Technical Uno clutch problem

[UnoMia]

Hi,
The other day I replaced the clutch on my Uno 1100 with a new kit, (thrust bearing, clutch plate and pressure plate), because I was fining it difficult to engage gears cleanly and having previously replaced the clutch master cylinder and slave cylinder there didn't seem much more left to change!
After a real struggle to get the box back in, everything was reconnected and I eagerly took the car for a test drive. Horror! - the thing still grated when engaging 1st (sometimes) and reverse gears. Also, when slowing down to a stop, almost at walking speed, with the car in gear and the clutch pedal held down, I get a 'juddering' from the gearbox, almost like when a learner driver is coming to a stop and doesn't push the clutch pedal down soon enough.
I've since re-bled the hydraulic system and things seemed slightly better but I'm still having problems getting reverse gear and still get the judder at walking pace.
The clutch pedal begins to bite about two or three inches off the floor, so I don't think it's the hydraulic system.
I did have a problem getting the thrust, (release) bearing to stay engaged with the fork in the bell housing when replacing the box and I'm hoping this is not the problem.
Does anyone know if there is supposed to be any sort of clip mechanism that holds the release bearing onto the operating fork? When I took the box out there was no clip on the old bearing but as I was having the same problem as I have now, then maybe any sort of clip had come off.
Any advise would be much appreciated. I don't want to have to take that gearbox out again!

 

[johorridoh]

Sometimes the fork gets bend or the thrust bearing is not in the right place.
If it is in the right place , it will side back and forth as the fork-lever is moving.
I had a bend fork that killed a new thrust bearing after a couple of kilometres.
Guess you will have to do the job again.

 

[alexGS]

It sounds to me like you have the dual problems of the clutch hydraulics and the clutch needing to bed-in which, together, make the job seem like a failure - but give it some time

Firstly the hydraulics sound like they're sorted out now, with the pedal biting-point a few cm off the floor.

Secondly, did you have the flywheel resurfaced? If not, you can expect that it will take a while for the friction material to wear in against the flywheel - it can be a little juddery until this happens. It will probably sort itself out if you give the clutch some hard use (but only for short periods as you don't want to overheat it).

Even if it doesn't quite reach perfection (due to the flywheel condition) it should continue to improve. There is the possible problem that johorridoh mentioned above, so if you decide after a while that it isn't getting any better, you have something to check next time.

On these models I'm fairly certain the release bearing is not clipped to the fork.

-Alex

 

[UnoMia]

Thanks for the replies, they are much appreciated!

I've been using the car today and as you said Alex, the judder on the clutch is beginning to improve. I do however notice that the problem is worse when the engine is at normal temperature, and I've determined that the low speed rattle/judder that seems to come from the gearbox may be the CV joints rather than the gearbox itself. I determined this by putting the car into 1st gear, with the engine off and gently rocking her back and forward. While the car moved, the drive shafts didn't and there was the same sort of noise that I've been hearing coming from play in the two out CV's. These were both replaced about two years ago but I was suspicious of the company that did the work at the time and it could be that they are the cause of the low speed rattle that I can hear. I'm going to take the car to a CV specialist tomorrow and get them checked.

Also, the suggestion of a bent operating fork is good. The only thing being is that I'll have to remove the box again to check this!

I'll keep you posted on what happens. Thanks again.

 

[johorridoh]

Have you checked your gear oil level ?
Has your car a high mileage ?
If so replace it with original FIAT gear oil.

 

[portland_bill]

Sound like the clutch is not disengaging when the pedal is fully pressed. (Much like holding it on the bite point all the time) Waiting for it to bed in will have no effect.

If the master and slave cylinders are working ok, without leaks, then you should be getting the travel you need. However, the release lever in the box can wear at its pivots, losing some of its travel as it effectively twists away from the release bearing. Fixing this can be difficult if it sits in the housing without bearings. I've looked on Eper, but can't find it listed, so can't see.

The clutch cover can cause this issue if its been dropped prior to or during fitment. When the pedal is pressed, the diaphragm spring is compressed. The pressure plate follows the diaphragm spring due to the three spring blades around the edge, these are the only things that keep pressure plate and diaphragm spring together. If the cover is dropped, from waist height, and it lands on edge, the uppermost of these springs at this time of impact takes all the force and loses its tension. Then when the pedal is pressed, the pressure plate does not withdraw properly, leading to drag. If the cover lands face down, all three springs can be weakened. Face up, you're lucky. Only cure for this is a new cover and an argument with the supplier as to whether you dropped it, or it was dropped before you got it. Good luck on that one. A good supplier will accept it back for refund, unless the cover shows evidence of damage where it hit the floor. For the supplier to be liable, you need damage to the box, none to the cover. To test this, place the cover on the bench, plate up. Try to lift the plate up away from the diaphragm at each of the spring straps. They should all be equally strong. Any one weak one is a scrap cover. Having used it, the area near the weak one may be showing signs of heat.

When fitting the gearbox it is important never to allow the box to hang on the centreplate as this will bend it. This makes it "wobble" when the pedal is pressed, effectively making it bigger than the space it is supposed to occupy, so dragging. Only cure is a new plate. Using it like this will eventually cause it to crack up and fall apart.

Gearbox and flywheel must be correctly aligned. If the dowel bolts are in the right places this should not be an issue, unless the engine backplate is cracked - worth checking, especially if it has ever impacted the road. If misaligned, the clutch effectively tries to work eccentrically, which will cause it to drag on release and to tear itself apart in a few weeks.

Sadly you are a long way away, so I can't come and look and I'm rubbish at drawing diagrams. Hopefully this all makes sense.

Gearbox oil does not have to be Fiat, but must not be EP gear oil as this will make the synchros work hard and wear quickly. If it smell like sulphur, it is not correct. That stuff is for rear wheel drive axles, and sometimes their gearboxes too, but not front wheel drive.

Knowledge gained working for a major car parts supplier, in their warranty department, with clutches being a speciality.

 

[UnoMia]

Thanks again for the replies.

After re-reading thought Portland-Bill's reply where he states, "Gearbox oil does not have to be Fiat, but must not be EP gear oil", got me thinking. After draining the box before pulling it out to do the clutch I'm sure it had EP gear oil in there, due to the really strong EP oil type smell.

If it was this was because a drive-shaft company refilled it with EP oil after replacing the CV's some two years ago. I just hope this hasn't stuffed the box up now! After doing the clutch I refilled with Castrol 75W-90 as recommended in South Africa. I'm now seriously thinking this might be why I'm hearing funny noises from the gearbox area!

 

[peterdt0260]

Thanks again for the replies.

After re-reading thought Portland-Bill's reply where he states, "Gearbox oil does not have to be Fiat, but must not be EP gear oil", got me thinking. After draining the box before pulling it out to do the clutch I'm sure it had EP gear oil in there, due to the really strong EP oil type smell.

If it was this was because a drive-shaft company refilled it with EP oil after replacing the CV's some two years ago. I just hope this hasn't stuffed the box up now! After doing the clutch I refilled with Castrol 75W-90 as recommended in South Africa. I'm now seriously thinking this might be why I'm hearing funny noises from the gearbox area!

Hi, what was the end results, may have ep90 in my ino box

 

[Ralf S.]

Just drain the oil and put the correct oil in there.

EP contains sulfur-phosphorus molecules that act by bonding with (steel) gearbox components. When the components come under extreme pressure, the sulfur-phosphorus molecules shear off the surface, along with the molecules on the opposite/mating surface, thereby protecting the surfaces of the metal parts. Then fresh oil gets onto the surfaces and the protection is restored... and this works for the life of the oil.

On cupric (brass and bronze etc.) components the sulfur-phosphorus molecules can react with the copper in those metals, so that when the oil molecules shear off, they don't separate cleanly... instead they take a bit of the surface with them, so eventually your component gets eaten away, and the oil gets filled with micro-particles of copper, which can themselves cause wear in other parts of the gearbox that otherwise don't mind the EP.


Ralf S.