85 Carrera Clutch Question

[mr914]

I'm over at a friend's house to help him adjust the clutch on his '85 Carrera.

He replaced the clutch cable, but it appears that the helper spring is rotating rather than compressing the arc.

After depressing the clutch pedal. You can hear the spring "thunk". Upon releasing the pedal, the spring partially returns but leaves no clearance between the adjuster nut and the lever arm.

If I back the clearance adjuster nut all the way out. the clearance remains at zero.

The spring appears not to be broken.

Any suggestions?

Thanks

[john walker's workshop]

could be the clutch is worn out. when you can't get clearance between the levers by backing out the bolt, that's generally the clue.

[addictionMS]

I think I have seen this before, is it like the clutch arm should pop back further but does not, kind of like it is getting stuck half way? Can you pull it back (away, really towards the front of the car) and have the spring and clutch arm pop back to a proper resting position?

Now I jsut have to remember what caused it....I think it is that the adjuster nut is too far in so when you release the clutch, it does not push the clutch arm past the "Pop" point, the point where the spring forces the arm to return it to the resting position you want.

maybe....


Jim

[mr914]

addictionMS - that is exactly what is happening. It's going past the pop point.

The clutch was replaced about 5,000 miles ago.

When I pop the arm back into position. There is plenty of room for vent clearance in the adjuster. 1.2mm when the cable is off.

I'm stumped.... The spring looks good.

Could it be the cable is too short at the trunion?

Hmm... Buddy just said that the floorboard is not reinstalled....


We'll reinstall and check that.

[mr914]

Just got back from the garage.

The floorboard is back in place.

And the helper spring still pops.

The helper spring is poping when the pedal is about halfway depressed.


I did notice that the helper spring (the side with only one layer) does not tightly wrap around the pin. It appears to be about 2-3mm wider than the pin.

How tight is the helper spring to the pin on your car?

When the helper spring is not poped, I have the proper clearance between the adjuster and the arm.

Any thoughts?

[mr914]

With a little more reading. I decided to remove the clutch actuator arm (short one) and experiment with the arm attached to the helper spring.

When the pedal is depressed 1/3 to 1/2 way the spring still pops.

Is there any other retainers for the helper spring besides the two pins?

[addictionMS]

try moving the adjuster the other way, so it is longer, ie it will push the clutch arm past the point of pop on the return stroke, it should still be possible to have the spec'd gap after the clutch arm has retuned to its resting position, post pop.

I am sure your problem is one of adjustment not broken parts....


Jim

[mr914]

Do you mean move it a notch or two on the splined shaft?

[gerry100]

It's amazing how one back and forth mechanism can cause so much consternation.

I had a similiar symptom ( no clearance for adjustment) with my 20,000 mile clutch last month. After a few nights on my back and time on this board I took it to my mechanic.

After reviewing the receipts of the the clutch replacement ( previous owner) he concluded that the cause was that the short arm shaft was mispositioned inside the transmission when the clutch was done. He compensated for this by reindexing the short arm one spline and installing a longer adjustment bolt. Everything works fine now.

During this time I also read in "101" that the helper spring could be installed backwards.

Don't know if this relates to your issue but thought it might help.

[addictionMS]

I will try to take some pictures tomorrow night to show you...


Jim

[mr914]

Decided to order a replacement spring. 100k on car.

I'm suspecting that when I put the new spring next to the old spring that I'm going to find the arc to be smaller on the old one.

This one's got me scratching my head.

[gerry100]

Mr 914-

I'd check and see if the old one is in correctly before you buy a new one.

Springs of all types are designed such that they operate welll within the fatigue limits of the materials used, most at a sufficiently low % of the limits so that life can be considered infinite ( for example valve springs).

This means that the helper spring will not fail or change shape as it gets old. Failure mode would more likely be to collapse due to severe corrosion. My mechanic agrees with this based on his experince.

[mr914]

New spring arrived, compared it with the old one. There was about a 1/2 Difference in the radius of the spring.

New one is installed and the spring is not poping out of position.

However, after several actuations, the gap is getting bigger between the small lever and the adjuster bolt.

Looks like it might be more serious of a problem.

[Jim Smolka]

It could be that the clutch cable is too tight. Also, did you replace the bearings in the arm. What shape is the peddle cluster.

Have a buddy help you (beer may be required).
First, loosen the locking nut at the peddle cluster (10mm wrench needed). Loosen the cable and remove by the cable. Turn the cable a few turns CCW as to lengthen the cable. Hook the cable back up. Insure that the C spring is in its home position the clutch peddle is fully up and that their is a small gap at the back of the cable where it hooks up to the arm. Then tighten the cable by the adjusting 15mm nuts. Set the gap to 1mm.

Also be sure that the peddle board is in good shape and that the clutch peddle stop is adjusted so that there is the required amount of cable travel (I think that spec is 25mm).

[addictionMS]

here is a picture of the parts we are talking about, my understainding of the problem is that when you step on the clutch, the cable pulls the spring arm through its motion causing the spring to pop and go into the assist mode, and engages the clutch arm. When released the spring arm does not get pushed back past the pop point returning it to this position, yes?

I have seen this and the reason for the problem I had was the clutch arm needs to push the spring arm beyond the pop return point, then the spring will carry it the rest of the way opening up the gap between the adjuster and the clutch arm per the spec. If the adjuster is not sufficently exposed, ie bolt threaded int the spring arm, the clutch arm does not push the spring arm past the pop return point and the whole thing comes to rest with the spring not returning the spring arm to its natural resting spot as pictured here .

see if that makes sense...

[mr914]

Pedal cluster and floor board are ok. The bearing in the spring arm moves freely. I did find some rust on the shaft that the spring arm rides on. I cleaned it up with a white scotchbrite and lubed with lithiums

In the above referenced picture, the Clutch arm is not returning properly. Rather than coming back fully each time, it does not return fully to position.

I tried readjusting the cluch arm by one notch, but it lines up with the spring arm.

I flipped the bolt around on the spring arm to give more length to adjust gap.

Push the clutch in 4-5 times and the gap gets bigger. Adjust gap again. Same thing.

I'm suspecting that the clutch actuator arm or bushings are bad inside of the bell housing.

I can drop a 914 engine and trans in 45min to an hour. How long for a 911 motor?

Thanks.

[addictionMS]

I have swapped a trani in 4 hours start to finish....but I knew the car well and everything had been touched before so there were no rusted or seized bolts/nuts.

Draining the oil is really the biggest pain.

Jim

[mr914]

Pulled engine.

Found arm that actuates throw out bearing to be cracked and bending. Bushings - 1 was missing (Thanks previous mechanic) and other one worn badly.

5 hours to do first engine pull. Next time will take less...


Thanks for the help!

[addictionMS]

excellent job, good the hear ( in an odd kind of way) that it was something beyond the things we were looking at but could not get past. I would have hated to find all was fine and it really was just an adjustment problem and all our collective advice could not get you through it.

Again, good job...

Jim