Clutch adjustment - pedal not fully returning?

[Locker537]

I attempted to adjust the clutch in my 1979 911 SC tonight. Prior to adjustment, there was no play in the stop bolt. The gap was 0. I'll explain what I did thoroughly in case I did something rather...inexperienced.

Prior to adjustment, the clutch engaged smoothly, pedal returned fully. Performed properly. I believe the clutch is only a couple years old and there are no signs of issues. I can triple check my records.

I loosened the cable quite a bit but did not actually remove it from the arm. I set the gap to .047 (stacking two feeler gauges - .026 + .021) by adjusting the stop bolt. I then re-tightened the cable until I had a gap of .040 (again, two gauges - .021 + .019).

At this point, I checked the clutch pedal and noticed it was depressed approximately 1/4-1/3 of its travel, as though it was sagging.

I repeated the procedure and ensured the pedal did not sag while adjusting my wedging it in the fully disengaged position with a roll of paper towels. This time, the pedal still does not fully return, but can be fully returned with a little tug.

I enlisted a helped (my wife, allowed during social distancing) and repeated the process again with her in the car so she could test and also tell me what the clutch was doing during adjustment.

Again, the pedal is failing to return fully. I captured some videos:



Is the omega spring binding?




Here's the view at the pedal, with pedal board removed.


I put the tiniest amount of lubricant on the clutch pedal spring recently, but don't believe that is related.

Thanks in advance for the help!

[icarp]

It looks like you need a new omega spring. thats a normal wear item

have fun with your car!
Ian

[Locker537]

Originally Posted by icarp

It looks like you need a new omega spring. thats a normal wear item

have fun with your car!
Ian

Are you referring to the primary "horse shoe" spring?

https://www.pelicanparts.com/cgi-bin/supertech/catalog.cgi?action=frameset&return-url=/cgi-bin/supertech/catalog.cgi%3Faction%3Dframeback%26page%3D13&catalog-url=https%3A%2F%2Fwww.pelicanparts.com%2Fcatalog%2 FSuperCat%2F0792%2FPOR_0792_TCLUTC_pg3.htm%3Futm_s ource%3DSuperTech%23item18

[Mike Andrew]

Had the same issue and it took a couple of tries to get it right. Works fine now.
Is cable snug?

[theiceman]

also make sure the helper arm is moving freely on its shaft . if it binds you can end up making the wrong adjustment for you 1.0mm gap.

[hughc]

Not sure if this applies in your case but I've noticed everytime i did a clutch adjustment the pedal would drop to the floor once the cable was removed at the adjustment end.
What i have been doing is putting a bungy cord around the clutch pedal, fastened to the steering wheel, to keep the pedal in place during the adjustment.
Once the adjustment is complete I remove the bungy cord and everything is fine. Great clutch engagement. Good luck.

[Locker537]

Originally Posted by Mike Andrew

Had the same issue and it took a couple of tries to get it right. Works fine now.
Is cable snug?

Not as snug / tight as it was prior to adjustment. I can wiggle the cable a bit by hand. That said, any tighter and I can't achieve the proper adjustment.

Originally Posted by theiceman

also make sure the helper arm is moving freely on its shaft . if it binds you can end up making the wrong adjustment for you 1.0mm gap.

It appears it is, but I will double check. I'm under the impression I caused this issue during adjustment as it was not happening prior.

Should I lube any particular parts of the assembly?

Originally Posted by hughc

Not sure if this applies in your case but I've noticed everytime i did a clutch adjustment the pedal would drop to the floor once the cable was removed at the adjustment end.
What i have been doing is putting a bungy cord around the clutch pedal, fastened to the steering wheel, to keep the pedal in place during the adjustment.
Once the adjustment is complete I remove the bungy cord and everything is fine. Great clutch engagement. Good luck.

Yes, I noticed this as well and I think it was one of the causes of challenges.

I also wonder if only having the rear of the car lifted it making it worse. Seems unlikely but I don't know.

Is there anywhere along the cable or in the pedal cluster where the cable can accidentally disconnect or bind if all the tension is removed?

[KTL]

Anybody please correct me if I’m mistaken but the omega/horseshoe spring isn’t providing return spring effect. It’s actually an over-center spring that provides assistance in disengaging the clutch. So its purpose is to reduce pedal effort and you can actually feel it “kicking-in” at some point when you push the pedal. Also need to have everything in good working condition, especially the cable, to have the clutch feel right (requires not much effort) and return properly

I remember my car, when my friend Mark (RIP) owned it, went through some clutch learning. He replaced the clutch and installed a new cable too. Something wasn’t right and he had to replace the cable. Turns out he routed the cable upside down and that compromised the new cable. He installed another new cable and it was a night and day difference. Clutch pedal effort was MUCH lighter and like I said you could feel the horseshoe spring kicking-in to assist in pushing the pedal

[stevej37]

Originally Posted by Locker537

Is there anywhere along the cable or in the pedal cluster where the cable can accidentally disconnect or bind if all the tension is removed?

Yes..definitely. I had my 84 in the shop a few years back after experiencing the same thing. Tried over and over adjusting the cable. Clutch was working...the cable just wasn't working right.
I got it back and the mechanic said it was a $5 part..(plus 2.5 hours of labor)
He said it was the pin in the pedal cluster for the clutch. With age, it wears down enough to give the cable too much slack, at times. He said he sees it often.
Been working perfectly since.

Edit: Just checked my receipt....$170 for part and labor. Fair price I figure. The receipt didn't state the pin part number.

[Mike Andrew]

Have you checked the clutch travel and verified .098 +/- .020 using a helper in the car? Have you tried tightening the cable a bit just to see if the pedal pops back? Could be that you can play with the tolerances to get where you need.
Seems to me that if it worked before you adjusted it, there is something amiss in your process and it should be fixable. Or, it was improperly adjusted to fix this pedal problem. I hate issues like this as they frustrate the snot out of me until I sort them out.

[KTL]

Also keep in mind for future reference that a cable refusing to hold an adjustment can be a cracked release fork

Clutch/Flywheel Analysis

[Locker537]

Originally Posted by Mike Andrew

Have you checked the clutch travel and verified .098 +/- .020 using a helper in the car? Have you tried tightening the cable a bit just to see if the pedal pops back? Could be that you can play with the tolerances to get where you need.
Seems to me that if it worked before you adjusted it, there is something amiss in your process and it should be fixable. Or, it was improperly adjusted to fix this pedal problem. I hate issues like this as they frustrate the snot out of me until I sort them out.

Exactly how I feel.

If you watch the video, I don't think there are any cracked or overly worn components. I agree that since it was working properly prior to adjustment, something I did is likely the culprit.

[Locker537]

Here's a couple pictures in case they reveal anything interesting:

[proporsche]

remove the little finger..it looks like you have too much thread behind the 15mm adj.nut to see.Basically loosen the nut towards the front of the car..the Omega spring will go back to its position.BTW there is nothing wrong with the OMEGA spring..Once you get the arm back to it correct position ,install the little finger back in place and to the adjustments..
Ivan

[Locker537]

Originally Posted by proporsche

remove the little finger..it looks like you have too much thread behind the 15mm adj.nut to see.Basically loosen the nut towards the front of the car..the Omega spring will go back to its position.BTW there is nothing wrong with the OMEGA spring..Once you get the arm back to it correct position ,install the little finger back in place and to the adjustments..
Ivan

Can you clarify what you mean by remove the little finger? Do you mean the smaller actuating lever arm?

I'll be heading into the garage to attempt to solve this in a few.

[proporsche]

yes ..back in the days how we called it..remove the c.clip then the arm plus the spring...once it is off..ease up on the adjustment on the 15mm open wrench nut...while doing this the arm will move back to the position if not ,use a big screwdriver and pull on it until it almost hit the exhaust cross pipe.only after this you pu t back the little finder and the spring ..
Ivan

[Locker537]

I have completely removed the cable and I believe ensured the arm is fully in the disengaged / resting position.

I ensured the cable is seated at the firewall.

I removed the pedal board and don't see anything obviously binding. That last inch of pedal play feels weird.

If I over tighten the cable, the pedal feels better, but still binds a little bit at the top of the travel.

proporsche - I'll admit I am a bit hesitant to pull that arm at the moment

[Locker537]

I remain defeated tonight.

I took a couple more videos to show the "binding" I'm experiencing and the pedal not returning the last inch or so.

[proporsche]

your clutch cable is too tight ..you have to release the cable so the Omega spring go back....to start with.removing the little finger will do you no harm ..when you remove it you will see most likely the problem..and the play between the clutch arm and the finger.....again your clutch cable is too tight..only when you get the adjustment right and if it would change by pressing the pedal you could consider broken cross shaft pin or even broken clutch fork.....

[icarp]

Originally Posted by icarp

It looks like you need a new omega spring. thats a normal wear item

have fun with your car!
Ian

Yep, horseshoe spring . How do I know ? Had the same problem , more than once .

good luck
ian