Clutch Changeout Issues with Hydraulics

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
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InlinePaul
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Clutch Changeout Issues with Hydraulics

Postby InlinePaul » Fri Mar 08, 2013 12:56 pm

I just had a new clutch in the Ranger (2001) at 80,000 miles. They put in the disc, pressure plate, pilot, release bearing, and a new slave. I got the truck back and the engagement was at the floor. There is not adjustment on the pedal and the shop said these Ford hydraulic clutches are a real pain on pedal height. They said in their experience if you drive it a few hundred miles it will improve. I drove a couple hundred miles and then it started not going into gear from a dead stop. My shop was closed so I took it somewhere else. The guy held the clutch pedal at the engagement point firmly and it slowly dropped indicating a leak. I told him it was fine the first two days and that all the clutch parts and slave had just been changed. He said that it is sometimes better to change the slave and master together because the new parts down below often put more pressure on the master and make it go out. At any rate, he put a new master in (bench bled, then further bled in the truck) and it is working fine. However...

my clutch engages about 1/2 to 1 inch off the floor (hard to measure this) and it seems to me that is a bit low. It was far worse before the new master was installed though. Now I would think that as the clutch disc wears the engagement point will slowly rise. However....

the Ranger pressure plate has a special self adjusting feature and I am not sure how that would affect the pedal height.

What you all think of this? Not much I can do when the pedal has no adjustment other than tear off the 3/16 thick rubber pad from the pedal stop to get more travel, but will that cause me to over extend the master and mess it up? We are talking maybe 1/8" more stroke of the master at most.
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A little more info on the broader scope. Two years ago I had a new clutch and slave in the F150 and the pedal was engaging at the floor. I drove it 9 months until cold mornings made it not go into gear until the engine warmed up. Had new master installed and the pedal was fine, right were you want it about halfway up from floor. The old master in this case was not leaking but the piston was not coming all the way back in it's bore, falling short by about half an inch--worked fine with old worn clutch, but new clutch needed that original stroke.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

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Re: Clutch Changeout Issues with Hydraulics

Postby Rope-Pusher » Sat Mar 09, 2013 10:32 am

Some hydraulic clutch release systems are very difficult to bleed. Air can become trapped past the bleed port. Also, not all line routing is done the way that Dog intended - uphill all the way from the slave up to the master and from the master up to the reservoir. In a well-routed system, air can find it's way up to the master cylinder out out from there through the reservoir hose. It might take overnight, it might be aided by some driving vibrations, but they tend to self-bleed. In a system with routing compromises, air can get stuck in intermediate high-points. When in doubt, bleed, actuate the pedal 50-100 times, bleed, actuate the pedal 50-100 times, bleed again, etc.

Yes, removal of those rubber down-stops can present an opportunity for increasing pedal reserve, but just make sure that the master cylinder doesn't become the downstop! They're not designed for that.

Make sure the pedal is not obstructed from coming all the way up, or the fill port on the master cylinder won't open. You need the fill port to be open to vent air and allow make-up fluid to enter.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

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InlinePaul
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Re: Clutch Changeout Issues with Hydraulics

Postby InlinePaul » Sun Mar 10, 2013 12:12 am

The tranny shop that did the master did bench bleed it before installing it so there should not be much in the way of air bubbles. But you point about self bleeding over time is interesting. That would support what my other shop said about the pedal improving with time (that and/or my theory that the master cylinder regained some of the original stroke over time). I won't attempt to bleed it so am at the mercy of the shops. My regular shop bled it last year after installing the new slave and it was fine, so I think they know how to bleed it. This time thought the master went out after a couple days (whether it also had a compromised stroke I don't know) but the new master sure helped.

Rubber stop is 3/16 inch. Pulled the pad and checked and the plastic plunger rod did not seem to stress at all on full pedal stroke, but the noise of metal upon metal was annoying every time I stroked the pedal while driving, so I put a 3/32 rubber pad in. Effectively I get about 1/16 more stroke, which is more of a comfort level to ensure am not shifting with partial engagement which would over time be wearing on the syncros.

Pedal travels freely in both directions and shows not obstruction on the up side.

Have to study clutch master cylinder design some to understand fill port. Assume at back of stroke the bore is open to the reservoir.

Anyway, thew ought to have some kind of simple adjustment to the pedal height, so it seems to me.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

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Re: Clutch Changeout Issues with Hydraulics

Postby Rope-Pusher » Sun Mar 10, 2013 8:45 am

Image
The fluid reservoir may be close-coupled or remote. If remote, it may be shared with the brake system. Either way, the port to the reservoir has to be blocked by the motion of the piston in the cylinder before pressure can be generated in the line going to the slave cylinder. Adding an adjuster on the rod could allow you to minimize the amount of free-play or dead pedal travel before the port is closed off' This would give you more pedal reserve - moving the release point up the arc of the pedal stroke, away from the floor.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

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InlinePaul
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Posts: 1438
Joined: Wed Mar 06, 2013 2:55 pm
Cars: 2001 Ranger 2.3L manual
Location: Detroit MI

Re: Clutch Changeout Issues with Hydraulics

Postby InlinePaul » Sun Mar 10, 2013 8:50 am

Nice illustrations. The clutch master is separate from that of the brakes on my Ranger. The master is below the brake vacuum diaphram and there is a line from it to a point about 10 inches higher where the reservoir is located. I've done all I can and it is working. Hopefully over time the engagement point will rise some. Of course some have the other problem where engagement is at the top and maybe not fully engaged, so I should be happy that mine is fully functional.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...


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