clutch cable adjustment help

[GMR911]

Just rebuilt my pedal cluster and installed new clutch cable. After installing the pedal cluster this morning spent most of the afternoon trying to adjust the cable. Set the clevis pin adjustment to 20mm at the pedal shaft. Adjusted the the rear as per spec, 1.2mm at the arm and adjusted the locking nuts until the arm clearance becomes 1 mm. Here is what I get- a clutch pedal that has little travel, won't return to normal upright position, the omega spring won't return to resting position. and the measured cable throw was about 14mm instead of the 25mm in was supposed to be. Before I did this work the clutch adjustment was fine, the omega spring returned to resting position and the clutch pedal travel was good. Any ideas to what I am doing wrong. Thanks Jerry

[rusnak]

Make sure the cable sleeve is fully seated in the firewall tube.

[boyt911sc]

Originally Posted by rusnak

Make sure the cable sleeve is fully seated in the firewall tube.

We did a clutch cable replacement a couple weeks ago and the initial adjustment was perfect. A few days later it changed dramatically and out of spec. We suspected that the cable sitting on the tube was not completely settled in when we did the initial adjustment. And after driving the car it somehow moved and shifted completely in position causing the clutch pedal to sag. After the re-adjustment and getting a 25 mm travel, everything seems to be back to normal and shifting very well.

Tony

[GMR911]

had a hard time getting the cable to seat over the tube on the fire wall but was seated properly when the adjustments were made, jerry

[Groesbeck Hurricane]

If you are still having difficulty I would suggest that you would try to pull the cable and re-install. As the other two posters intimated, the culprit could be the cable getting in a bind.

Check that you have attached the cable to the correct locations on both ends and that the omega spring is properly installed.

[bob deluke]

Gerry,

You didn't get the clutch cable twisted over the accelerator cable did you? Are you sure there are no remnents of the old clutch cable housing left in the clutch tube? Are you absolutely sure the clutch cable housing is seated properly?

[sabeo.m]

Jerry, I remember when I replaced my cable the cable was not fully seated at the tunnel and the nut on the clevis pin was not fully tighten making the adjustment out of spec every time I moved the cable. It's kinda of a pain to fully tighten the clevis nut so that it doesn't move.

[Gunter]

Originally Posted by GMR911

Just rebuilt my pedal cluster and installed new clutch cable. After installing the pedal cluster this morning spent most of the afternoon trying to adjust the cable. Set the clevis pin adjustment to 20mm at the pedal shaft.
Why 20 mm? 20 mm is about 3/4". That's a lot. I recall JW saying that ~8mm (3/8") is recommended because if it sticks out too much it might interfere with travel

Adjusted the the rear as per spec, 1.2mm at the arm and adjusted the locking nuts until the arm clearance becomes 1 mm. Here is what I get- a clutch pedal that has little travel, won't return to normal upright position, the omega spring won't return to resting position. and the measured cable throw was about 14mm instead of the 25mm in was supposed to be. Before I did this work the clutch adjustment was fine, the omega spring returned to resting position and the clutch pedal travel was good. Any ideas to what I am doing wrong. Thanks Jerry

The curved tube angles upward, directing the flex tube up over the throttle bellcrank. the clevis fork at the pedal end needs about 8mm of thread protruding out of the middle of it in order to get a decent adjustment at the rear. JW

Help with the bow in clutch cable - Pelican Parts Technical BBS

[Peter Zimmermann]

Something in this article that I wrote a while ago might help...

Clutch cable installation – 1977-1986

OK, first I must make a few assumptions; (1) the pedal assembly area has been cleaned, (2) the clutch pedal helper spring on the left side of the pedal tray is in good condition, (3) the clevis pin bushing has been replaced, (4) the rear of the car is in a raised position, and properly/safely supported, and (5) if your old cable, at its Bowden tube, passed through a hangar/anchor attached to the side of the transmission, roughly above the throttle lever, remove that anchor and re-install the nut with a wavy lock washer. The hangar will not be re-used.

First, put a thin coating of grease (I like amber disc brake wheel bearing grease) on the new clutch cable. Installation into the car is tricky, because you don’t want that greased cable to touch anything, and drag dirt along with it. While lying under the car guide the clevis end of the cable over the throttle lever on the side of the transmission (clean towels, rags, even newspaper, placed to help keep the cable clean can be invaluable), and into the cable attachment tube welded onto the firewall. Push the cable forward until the Bowden tube reaches the firewall tube, and push the cable home over the firewall tube.

Move to the inside of the car, locate the front end of the cable in the tunnel, and pull it out from the tunnel. Wipe the threads off because usually a little bit of dirt will be sticking to them. Screw the jamb nut on to the cable. On cars with a known good clutch, leave six threads on the clutch cable showing between the rear side of the jamb nut and the rear end of the threaded section of cable (in other words, screw the nut on until it almost bottoms out, then back it off until you can count six threads). Screw on the clevis fork until it reaches the nut, but don’t tighten it; the chance that the other end of the cable is at the correct position to install over the hook will be slim. Push the cable into the tunnel until the clevis fork lines up with the clutch pedal shaft, and push the clevis pin home with a light coat of high quality grease. Your final step before getting out of the car is to pull the clutch pedal up from the floor and support it in that position (I use a 13mm open/box wrench for this, probably because it works so well I’ve never bothered to make a tool).

OK, back under the car. Take your pry bar (large flat-bladed screwdriver), your 2x 15mm open end wrenches, 2x 13mm open end wrenches, and your circlip pliers with you. Hook the cable onto the hook on the long cable arm and use the pry bar to push that arm toward the rear of the car – use your head, the spring is very strong, and you don’t want fingers in the way. Loosen the adjustment bolt jamb nut, also on the long arm, and back off the bolt a little. Grease the splines on the TOB fork shaft, slide the short arm on, and install the circlip. Take the end of the Bowden tube, spread the 15mm nuts apart enough to fit over the aluminum anchor, and, with a lock washer on each side, slip the cable into place on the anchor. To save a problem later, slide up under the firewall and make sure that the forward end of the Bowden tube is properly seated.

Now, go back inside the car and take a 12mm and 10mm open end wrench with you. Remove your clutch pedal brace, and push the pedal down to the floor and hold it there while snugging the jamb nut to the clevis fork (I use my left elbow against the clutch pedal, use my left hand to hold the 12mm wrench in place on the clevis, and snug the nut using the 10mm wrench in my right hand). It’s a little awkward, but you can figure out the best way that will work for you. Release the clutch pedal from the floor; it should come up close to the top of its regular travel.

Now for the fun part, cable adjustment. You should be back under the car, hopefully you still have your 15mm and 13mm wrenches with you, and you also need two feeler gauges; a 1.0mm and an 0.2mm. You can also use, of course, a 1.2mm gauge along with your 1.0 gauge; I found it easier to have the first two gauges, and use them together for the initial setting, then use only the thick one for final adjustment.

With the clutch cable slack, adjust the distance between the end of the adjustment bolt and the tip of the short arm to 1.2mm. The gauge should come out with a bit of resistance. Hold the head of the bolt and snug down the jamb nut. Next, use the two 15mm (wrench size) nuts to gradually tighten the clutch cable, keeping in your vision where the arc of the Bowden tube is, and concentrating on the gap that you’ve set to 1.2mm. The Bowden tube should rest about an inch from the side of the transmission, and you can actually see your gap at the adjustment bolt begin to close. When it does, wiggle the cable near its hook, it should be pretty tight. Insert your 1.0mm gauge in between the adjustment bolt and the tip of the short arm, and use the 15mm nuts to continue to tighten the cable until your gap is 1.0mm. Watch the Bowden tube as you final snug the two 15mm nuts, depending on how you turn them the tube will want to move out of its desired position.

Re-enter the car, and depress and release (by hand or foot) the clutch pedal a few times. Go back under the car and recheck your cable tightness, and your measured gap. Adjust as necessary keeping in mind that all changes must be done by keeping the Bowden tube in position, the cable tight, and the final gap at 1.0mm.

Go inside the car, reinstall the floorboard and carpets (make sure that the gas pedal rod is seated properly in the gas pedal), pat yourself on the back and go for a drive.

[GMR911]

Thanks for all the replies- Peter, I uses your article for one of my sources. I may change the the length of cable at the clutch pedal. If I go to 22 mm(the old cable was set at 23mm) from the 20mm where i set it initially what effect would this have on the pedal height or omega spring. Remember, 2 of the issues are the omega spring not retuning fully to rest and the clutch pedal not returning all the way, Thanks again Jerry

[Gunter]

Scratching my head here.

If someone like JW says it should be 8 mm, why would you go to 23 mm??

Just think about how a Bowden cable works: Whatever you do on one end will have an effect on the other.

How about posting a picture showing the complete set-up underneath in situ?
And what type/year is this 911?

[BernieP]

For what its worth my 1980 SC does exactly the same thing. It shifts fine but the pedal will not return fully up. I have tried everything but moving the arm on the throw out shaft.

[Flieger]

This is my 1971 911

[Peter Zimmermann]

Originally Posted by GMR911

Thanks for all the replies- Peter, I uses your article for one of my sources. I may change the the length of cable at the clutch pedal. If I go to 22 mm(the old cable was set at 23mm) from the 20mm where i set it initially what effect would this have on the pedal height or omega spring. Remember, 2 of the issues are the omega spring not retuning fully to rest and the clutch pedal not returning all the way, Thanks again Jerry

I'm still not completely clear on the 20mm/23mm measurement that you are using. What exactly is that dimension for, the amount of threaded cable that you can see inside the clevis?

From above...On cars with a known good clutch, leave six threads on the clutch cable showing between the rear side of the jamb nut and the rear end of the threaded section of cable (in other words, screw the nut on until it almost bottoms out, then back it off until you can count six threads).

[GMR911]

The measurement is 20 mm from the locking nut to the end of the cable before the clevis pin is put on. after the clevis pin is put on about 8mm is left showing. The 23 mm that the previous cable was adjusted to yielded 11 mm of thread.The car is a 77. Thanks again Jerry

[GMR911]

Just came in from the garage, very frustrated, with lots of questions. I started this project a few weeks ago, pedal cluster rebuild and clutch cable replacement. The omega spring was always in the most rearward position and the clutch pedal was always at the top of its travel(with little freeplay), like the omega spring was pulling the clutch pedal to the top of it travel. Now after numerous attempts of adjustments and after depressing the clutch pedal the pedal won't come to the top and the omega spring doesn't spring back. Questions
1) The omega spring seems to have 2 positions of rest, one forward and one rearward. to get the rearward position you need to pry the lever backward and the omega spring springs back to this position. a) as stated before my omega spring always seemed to be in the rearward position at rest pulling on the clutch pedal without having to pry it into this position, is that normal, now when I depress the clutch pedal it won"t spring back to that position. b) at what position of the omega spring do you set the adjustments the forward or rearward position.
2) what effect on does lenthening or shortening the clutch cable have on the pedal/omega spring
3) My clutch cable rests against about a 1/2 " tube protruding out of the fire wall. The cable slides over and seats over a tube that protrudes from this tube from the fire wall, Any one have a picture of their cable seating at the firewall?
4) What effect does adjusting the clevis(at the clutch pedal lever) forward or backward have on the system.
Thanks for any info, Jerry

[GMR911]

Also, my omega spring when snaps back hits and stops at the cross over pipe. I don't think it is fully snapping back all the way. There is a stop pin on the mechinism and it is not even getting close to that stop. I have SSI's and the lip of the SSI has been pounded flat so when the omega spring goes forward there is clearance. I also read that there is different positions the omega spring can be attached? Thanks Jerry

[lindy 911]

Post a picture of your Omega spring and the cable attachment. Mine was on backwards when I first re-installed my '78 3.0. The spring, when installed correctly, will snap back to a rested position pulling the cable and pedal back to upright. Do you have a Bentleys manual?

Lindy

[Gunter]

GMR911,

It might help if you post a picture like this:

[GMR911]

Yep, omega spring on backwards. My spring faces the back towards rear of car. It broke 30 years ago when I first bought the car. The mechanic who put it on put in on backwards. Been driving like that for 163,000 miles! Maybe its a universal application, either way? Ha Ha. Now, how hard is it to take off? Any do and don"ts to this job. When taking off the arm does it have to be indexed to the spine when pulling it off. The spring should be in the relaxed position I would think. Any other thoughts. Thanks for all the replies, Jerry