Transmission speedometer gear replacement help needed

[adreyer]

I am looking for help with replacement of the speedometer gear in the transmission on a 74 911 Targa. I am wondering if replacing this gear is something I should take on myself, or should take to a professional for help. As you can see on the attached photo, the gear has sheared off at the front of the transmission. I have had the car for three months, and have identified this broken gear as the source of the non-working speedometer. As I understand it, removing the plastic lock ring and rubber oil seal should allow for changing out the gear. It appears this may be possible to do without dropping the engine and transmission. Would it be a mistake to take this on myself? I feel up to the task, although am essentially a novice. I anticipate draining the transmission fluid, removing the ring and seal, then replacing the gear. I can order a new seal and lock ring with the new gear. Does the engine and transmission need to be removed to make this possible? Your input would greatly appreciated.

[ducatithunder]

IIRC when I took my trans apart that piece gets pushed out through the case. Under the seal there is a small circlip that holds the geared drive in place. I didnt know that and broke the clip by using a press to push out the gear. Just had to get a new clip .. no biggie just a good lesson. Pull the clip and it should pop right out. The circlip keeps the little gear wheel from being pushed into the transmission case and meshed with the speedo cable. I had the rear cover removed as the trans was being rebuilt. So in my experience the cover has to be removed and oil will have to be drained. Not sure if you have enough room to take the cover off with the trans in the car or not. Here is a picture of the parts assembly.

[Steve]

You will need to remove the engine & transmission from the car to remove the 915 front cover & gain proper access to everything. Naturally, you'll need to drain the oil from the transmission, too.

[adreyer]

Thanks much! That is what I feared. Time for expert help!! Glad I did not start to pull it apart myself.