clutch bleeding

[Gold_TD5]

Here's the thing, since I got my Disco a year ago, the clutch has never felt right or more to the point the pedal.
Works fine, no slip. it's just that it take up early from the floor so you have to depress the pedal all the way to the floor to fully disengage.
So all was good in the world till I drove my cousins Disco, lo and behold his clutch feels great in comparison to mine.
In our infinite wisdom we decide that maybe all it needs is a bleed.
Note: we both know our way around mechanical things and are competent at bleeding brakes and clutches.
We ended up almost losing the clutch altogether, we got a fair amount of air till it was only oil, then it was all down hill.
So we then reverse bleed the system, small improvement. BUT, not as good as what we started with.
To cut along story short, we got the clutch back to being drivable but we had some drag, so I'm thinking we are up for a new master cylinder.
I have then driven back to Hervey Bay from Brisbane, parked, got up the next morning gone to work, what do you know, the clutch has improved.
Three days later and the clutch is now back to it's good old self and exactly how it was before we started.
Note: there is no fluid leaks any where and the level in the reservoir has not changed.
WTF is going on?
At $350 for a new master cylinder, I'm not rushing out to buy one if I don't need it.
Ok Tech heads, your thoughts please.
Cheers Lionel

[Rudolf]

See reply No. 9.
http://www.aulro.com/afvb/discovery-2/83703-d2-clutch-dance.html

[Gold_TD5]

See reply No. 9.
http://www.aulro.com/afvb/discovery-2/83703-d2-clutch-dance.html
Just curious Rudolf, did your clutch pedal return to the top of it's travel or did it sit lower than the brake pedal with the broken spring?
Mine works fine, just there is no resistence for the first part of the travel.
A broken spring could be my problem as it would explain the piston not returning all the way in the master cylinder body.
Cheers Lionel

[Blknight.aus]

check the flex hose.

[Rudolf]

Just curious Rudolf, did your clutch pedal return to the top of it's travel or did it sit lower than the brake pedal with the broken spring?
Mine works fine, just there is no resistence for the first part of the travel.
A broken spring could be my problem as it would explain the piston not returning all the way in the master cylinder body.
Cheers Lionel

Travel was normal but the feel was very light.

[Gold_TD5]

check the flex hose.
As in the hose from the reservoir to the master cylinder?
Cheers Lionel

[AKW]

All the hoses can brake down inside and cause problems.
I use copper grease on all bleed nipples to stop
sucking air.

Andrew

[Blknight.aus]

yep the flexy one thats down on the slave cylinder.

It may be internally delaminating. Its supposed to be replaced with the brake lines (every 2 years ish) but usually isnt.

[d2dave]

Lionel,
Is the master cyl push rod adjustable? I have seen many a vehicle with adjustable push rods causing a problem similar to yours. Sometimes adjusted too short or the lock nut has come loose they self adjust.

Dave.

[Rudolf]

All the hoses can brake down inside and cause problems.
I use copper grease on all bleed nipples to stop
sucking air.

Andrew
On the slave I used teflon tape.
Was the only way I could get the system to blead.

Also see my reply with the link.
The master cylinder is not adjustable.

[Blknight.aus]

the master cylinder IS adjustable but its only the freeplay adjustment for the pedal.

if you get that wrong (or the locking nut is loose and working its way off) you either wind up with a clutch that gets further and further up the pedal and eventually wont engage OR you wind up with so much free play you cant push the master cylinder far enough to get the clutch to disengage.

[Gold_TD5]

I doubt very much that I have air in the system, when you reverse bleeding there is no real chance for air to enter the system if you do it right.
After Ruldolf's picture, I'm thinking I have a boken spring and the piston is not returing to the start of it's stroke hence the pedal has to travel a few MM before it come in contact with the piston and this is why there is a lot of initial freeplay.
Blknight, there is no freeplay adjustment on my clutch, the push rod attaches direct to the clutch pedal with a pin.
Just for the record, the clutch works fine, only difference between mine and my cousin's is that his disengages early from the top and mine engages early from the bottom, about a half inch off the floor. There is no drag when the pedal is pushed to the floor and the operation is faultless.
Thanks for your input but I think I will solve this issue when I dissasemble the master cylinder but I'm not going to mess with it till it starts to give me drama or it fails.
Cheers Lionel

[Graeme]

I've recently replaced the cups in my m/c because the clutch engaged close to the floor due to air getting past the rear cup on the return stroke, with the pedal having no pressure for the 1st half a stroke and continually finding air in the system. Its 100K since the m/c was replaced at 100K for the same problem. Clutch pedal pressure is high now but there's a shudder/snatch, engagement fairly low down and some resistance to selecting 1st gear that smacks of a faulty pressure plate. I have to try another bleed but as the pedal feels good, I doubt that air is the problem.

[Blknight.aus]

my bad, forgot you were a disco and not a deefer.

[Gold_TD5]

I've recently replaced the cups in my m/c because the clutch engaged close to the floor due to air getting past the rear cup on the return stroke, with the pedal having no pressure for the 1st half a stroke and continually finding air in the system. Its 100K since the m/c was replaced at 100K for the same problem. Clutch pedal pressure is high now but there's a shudder/snatch, engagement fairly low down and some resistance to selecting 1st gear that smacks of a faulty pressure plate. I have to try another bleed but as the pedal feels good, I doubt that air is the problem.
Where did you get the cups from Graeme?
For all intents there is no kit, you have to buy a new M/C
I'm starting to think my problem is in the M/C but as I said before I might wait till total failure unless I could source a kit to rebuild it.
Cheers Lionel.

[Gold_TD5]

my bad, forgot you were a disco and not a deefer.
All good Dave, you still know more about LR's than most of us here,;)

[Graeme]

The cups were P8956 & P7483A replacing the original Lockheed 3871-502 and 3871-505 obtained from my local brake parts supplier. He initially supplied a kit but the cups were for an 11/16" bore rather than 5/8", listed for the D2 but perhaps for the V8.
The spring appeared to be in good condition.

Edit: The 2 cups cost $20 total.