Release bearing clearance....

[syncrodoug]

What sort of clearance should there be between release bearing and fingers of pressure plate? - in an ideal world!
And has anyone fitted a hydraulic realease bearing?

[Red Westie]

The clearance isn't realy measured at the release bearing, it would be virtually impossible to do it that way, rather the clearance is the FREE TRAVEL in the clutch pedal itself (the amount of clutch pedal travel before you feel the bearing begin to release the clutch) That 'free play' is several inches and as far as I am aware is NON adjustable anyway as the hydraulic mechanism is self adjusting (unless of course you have an early cable operated clutch)
Martin

[syncrodoug]

Thanks for info Martin.
Rather a long story but the salient points are I've mated a VW PD 1.9 diesel to the T3 syncro gearbox using the PD flywheel (dual mass), friction and pressure plates - had an input made to suit.
First attempts proved about 90% successful - only problem was clutch slip when in third and fourth and a heavy right foot. Thought problem was clutch not be allowed to engage fully, so addressed this by reducing overall height of release bearing (it was a 'special' to start with) and relieving the back of the bell housing to allow for a little more backward movement.
Measured every thing and calculated that I had 2mm clearance between release bearing and finger springs, the problem now is that it appears the clutch is not travelling far enough to diesengage fully.
I'm begining to wonder whether the PD clutch/flywheel set up requires a long throw than that for the 'standard' syncro diesel set up.
Grateful for any comments.
Doug

[syncroandy]

Hi Doug,

Have you looked at any of the TDi forums for advice ?

Andy

[bigherb]

With hydraulic clutch's there is not any clearance they use contant contact relaease bearings. If you have used a concentric release bearing which has a larger bore area as there is no mechanical leverage you may have to increase the master cylinder bore to achieve full travel.

[syncrodoug]

Have got engine/gearbox back in van and plesaed to report the slipping in third and fourth appears to be cured!
However, although I can engage first gear ( and the others) with engine off, very difficult with engine running - I assume this is due to the incomplete disengagement of the friction plate.
I have increased the length of the clutch master rod about 1.5mm, contemplating increasing the length of the slave cylinder rod by the same.
Grateful for any comments...
Doug