Sportomatic issue - desperate

[AUS911SC3]

Please help... My 78SC has a 3speed. All is running well except when at cruising speeds it keeps falling out of 3rd gear into neutral. You can keep in third but the moment you accelerate it falls out, so annoying !!! Any suggestions as to the issue... Yeah, Yeah I've already heard convert to manual. Thanks all

[Oh Haha]

I don't know a thing about Sportomatic but I think I found a thread that might help.

Good luck with your problem.

http://forums.pelicanparts.com/porsche-911-technical-forum/554855-sporto-fun-games.html

[Scott Douglas]

By 'falling out of 3rd gear' do you mean you have to physically move the shifter back into gear?
If that's the case I think your problem is in the gear shift linkage itself.
What does it do in 1st and 2nd when you step on the throttle?
If it stays in gear and accels fine, it might be your 3rd gear synchro is shot.

And no, you don't want to change over to a manual shift. =;>)

[Joe Bob]

Likely the autoclutch switch is failing.

[AUS911SC3]

Scott, it accelerates and holds beautifully in 1st and 2nd but drops out under acceleration in 3rd. I have to then put it back in 3rd and physically hold it.

[Scott Douglas]

My best guess is there's something amiss with the 3rd gear in the trans itself then. If your Sportomatic system is working as designed, when you floor it the clutch should be fully mechanically engaged and the diaphragm should be seeing atmospheric pressure on both sides so it shouldn't be influencing the clutch linkage at all (ie disengaging the clutch).
When you physically hold it in gear I assume you're holding it below the articulated portion of the shifter so you're not activating the micro-switch.
Correct?

[AUS911SC3]

That's right Scott, it's a fine position of holding it in gear and activating the microswitch. The funny thing is, above 100 kph the falling out of gear is not as sensitive as it is below 100 kph. Although it does still do it above it's not quite as sensitive.

[Scott Douglas]

Has anything changed with regards to your engine/trans mounts?
I'd also look at the shift linkage to be sure it's going completely into gear when in 3rd.