Technical Clutch drag. What to check

1500500 · Jun 5, 2019

Hi. The clutch is not disengaging on my classic 500. It has all new parts and as far as I can tell I have reduced the free travel. Makes for an exciting trip up My driveway bit I don’t want to go any further with it like that. What should I look for?

Toshi 975 · Jun 5, 2019

Have you got a locknut on the cable adjustment nut. It is amazing how quickly the clutch can unadjust without one?

the hobbler · Jun 5, 2019

Hi Geoff;
The clutch pedal free-play is surprisingly small at the pedal---according to "the book of words" it is between 1-3/8in and 1-9/16in (35-40mm) at the pedal. At the clutch end, the cable should have a 10mm nut that locks the 17mm adjusting nut in place. Have you got the return spring in place at the release fork end? It goes between the release fork and a notch on the bell-housing edge. Lastly, is the clutch-cable outer sheath clamped to the side of the gearbox. The outer sheath should have a little bracket built into it near the rear end of the sheath.This bracket locates onto a stud (10mm nut) and is curved at its top; the curve locates into a cast-in slot in the side of the gearbox just above the stud.

fiat500 · Jun 5, 2019

the hobbler said:
Hi Geoff;
The clutch pedal free-play is surprisingly small at the pedal---according to "the book of words" it is between 1-3/8in and 1-9/16in (35-40mm) at the pedal.

It's actually smaller than that.

I've disagreed with the figure previously as it refers to the early type of clutch which uses coil-springs. "F" or "L" with a diaphragm-spring should be adjusted to 15 to 30mm free movement at the pedal. As said previously, I do it by checking that the clutch release-bearing is just clear of the fingers of the pressure-plate springs. This is easy to feel if you remove the return spring whilst you check. The actual clearance required here is just 1.5m.

If you do this you gain the maximum, safe pedal-stroke and thus avoid ~~dragon~~

drag on the clutch.

1500500 · Jun 5, 2019

Toshi 975 said:
Have you got a locknut on the cable adjustment nut. It is amazing how quickly the clutch can unadjust without one?

Lock nut in place. Thanks

1500500 · Jun 5, 2019

the hobbler said:
Hi Geoff;
The clutch pedal free-play is surprisingly small at the pedal---according to "the book of words" it is between 1-3/8in and 1-9/16in (35-40mm) at the pedal. At the clutch end, the cable should have a 10mm nut that locks the 17mm adjusting nut in place. Have you got the return spring in place at the release fork end? It goes between the release fork and a notch on the bell-housing edge. Lastly, is the clutch-cable outer sheath clamped to the side of the gearbox. The outer sheath should have a little bracket built into it near the rear end of the sheath.This bracket locates onto a stud (10mm nut) and is curved at its top; the curve locates into a cast-in slot in the side of the gearbox just above the stud.

I may have forgotten the bracket attached to the gearbox. That would explain why it lurched uncontrollably under load.

I will check tonight.

1500500 · Jun 5, 2019

fiat500 said:
It's actually smaller than that.

I've disagreed with the figure previously as it refers to the early type of clutch which uses coil-springs. "F" or "L" with a diaphragm-spring should be adjusted to 15 to 30mm free movement at the pedal. As said previously, I do it by checking that the clutch release-bearing is just clear of the fingers of the pressure-plate springs. This is easy to feel if you remove the return spring whilst you check. The actual clearance required here is just 1.5m.

If you do this you gain the maximum, safe pedal-stroke and thus avoid ~~dragon~~ drag on the clutch.

Thanks

I think I forgot the bracket. Will check tonight and then adjust.

Cheers

1500500 · Jun 6, 2019

All those months ago I did attach the bracket
A short drive today wit no changes and it behaved normally.

Oh well. I will do some fine tuning on the weekend ab try a longer drive.

Toshi 975 · Jun 6, 2019

1500500 said:
Lock nut in place. Thanks

I found that adjusting the clutch was a bit tricky getting two spanners in such a close space. So I now fit an M6 long nut/stud extender instead of the ordinary nut. So much easier to get the 10mm spanner on there.

1500500 · Jun 9, 2019

I am living in bizarro world.

The clutch worked normally two days ago. Now I cannot select gears when it’s running again.

Could it be the main shaft in the end of the crank that is sticking.

From the outside the cable appears to be doing its job.

the hobbler · Jun 9, 2019

Now this may sound a strange (even bizarre) suggestion---check that all your engine and gear-box mounts are tight and that the engine/gearbox isn't moving forward and back. The reason that I suggest this is that twice (many, many years ago) I had accidents (in my 'at that time' 500) which involved me sliding gently up the rear-end of the car in front of me---and before you all accuse me of driving 'too Italian' (!), on both the occasions the weather was atrocious.
On both of the accidents I could not get 1st or 3rd gears---the engine/gearbox unit had moved slightly forward due the impact, I could only get 2nd, 4th and reverse. On both occasions, after work I was able to put the car on a ramp, loosened the gearbox mounts and move the engine/gearbox unit back to its correct position---full gear selection was attained.
The reason that I am suggesting this is that it seems strange that your gear-selection problems are not consistent.

1500500 · Jun 9, 2019

the hobbler said:
Now this may sound a strange (even bizarre) suggestion---check that all your engine and gear-box mounts are tight and that the engine/gearbox isn't moving forward and back. The reason that I suggest this is that twice (many, many years ago) I had accidents (in my 'at that time' 500) which involved me sliding gently up the rear-end of the car in front of me---and before you all accuse me of driving 'too Italian' (!), on both the occasions the weather was atrocious.
On both of the accidents I could not get 1st or 3rd gears---the engine/gearbox unit had moved slightly forward due the impact, I could only get 2nd, 4th and reverse. On both occasions, after work I was able to put the car on a ramp, loosened the gearbox mounts and move the engine/gearbox unit back to its correct position---full gear selection was attained.
The reason that I am suggesting this is that it seems strange that your gear-selection problems are not consistent.

Thank you. I will hop under the car now and have a look.

1500500 · Jun 9, 2019

One gearbox mount nut needed tightening. I have tightened it and adjusted the clutch cable again.

Will try a test drive in the morning.

1500500 · Jun 10, 2019

Still Does not disengage properly. With flywheel cover off I can see that the pressure plate is working and I can turn the driven wheels without turning the engine with the clutch pedal down. But it is not easy.

With pedal down the friction plate can be jiggled between the flywheel and pressure plate. Maybe it is damaged.

Back in the car if I put the car in reverse, handbrake off and clutch pedal fully down, engage starter motor - the car moves backwards.
Put foot on the brake and the starter struggles to turn the motor but just can.

I will pull the engine out and have a closer look...

F123C · Jun 12, 2019

I had a similar problem with a 500. :bang:

Turned out that one of the clutch hub cushdrive springs had broken and a piece of it occasionally jammed the disc to the flywheel.

:idea: Instead of removing the engine to check out the clutch, maybe you can unbolt the clutch pressure plate 2 bolts at a time from below and see if any bits of spring fall out....

AL.

1500500 · Jun 12, 2019

F123C said:
I had a similar problem with a 500. :bang:

Turned out that one of the clutch hub cushdrive springs had broken and a piece of it occasionally jammed the disc to the flywheel.

:idea: Instead of removing the engine to check out the clutch, maybe you can unbolt the clutch pressure plate 2 bolts at a time from below and see if any bits of spring fall out....

AL.

Thanks

I’ll do that

Cheers

Geoff

1500500 · Jun 15, 2019

Looks like the clearance in the crankshaft brass bush was too tight. On first inspection my clutch aligning tool was a very tight fit and was difficult to remove. I used a drill bit to lightly smooth out the bush by hand. Now the aligning tool can spin smoothly.

What grease is usually used here?

fiat500 · Jun 15, 2019

1500500 said:
Looks like the clearance in the crankshaft brass bush was too tight. On first inspection my clutch aligning tool was a very tight fit and was difficult to remove. I used a drill bit to lightly smooth out the bush by hand. Now the aligning tool can spin smoothly.

What grease is usually used here?

So your own first diagnosis was the right one.

I think I found out (after I fitted the bush :bang

that it's meant to be soaked in oil for a while...it must be microporous bronze or brass. I think a very light coating of engine-oil or high melting-point grease would work OK. Once it gets used a bit it's going to loosen-up and it's only when you have your foot on the clutch that any load-bearing is going on.

That must be relief to have sorted.

1500500 · Jun 15, 2019

fiat500 said:
So your own first diagnosis was the right one.

I think I found out (after I fitted the bush :bang that it's meant to be soaked in oil for a while...it must be microporous bronze or brass. I think a very light coating of engine-oil or high melting-point grease would work OK. Once it gets used a bit it's going to loosen-up and it's only when you have your foot on the clutch that any load-bearing is going on.

That must be relief to have sorted.

Yes . At least there is An obvious reason . I think the day it worked ok was just luck but once it warmed up a bit it really stuck. It was quite difficult to separate the engine from the gearbox. I will try to get the engine back in tomorrow afternoon and go for a proper drive.

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