Muncie speedo gears
Thread Starter
Burning Brakes
Joined: Jul 2009
Posts: 1,240
Likes: 294
From: ESCONDIDO CA
2025 C2 of the Year ('63 and '67) Finalist - Unmodified
C2 of Year Finalist (appearance mods) 2019
Muncie speedo gears
I have a muncie M21. I need advice on how to and what to look for when taking off the tail piece to replace the INTERNAL speedo gear. Mine is mia. Can I still buy the gear?
Limping across the line
Joined: Oct 2002
Posts: 5,299
Likes: 109
From: Peoria Az
Your drive gear is missing?
First thing then is to pull driven gear adapter, and with a sharpie mark the mainshaft thru the hole. Now remove reverse gear arm. Tap out pin that keeps reverse lever shaft in place. Pull reverse lever shaft outwards. It wont come out of the case it will just disengage from reverse gear. now you can remove tail housing.
Install new drive gear by warming it in oil the hotter the better. Observe mark you made in the first step. that should be close to the center of the gear. If you do a disassemble of a complete trans you measure the distance from end of shaft to the edge of the gear..It's going to be roughly 6.75" from end of shaft to rear edge of gear.
Using gloves slip the new gear over the shaft if needed tap lightly with a brass hammer.
reinstall tail shaft and check driven gear interface before final assembly.
complete assembly in revers order of disassembly.
Yes the gear is still available
First thing then is to pull driven gear adapter, and with a sharpie mark the mainshaft thru the hole. Now remove reverse gear arm. Tap out pin that keeps reverse lever shaft in place. Pull reverse lever shaft outwards. It wont come out of the case it will just disengage from reverse gear. now you can remove tail housing.
Install new drive gear by warming it in oil the hotter the better. Observe mark you made in the first step. that should be close to the center of the gear. If you do a disassemble of a complete trans you measure the distance from end of shaft to the edge of the gear..It's going to be roughly 6.75" from end of shaft to rear edge of gear.
Using gloves slip the new gear over the shaft if needed tap lightly with a brass hammer.
reinstall tail shaft and check driven gear interface before final assembly.
complete assembly in revers order of disassembly.
Yes the gear is still available
Last edited by AzMotorhead; Sep 25, 2010 at 02:38 PM.
Racer
Joined: Jan 2007
Posts: 308
Likes: 18
From: Sweden
Ok, two questions:
1) Should reverse gear arm be in "reverse" or "neutral" when pulling the arm? (Or no importance)
2) Why mark the shaft, can't I just measure from end of shaft to center of the gear? Mine is 6.5" to center so that would make it around 6,1" to the rear end of gear???
3) You are describing the procedure for a metal gear I guess, but I have a plastic gear in mine (the gear is there, just not fixed on the shaft).
Well, that was three questions...
1) Should reverse gear arm be in "reverse" or "neutral" when pulling the arm? (Or no importance)
2) Why mark the shaft, can't I just measure from end of shaft to center of the gear? Mine is 6.5" to center so that would make it around 6,1" to the rear end of gear???
3) You are describing the procedure for a metal gear I guess, but I have a plastic gear in mine (the gear is there, just not fixed on the shaft).
Well, that was three questions...
Limping across the line
Joined: Oct 2002
Posts: 5,299
Likes: 109
From: Peoria Az
leave shift in Neutral.
mark is for reference so you can get it close.
Plastic gear is held in place by a spring clip metal gears are press fit.
All Chevys I have done have had the metal gears while a couple of Olds trans I have done have been plastic drive gears with spring clips
mark is for reference so you can get it close.
Plastic gear is held in place by a spring clip metal gears are press fit.
All Chevys I have done have had the metal gears while a couple of Olds trans I have done have been plastic drive gears with spring clips
Racer
Joined: Jan 2007
Posts: 308
Likes: 18
From: Sweden
1969ray,
Have you opened it yet?
If you need the gear, check this place out:
http://www.transmissioncenter.org/GM...eter_Gears.htm
Turns out my gear clip was broken, so I bought one from them.
Draining the oil:
The hardest part was removing the pin that holds the reverse lever. Had to heat the case with a torch to get the pin moving, but I still managed to slightly damage the aluminium. The hole for the pin is now oversize so I have to use a new type of pin.
Because of all this the lever got a bit stuck so I had to use a socket to pull it out 1/2 inch or so.
Now it's just a matter of removing the 6 bolts and remove the tail housing. Here you can see the plastic drive gear and the clip thats supposed to hold it...
...but it turns out that the little bent part of the clip that goes into a hole in the shaft was broken. So much work for a $3.50 part.
Have you opened it yet?
If you need the gear, check this place out:
http://www.transmissioncenter.org/GM...eter_Gears.htm
Turns out my gear clip was broken, so I bought one from them.
Draining the oil:
The hardest part was removing the pin that holds the reverse lever. Had to heat the case with a torch to get the pin moving, but I still managed to slightly damage the aluminium. The hole for the pin is now oversize so I have to use a new type of pin.
Because of all this the lever got a bit stuck so I had to use a socket to pull it out 1/2 inch or so.
Now it's just a matter of removing the 6 bolts and remove the tail housing. Here you can see the plastic drive gear and the clip thats supposed to hold it...
...but it turns out that the little bent part of the clip that goes into a hole in the shaft was broken. So much work for a $3.50 part.
Thread Starter
Burning Brakes
Joined: Jul 2009
Posts: 1,240
Likes: 294
From: ESCONDIDO CA
2025 C2 of the Year ('63 and '67) Finalist - Unmodified
C2 of Year Finalist (appearance mods) 2019
Hello Johan,
Thanks for the resource, I was able to get the gear from a man in Az. Mine is like yours in that it has the plastic gear and clip. I haven't opened it up yet-that should happen today-so I really appreciate the pics. I haven't even looked at the pin. Did you have to drive it out or pull it?
OK, drive it. It was easy-all went like it should. One wrench!
Thanks for the resource, I was able to get the gear from a man in Az. Mine is like yours in that it has the plastic gear and clip. I haven't opened it up yet-that should happen today-so I really appreciate the pics. I haven't even looked at the pin. Did you have to drive it out or pull it?
OK, drive it. It was easy-all went like it should. One wrench!
Last edited by 1969RAY; Oct 4, 2010 at 07:09 PM.
