Technical Clutch problems 1972 500R with synchro box

[Sleek Lemur]

Ever since I rebuilt the car, the clutch has been very heavy. Cable seemed to be unobstructed. Then the cable started stretching with the effort and I noticed the pedal box flexing. Out of ideas, I replaced the entire clutch and immediately the problem was solved. Lovely soft and smooth at the pedal. (Returned the old one for Recambio to send to return to manufacturers). Then, after a very short time, the pedal has stiffened up again and feels "coarse" under-foot. Only just managed to engage gears to get back home. Feels like the cable has stretched again. Have bought a new cable and awaiting delivery.

I'm all out of ideas! Help! This is starting to affect my mental health!

Tim and Dino

 

[smart51]

Heavy pedal, pedal box flexing, cable stretching. That says something in the box is not moving freely. You're pushing harder and bending stuff. I don't know what's stuck but there aren't many moving parts. The cable pulls the clutch lever, which moves the release bearing, which pushes the clutch plate. If you disconnect the clutch cable from the arm and the pedal and cable move freely, your problem must be in the bell housing.

 

[RalphM]

Is the clutch operating shaft that goes into the bell housing turning freely ie not stiff.

 

[Sleek Lemur]

Is the clutch operating shaft that goes into the bell housing turning freely ie not stiff.

Good suggestion thanks, but all seems good there. In fact I replaced the bushings on the rebuild. Thanks, though, and I will check again when I change the cable. Keep those ideas coming please!

 

[fiat500]

Have you got the cable mounted to the gearbox correctly?

 

[the hobbler]

Have you got the cable mounted to the gearbox correctly?

Two things spring immediately to mind---(1) Have you secured the clutch cable outer,at the gearbox end, to the side of the gearbox with the lilttle bent bracket and (2) I recently put new bushes into the bell-housing of a gearbox, and the clutch-arm/pivot-rod was so tight that I could not move it bacwards/forwards (as if I was operating the clutch). Eventually the only way to cure the problem was to fit a pair of 'nearly new'bushes--no play in the pivot-rod bushes, but the difference was "chalk and cheese". Are the bushes in your bell-housing so marginally tight that when they get hot, they semi-sieze?

 

[Sleek Lemur]

Thanks very much for the replies! Much appreciated.

I do have a doubt about fixing the outer cable to the gearbox. The only obvious place does mean I have a gentle "s" in the outer cable. But this is the only place I can see to fit it (I do have a 126 'box'...

As for the pivot rod, all looks good there, though I will check it when the engine is good and hot.

HOWEVER (!) I did find an issue. The tube through which the cable runs in the tunnel had come away from the car floor ar the front end. The spot weld had failed on one side and the metal had broken on the other. This meant the whole tube was lifting when the pedal was pressed. Essentially, the first half of the pedal travel was simply lifting the tube. I made a new "top hat" and bolted it down and that gave me a good inch extra adjustment on the cable.

I did buy a new cable, and comparing it with the old one showed no stretching.

All back together and seems to work well, though have only been up the road once, so far. I mangled the clip that holds the cable to the pedal shaft, so need to get a replacement for that before I venture further.

Question is, did my heavy clutch break that mounting, or was it simple fatigue?

Thanks again for all the replies. I will get back to you when I've done some miles!

 

[RensdeKooker]

Just wanna hop in here with a question because this sound like the same problems I am having in my 126. I did a complete clutch replacement with new bushings and new cable. My problem starts acting up though with heat... will check for the same tube at the front end...

Now the question: did you notice the bite point moving up and down with the heat of the engine or was it constant?

 

[Sleek Lemur]

Good question, Rens. The problem did increase with heat, but I think that was coincidental. The release bearing shaft doesn't stiffen up.

At it's worst, I adjusted the cable so that there was very little left on the adjustment rod and I did notice how the release bearing was hard up against the clutch plate. Then, after a 20 min Drive, I couldn't engage gears without a real struggle, with my clutch foot hard on the floor. When I checked, the cable had not stretched at all.

After noticing that the metal pipe had come away from the floor at the front of the tunnel and fixing that with a metal bracket, I could slacken off the adjustment and in fact I can now adjust the cable with my fingers, rather than a spanner as previously. The cable is a lot less taught and the release bearing is sitting nicely, just touching the clutch plate.

I've driven 20 miles or so and the clutch is still nice and easy with the bite point near the top, where it should be.

So.....fingers crossed!!!

 

[Sleek Lemur]

Good question, Rens. The problem did increase with heat, but I think that was coincidental. The release bearing shaft doesn't stiffen up.

At it's worst, I adjusted the cable so that there was very little left on the adjustment rod and I did notice how the release bearing was hard up against the clutch plate. Then, after a 20 min Drive, I couldn't engage gears without a real struggle, with my clutch foot hard on the floor. When I checked, the cable had not stretched at all.

After noticing that the metal pipe had come away from the floor at the front of the tunnel and fixing that with a metal bracket, I could slacken off the adjustment and in fact I can now adjust the cable with my fingers, rather than a spanner as previously. The cable is a lot less taught and the release bearing is sitting nicely, just touching the clutch plate.

I've driven 20 miles or so and the clutch is still nice and easy with the bite point near the top, where it should be.

So.....fingers crossed!!!

Ps...I can't get the correct clip to hold the cable to the pedal shaft. Using an e-clip at present, but it's not as secure as the original. Can't seen to get one in UK and Italian Ricambi company was €45 delivery to UK.