Newbie Clutch Question

deanp · 10-09-2003, 06:50 AM

Driving to work this morning and clutch let go. Depressed pedal to downshift, pedal stayed on the floor. I was able to nurse her home, but am not sure if the problem is a spring, cable or other. Clutch action prior to the was smooth and normal. Pedla is now at the floor, there is reistance when pulling it off the floor and when released it springs back the floor. I want to order from Pelican today and have them overnighted for repair on Saturday?

What is this indicative of? Return spring? Clutch cable? Clutch helper spring at tranny arm? Pedal problem? Car is 1976 911S.

Thanks for quick responses.

Tim Walsh · Tim Walsh's Garage

what year car do you have?

deanp · 10-09-2003, 06:53 AM

sorry, 1976 911S. Edited ist post.

Superman · 10-09-2003, 07:54 AM

You likely have a broken cable. There is a spring in the pedal cluster that tries to depress the pedal. The reason it stays up is because the clutch cable holds it up. Sounds like the clutch cable is no longer doing that. Investigate.

MarkL · 10-09-2003, 09:26 AM

What a coincidence! I just had the same thing happen on the same year car! After reading up a little, I started my investigation at the pedal assembly. After removing the carpet and the wooden floor board, I found half of the trunion pin laying on the floor, with the other half still attached to the clutch cable! This is the piece that connects the clutch cable to the bracket that is attached to the clutch pedal. That sounds a little confusing, but check out the tech article on replacing the clutch cable, the pictures show this area very well. Anyway, I'm not sure if your car has the same problem, but it will give you someplace to start.

BTW, I decided to install a new clutch cable and helper springs in addition to the trunion pin. I just recieved the parts and will hopefully tackle the job this weekend. Let us know what you found.

Mark

grant lyon · grant lyon's Garage

Probably a broken cable at the clutch release lever end. Suggest you take time to see what cable and clutch release lever configuration you have because '76 can be a peculiar transition year, and parts from later series cars can be retrofit. For instance I have a cable with 6mm threaded screws on both ends. In my case, the cable wrapped 90° around the clutch lever to avoid exhaust plumbing (brilliant design, not). If you have this flavor of lever, when the time comes about 1/2 the cable wires break (from the bending) and the pedal droops -- leaving you with enough cable strands to execute 3 to 10 (partial) clutch pedal cycles before total cable failure.

juanbenae · juanbenae's Garage

order a new trinion pin/fork too. the thing is a ***** to remove. i ended up breaking mine and replacing it after talking to a wrench. the best $6 i ever spent.

deanp · 10-10-2003, 04:39 AM

The trunion pin was sheared, found part of it still in the fork and the other 2/3's is gone.

Thanks for pointing me in the right direction.

Jdub · 10-10-2003, 07:54 AM

Yes, the trunnion pin will be sheared, but that is because the bushing in the small hole is gone and now the clutch lever's end that goes through the pedal rack and into the tunnel has a nice gouge in it. Take a close look and you'll see it.

With that gouge, you now have a situation where even a new bushing will not prevent the same problem: rubbing of the trunnion pin directly on the clutch end in the tunnel.

What to do? Rebuild the pedal rack with brass bushings from Pelican. Figure in the need, once disassembled, to bring the pedal ear piece to a welder. They will, for a pizza or sixpack, weld a small glob in the hole that you can file back circular with a rattail file. Once you have done this, you are now back to having a nice round hole in which the bushing sits, now with support.

It all becomes clear when you pull the pedal rack apart.

John

deanp · 10-10-2003, 08:12 AM

Already saw the gouge you mentioned. Will be taking care of that over the weekend so I am prepared when the parts arrive early next week. Thanks for pointing it out though!

Jdub · 10-10-2003, 09:07 AM

Sounds likeyou are all over it. I mentioned this only because it didn't appear you would be putting in fresh bushings.

Jw

deanp · 10-10-2003, 09:24 AM

I found a master cylinder leak while I was chcking things out, so i figured I may as well do it all at once...

MarkL · 10-13-2003, 05:26 AM

Jdub, could you please expand on this a little? As I mentioned above, I have the same problem with the same year car. What do you mean by "the bushing in the small hole is gone and now the clutch lever's end that goes through the pedal rack and into the tunnel has a nice gouge in it." Are there any other resources that I can check out for information on this? I would rather not rebuild the pedal cluster right now, but if I must, I must!

Thanks,
Mark

deanp · 10-13-2003, 05:44 AM

The end of the rod where the fork fits over has a round hole with a small bushing in it. The pin goes through the bushing so that there is no metal to metal contact when the assembly pivots. The bushing wears out resulting in metal to metal contact, wearing the round hole into an oblong hole and wearing the pin until it breaks. If you just put a bushing back in it will be unsupported where the metal on the rod arm is worn away and only expedite the wear process on the new bushing.

Jdub · 10-13-2003, 08:31 AM

Like Dean said Mark...

The clutch pedal is made up of the pedal and a tube that goes the length of the pedal rack, into the tunnel in the center of the car. When you push on the clutch pedal, you cause the tube to rotate and the other end to move as well, in the tunnel.

That end, in the tunnel, I often call the clutch pedal ear. It has a hole in it in a plate into which the clutch cable goes by way of an H shaped trunnion with safely snap. Over the years, as the bushing in the hole disappears, the trunnion pin, once ensconsed in bushing, now scrapes directly on the clutch pedal ear and eventually wears the original hole oblong.

John

Danskman · 10-13-2003, 08:38 AM

If you get a new clutch cable, be sure it's made by GEMO. There are some Italian cables out there that are no where near the quality in both materials and construction.

MarkL · 10-13-2003, 09:02 AM

Thanks for the replies, I understand exactly what you are talking about now. I will check it out tonight to see how badly it is worn. Are there any other fixes besides welding some material back? Maybe drilling the hole slightly larger and installing a bushing with a larger OD? I'm not sure where one would get such a bushing, but just a thought.

I got the clutch cable from Pelican and I believe it is OE Porsche part, but I will look at it again tonight.

Mark

MarkL · 10-14-2003, 05:34 AM

Checked it out last night, and it is just as described, an oblong hole with half of a plastic bushing! So is there any other way to fix this besides welding some material back in? As I mentioned above, maybe increasing the size of the hole slightly and using a larger OD bushing? What do you guys think?

Jdub · 10-14-2003, 06:34 AM

Mark:

I think it is going to be a tough go finding a bushing that had both the correct ID and the correct OD, all in the same item.

However, if you can find some solid brass stock whose OD fits whatever hole you are proposing to drill, you can now drill the inside hole to fit the trunnion without difficulty. At least this way you get to choose both diameters.

I would advise going to a welder though and getting some weld put in to support the brass bushing that Pelican can supply.Also, with the pedal rack out, you would do well to replace all the bushings. It is AMAZING how different the pedal will feel once you have done the pedal rack, the clutch cable, and the horseshoe spring.

Finally, be sure to purchase a new rubber stop for the clutch pedal. This item fits in the wooden board you had to remove to get to the pedal rack.

Believe me, you can do this and the difference will just amaze you.

John

MarkL · 10-14-2003, 11:44 AM

Thanks for the response. That was my thought exactly. I have access to a machine shop here at work, and can operate a lathe, so making a bushing should be no problem. My only concern would be weakening the clutch ear by opening the hole too large. I guess I will order up the bushing kit and pull the pedal cluster out and go from there. I already have the new clutch cable, horseshoe spring, and also the clutch pedal spring. I guess I might as well order a new brake pedal spring while I am at it. My first 911 project is multiplying quickly!