Clutch Diagnosis

[manic]

I cannot actuate the clutch, and now looking for some ways to pin point the cause.

Issues started when I converted to a puma pedal box that came with a master cylinder (used).

Once installed I experienced some notchy gear changes, but not too bad. I figured I had not bled 100% effectively or the pedal adjustment was off. But I left it to revisit some other time.

Fast forward to last weekend. 6 hour drive to Mildura, all went well. Come the morning I struggled to engage first gear. By the time I filled up at the station, I couldn't get a gear at all. I had to start off in first. The rest of the trip was clutch-less gear changes. Not too bad in low range, third gear all day - but a bit stressful when we got back to the traffic lights.

I found that firing up in 1st with the clutch depressed was easier, so there was some slip with the pedal down - the pedal still had some action, just not enough for gear changes.

I tried adjusting the pedal master rod position whilst out on the trail, but too fiddly and in the end zero improvement. So today I reverse bled the clutch, bubble free, and pedal feels OK. But still cant get into first.

MC, fluid and pedal adjustment are main suspects (from puma pedal swap). But you never know.

It doesn't look like the pedal adjustment could be that far wrong, but:
Should I be measuring to see if the MC rod has been pushed in far enough when pedal depressed?

Slave cylinder:
Is it worth unbolting and observing the action on pedal down to see if its actuating properly?

Any way to test the MC?

Might have another go next weekend - any tips, tricks or motivational comments welcome.

[Blknight.aus]

If its not loosing fluid its the MC recirculating.

this will be the fast fill valve and if it was left without fluid in it for a while or youve put different fluid in from what was in it (dot 3mineral -dot 4) it will have "dried out" and wont seal.

end result is instead of creating flow then pressure down the pipe to the slave it just displaces the fluid until the fork takes up then pushes it back to the reservoir.

[karlz]

If its not loosing fluid its the MC recirculating.

this will be the fast fill valve and if it was left without fluid in it for a while or youve put different fluid in from what was in it (dot 3mineral -dot 4) it will have "dried out" and wont seal.

end result is instead of creating flow then pressure down the pipe to the slave it just displaces the fluid until the fork takes up then pushes it back to the reservoir.

Wow. If thats true, what a diagnosis. Impressed.

[Blknight.aus]

Wow. If thats true, what a diagnosis. Impressed.

not specifically impressive,

the same 3/4 inch MC has been in use since about 1965 and theres only handful of failure methods.

if its not loosing fluid and its bled properly its usually only ever 3 sometimes 4 things if you have the right gearbox.

1. MC recirc
2. no freplay on the MC pushrod meaning the fast fill wont open.
3. bending push rod on the slave
4. failed clutch fork/carrier.


the last 2 have other mechanical symptoms, get worse, wont recover and are rare on the ford clutch assembly

the second one will over time change its behavior as the seals arent perfect so as temperature changes and the fluid volume changes the clutch behavior changes slightlly. sometimes if you leave the clutch long enough it will work correctly once or twice and then stop working. It also inhibits bleeding, as the fast fill never opens up once you clear the fluid from the return action of the fork against the slave you dont get another effective fluid purge. Typically the second failure method is diagnosed from a symptom similar to "I tried to bleed the clutch and I got a couple of spurts of fluid, the MC is full but no matter what I do the level of the fluid doesnt change.

as none of the symptoms for failure method 2-4 were mentioned that leaves only one likely cause.

Id almost be willing to bet that if he cracks the bleed nipple before he presses the clutch pedal he can get a good flow from the bleeder but with it locked up if he pushes the clutch in slowly and holds it before he bleeds he wont get the same volume of fluid.

As a tip for bleeding landy clutches.

Park em facing up hill. bout 18 inches higher at the front than the rear for a 110 as a minimum guide... after you get the first fluid flow you'll get a good bleed with 2 more actions of the bleed nipple.