1985 Porsche 911 1985 Porsche 911 transmission issue

TXPORSHE

MEMBER
1985 PORSCHE 911
6 CYL
2WD
MANUAL
60,000 MILES

My 1985 911 transmission seems to be slipping. It's most noticable in 2nd or 3rd gear. When you try to accelerate hard the engines revs but does not accelerate, then you back off a bit and then it engages ok. I don't think its' the clutch. 1st gear does not seem to be a problem taking off. And from a stop and trying to start in 4th gear it does not slip, you can get going without reving the engine. Any thoughts on what it could be? What it would take to repair?
Thanks!

3 Replies

JAMES W.

MECHANIC
2,395 POSTS

It has to be your clutch. A manual transmission can't slip. If it did only one time, it would destroy itself.

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Sunday, March 29th, 2009 AT 8:02 PM

TXPORSHE

MEMBER
2 POSTS

. But how do you explain the no slipping in 1st when taking off and being able to take off from 4th?

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Sunday, March 29th, 2009 AT 9:31 PM

JAMES W.

MECHANIC
2,395 POSTS

In 1st gear the ratio is so low, there's not a lot of strain on the clutch so it's less apt to slip. In 4th gear, the engine "power curve" is so low it doesn't generate enough hourse power to slip the clutch. A 911 engine is high horsepower but low torque. It doesn't generate higher horsepower and torque until they get up in the revs.

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Tuesday, April 7th, 2009 AT 1:33 AM