Speedo Drive 915

Snow is melting, so I am planning the works for spring, basically stopping oil leaks.

My 915 tranny seems to leak from the speedometer drive, attached to the front end of the housing. Is there any way to replace this without dropping the engine/tranny?
What will cause the leak? O-Ring?

Thanks for any suggestions,

Jens
'76 CIS with '73 body conversion

Anyone???

Mine's doing the same - I thought I'd fixed it by tightening it when I had the engine out but it's still leaking. I plan to fix it this weekend. Mine's a 901 transmission but I think the procedure is near enough the same.

Jack up the back end of your car and support it on axle stands under the torque bars.

Jack or block up your transmission case at the front end. Remove the transmission support bar which will give you decent access to the speedometer drive to remove it.

Inside there is a speedometer drive seal (999.701.349.40 see Stoddard catalogue)it's described as an "O ring" and costs about a buck. My plan is to remove and replace it.

There must be different versions of the speedo drive from the 915 tranny because my drive is electrical, located near the passenger side final drive.

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'83 SC

Allan, keep me posted!

Superman, you are right. I think in '76 they switched to the electrical tach. But mine is still mechanical (Porsche was often using parts which were available, even if the majority of cars were equipped with a modification already).

Thanks guys, my spring project grows but is looking managable again...

Jens

Just a thought. Have you identified exactly where the leak is. As far as I can see there are two possibilities. You need to check the Haynes manual for the exploded view. You will see there are two places it can leak and there are two seals to prevent this.

The speedometer drive comes off by undoing the exterior nut, at the base of the drive there should be an "O ring seal". This is the seal I referred to before. This is the seal I plan to replace because the leak I have is through the speedometer drive.

When you remove the speedometer drive you do not remove it from the gear casing but from a sleeve in the casing which is held in place by a lock screw/bolt through the side of the casing. If the oil leak is from between this sleeve and the gear casing then you will need to pull this part and change it's seal.

If you're not sure then it's probably a good idea to change them both.

I believe it was designed this way with two parts so that the speedometer drive can be changed without draining the gearbox. If you pull the outer sleeve without doing so you'll probably wind up with a quart of oil in your armpit.

Thanks for the warning!

I have already some experience with oil (maybe you remember that my oil tank screw is still frozen).

Jens

Thanks for the warning!
I will look into the Haynes'.

I have already some experience with oil (maybe you remember that my oil tank screw is still frozen).

Jens