M8 Greyhound clutch problem

[Malcolm Towrie]

Darryl, i certainly agree 1/2" tubing is way overkill for the clutch line. It's a mystery why the OEM spec'd it. I suspect a massive typo.

I don't know what version of the parts manual you have, but mine shows that the original spec was lengths of 1/2" flexible hydraulic line! That's even weirder.

As someone mentioned above (maybe you), using 1/2" tubing just makes bleeding much more difficult as you won't get enough fluid velocity to carry air bubbles along the tubing.

So that's a 1/2" UNF thread on the m/c outlet. That's why I couldn't get the as-found 1/4" NPT fitting to seal!

Malcolm

[Lynn Eades]

So guys with a 1/2" UNF thread it will require a banjo fitting and a couple of copper washers.

[Big D]

Hi Lynn

Yes, that’s what I’m going to use. It seems there was no fitting or combination of fittings to adapt the 1/2” or even 3/8” tube to the 1/2” connection on the master cylinder, thus their recommendation for 5/16” tube.

[David Herbert]

I wonder if the 1/2" tube was used so that air bubbles could move along the tube by themselves to the highest point, to be removed at the bleed point by the bulkhead. They might have had the same trouble as you guys in trying to push bubbles to the bleed on the slave cylinder. It is hard to see how this system is much different to an ordinary brake system but there is obviously some reason that they went for 1/2" unless as Malcolm suggested it is actually a mistake by the designer - seems unlikely though. The larger pipe would have made any problems due to heat worse as there would be more fluid expanding by the same % so more to accomodate.
I think I would use 5/16" tube and follow the original route and include the extra bleed point as that aught to be where air would collect by itself.

David