Hi, i have a 78 x19 1.3 litre. can anyone tell me why the workshop manual says not to machine the flywheel when fitting a new clutch. it says fit a new flywheel. If i machine the flywheel what will happen?

Generally it is better to leave the face of the flywheel alone although I can't envisage any particular problem unless you take a lot of material off in which case the clutch cover and plate will not necessarily be in the right place but this shouldn't be significant. A mislocation of 1mm or maybe 2mm should be within tolerance. The clutch release arm should still operate too...

Why are you looking to machine the flywheel?

thank you for your reply, I have a problem with the clutch. when i bought the car the clutch was at max adjust and the gearbox was noisey. i removed the gearbox to be overhauled. the clutch plate linings had almost no wear but the damper springs were all broken. I bought a new clutch kit, ie pressure plate, clutch plate and bearings and had the flywheel machined as there were a few hot spots visable, we only took off a few thou. the gearbox was fitted but the is still at max adjust at the slave cylinder. I have replaced the clutch master cylinder and slave cyinder and it is properly bled. it seemed as if the fork wasnt being pushed far enough to disengage the clutch, there is no problem with the fork (bolt not broken or weld broken.). I have measured the slave cylinder push rod movement and master cylinder movement and it is within specs. (28mm). It just seems like the fork needs to move another 10mm to disenge the clutch and i cant seem to work out why.the workshop manual says not to machine the flywheel so i wondered why it shouldnt be machined. any help with this would be much appreciated.

Sounds like someone has fitted the slave cylinder wrong, or the wrong slave cylinder. I've seen a lot of cars where the cylinder position has been adjusted with packing washers to get over this.

The difficulty is that by machining the flywheel you make this exact problem worse...

The slave cylinders used by Fiat in that era all look about the same but (and I've never tried to verify this) I suspect there are some minor differences in the locating points on the cylinder or the gearbox that result in the problem you've described. It could be people borrow the slave cylinder from other manufacturers because they are "close" to the same dimensions.

The other problem is that it is a real nightmare to bleed the clutch hydraulics, again with the same result, the clutch doesn't quite disengage. I don't normally recommend positive pressure bleed systems on old Fiats but in this particular scenario it is a godsend!

I have checked the slave cylinder and it all looks to be correct. it is a 3/4 bore same, as the master cylinder. It appears to be mounted in the correct place. It seems as if the pressure plate or flywheel height is wrong. I have checked pressure plate heights and the earlier x19, up to 74 have the same clutch plate and bearing but the pressure plate compressed height is 7mm higher. I have checked the engine and chassis nos, the engine is original ie 1978. so i dont think anyone has changed engines etc. Would you know how close to the bell housing should the clutch fork arm be when the clutch pedal is depressed. do you know the thickness of the flywheel.?

cheers

On the 1300 models is there a semi circular half barrel shaped plastic Shim on the end of the gearbox fork,like on the 1500 models? If this was missing or badly worn that could be your 10mm...
It fits on the end of the slave cylinder push rod and slots into the fork.

Hi, The 1500 must be different, mine has steel domed nut that fits into the clutch lever. My workshop manual diaghram shows it as mine is.

is the 1300 x19 flywheel stepped?