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I have checked the forum and could not find the info I am looking for. My car has an M21, 3.08 gear, 215/70/15 tire. The speedometer works, the cable is good. I ran a drill on the end of the cable and the speedo turns easily. I pulled the speedo gear housing from the trans, it looked to be seated properly. I pulled the gear, its white with 19 teeth. I looks to be in good condition, no teeth worn or broken. I inserted the end of the speedo cable into the gear and it fits snuggly (not stripped) . I put my finger in the trans, with the trans in neutral and rear whhel on the ground I can spin the gear inside easily, In did not feel any missing teeth and the gear did not move side to side, so it appears to be good...but the speedometer does not work. From what I read, there is only one speedo gear housing for this transmission (bullet type) and thats what I have. It also seems, from what I have read, that the 19 tooth gear is correct.
Lastly, I have an extra speedo cable, so with the gear installed in the housing and in the trans, I inserted the end of the spare cable into the gear and tried to spin the cable to turn the gear and could not.
Would appreciate any insights you can provide. Thought's? Thanks in advance.
Don't have a manual trans but something doesn't sound right. you said you can put your finger in the trans and spin the gear easily. i would think that the drive gear in the trans should not be able to be spun. if it's like an auto the gear should only turn when the output shaft is turning. but maybe i am misunderstanding what you said.
Pat
Don't have a manual trans but something doesn't sound right. you said you can put your finger in the trans and spin the gear easily. i would think that the drive gear in the trans should not be able to be spun. if it's like an auto the gear should only turn when the output shaft is turning. but maybe i am misunderstanding what you said.
Pat
The trans is in neutral (M21 4spd). I put my finger in the trans (where the speedo gear goes) I can move the internal gear with my finger. Not sure if this is what its supposed to do.
The trans is in neutral (M21 4spd). I put my finger in the trans (where the speedo gear goes) I can move the internal gear with my finger. Not sure if this is what its supposed to do.
It's not supposed to do that. It's supposed to be clipped to the output shaft and you cannot turn that with your finger.
I also checked...the transmission is in gear, and I cannot spin the internal gear with my finger. I believe this is the behavior of the internal gear.
This is a cutaway diagram of a Muncie. How is that gear, number 23, going to turn with your finger in gear or out of gear without turning the main shaft, number 14? https://selectric.org/manuals/muncie/muncie01.jpg
I tried again, you are correct. I thought I was able to move wit hmy finger, but it does not. So...does all mean that the inop of the speedometer is due to the plastic gear, as the only possibility? I ordered some new gears today 18 tooth-22 tooth to try them out and a new speedo gear housing.
I tried again, you are correct. I thought I was able to move wit hmy finger, but it does not. So...does all mean that the inop of the speedometer is due to the plastic gear, as the only possibility? I ordered some new gears today 18 tooth-22 tooth to try them out and a new speedo gear housing.
The 22 tooth count is wrong for a 3.08 with 215/70x15.
Factory parts book shows 19 tooth original part number 3987919 or 18 tooth 3987918
Diagnosing Speedo not working
