Another clutch adjustment oddity

[Slow Loris]

 

New clutch master and slave. New hose and hard lines. 
 

I’m adjusting the play between ball nut on adjustable slave pushrod and the clutch fork, problem is, if I adjust the nut to allow for some clearance as soon as I let go of the slave pushrod, it pushes itself right back out against the fork taking up all the play I just created. The clutch pedal is not connected to the master. Spring not on for this step (and it’s not just the fork migrating towards the nut)

 

I opened the bleeder on the slave and pushed the rod all the way in, then closed the bleeder, still it pushes right back out. The pushrod on the master feels to be at fully out position, it’s not stuck or anything.
 

What does this mean?

[banzai510(hainz)]

2 hours ago, Slow Loris said:

The clutch pedal is not connected to the master. Spring not on for this step (and it’s not just the fork migrating towards the nut)

be more clear on this please

But when I do new  521 masters most are taiwan made units and the master cyl the rod is sometimes too long and needs to be cut. I try to get close to the orginal length. soemtimes the rod longer and it actually pushes the master in under the pdeal when its goes up to the fire wall when bolted it.

 

i get it set right and pedal adjusted. the slave you are correct to get the 16th gap on the fork by the slave

[datzenmike]

 Is there a place on the slave for the spring to attach?

[Slow Loris]

@banzai510(hainz)

 

To clarify:

 

1) it’s not the pedal causing the pressure in the slave because the master is not connected to the pedal right now (to eliminate it as the cause of this)

 

2) it’s not the fork-to-slave spring taking up the gap because it’s unhooked (@datzenmike yes the slave does have a spot to hook it in)

 

So my problem is I can’t gap at the fork/slave because the slave keeps pressing out the rod, eliminating any gap I can set. 

 

I took the slave off with the hose still on, bottomed out the piston with my finger, opened the bleeder, closed it, and then watched the piston slowly return to the edge of the slave bore. It stopped eventually right at the mouth of the bore.

 

Somehow there’s enough pressure in the line to push on the slave it seems. Is this a faulty master or slave, or just some air, or am I misunderstanding the process?

[Crashtd420]

Isn't there a spring inside the slave?

 

[datzenmike]

It's the vertical weight of the hydraulic fluid pushing down on the slave. However there should be a snap ring in the slave bore behind the dust boot that prevents the piston over extending and coming out.

 

Push the push rod back into the slave till there is clearance with the clutch arm and adjust as needed. 1 or 2mm is fine.

 

 

Later slaves were different requiring no return spring. The slaves for these also did not have the snap ring.

[Slow Loris]

Okay, so in the end there won’t actually be any clearance with the clutch arm because that hydraulic pressure will take up the slack as soon as I let go of the rod. That’s fine then since that’s small pressure compared to that from the pedal?

[datzenmike]

That's what I think. Like I say later slaves are different and no adjustment. There's nothing to stop the slave piston from popping out if the push rod is removed.

[Slow Loris]

Thank you. I will go with that approach and see how we get on.

Obviously there’s a backstory why I’m screwing with this so here’s hoping this is it!

[banzai510(hainz)]

9 hours ago, datzenmike said:

However there should be a snap ring in the slave bore behind the dust boot that prevents the piston over extending and coming out.

I cant remember ever seeing this . If over extended I throw them away.  theres a ring on outside for the rubber dust boot

 

I cant remember if there is a spring in the bore, I dont think so.

 

The outer spring  I have them and have run without when they rust out. I just use the fork to push in and calculate the gas on the round ball.

[Slow Loris]

Ok I got that clearance sorted at the fork arm, I had far too much.

 

Free play at the pedal/master all good.

 

Pedal height I think is close enough though I’ve seen both 163 mm and 150 mm referenced.

Bled. Good amount of travel for the fork arm.

 

Anyway, clutch pedal still hits the floor. What’s up with that?

[banzai510(hainz)]

34 minutes ago, Slow Loris said:

clutch pedal still hits the floor. What’s up with that?

Does it move the clutch arm by the trans?

If feels like not pressure. I put my finger over the hole in the master and had soemone pump then it created a vaccum then started working.

 

I dont know if this helps

[datzenmike]

52 minutes ago, Slow Loris said:

Ok I got that clearance sorted at the fork arm, I had far too much.

 

Free play at the pedal/master all good.

 

Pedal height I think is close enough though I’ve seen both 163 mm and 150 mm referenced.

Bled. Good amount of travel for the fork arm.

 

Anyway, clutch pedal still hits the floor. What’s up with that?

 

 

If hitting the floor you may not be getting full travel of the master push rod.

 

From top of rubber pedal pad to the floor should be 163mm, 6.42". There is a stopper with lock nut that sets this height and its just above the master push rod clevis and in front of it. You may have to pull the pin and take the clutch master push rod off the pedal to allow this setting. Now loosen the lock nut on the master push rod clevis and turn it out till the clevis fits the pedal arm.

 

Now the master gets a full stroke and the pedal should stop approximately 1.16" above the floor. It's give or take, one inch is fine.

[Slow Loris]

@banzai510(hainz) it is moving the clutch arm.
I’m getting about 7/8” of travel at the clutch arm. So there is fluid flowing. Not sure if that seems like enough? 

 

@datzenmike well I’m 163 mm from pad to floor and then what stops my pedal travel is the wheel well hump hitting the left side of the pedal. 

 

Perhaps my superhuman leg strength is to blame.

[banzai510(hainz)]

it dont take much movement to disengage the clutch. I havent seen movement down there in a long time but I think that amount should work

when you said hitting the floor means to me no pressure being made and just goes to floor with no resisitance

 

I don know whats going on.

Edited November 20, 2023 by banzai510(hainz)

[Slow Loris]

Okay yeah maybe it’s irrelevant then if the fork is moving enough. I think fixing the adjustment at the fork will help most of my earlier problems, so thanks for the advice there. Need to test drive still!

 

Maybe the pedal to floor issue is a quirk of the ‘69 cab swapped into the ‘70 frame causing some funny geometries?