Clutch Cable Replacement

msk1986911 · 08-30-2008, 08:27 PM

After much second guessing of myself and my abilities, i replaced the clutch cable on my '86 911 since my mechanic had told me the cable was misrouted (rubbed against the throttle linkage). After over 2 hours, I think I have it all buttoned up,

although I've not had a chance to road test it

. I started the car and shifted into reverse as suggested in the "101" book; no grinding.

I did notice that the clutch seems to engage sooner than it did before (less than about 1/2 through the pedal travel from the floor. It actually seems pretty good, although, I will have a better idea as to how I like it when I take it on the road tomorrow morning. What do you think of the clutch travel? Although it seems good, it seems quite different from what I had before.

The car has about 84K miles on it. As far as I know I am still on the original clutch.

Thanks.

Mike

robert walsh · 08-31-2008, 04:26 AM

I'm doing mine today, looked it over closely, although a pita i can do it, the throttle linkage discussed i assume is in the rear tunnel area, my cable currently does rub against, how do you avoid this and why is this a problem, it is not sticking on it at all and there appears to be proper bow in the cable, I bought new one w/rear omega helper spring and might as well install them. The omega helper seems like the bigger PITA too me, did you have to re-adjust your new cable at the front or did you go with the pre-set suggestion of 8mm into the clivis fitting? It seems like a nitemare to redajust the front after getting that re-installed, my hands just dont fit.

msk1986911 · 08-31-2008, 05:35 AM

On mine, it was the rubber coated housing that was resting against the throttle linkage. Whereas Wayne's book shows the cable beneath the linkage, I was unable to not get the housing to rub that way. Installing the cable over the linkage I was able to avoid the rub. I did not do the omega spring. Also, I did do the 8mm adjustment as suggested. That would be a pain to readjust. In any event, I just did a road test...my observations are...it takes less pedal travel to engage the clutch (could be that I meesed with the clutch travel when I removed the floor board. Also, I have occasional shudder when moving from a dead stop...not quite sure what is causing that.

zi predict a massive search on this board today.

Mike

javadog · 08-31-2008, 05:56 AM

Quote:

Originally Posted by robert walsh

... the throttle linkage discussed i assume is in the rear tunnel area, my cable currently does rub against, how do you avoid this and why is this a problem...

The reason you don't want contact between your clutch cab;e and throttle mechanism is that it can cause the symptoms of clutch chatter, which is what you have been trying to eliminate for some time. Porsche had a service bulletin about this very issue, years ago.

Make sure it doesn't touch anywhere inside the tunnel or at the rear of the car.

JR

javadog · 08-31-2008, 05:58 AM

Quote:

Originally Posted by msk1986911

What do you think of the clutch travel? Although it seems good, it seems quite different from what I had before.

Make sure that you have the correct free play, the correct preload and the correct pedal travel. Did you do all of these things, or just set the free play?

JR

robert walsh · 08-31-2008, 06:06 AM

JR you nailed it and i'm going down in 1/2 hr to replace, the shudder or chatter is what i'm trying to eliminate, any last 1/2 hr suggestions, the fellow that just did his had no apparent chatter and now does, with the new cable. My repair manuual "still" has not arrived, read and heard just about all i can, so i'll wait 30 mins. for last words of wisdom, then i'm goin in. thanks, any specific routing or techniques?

msk1986911 · 08-31-2008, 06:11 AM

Showing how much of a newbie I can be...please describe correct free play, the correct preload and the correct pedal travel. I think I may have messed around with the travel adjustment beneath the clutch pedal. I am waiting for the car to cool down after my road test before I get back under it and do some more digging.

Can the cable be reattached to the hook on the transmission after it has been attached at the pedal cluster? That was a real problem for me in the installation.

Thanks.

Mike

javadog · 08-31-2008, 06:11 AM

Just follow the info that has been posted here on the forum and in the tech info center. There have to be thousands of posts about clutch cables.

I am a fan of not having excess cable threads protruding through the end of the clevis, as I stated in a previous post. Every car is a little different. You may have to do a little adjusting. Make sure you do all three adjustments on the cable; preload, free play and travel.

JR

javadog · 08-31-2008, 06:16 AM

Quote:

Originally Posted by msk1986911

Showing how much of a newbie I can be...please describe correct free play, the correct preload and the correct pedal travel. I think I may have messed around with the travel adjustment beneath the clutch pedal. I am waiting for the car to cool down after my road test before I get back under it and do some more digging.

Can the cable be reattached to the hook on the transmission after it has been attached at the pedal cluster? That was a real problem for me in the installation.

Thanks.

Mike

Yes, it can.

With the cable disconnected at the transmission end, adjust the free play at the lever to 1.2mm. Now install the cable and adjust the nuts on the threaded portion of ther housing to reduce the free play to spec, 1.0mm. ( I am guessing what car you are working on, use the correct spec for yours.) Now, measure the cable travel and adjust the pedal stop to get it exactly correct.

JR

robert walsh · 08-31-2008, 07:06 AM

JR, what do you feel i good statring point for the cable thru the clevis end should be, 8mm has been mentioned, you say your not a fan of too much going thru, why , just out of curiosity>

javadog · 08-31-2008, 07:37 AM

One of the things you can do to try to eliminate clutch chatter is to increase the amount of bow that you have in the clutch cable outer sheath (the bowden tube, as it is sometimes called.) To do this, it helps to make the clutch cable's effective length a little longer. The extra threads protruding from the end of the clevis don't really serve any purpose. The clevis can't rotate, the cable can't come unscrewed and there isn't any strength to be gained in the attachment between the two parts.

You can try it either way. All of these cars are a little different here and there and sometimes what works on one has no effect on another. You've been chasing this problem for a while, so be willing to experiment a little. If you install it one way and it doesn't help, try it another way. It's not hard to change the cable. You may wish to remove the driver's seat to make a little more room for yourself.

One other thing, make sure that you get the cable housing firmly seated where the cable tube protrudes through the end of the tunnel.

JR

robert walsh · 08-31-2008, 07:47 AM

JR, my cable current goes up and over the theottel linkage bar i assume that is the correct way, the photo above on this thread is showing it below? My coputer is getting greasy as i am doing this "now" , keep you posted. thanks

msk1986911 · 08-31-2008, 08:56 AM

I've done the adjustments as JR suggested; thanks for talking me back from the edge. No road test just yet. In any event, here is a picture the cable installed, showing it going over the throttle linkage.

Mike

Gunter · Gunter's Garage

Quote:

Originally Posted by msk1986911

On mine, it was the rubber coated housing that was resting against the throttle linkage. Whereas Wayne's book shows the cable beneath the linkage, I was unable to not get the housing to rub that way. Installing the cable over the linkage I was able to avoid the rub. I did not do the omega spring. Also, I did do the 8mm adjustment as suggested. That would be a pain to readjust. In any event, I just did a road test...my observations are...it takes less pedal travel to engage the clutch (could be that I meesed with the clutch travel when I removed the floor board. Also, I have occasional shudder when moving from a dead stop...not quite sure what is causing that.

zi predict a massive search on this board today.

Mike

Some observations:
The throttle linkage parts need lube!
Pop off the socket from the ball, disconnect the cotter pin, pull the part off the shaft, lube and re-connect. Lube the ball/socket too.

The slack in the clutch cable doesn't look right.
Make sure it seats properly in the tunnel tube.
Take a picture so we can see the Clutch lever, position lever, Omega spring and adjusting screw.
These parts also need lube.

javadog · 08-31-2008, 09:13 AM

Robert,

Yes, the clutch cable goes over the top of the throttle bell crank shaft.

Gunter,

If you are talking about the cable seen in the lower part of the photo, that's the cable for the heater valve. It is hanging too low.

JR

msk1986911 · 08-31-2008, 09:45 AM

The picture with the cable hanging low is actually figure 7 from the tech article.

Mike

robert walsh · 08-31-2008, 10:48 AM

It is done! believe it or not, the chatter is gone, a little final adjustment and i'm done, thanks to all that helped and those that listened to me whine. P.S the old cable bad broken strands stuck in the middle making it bind up, also the nylon tube had dislodged.

robert walsh · 08-31-2008, 04:13 PM

I am now doing the final adjustment, the gab at the clutch arm cable attached has to be 1mm at adjustment bolt, again with cable in place the difference between the cable fully extended vs w/clutch pedal pushed in must be 25mm (give or take .5mm) not a heck of a lot of room in that equation. How the heck do you ever come up with exactly the 25mm difference with each time you adjust a setting it is in effect changing the other measurement?? Unless the through of the clutch pedal distance to the cable remains constant (IE: 30mm). Finally if I adjust the mount bolts on the cable underneath all the way forward (towads the front of car) will that increase the amount of "bow" , in other words I feel i should adjust them as far forward as i can while still being able to maintain the 25mm total difference.

msk1986911 · 08-31-2008, 05:32 PM

I thought the pedal travel was set by the adjustment under the clutch pedal itself, although, as my previous posts attest, I am by no means an expert.

javadog · 08-31-2008, 05:39 PM

From my earlier post:

Quote:

Originally Posted by javadog

With the cable disconnected at the transmission end, adjust the free play at the lever to 1.2mm. Now install the cable and adjust the nuts on the threaded portion of ther housing to reduce the free play to spec, 1.0mm. Now, measure the cable travel and adjust the pedal stop to get it exactly correct.

You adjust the clutch pedal stop on the driver's floorboard to adjust the travel of the clutch cable. You don't adjust the cable for this.

It sounds like you need to start over.

JR