Speedometer drive gear replacement

[ak1961]

I recently purchased a 61 Bird. The speedometer drive gear inside the transmission needs to be replaced, it appears to be stripped and will not mesh with the driven gear on the speedometer cable. My question is, can the drive gear be replaced without removing the transmission from the car? Is there enough room to remove the tail shaft housing to do this?
Thanks, Dennis

[Karl]

G'day.
Are you sure that the drive gear is stripped. This is steel, the driven gear is plastic, one would think that the plastic gear would fail a long time before the steel.
The driven gear does not look like a normal gear, it has the teeth cut on a strange angle I think this is so it will mesh with a number of different teeth driven gears.
Karl.

[ak1961]

Looking into the transmission through the hole where the plastic driven gear and cable goes I cannot see or feel the drive gear. There is nothing there to drive the plastic driven gear and cable. The transmission is pretty clean so I am fairly certain that it was out of the car before I bought it, maybe the gear is missing?. I would like to know if the drive gear can be replaced without removing the transmission from the car? I realize that the drive shaft, tail shaft housing, and cross member would all need to be removed. I just want to know if I would be wasting my time by trying to replace this gear with the transmission still in the car.
Thanks, Dennis

[Karl]

G'day.
As far as being able to remove the driven gear from the transmission I have never done this, all I have done is take the transmission to a workshop for repair. Just ring a automatic transmission place who deals in this type of transmission, they would tell you if it is possible.
I am still puzzled why the drive gear would be missing or broken. Was the driven gear in good condition?
Karl.

[ak1961]

Karl
I have zero history about this car. It had been stored in a garage for about 25 years before I got it. It appears that the previous owner did a lot of questionable work to this car before possibly giving up on it and putting it in a garage in the early 1990's. I am happy to say that I corrected most of his attempted restoration and repair work last winter (long winters in Alaska).
Yes, the driven gear on the cable is in good shape.
Thanks for the suggestion about the transmission shop but if I have to pull the transmission i will do the repair myself, pulling the transmission is the hardest part of the job. I have plenty of time, winter is almost here again. I'm simply asking if anyone knows if this speedometer drive gear can be replaced while the transmission is still in the car.
Thanks, Dennis

[redstangbob]

Dennis, welcome to the forum. You should get online and purchase a shop manual for your car right away, they are invaluable. I'm going to say that the extension housing will come off after dropping the cross-member (and drive line of course). There could be an inner seal or packing for the output shaft. The gear is driven by a ball bearing if I remember, and retained by a spiral lock ring. good luck, Bob C

[ak1961]

Thanks Bob,
I do have a manual for my 61, it has been extremely helpful sorting out many issues. It looks like the drive gear problem can be addressed without removing the transmission from the car but want to make sure that I'm not missing something. I know the job would be fairly simple with the transmission on a work bench but I don't really want to pull the transmission just for a speedometer gear. I'm gonna give it a shot this winter without removing the transmission .
Thanks, Dennis

[Blobird]

Hi AK1961, I've switched the driving gear on a 1964 Thunderbird once and it went smoothly. (1963 and 1964 are the same at that point)
You do not even need to drain the oil from the pan.
As you said, you need to lower the rear of the box and support it, and take down the driveshaft ofcose.
Remember to lift the rear end of the car more than the front so that the oil does not drain when taking down the rear of the gearbox.
PS: On the 64 T-bird that I switched the driven gear on, the original was a plastic gear that had broken in two parts, but I mounted one of steel from anather cruse o matic ,and it went well,

Good luck :-) /Lennart Sahlin Sweden

[ak1961]

Thanks Blobird,
That is exactly the info that I wanted to hear. It seems that there is enough room under the car to do this repair but I just wanted to make sure that I wasn't missing something.
Thanks, Dennis