't look too difficult while the tranny is sitting on the bench.  I'm sure it will be much more exciting if I need to do this without dropping the tranny completely. :) 
YouTube "suggested" a couple other videos, and I found this one which helps you figure out which Drive Gear and Driven Gear combo is needed to get accurate speedo readings. 
 
This link goes straight to a calculator page.  I have a feeling I'll be needing this myself.
 Reply Reply  Quote Reply w/Quote
6/20/17 4:16pm - Reply: 'Re: Speedometer gear'
stingrayjim jr Lifetime Member
Lifetime Member
- Send Private Message


SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
Good luck !!  not so sure you can remove the tail shaft while the transmission is in the car, but, i suppose it can be done just not a lot of room to work on anything under there... might have to unbolt the transmission crossmember and let the engine and transmission tilt downward.... just be sure to brace everything, lets not make more work out of it :)

____________________________________
StingrayJim
NCM Lifetime Member #1936

Stingray's '76                             StingrayJr's '78                           Lil Red '94

(click each one to see a bigger version)
 Reply Reply  Quote Reply w/Quote
6/23/17 2:20pm - Reply: 'Re: Speedometer gear'
Espressomorning
Limited Member
- Send Private Message


, - Canada

Vette(s):
1972 Corvette Stingray Coupe, 350 Base engine, p/s, p/b, a/c, automatic. All as original, 55,000 miles.

Joined: 7/13/2016
Posts: 2
My '72 was easy to do, only had to jack up enough to get under the car. I was only putting in a new o-ring and seal; would've ordered a new plastic gear too if I had known it was a good idea to replace it as well ahead of time. I left the old seal on and added the new one on top of it.
 Reply Reply  Quote Reply w/Quote
 New Topic New Topic Post Reply Reply New Poll New Poll Search     Search Page [1]  
 Forums -> C3 Driveline Components
(Moderator: Adam Wartell, Norsky, Adams' Apple)
 

 
Official C3 Vette Registry Community:
Home | Forums | Email | Who's Online | Clubs | Events | Member Stats

Other Official C3 Vette Registry Areas:
Members | Research | Shop | My Account | About C3VR
 

Corvette is a registered trademark of the General Motors Corporation(GM) & Chevrolet Motor Division. Vette Registries, LLC is responsible for all site content (except for member submitted content or where otherwise noted) and does not claim or imply that Chevrolet or GM is responsible for Official C3 Vette Registry content. Vette Registries, LLC is independent from GM and is not affiliated with, sponsored or supported by GM.  Copyright/trademark/sales mark infringements are not intended, or implied and are in fact used to support GM, Chevrolet and Corvette

Official C3 Vette Registry content is Copyright 2001-2017, Vette Registries, LLC. Content may not be reused without written consent. All Rights Reserved. NS

Corvette (Vette) Model Years on this site: 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 30