Clutch mystery

[TallPaul]

So I had the clutch, pp, release bearing, slave, and master cylinder changed out in the 2001 Ranger about 2 years and 20,000 miles ago. The pedal engaged close to the floor (maybe half inch or so).

A couple months ago the engagement got closer to the floor. A couple weeks ago it got so bad I could not always get it into first gear easily from a stop. Once driven for a distance, or in warmer weather it is not bad.

I had it to the shop yesterday. They put it on a hoist and verified that with the pedal all the way down, the pressure plate was fully released and could not move any farther away from the disc. But they could not check it when it was cold because it was not that cold yesterday morning and they test drove it first.

So, it seems in cold conditions it engages closer to the floor. There were no apparent leaks and if it had an interal leak the pressure plate would not have gone all the way back. He said, even if the linkage could be adjusted, you could not get the plate to move any farther away.

 

[demarpaint]

What vehicle is this? If its a Ford check and make sure the floor/firewall anywhere near the gas pedal where it meets the floor when depressed isn't flexing when you step on the clutch pedal. Even a tiny amount of flex will cause problems. Especially during cold weather.

 

[BigCahuna]

I had the exact same problem years ago. It turned out that the problem was that in my hurry to get the job done, I didn't have the flywheel cut.Took it all apart again, removed the flywheel Took it to my friend garage, and he put it on his machine and put a new surface on it. That's all it took to cure the problem . I replaced the disc a second time at that point. Ran like new after that.,,,

 

[TallPaul]

Originally Posted By: BigCahuna
I had the exact same problem years ago. It turned out that the problem was that in my hurry to get the job done, I didn't have the flywheel cut.Took it all apart again, removed the flywheel Took it to my friend garage, and he put it on his machine and put a new surface on it. That's all it took to cure the problem . I replaced the disc a second time at that point. Ran like new after that.,,,


That is interesting because I was told that low pedal ususally happens if the flywheel is cut because it makes the clutch assembly sit a little farther from the slave cylinder, and that the cure was to shim the flywheel. We did not cut the flywheel, but hate to tear it all down if it is driveable (should be much better over the summer), and as the mechanic said, the presure plate is fully backing off to the limit.

The flexing firewall is something to consider. Had that happen on my '84 F150.

Thanks

 

[TallPaul]

Guy at the tranny shop said that instead of checking that the pressure plate is all the way back with the pedal to the floor, should check that the pressure plate starts moving early in the pedal stroke. If not, then the master may not be giving a full stroke.

The pedal goes the first 1 to 1.25 inches of travel with hardly any resistance, then firms up, but that may be normal. I wonder if there is a way to know what the stroke of the master cylinder is suppose to be. Then I could measure it under the dash from the point of resistance to fully depressed.

Also I looked at the firewall and don't see any rust. Looks sound.

 

[Drew99GT]

Try adjusting the freeplay in the master cylinder pushrod. 1 inch of play is way too much.

It's easy to do by yourself; there will be a jamnut screwed on the pushrod where it locks to the clevis (the part that connects the master cylinder to the clutch pedal. Unscrew the lock nut and turn the master cylinder pushrod clockwise a few turns and push on the pedal with very little pressure until all that slack gets taken up. You want about a 1/4 inch of freeplay in the pedal. In fact, it's easier to just unscrew the pushrod and get a bucnh of slack in it so you can feel with your finger pressing on the pedal what slack feels like, and then slowly turn the pushrod clockwise to take the slack up to 1/4 inch of freeplay. That way you'll get the feel just right and not overtighten it.

It sounds like there's too much slack in the pedal and the master cylinder isn't getting enough stroke.

 

[TallPaul]

Well that is part of the problem, there is no adjustment to the pushrod. I was thinking if it is metal I can remove it, cut it in half and use a die to cut threads on each side, but they have to be opposite threads, like a turnbuckle, then use a turnbuckle sleeve on it. They actually sell adjustable pushrods too.

The other problem is that I now remember the pressure plate has self adjusting mechanism so that the pedal will always remain pretty much in the same place. A nice feature, but working against me now since at 20,000 miles the pedal should have come up some.

I did discover that if I am patient and hold the lever against the gate it will go into first at a stop after a second or so.

 

[demarpaint]

Originally Posted By: TallPaul


Also I looked at the firewall and don't see any rust. Looks sound.


Don't let that fool you. I had two vehicles with no rust, I mean zero rust, and had floor flex drive me nuts. With the engine off get under the vehicle and have someone in it pumping the clutch pedal up and down look for flexing of the firewall and floor where the master cylinder goes through it. Even an 1/8" will cause problems.

 

[TallPaul]

Originally Posted By: demarpaint
Originally Posted By: TallPaul


Also I looked at the firewall and don't see any rust. Looks sound.


Don't let that fool you. I had two vehicles with no rust, I mean zero rust, and had floor flex drive me nuts. With the engine off get under the vehicle and have someone in it pumping the clutch pedal up and down look for flexing of the firewall and floor where the master cylinder goes through it. Even an 1/8" will cause problems.


Will check it out.

Also read somewhere to make sure the master cylinder was not installed with too much sealer between it and the firewall as that will push the master farther from the pedal.

 

[demarpaint]

Originally Posted By: TallPaul

Also read somewhere to make sure the master cylinder was not installed with too much sealer between it and the firewall as that will push the master farther from the pedal.

I think I read that somewhere too. My problem was flex, I forgot about that.

 

[TallPaul]

Not sure why sealer is really needed. Top keep out drafts? Ha, my '77 had a hole in the floor for the clutch mechanical linkage with a rubber boot, but the boot was gone for many years. Never had a problem. Maybe loosen the master and scrape out the sealer if I could get to it, but it is buried almost as badly as is the slave cylinder.

Bean counters and the bottom line. If the car makes it through the first lease and can then be resold at top dollar, they apparently don't care about anything else.

 

[demarpaint]

Originally Posted By: TallPaul
Not sure why sealer is really needed. Top keep out drafts? Ha, my '77 had a hole in the floor for the clutch mechanical linkage with a rubber boot, but the boot was gone for many years. Never had a problem. Maybe loosen the master and scrape out the sealer if I could get to it, but it is buried almost as badly as is the slave cylinder.

Bean counters and the bottom line. If the car makes it through the first lease and can then be resold at top dollar, they apparently don't care about anything else.


I have to look for sealer next time i change the oil. I can tell you this, my floor was flexing like mad in both vehicles. I had to get them back to the way they were supposed to be and then beef them up. It was a tremendous improvement.

 

[TallPaul]

Here is what I just found. There is wetness at the back of the master cylinder (ovals). There was in the rectangle but I swiped my finger across that part. It felt oily. Could not discern an odor.

 

[TallPaul]

Now if the seal at the plunger is seeping, you would think that lost fluid would be replaced by the reservoir.

Anyways it looks like I am in for a new master. This one is a Sachs according to the work order from when it was installed. I thought that was a good brand. What is a good one? Do they make any with metal bodies?

 

[andyd]

Hook up the line to the slave with the MC not mounted to the fire wall. Mounted they trap air because they are pitched wrong.

 

[TallPaul]

Friday when I checked the leakage, I wiped the leaked fluid from my finger onto the bedrail and rubbed it into the paint. Two days later I see nothing wrong with the paint. I thought brake fluid was supposed to eat paint.

 

[ryanschillinger]

Try applying vacuum to the bleeder on the slave and flush the fluid. Maybe air in system.

 

[TallPaul]

It's going in tomorrow for a new master cylinder. They will bench bleed it before installing it in the firewall.

What I don't get is that brake master cylinders typically last the life of a vehicle, so why not clutch master cylinders? Or is it just that the clutch linkage is more sensitive than a braking system?

At least they could include an adjustment to the hydraulic clutch.

And what is the great advantage in a concentric slave cylinder? I understand external slaves are still common in manual transmission applications.

 

[Kiwi_ME]

Originally Posted By: TallPaul

What I don't get is that brake master cylinders typically last the life of a vehicle, so why not clutch master cylinders?
...
And what is the great advantage in a concentric slave cylinder? I understand external slaves are still common in manual transmission applications.

Considering how often you use the clutch compared to the brake, I think both slave and master get a beating.

Concentric slaves are more compact, my '81 Saab had one. But the clutches in my '14 VW DSG use forks.

 

[TallPaul]

I had an '84 F150 I bought new that went 300,000 miles (I know the second owner--it's long gone now though) on the original clutch hydraulics. It had an external slave. I remember changing out the clutch and PP at 90,000 and not having to bleed, just bolt the slave back in place. Everything worked fine.