Well, after going through a couple of plastic speedometer gears, I looked up in the hole and found the steel gear that drives the plastic gear is not on center with the hole. It is to far forward and the speedo plastic gear is just riding on the edge of it.
Is that gear a tight press fit on the shaft?
Can I pry it back with a screwdriver through the hole or does the tranny have to come out and apart to reposition the gear?

You cant move it with a screwdriver I dont believe. If you could it wouldnt be accurate at speed.

edit: oops, My bad. He did say steel gear. Yes they are pressed on but come off fairly easy. (see Jims post below) Sorry...Jb

???

Could be there are differences thru the years, but my old muncie used a steel gear that was press fit on the shaft. No clips there of any kind. Also no stops to put the gear in the correct place.

I used reverse gear as a slide hammer to get it off, and a peice of pipe to drive it back on. Tail housing has to come off.

He said the steel gear that drives the plastic gear is off center, so his drive gear is steel. I think JimM's comments apply here.

I had the exact problem with my M20. It was the pressed on gear. 2 problems, it was the wrong gear...it was a 7 tooth I think which was an M22 gear, and it wasnt centered looking through the speedo hole. There is a measurement for how far that speedo gear is supposed to be from the midplate.

I'm afraid your taking that trans out to do this, but that's only a 20-30minute job. Make sure your gears are cpmpatbile with each other.

I used reverse gear as a slide hammer to get it off, and a peice of pipe to drive it back on. Tail housing has to come off.

Reverse gear as a slide hammer? Maybe this will make more sense when I get it apart.
So it looks like a tight fit and I will never get it moved through the hole, but I can get the tail shaft housing off without removing the trans.

Thanks guys!

I had the exact problem with my M20. It was the pressed on gear. 2 problems, it was the wrong gear...it was a 7 tooth I think which was an M22 gear, and it wasnt centered looking through the speedo hole. There is a measurement for how far that speedo gear is supposed to be from the midplate.

I'm afraid your taking that trans out to do this, but that's only a 20-30minute job. Make sure your gears are cpmpatbile with each other.

This is an M20

That measurement would be nice, but I think I can get it from trial and error looking through the hole to see when it is centered.

I think I have the correct gears because the speedo actually will work good for a while, then the speedo needle gets jumpy and quits.

Reverse gear as a slide hammer? Maybe this will make more sense when I get it apart.
So it looks like a tight fit and I will never get it moved through the hole, but I can get the tail shaft housing off without removing the trans.

Thanks guys!
Yes, it will be obvious when you get it off. Reverse is held onto the front of the tailshaft with a clip. I took off the clip, then slid the gear down the shaft hard... BAM! again BAM! One more time BAM-POP speedo gear slid off.

The speedo drive gear mounts 6.25" from the end of the shaft. I put one on a few days ago and that measurement centered it with the driven gear.

The speedo drive gear mounts 6.25" from the end of the shaft. I put one on a few days ago and that measurement centered it with the driven gear.
To the center, front, or rear of the gear?
Thanks

This is an M20

I think I have the correct gears because the speedo actually will work good for a while, then the speedo needle gets jumpy and quits.


Mine worked great to...for a while...then stripped out again after 100 miles or so. Some "driven" teeth (speedo gears) are only to be used with certain "drive" teeth (on the trans). Just keep an eye out.

To the center, front, or rear of the gear?
Thanks

Good question... From the end of the shaft to the closest edge of the gear.

What tail housing extension do you have on your Muncie? Is it a 584, 429, or 764?

What tail housing extension do you have on your Muncie? Is it a 584, 429, or 764?
I don't know for sure, but believe it is the original tailhousing for a 68 Camaro with the right side speedometer.
Which one would that be?
If it makes a difference, I can check it later.