911 engine mounts to stiff for a 914, 1.7?

[lars s]

I changed all 4 of the cracked engine and gearbox mounts to the 911 type (since the 914's are not available anymore).
Porsche 914 Main Engine Components - Page 2

The car is an all original 1.7 tail shift.
Tightned them to 3,0 kgm which I believe is the recommendation. This caused terrible vibration/noise in the coupe, losened them quite a bit and the noise was OK.

Anyone has any experience on this?

I have also discovered that the mountings maybe only are recommended for the front?


/Lars S

[Joe Ricard]

Really? I used Polyethelene (plastic cutting board) for the front motor mounts and transaxle mounts. I thought it was just fine. But I had a fire breathing Raby 2316-210 kit and Tangerine header, no firewall pad. Shifted GREAT !!!! and fast as crap.

[luskesq]

I have a '70 tailshifter and used the sport mounts (purchased from our host) for both the engine & trans. No issue with vibration or noise. I certainly wouldn't be loosening them. I would suspect you have another issue with regard to the vibration. Assume your lugs are correctly re-torqued.

Good luck,

Keith

[lars s]

Thanks everyone!
The vibrations are already when standing still and reving up/down and especially at heavy acceleration.

/Lars S

[Joe Ricard]

Then it's the motor, Maybe time for a tune up and check things for looseness.

[TheCabinetmaker]

I see three different brands of mounts offered on this website for the 911 motor mount. Could there be a differenace in stiffness between the brands offered?

I have the 911 type on my 914 with no ill effect.

could it be you were just used to a very low vibration level with your old worn out mounts, and now the new mounts seem too stiff becuase that is not what you where used to?

I guess it is kind of hard to gauge the vibration you are feeling. Maybe it is normal?

I had a horrible vibration on one car, it turned out to be the pilot bearing. with the pilot bearing out of action, the clutch disc would end up where ever it wanted to be (usually off center)_ and that caused a lot of vibration.

[lars s]

Thanks everybody!

Yes I also believe it is the motor, it has just been put togeter and the pilot bearing was checked OK.

There is also one (1) strange heavy "clonk" once at every turn when using the starter but no strange sounds at running...maybe some more vibrations then normal.
History of the engine is a bit unknown but the old flywheel had cracks from center from hard driving i assumed but maybe it was from unbalance.
New flywheel and clutch was taken from a good running engine so that should be OK.
All bearings new, crank turnded smoothly on bench.
Now I have to take things apart again.
Can the crank be out of line...?


/Lars S

[Dave at Pelican Parts]

Flywheel/crank assembly may be out of balance...

--DD

[lars s]

Originally Posted by Dave at Pelican Parts

Flywheel/crank assembly may be out of balance...

--DD

Thanks Dave!


It also has that heavy "clonk" once every turn only when operating by starter...maybe the flywheel isnt 100% aligned/set and the starter has to "jump" on the notches once every turn sins the flywheel is at wrong angle...possible?


/Lars S

[lars s]

Changed back to the old mounts in the front- everything seems OK, no "clonk" anymore, vibrations only as they have been before.

New question:
When I crank the engine I can see that the clutch arm is wobbling a bit (approx 1mm in its outer end) is this normal?
Through inspection holes I can see flywheel and clutch non wobbling.


/Lars S

[TheCabinetmaker]

I havent looked on the clutch arm movement on my car, but there should be a small amount of free play in the clutch cable when it is engaged. thus I would expect a small amount of free play in the arm when clutch is engaged. if you were to suddenly get a lot of free play I would suspect a failing clutch cable, or failing arm pivot point (plastic cup in ball housing) If your cluth is engaging/disengaging normally I wouldn't be concerned with this small amount of play (1 mm)

[lars s]

Originally Posted by TheCabinetmaker

I havent looked on the clutch arm movement on my car, but there should be a small amount of free play in the clutch cable when it is engaged. thus I would expect a small amount of free play in the arm when clutch is engaged. if you were to suddenly get a lot of free play I would suspect a failing clutch cable, or failing arm pivot point (plastic cup in ball housing) If your cluth is engaging/disengaging normally I wouldn't be concerned with this small amount of play (1 mm)

Many thanks!
I think the clutch pedal spring (which wants to push the pedal DOWN on these cars ) will elliminate the play in the clutch arm when it is released, making the release bearing softly in touch with the clutch...or am I wrong there...?


/Lars S