Help - Clutch seems to engage at full throttle

[sexydego7]

I'm having a problem that I wanted to get some opinions on. I have been reading all through the forums here and have some ideas currently. I have a 1978 911 that when I really get on the pedal, regardless of gear, the car acts like I have just pushed in the clutch. It revs up really high. To "fix" it, all I have to do is ease off of the pedal to about half way, and then it seems to catch and it runs fine. As long as I don't go about 3/4 down to the floor, then the car has no troubles at all. Shifting isn't difficult or anything and, under normal conditions, the clutch pedal has about an inch play or so before it begins to engage when I push on it, which I believe is about right.

A guy I know who is good with these told me to make the problem happen, and check the clutch as it is happening, to see what the pedal feels like. When I get a chance to do that, I will post it. As far as possible problems, he says that it's possible the clutch needs adjusted, the clutch cable has stretched (as they are prone to do in these years), or maybe the motor mounts are bad or loose, causing the engine to move slightly when I get up to that high torque and thus engaging the clutch.

Sorry this is so long, but I figured I'd get it all out to give you guys out there the full picture. Thanks for all your help in advance!

[equality72521]

Sounds like a worn clutch disk to me. Sounds like it's slipping under full load.

[JerryL]

Originally Posted by equality72521

Sounds like a worn clutch disk to me. Sounds like it's slipping under full load.

+1
If you have no freeplay you may get lucky with cable adjustment but most likley you are in for a new clutch.

Regards

[doublestuff]

Just for the record, when you depress the clutch pedal, you are DISENGAGING the clutch, as it is breaking the connection between the trans and the engine.
And my guess is you need a new clutch.

[kidrock]

+2. Sounds like a clutch disk replacement is probably in your near future. To make sure, adjust your cable to give yourself more free play in the pedal. If this does not solve the slipping problem, replace the clutch.

[175K911]

Or possibly a worn out pressure plate. If the fingers are getting weak, they may not be able to maintain the pressure on the clutch disc necessary to keep everything engaged under full load. Cable adjustment might help but I'm thinking a clutch assembly replacement might be in order, sorry

[Gunter]

Originally Posted by sexydego7

I'm having a problem that I wanted to get some opinions on. I have been reading all through the forums here and have some ideas currently. I have a 1978 911 that when I really get on the pedal, regardless of gear, the car acts like I have just pushed in the clutch. It revs up really high. To "fix" it, all I have to do is ease off of the pedal to about half way, and then it seems to catch and it runs fine. As long as I don't go about 3/4 down to the floor, then the car has no troubles at all. Shifting isn't difficult or anything and, under normal conditions, the clutch pedal has about an inch play or so before it begins to engage when I push on it, which I believe is about right.

A guy I know who is good with these told me to make the problem happen, and check the clutch as it is happening, to see what the pedal feels like. When I get a chance to do that, I will post it. As far as possible problems, he says that it's possible the clutch needs adjusted, the clutch cable has stretched (as they are prone to do in these years), or maybe the motor mounts are bad or loose, causing the engine to move slightly when I get up to that high torque and thus engaging the clutch.

Sorry this is so long, but I figured I'd get it all out to give you guys out there the full picture. Thanks for all your help in advance!

Get the Bentley SC Repair Manual.
Adjust the clutch as per manual.
If the problem persists, most likely disk is at its lifes end.
Post a picture of the underside showing the clutch levers.
The positioning lever can indicate if the disk is worn.
Lots of miles on the clutch?

While you're under there, eyeball the mounts.

[sexydego7]

Thanks for all the suggestions here... I will check it out and get back to you. Just moved so it's a bit slow getting to work on my baby here. I'll post some pics once I can get under it.

Question - If a disk is bad in the clutch, can that be replaced, or do you have to replace the entire clutch? I have never had the "pleasure" of working on a clutch before.

[sexydego7]

Oh, one more thing. I cannot verify the mileage on the clutch, though the last owner did not change it or anything. The chassis has 93000 miles on it, so I can assume the like for the clutch. Engine had a rebuild about 7000 miles ago.

[9dreizig]

Clutch plate only can be replaced, however be sure to re-surface the flywheel and pressure plate at a minimum.. There are some shops that can do some measurements on the pressure plate and tell you if it's ok or not.

[JoeyD911]

There is no way someone would do a complete rebuild and not replace a 90K plus mile clutch and pressure plate. It's just one of those, hey while i've got the engine out, kind of things. Who did the rebuild? If they did replace the clutch at that point they should be able to tell you. Is there any clutch smell when this happens. Ypu can't miss clutch smell. it's nothing like gas or burnt oil. Any noise other than the engine reving?

[MURF]

check the easy things first..are you sure your clutch cable is routed correctly at the accelerator ..not wrapped around it?

[sexydego7]

I am most definitely going to check the easy stuff first. I am going to check the clutch cable at the accelerator too. i have never verified that.

As a side question in case the worst is true - does anyone know if you can take out the trans-axle without removing the engine? That would make messing with the clutch if the plate needs replaced much easier!

[9dreizig]

Nope, you've got to drop the engine, not that bad really.. Where are you, I'm sure there's a Pelican or two around to help you.

[Flat6pac]

Check and make sure your connectors at the pedals are not crossed. 30 years ago I had a914 that if I hit the clutch it would rev the engine.
Turned out to be crossed clutch cable and accelerator cable

Bruce

[Gunter]

The Bentley will be a great help to adjust the clutch and, if necessary, in removing the engine/transmission together to access the clutch for replacement.

Read up on the procedure; get a big floor jack and the necessary tools and search PP for details/pictures on engine-removal.

Follow the steps, mark the wires and hoses for easy identification later, take pictures.
It's doable but not quite as easy as some people make it out to be; play it safe.

[sexydego7]

I just ordered a new clutch cable and that spring near it. Figured it wouldn't be a bad idea to replace it anyway, especially since they can go bad. Maybe I'll be lucky and it just needs adjusted, but if not, out the engine will come.

Unless someone thinks it is a bad idea, I may just wait out the driving season here in PA, and make it a winter project, take my time, etc.

Now if I do need a clutch, anyone have any recommendations on clutches, because now is the time to upgrade :-)

[Mattcamp]

Take a picture of the clutch arm where the cable attaches. There is a bolt w/ a lock nut on it that is suppose to be adjusted. That adjustable bolt will tell a story about the clutch.

Post Pic!

[Gunter]

Ill say it again:

Get the Bentley SC Repair Manual.
Adjust the clutch as per manual.
If the problem persists, most likely disk is at its lifes end.
Post a picture of the underside showing the clutch levers.
The positioning lever can indicate if the disk is worn.
Lots of miles on the clutch?

While you're under there, eyeball the mounts.

[gregwils]

Where are you in Western PA? I am in North Hills of Pgh. Just did my first engine drop for a clutch, but the project is still under way. I haven't reinstalled the motor yet, so hopefully no surprises await me.