The speedometer in my 65, 4 speed works periodically. I have verified that the dash unit, cable and driven gear are all working properly by spinning it with a electric drill. I can stick my finger in the drive hole and spin the drive gear on the output shaft. Don't think this is right, shouldn't the drive gear be tight to the shaft? Is the gear an interference fit, shimmed tight or some other mechanical fastener?

If it is an interference fit and has come loose would it be possible to remove the drive shaft and use some sort tool to try and force it tight to the shaft. If this won't work can the trans tail shaft housing be removed while the trans is still in the car? Then acces the drive gear and somehow lock it to the tail shaft?

 

If you can spin the drive gear then you found your problem...

Now the bad news...the tail housing needs to be removed to fix it..

 

If it was never positioned properly and driven or pressed on originally, I think you might be able to drive it back on the shaft (assuming it has moved toward the rear of the shaft) with the right size pipe inserted thru the tail shaft. I am thinking 1-1/4" pipe is what I use, but it must fit into the bushing. Never tried it with the tail housing in place.
Is the gear toward the front of the hole or back of the hole?

The speedo drive gear is steel in the M20 in R66. I assume yours is also. It is an interference fit (press on). Some of the automatics used a plastic drive gear and a clip to hold them on the shaft.

I've got a few extra Muncie parts and a complete tranny laying around. I'll go out this morning and do some measuring.

Ron

 

I'll try this again. Here are some pictures of the shaft and gear. Assuming you have a M20 or M22 Muncie, The shaft is approx. 1-3/16" o.d. behind the raised area the speed gear fits on and the bushing in the tail housing is approx. 1-5/16" i.d.

Check and see if your speedo gear is plastic or steel. A magnet will tell.
If it is plastic, the tail housing has to come off. Plastic gears are held on with a clip that fits in the hole in the shaft and holds the gear in place and it is probably in the housing somewhere.

If it is a steel gear and positioned behind the raised portion of the shaft where it fits, you might be able to take a piece of 1-1/4" EMT conduit (I think) and drive it back on the raised area of the shaft. If it slides too easily, BUBBA has got you. Don't try to drive it in one lick as it has to be driven on squarely to fit, If you **** it, it won't go. Check the location of the gear as you drive it on to make sure you do not drive it past the raised area. Try to center it in the hole. If it fits loosely, the tail housing will have to come off as BUBBA got you.

1st pic shows raised area on shaft with hole.
2nd pic shows steel gear at the raised area on the shaft where it fits
3rd pic shows EMT conduit over the shaft to drive the gear on
4th pic shows steel gear on the left and plastic gear on the right
PM me and I'll give you my number if you need more help. I am about 50 miles away.

Ron

 

Perfect response, thanks so much. Won't be able to get under it until next week. Pretty sure the gear is metal as I could see it through the hole. Got to located a piece of conduit to drive it with also.
If your coming down for the fair, come see me. I'll buy lunch.

Thanks,
Don Stowers

 

Glad I could help.
I hope the size of the EMT conduit is correct. Measure it before you buy it. If you can't find anything, let me know and I'll mail the piece I have to you.
I think I still have your number on your last PM and will call you if we get that way.
I have a dentist appointment and doctor's appointment next week. Depending on the outcome, I may try to get over that way. I have a sister in Springfield that I haven't seen for quite a while.
Don't think we will drive R66 there next week as Springfield gets crazy at fair time. The wife and I are RETARDED and have a little trouble with a lot of walking. Maybe just LAZY.
Would love to meet you all and see your 65. If you find yourself over this way, we are 1/4 mile north of the camp ground at Clinton Lake.

Ron

 

Don, great talking to you yesterday. Looking forward to seeing your COPO and meeting you all.

Got to thinking (hard these days) and would like the Muncie experts to chime in on doing this.

I am thinking if we driving on the speedo gear, we are possibly moving the shaft forward into the input bearings. I don't think so, as the rear bearing is held to the shaft with a snap ring and the bearing is held to the rear bearing retainer. I believe it would take a lot of hard blows to damage anything.
Being as though you are not in a hurry, maybe some of the Muncie experts will chime in and give us their opinion.

Ron