Changing the internal speedo gear
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Joined: Jul 2005
Posts: 91
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From: Chattanooga TN
Changing the internal speedo gear
Hey guys..
I have been searching, and have found nothing that gives alittle more information on changing the internal speedo gear on a Muncie 4 speed. I have the tailshaft housing loose, but it will not slide out more than 3/4 of an inch. I do not know if I need to drive out the pin on the reverse cam boss or what I am missing.. Thanks guys..
sal
I also have the slip yoke out, the shifting assembly loose and the tranny mount off..
I have been searching, and have found nothing that gives alittle more information on changing the internal speedo gear on a Muncie 4 speed. I have the tailshaft housing loose, but it will not slide out more than 3/4 of an inch. I do not know if I need to drive out the pin on the reverse cam boss or what I am missing.. Thanks guys..
sal
I also have the slip yoke out, the shifting assembly loose and the tranny mount off..
Burning Brakes
Joined: Jul 2000
Posts: 1,118
Likes: 0
If you're talking about the plastic gear for the speedo adapter, it should come out of the adapter's hole. It's only held in place by the adapter and a stop. Pull the adpater out and the gear will be loose, so just work it out. It may not look like it'll come out, but it will... just barely.
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
Sal, I got my retainer at the local Chevrolet dealer. They still stocked that one when I needed it about 4 years ago. Hopefully they still do.
Drifting
Joined: Sep 2004
Posts: 1,532
Likes: 4
From: Fairview Heights Illinois, near Saint Louis MO, STL C3 Shark
stingraysallie, is the tranny still in the car? I need to replace my drive gear too, the driven gear I bought to correct my speed won't contact the drive gear teeth because it was worn and "cupped" I decided to live with the messed up speedo cause I figured I would have to remove the tranny to get the tailshaft off 
Burning Brakes
Joined: Feb 2001
Posts: 929
Likes: 5
From: Marietta GA
Sal, if you're talking about the "drive" gear on the rear main shaft in the tailshaft housing, it will need to be pressed off. I can't remember exactly, but inside the talishaft housing on the reverse lever is some type of locking dog which must be disengaged. Once it is disengaged you can pull off the tailshaft housing and access the drive gear. When I rebuilt my Muncie 4 speed a few years back, I had everything pressed off the shaft and then I re-assembled. To install it, I heated up the drive gear and then slipped it on the shaft and let it cool. Getting it off is another story (you need a press). I think depending on the year and differential ratio and whether automatic or manual, the gear has more or less teeth and could be plastic or metal. Also, before removing, make sure you note the exact location along the shaft because if you screw it up, the transmission will need to come apart again. You could probably measure and/or use a Sharpie marker to note the location.
