Clutch pedal question after pedal cluster rebuild

[swoodard23]

Wow, rebuilding the pedal cluster is a pain! At least the first half. Since I had it out, I went ahead and replaced the clutch and brake springs. The car is a 67. When I reinstalled the pedal cluster, the clutch pedal is much lower than the brake pedal. I did not make note of its position before the rebuild but it was functioning properly. On my 77 911, I am unable to pull up on the clutch pedal. On my 912, I can pull it up about an inch. I looked on the trans end of the clutch cable and there appears to be holes for a spring but I do not have a spring. I have not attempted to drive the car yet as I do not want to mess up anything. Just wanted to check and see if my situation is normal.
Thanks,
Scott

[swoodard23]

If I understand correctly, the clutch spring on the pedal cluster pulls the pedal towards the floor. My theory is the new spring is exerting more force than the old worn out spring. If this is so, could I just shorten the cable by tightening the adjustment screws at the trans end? Thanks in advance.

[Grady Clay]

Scott,

Did you change the clutch shaft / lever arm?
Is the white plastic bushing in the lever arm (at the clevis pin)?


Originally, your ’67 (912 or 911) had two springs in the clutch cable system.
(Earlier cars only had the transmission spring.)
One at the pedal assembly (that holds the pedal toward the floorboard) and one at the transmission (coil tension spring to a rivet in the transmission).
With both springs, the spring at the transmission had a stronger effect and the pedal remained ‘up’.
This maintained ‘free-play’ clearance to the clutch release (TO) bearing.
The clutch pedal had to travel the ‘free-play’ before operating the clutch.

In 1967, Porsche changed TO bearings to a ‘constant contact’ version (901.116.081.11).
The spring at the transmission was not installed (although the rivet anchor remained for a while).
This had the clutch pedal ‘lower’ and operated the TO bearing immediately with movement with the pedal.
The ‘free-play’ was now measured by pulling ‘up’ on the pedal.

Starting in 1968, all of the Porsche replacement TO bearings were the constant-contact version.
Every car was expected to ‘convert’ to the newer system.
This involved the new TO bearing, two plastic supports alongside the TO bearing ‘ears’ (901.116.825.11) and removing the spring at the transmission.
Seldom was the spring removed.
In some cases the spring was added since the provision was there (like yours).

So … Do you have the later ‘constant-contact’ TO bearing?
I would think so after all this time – and you have the necessary spring on the pedal assembly.
Over the past few decades, only a few extreme ‘purists’ have managed to retain the earlier version.

Do not install a spring at the transmission. If there is one, remove the spring at the transmission.
Adjust the cable length (both ends) to have the pedal position where you like (roughly the same as the brake pedal).
Adjust the clutch pedal stop to limit the travel to just past the clutch completely releasing (too far can over-stress the clutch and cause it to break).
With the transmission warm, use the shifting into reverse to see where the clutch first starts to spin the transmission.
Check the ‘free-play’ by pulling ‘up’ on the pedal – it should be 2-3 cm. (More is okay but there must be some.)


Some asides:
At the front, make sure the threaded end of the cable doesn’t extend too far through the clevis and contact the lever arm when actuated.
If too long, cut it off a bit.

There is a ‘lip’ on the pedal assembly side of the tunnel (just above and to the left of the clutch clevis) that can interfere with the throttle bell-crank.
Bend that lip for safe clearance to the throttle linkage.

At the rear, do not use the plastic piece at the clutch arm.
There is a steel (914?) part that works better.
Using this steel part, you must grind a bit of clearance on the arm so the steel piece sides won’t contact the arm during actuation.

Check the chassis where the Bowden tube seats.
The chassis sheet metal can crack here.

Grease the cable, the Bowden tube and the clutch cable tube in the chassis.

Make sure the cloth retaining strap for the Bowden tube is in place.

If you have the engine out, there are more.

Best,
Grady

[gregwils]

Does anyone know if there is a USB or ethernet connection into Grady's brain?

[swoodard23]

Grady,
Thank you for the very detailed reply! Do I check the freeplay at the pedal or at the TO arm like on 915 transmission?
I posted the same question on a 912 forum board. If you would not mind, I would like to cut and paste your answer on that forum as it contains so much useful information. I would credit you of course.
Thanks!
Scott

[DRACO A5OG]

I just rebuilt my Pedal Cluster on my 3.2. Agreed Big PITA.

I was a bit worried about the orientation of the clutch pedal, there really is only two ways it can go on the shaft to match the arm at the cable connection. I just made sure the pedal arm and cable arm were at similar orientation, "UP". With the return spring on, my pedal was either all the way back or all the way forward, I reinstalled with the pedal forward, then used a piece of block to hold it up while I reconnected the cable end. BINGO!

[rolls 912]

Don't want to hijack this thread but I've got a sticky accelerator on my 68 due to engine conversion logistics. Would a second spring at the pedal assembly be detrimental to the throttle body?

[RWebb]

you should go thru and clean or replace all parts that need it

no Band-Aids

[Grady Clay]

Scott,

No, checking and particularly adjusting the clutch is VERY different between your ’67 and your ’77.
The ’77 has all the ‘modern’ features of over-center helper springs that greatly complicate adjustment but are necessary with the far more powerful clutch.
Your ’67 is easy. Lift the pedal.

As you would expect, age and corrosion are the villain with the ’67 parts.
If (when) you have the occasion to have the engine out, there are some simple things you can do to ease the clutch operation:
Clean and lube the TO bearing guide tube and in the bore of the TO bearing.
Check (replace) the white plastic cup in the clutch arm. Inspect & lube the pivot ball.
Clean & lube (but not too much) the splines on the input shaft and in the hub of the disc.



Feel free to ‘spread the word’.
Easiest is to click the (permalink) button at the lower right of the post and then copy the shortcut or URL at the top of the screen to your destination.
Most important is to credit Pelican and provide the link to this thread.

Originally Posted by gregwils

Does anyone know if there is a USB or ethernet connection into Grady's brain?

Yes. There is a super-secret URL

Best,
Grady

[304065]

Originally Posted by Grady Clay

Scott,

Did you change the clutch shaft / lever arm?
Is the white plastic bushing in the lever arm (at the clevis pin)?


Originally, your ’67 (912 or 911) had two springs in the clutch cable system.
(Earlier cars only had the transmission spring.)
One at the pedal assembly (that holds the pedal toward the floorboard) and one at the transmission (coil tension spring to a rivet in the transmission).
With both springs, the spring at the transmission had a stronger effect and the pedal remained ‘up’.
This maintained ‘free-play’ clearance to the clutch release (TO) bearing.
The clutch pedal had to travel the ‘free-play’ before operating the clutch.

In 1967, Porsche changed TO bearings to a ‘constant contact’ version (901.116.081.11).
The spring at the transmission was not installed (although the rivet anchor remained for a while).
This had the clutch pedal ‘lower’ and operated the TO bearing immediately with movement with the pedal.
The ‘free-play’ was now measured by pulling ‘up’ on the pedal.

Starting in 1968, all of the Porsche replacement TO bearings were the constant-contact version.
Every car was expected to ‘convert’ to the newer system.
This involved the new TO bearing, two plastic supports alongside the TO bearing ‘ears’ (901.116.825.11) and removing the spring at the transmission.
Seldom was the spring removed.
In some cases the spring was added since the provision was there (like yours).

So … Do you have the later ‘constant-contact’ TO bearing?
I would think so after all this time – and you have the necessary spring on the pedal assembly.
Over the past few decades, only a few extreme ‘purists’ have managed to retain the earlier version.

Do not install a spring at the transmission. If there is one, remove the spring at the transmission.
Adjust the cable length (both ends) to have the pedal position where you like (roughly the same as the brake pedal).
Adjust the clutch pedal stop to limit the travel to just past the clutch completely releasing (too far can over-stress the clutch and cause it to break).
With the transmission warm, use the shifting into reverse to see where the clutch first starts to spin the transmission.
Check the ‘free-play’ by pulling ‘up’ on the pedal – it should be 2-3 cm. (More is okay but there must be some.)


Some asides:
At the front, make sure the threaded end of the cable doesn’t extend too far through the clevis and contact the lever arm when actuated.
If too long, cut it off a bit.

There is a ‘lip’ on the pedal assembly side of the tunnel (just above and to the left of the clutch clevis) that can interfere with the throttle bell-crank.
Bend that lip for safe clearance to the throttle linkage.

At the rear, do not use the plastic piece at the clutch arm.
There is a steel (914?) part that works better.
Using this steel part, you must grind a bit of clearance on the arm so the steel piece sides won’t contact the arm during actuation.

Check the chassis where the Bowden tube seats.
The chassis sheet metal can crack here.

Grease the cable, the Bowden tube and the clutch cable tube in the chassis.

Make sure the cloth retaining strap for the Bowden tube is in place.

If you have the engine out, there are more.

Best,
Grady

Grady, where does the cloth retaining strap for the Bowden tube on a 901 attach to the transmission?

Also, do you know where the mounting brackets for the hose clamps that retain the long oil hose attach?

THANKS!

[zarl911]

same issue myself