Installed clutch cable... need some help troubleshooting

[khamul02]

So... I was driving awhile back and my clutch went straight to the floor. I couldn't change gears. I thought it was the clutch cable. I pulled it out to replace it and it was frayed and maybe 15% of the smaller cables were broke. So I am assuming that was the issue.

I replaced the cable, clevis fork and pin for good measure. I went to make the adjustments and noticed that even with everything attached the clutch would not return to the depress state. But to get it even to that state initially I had to use a small pry bar on the arm.

No adjustment would bring the pedal up.

So I'm hoping it is the helper spring or something else that failed at the same time the cable failed.

This first image is after I gave it an assist with my prybar.



This is what happens when I press the clutch... it doesn't return... under any adjustment to the 3 screws under the car.

[pete3799]

Your adjustment is way off in the first picture. I suspect you have a cracked clutch fork unless you repositioned the small clutch arm on the spline ( the one with the spring on it).

[khamul02]

How would I know if it is cracked... This is after I adjusted things a few times. I left everything roughly in the same place as it was with the old cable. These picture represent the last place the adjustment screws were in, trying to raise the pedal.

[pete3799]

Unfortunately the only way to tell if the fork cracked is to drop the motor/trans. and inspect it.

With the cable disconnected you should have a 1.2mm gap between the adjusting bolt and the small lever. Then reconnect the clutch cable and adjust the 2 nuts on the new cable until you have a 1mm gap. Make sure your pedal is all the way up for the last adjustment.

[DRACO A5OG]

^^^ +1 but if actually snapped you can feel for the fork to see if it will move or not via the inspection port but if just fractured and bent/flexible it will still move the throw out bearing. Stick your finger in there and feel for the top of the FORK and Throw Out Bearing. Ask a Helper to press the clutch and feel for movement.



Here is how the 915 should operate, gap after initial two step adjustment should be 1.00M gap between the clutch arm and bolt on the helper arm. The cable via the pedal should be a difference of 25.0MM +/- 0.50MM.

[JTL]

Did you check the clutch pedal shear pin? Sounds like it may of failed...

[khamul02]

Jt,
I did not. Which thingy is it?

[khamul02]

DRACO,
I'm a bit of a noob... the complex things I have done are valve adjustments and replace the entire AC system.

I'm going to take the cable off and try to start over. Am I supposed to start with the arm in the first picture position which is when I pry it back?

Can you tell me what I'm supposed to feel if it is ok or broke? Also, I assume I'm feeling while the clutch is being pressed which is an issue now because without a pry bar you only get one shot to engage the clutch. It doesn't return.

I have the Bently, 101, and workshop books to help but again, I'm a noob.

Thanks!

[khamul02]

Pete,
I didn't touch that one. Do you think if I have a cracked clutch fork this happen when the pedal dropped the day I was driving it? Or is this something I could have screwed up trying to adjust the clutch?

Originally Posted by pete3799

Your adjustment is way off in the first picture. I suspect you have a cracked clutch fork unless you repositioned the small clutch arm on the spline ( the one with the spring on it).

[DRACO A5OG]

Originally Posted by khamul02

DRACO,
I'm a bit of a noob... the complex things I have done are valve adjustments and replace the entire AC system.

I'm going to take the cable off and try to start over. Am I supposed to start with the arm in the first picture position which is when I pry it back?

Can you tell me what I'm supposed to feel if it is ok or broke? Also, I assume I'm feeling while the clutch is being pressed which is an issue now because without a pry bar you only get one shot to engage the clutch. It doesn't return.

I have the Bently, 101, and workshop books to help but again, I'm a noob.

Thanks!

We are all Noobs Brother :-D

No need to remove the cable, you have the Bentley and Workshop manual. Take your time and re-read the procedure and try to visualize how it should work then tackle it.

In the inspection port, literally, you can feel the Throw Out Bearing and Fork. But let's deal with that later.

I will list the steps:

Part 1

1. Make certain the Cable is connected at the pedal properly, that it is sitting on the clevis. I assume you matched the position of the adjustment jam nut with the old one.

2. Now under the car, make sure the new cable's black housing tube is seated all the way in the cable port from the chassis. Some times it hangs up and is not fully seated. Pull and Push to verify.

3. Bowden ( metal corner bent piece ) make certain this is in the proper position and not hitting any thing, position is vital to insure accurate readings and cable movement without binding.

4. From your 1st pic, it appears the clutch arm is way off and the adjustment bolt is in at the maximum position ( the 13mm bolt head in the helper arm ). Turn that one out about half way.

5. Use a circlip remover and remove the circlip from the clutch arm so it can be prepared for removal and re-positioned. Use a needle nose and remove the small spring attached to the gear box. Remove the clutch arm off the splined shaft. Position the clutch arm going toward the helper are by a spline. Until you see the clutch arm and helper bolt almost touch. Use 1.00MM and 0.20MM feelers and adjust the helper arm 13MM bolt until you feel the feeler liken to a heavy magnet when pulled. That should do it.

6. Place cable on the Helper Arm LOOSE. Use a Feeler gauge and place between the clutch arm and helper arm adjustment bolt using 1.00MM feeler. Start turning the forward 15MM nut back until the feeler when pulled feels like a heavy magnet drag similar to the above step but not too much where you see the clutch arm starting to move. Lock the other 15MM jam nut. Do not over tighten, just enough so the cable is firmly in place, the aluminum gear box is very soft. and you do not want to deform the bowden.

7. Press clutch pedal several times to take out any slack. Re-measure to insure it is still 1.00MM with the cable on.

Part 2

7. Now it is time to verify and if needed adjust pedal throw, goal is to obtain 25.0MM +/- 0.5MM

8. You need a helper now. Press the clutch several times quickly. This will take out any slack. Use a digital caliper ( it is allot easier ). Place one end on the tip of the cable adjustment threaded tube/bowden and the other on the base of the cable eye loop. Turn on the caliper and reset to ZERO. Ask a helper to slowly but steadily press the clutch all the way to the stop on the floor board. Note the reading. It should be at or near 25.0MM +/- 0.5MM. If not, you need to adjust the pedal stop on the floor board. If good, then you are done

9. Adjusting at the Floor board pedal stop. Insure floor board is sitting correctly and bolted down with that 10MM nut. Use a allen tool to loosen the two bolts so the stop will slide but not too loose where if flops around, just enough to let it slide. I would mark it so you have a good reference point. Up to lengthen, down to shorten the throw. Small increments to fine tune this part. Once the reading is close to 25.0MM you are done.

Test clutch engagement, it should catch 1/2 way on the pedal throw.

If it does not catch, then we use the inspection port to confirm the fork is damaged or broken.

As in my video, you reach in and feel for the fork and have your helper press the clutch pedal. If you can not feel it move significantly, then most like the fork is compromised. Car is off at this procedure!

Hope this helps, others will chime in for steps I missed.

Jim

[khamul02]

Thank you so much. I'm going to give it another go tonight!

[DRACO A5OG]

PM me if you need more specifics.

[JTL]

Tom,
Is looks like the shear pin is #31 in the diagram. It couples the clutch pedal with the shaft. I would verify that pushing the pedal down actually moves the shaft & cable.
There isn't very much room around the pedal cluster...

[khamul02]

I'm just now finding a minutes to get back under the car.


So I detached the cable at the rear, and used a ply bar to move the arm into the above position. All of the instructions I have read mention using the feeler gauge at this point to set the clutch clearance. The problem is the gap... doing this at this point is impossible.



BUT Draco mentions "remove the circlip from the clutch arm so it can be prepared for removal and re-positioned."

I'm assuming I just need to take the clutch arm off? Like the picture below (almost off)



Just to verify, I do take the arm off? And move it until the gap pictured above is close enough to set with the feeler gauge?

Thanks in advance.

[moneymanager]

Whatever you do don't drop the engine without being sure the pin in the pedal cluster that locates the clutch pedal hasn't sheared, or partially sheared. You will have to pull the cluster to be sure. Lot easier than dropping the engine. Mine sheared years ago. Car would drive nicely for some time, then the pedal would slip enough (go to the floor) to disable the clutch. Adjustment would bring it back, only to see it slip/fail again. The pin sheared, but not cleanly, and normal functionality would reappear for a random amount of time, then disappear.

[DRACO A5OG]

Originally Posted by khamul02

.

That's it, now slip it off and reposition so the gap is not so crazy. You may need to loosen the adjustment bolt and jam nut to accommodate the new position of the clutch arm. I would also get a new dust guard, if this is your clutch, it is toast.



Here is what it should look like:

[mreid]

Repositioning it will do nothing. You need to replace the fork. Nothing puts it that far out of adjustment when it was good except a bent or broken release fork.

[khamul02]

That picture isn't mine. Only the one that says gap. Could the fork have broken when the cable gave way? It was shredded but not snapped.

[DRACO A5OG]

Yes, it is possible.

But let's be hopeful :-D

[Ruben911]

Ditto on the shear pin. I dropped the engine thinking it was the fork and found out it was the shear pin afterwards. I moved the clutch pedal up and down and the lever that engages the cable at the tunnel also moved up and down so I ruled the shear pin out. Turns out there was still enough engagement of the shear pin to give me a false indication that it was not the shear pin. It is also a good idea to replace the shear pin when you replace the clutch cable.

Ruben911
1976 911s 2.7L