speedometer gear

I know this forum is for 64 and older cars but I need some help, I have a 1965 chevy elcamino, it has a 283 with a muncie m-20 manual 4 speed tranny, the speedometer was working even though it is off about 10 miles per hour(slow) I changed the bullet which holds the speedometer gear but when I put it in the transmission and rotate the driveshaft the gear will not turn, I took it back out and looked at the main drive gear through the speedometer hole and it looks ok, but no one can see through metal .I do not know how to work on a 4 speed tranny, can anyone out there give me some advice on what to do? You can e-mail me at ltremayne45@gmail.com, any help would be greatly appreciated, I was told it could be the speedometer gear (inside) the transmission, thanks Lloyd

 

Explain better?

You put a different size output gear and now it does not turn?

If yes, then the inner gear needs changing. As I recall there are certain sizes of the outer driven gears that must be used with a certain driving gear

 

if they still have speedometer shops in your area, give them a call. If not, find the oldest guy at the oldest Chevrolet dealership and see if they have any old parts books or microfiche files with schematics. Other choice is to call any of the shops that specialize in Muncie fourspeeds (google it) and see if they can provide some savvy insight - bet it's not anything serious.

dj

 

Need more info here....did you change the gear? if so, what gear did you take out, which did you put in? (color and tooth count)

 

Muncie M 20 ,had same type problem,had the red driven gear in and was to small to make enough tooth contact and stripped out right away ended up I had to go to the green larger gear or vis versa. Depends how many teeth and size of drive gear that determines size of driven gear they to are color coded.I think 7,8,9 teeth plus 2 differant diameters. good luck on this If I remember correctly my 67 chev M 20 had 8 tooth count and was metal for drive gear. Tail housing has to be removed for replace.If you are lucky its metal and pressed on rather than plastic. If metal chances are it is not stripped or slipped. Flashlight and mirror and try to peek through hole at least to check color of drive gear.There is info on web but it is confusing. Chev 350 uses same gears from what I understand.