Nicolas911

Hello to everyone,
Sorry for the mistakes but English is not my native language.

I'm restoring my '77 911. But I can't adjust my clutch. Something is wrong here or I haven't understood everything.
After engine rebuild I installed a new clutch and most components including :
- Pedal cluster rebuild with new bronze bushings and clutch axle
- Clutch cable clevis and clevis pin
- Clutch cable
- Clutch release fork
- Clutch mechanism, throw out bearing
- Sachs sport clutch
Well that should erase most problem
Thoug it's a 77, I have an earlier single arm to actuate the fork (similar to 76 and before). Maybe it's because I have a factory limited slip differential.
Still, once everything installed, and after reading 4 manuals, I screwed till I have a freeplay of 2.5cm (1") at the clutch pedal. After making sure I have 20mm from clevis end to thread top of the clutch cable. Cable is well seated on the fire wall.
Car was on jackstands so started the car, selected 3rd, the car went into gear and drove. But it looks like the synchro did the job, as when I tried with reverse, big grinding. Same story when the car is on the ground, gears are not OK.
So at this point I should just tighten the screw of the cable at the arm end for the gear not to grind anymore.
But hey, it doesn't work, and no matter how far I go, the clutch would'nt disengage and gears can't be passed.

I checked the travel of the arm and I got 11mm of travel. Manuals recommand to have 15mm.

Did I break something on the way, or installed something wrong ? Or is there an adjustment I missed. It should be pretty straight forward and not so complicated, as it's my only blocking point after having rebuilt a full car.

One thing I haven't understand, because nearly no infos on the manuals. The adjustment at the clevis, is properly done at 20mm, but is it here that I should play with in order to get the clutch to engage ?

Before full disassembly, the full gearbox/clutch was working like a charm.

Thanks in advance for your help !

By the way, my fork arm looks like this one (which is unusual for a 77) I had to buy a clutch cable for a 76.

TheTorch

Sounds like the clutch is not fully disengaging. 11mm sounds like too little movement.

Things to check:

1. Make sure you setup the clutch cable with the correct backlash/slack at the pedal. About an inch is correct IIRC.
2. Make sure your clutch pedal stop on the floorboard is not limiting the travel of the clutch pedal / cable.
3. Make sure the roll pin that secures the clutch pedal to the pedal shaft is solid, Mine disintegrated little by little and I eventually could not get the cable tight enough. The pedal goes down but the pedal shaft only partially moved.
4. You can take some slack out at the clevis side, at the pedal cluster to try to get the additional pedal travel.
5. How did you setup the shift coupler? If you have the fore/aft wrong, it will go into 1/3/5 but not 2/4/R properly.
6. Be sure you have the right cable.
7. Make sure you have the rear cable cleavis. Looks like this:

As a temporary fix if you think it's simply a problem with the cable not being able to travel enough, slip a larger bolt (so it can slide freely, probably an M10 with the threads drilled out) on the end of the clutch cable as a spacer before you install the 2 threaded bolts (behind / after the rear cleavis).

Good luck.

Nicolas911

Hi TheTorch, and thank you for your feedback

To answer your questions one by one and narrow down the troubleshooting

1. Make sure you setup the clutch cable with the correct backlash/slack at the pedal. About an inch is correct IIRC. // That's alright
2. Make sure your clutch pedal stop on the floorboard is not limiting the travel of the clutch pedal / cable.// I did it with the alu floorboard and no pedal stop, then no floorboard but no result
3. Make sure the roll pin that secures the clutch pedal to the pedal shaft is solid, Mine disintegrated little by little and I eventually could not get the cable tight enough. The pedal goes down but the pedal shaft only partially moved.// roll pin is new, changed with the pedal cluster rebuild
4. You can take some slack out at the clevis side, at the pedal cluster to try to get the additional pedal travel. // I think here is the solution, should I screw it more or less (more or less thread visible at the clevis end) ? I'm currently at 20mm from cleavis to thread end. They recommand 17 to 22mm. Which way should I go and by how much ?
5. How did you setup the shift coupler? If you have the fore/aft wrong, it will go into 1/3/5 but not 2/4/R properly. // New coupling and new shifter bearings but I did the adjustment procedure.. Though I might try it again just to take that aside
6. Be sure you have the right cable. // The first one I got wasn't OK, this looks like the good one
7. Make sure you have the rear cable cleavis. Looks like this: // This part I have and 2x M7 bolts to adjust behind this

I'm not sure I understand. If I place a spacer (let's say a M10 bolt as suggested) between the M7 bolts and the rear clevis, how can it travel more ? In this case should'nt I just remove the circlip holding the fork arm and rotate the arm by one slot ? As it should just offset the catching point of the 2x m7 bolts ? Or did I miss the logic in that ?

The picture below is not mine but shows well the adjustment. To have more fork travel, which way should I go ?
​​​​​​​

TheTorch

My mistake. M10 nut, not bolt. The m10 nut as a spacer will effectively make the clutch cable shorter, allowing you to get more travel. You do not seem to be able to get the arm to travel far enough to disengage the clutch.

Per your photo, shorten the cable at the front clevis. So more of the threads are exposed inside the clevis, just not so much that it affects the range of motion at the bushing. Guessing you could go 30mm at least.

Your clutch fork arm should be at 90 degrees to the transmission.

Also, did you make sure the release fork is in the release bearing when you mated the transmission to the motor?

Nicolas911

Thanks again

Not entirely sure the fork is in the release bearing. But I did it nearly 2 years ago so I don't remember. I think I just placed the engine and gearbox together and that's it. As the gearbox was still in the car, I haven't really care for the fork. You mean the fork "teeth" should go in the slot I marked in red below ?
If yes, then I think that if I release the clutch cable, the fork arm should not be able to travel if rotated by hand. If it does, then the two "teeth" of the fork are not "armed" in the release bearing and that would explain my problem.

TheTorch

Yes, the fork sits in the bearing.

There are sight holes on the left hand side of the transmission near the engine case so you can see the release bearing to make sure the fork in in correctly. The lower one is small, the upper one you will need a small mirror as it is on top side, opposite the starter. You do not need to remove the transmission to see in there.

theiceman

this is where a cheap borescope run through your cell phone works very well... and also for checking triangle of death on a cis car.. for leaking.

we actually used one the other day to check a car with clutch issue, we went in and saw the release bearing blown out, so we knew what we were dealing with before we went in.

Nicolas911

Great, thanks for your answer. When the car comes back from paint shop next week, I'll check the underneath through the sight hole.
Thanks for the tip the iceman. I have one of these. Bought it to check in details dilavar studs. Only 7 were broken. Hence the engine rebuild. And therefore the triangle of death is leak free for now.
Though the funny part is that it won't be the end of the world if I have to remove the engine. Because the Gearbox sat for 3 years without working. And as it was working very well, I haven't touched it. Though after reinstalling the engine and doing the first start ups, the shaft main seal started to leak only when the car is inclined (on jack stand at the front to sort out the full front axle). Therefore, engine has to come out to tackle that. Yes I know... I should have done it while I was there .

So in less than 2 weeks we will know if that was the problem, and I hope it was as it doesn't look like rocket science to adjust the cable, and after so many years and hours working on it, I really want to enjoy the car this summer !

theiceman

"only 7 were broken "

good news was 5 were not

On mine one was broken , i removed engine, put it on an engine stand, rotated it around and 2 more fell out.. i guess i was due...

Nicolas911

I run a second project in parrallel with a 3.0sc to do an ST resto mod with a wildly prepped 3.2SS. Just cracked the engine open to see how it looked like and that one had 3 broken studs only as well. Engine was pulling much stronger though.

Next time I'll try a 2.7 engine to have pulled studs instead of broken ones, that will be a nice change !

snbush67

Make sure the clutch cable isn’t twisted around the throttle cable at the pedal end, it is easy to do and easy to miss, it will look right but it isn’t.

Nicolas911

Thanks for the tip. I will check it but I don't think so, as the pedal cluster went out, both cables ran freely into the tunnel.

Vane

Maybe I misunderstood, but are you sure that your transmission linkage is adjusted properly?
Plenty of how-to on internet.
Have you tried this:
- Select one gear
- Press clutch
- Have some one turn the wheel
You have LSD so if you can turn the wheel, the clutch work. Try with all gears.

r911

Make sure the clutch cables for '76 and '77 are the same; that you have a clutch cable that matches your arm setup etc.

Nicolas911

Hello guys,

Thanks for all your tips.

The fork was not in the throw out bearing.
I took the engine out. Back in with the fork in the throw out bearing.
Checked the 25mm free play and have someone press the clutch to check the length of movement. 15mm straight. Victory I shooted... but maybe too early. The clutch stayed down to the ground and would'nt come back by itself. Moved it back up but the adjustment was not right anymore. so retighten the clutch and did all checks back and surpise. Back to 11mm.

I guess the fork went out of the bearing. It looked firmly attached before but the fork looks like this now :






I guess both sides should be parallel and the full thing not that bent, Am I correct ?

Is it possible that, as the fork wasn't properly slided in its throw out bearing, the fork was bent against the gearbox case. Then when I slided it back in, the bending meant that it woudn't stay in the throw out bearing slot ?

The good news is that : with my adjustments, I got for the first time the 15mm wished at the fork arm. Before it get back to 11mm. For sure the fork was properly seated inside the slot, as we could feel a 2 step action during the test :
First pedal test : 15mm but didn't come back to position : the fork started to get out of the slot and stayed on position
Second pedal test, approx 15mm but strange feel on the pedal and after mesuring we were at 11mm. So maybe the upper most bent part of the fork slided out, then the lower part to be fully out.

Did anybody experienced that already ?

Is the fork really bent or is it like this from the factory ?

I think I will buy a new fork and also clutch cable, though it was new, it didn't work so properly here if the fork is bent I guess the new cable could have trouble here.

What do you guys think ?

The fact that I had for the first time the wished 15mm of travel at the fork arm means that everything was well set at the beginning. And again, with this problem, I check my 3 different Porsche manuals, plus many internet posts, I don't think I'm wrong here.

Thanks again for your help !