PFF - Pennock's Fiero Forum, PDA Edition

Unusual clutch issue (Page 3/8)

stevep914

JUL 27, 05:24 PM

Got the system bled, and went out for test drive. $#%* This time it didn’t even make it back to the house. About 40 minutes in, one minute I have full pedal, the next, nothing- pedal dropped to the floor with no gear selection. In traffic, where I had to stop, get out of the car, and push it off the road.I had been testing the pedal after 30 minutes constantly, and it was solid. I let the car sit for 10 minutes. Got it into 2nd, and limped it home. NOT a happy camper! Fed up with it today, but maybe tomorrow I will try to bleed it, and see if any air comes out. While bleeding, I checked pushrod travel , and it is getting full travel about 1 and 1/2 inches or close when the pedal is good. By the way, after bleeding, the “slop in the pedal went away, and it was firm right from its resting position. Steve

Patrick

JUL 27, 05:43 PM

I feel your frustration.

quote

Originally posted by stevep914:

By the way, after bleeding, the “slop in the pedal went away, and it was firm right from its resting position.

There needs to be some slop. When the system is fully bled (and supposedly no air in the system), disconnect the clutch pedal and see if it pulls further up. What you're checking for is that the banjo (while connected to the pedal) is not preventing the master cylinder from fully returning to its resting position. If it's not able to fully return, there's a chance that the valves within the master cylinder aren't able to function properly... and maybe this is somehow exacerbated when everything has heated up. (Make sure to reconnect the banjo with the loop located upwards.)

[EDIT] I seem to recall from years past of someone here who had clutch issues created by the clutch safety switch being adjusted incorrectly. This was preventing the clutch pedal (and therefore the master cylinder) from reaching its proper resting position.

[This message has been edited by Patrick (edited 07-27-2022).]

Spoon

JUL 27, 07:09 PM

quote

Originally posted by stevep914:

My bleeding procedure is by the book,

Whose book are you using? Give step by step in detail the procedure you are using. Perhaps something is missing and you're not getting all of the air out.
I have a 86 4 speed Muncie. I replaced the front master and rear slave. Parked with nose on a downward angle since air will rise to the highest point at the slave. Removed bleeder from slave and added fluid to the master. Within minutes bubbles began coming out of the slave bleeder. I added more fluid so the master would not pick up more air. Pretty soon the bubbles stopped and I was getting fluid. I let it flow until the fluid became clear. This told me that the old fluid had been evacuated. At that time I depressed the short push rod and closed the bleeder. I then topped off the master and put the cap back on. Pushed the clutch pedal several times. Did a test drive. End of story.
I believe the angle I parked the car helped get the air out. No pumping or helper required. Results may vary.

Let me know if this helped.

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

stevep914

JUL 27, 07:18 PM

stevep914

JUL 27, 07:30 PM

I believed it said somewhere on this forum to elevate the FRONT of the car for gravity bleeding to take place. I had my wife depressing the pedal, while I handled the bleeder valve . No pumping of the pedal- just depress, and bleed, close bleeder valve and release pedal. I purged all the old clutch fluid; replaced with dot 4 and then pushed the pushrod back into the slave. Tomorrow, I will check out Patrick’s suggestion, and follow your procedure with the back of the car elevated-. At this point, I will try all and anything to resolve the issue, Today was NOT fun, and major embarrassing! Steve

Patrick

JUL 27, 07:58 PM

quote

Originally posted by Patrick:

I seem to recall from years past of someone here who had clutch issues created by the clutch safety switch being adjusted incorrectly. This was preventing the clutch pedal (and therefore the master cylinder) from reaching its proper resting position.

Found it. It was 12 years ago, so apparently my memory isn't totally shot.

This thread is worthwhile reading for bleeding info, and in there I found reference to This thread that I was mentioning above.

By the way, the majority consensus is to bleed with the nose raised, and the driver's side of the car raised (slave/bleeder screw tilted up). I understand the confusion, some might think that you'd want the rear of the car raised so that the air bubbles could "rise" towards the slave... but with the nose up, the fluid moves fast enough to carry the air bubbles downward... and out the bleeder. With a clear tube attached to the bleeder valve, and the other end inserted into a clear container/bottle, it's easy to see the air bubbles coming out... until they eventually don't. End of bleed!

[This message has been edited by Patrick (edited 07-27-2022).]

fierofool

JUL 28, 11:23 AM

I have used the gravity bleed method for a long time. Not having anyone to help, there was no one to depress the pedal. Pumping the pedal can break up the air bubbles, only to come back together later. If the pedal pump method is used, the pedal should only be depressed and held one time for each opening of the bleeder.

If I'm bleeding at home, I jack the left front of the car underneath the front subframe just enough to lift the tire off the ground. If it's underneath the left front control arm, I raise it about 6 inches off the ground. This places the master cylinder higher than the slave cylinder.

I then fill the master cylinder to the top, leaving the cap off the brake fluid and the reservoir for easy refill. Next, I go to the rear and open the bleed valve. As the fluid starts to flow, I use a heavy object and strike the side of the slave repeatedly. This dislodges any air bubbles that may be stuck at the pushrod end and lets them flow upward to the bleeder valve. With the pump method, the bleeder is directly above the fluid inlet and bubbles at the pushrod end will usually stay there.

Keeping watch on the reservoir, I close the bleeder before the reservoir empties, top off the reservoir and repeat. I usually run about 3 reservoirs of fluid through the system, then when the level drops to the FULL mark, I close the bleeder and I have pedal.

When I had the incident I related previously, I ran the left front up onto a curb at the grassy edge of the parking lot. Gravity bled the system and returned the 12 miles home to diagnose the problem. I was lucky that it was an undeveloped outparcel parking lot that wasn't being used. I have bled other person's systems by angling at 45* on their sloped driveway.

sanderson231

JUL 28, 01:04 PM

The first generation and second generation clutch master cylinders are functionally different.

The 1st generation with the reservoir on the end has a valve in it and the master can be easily bled similar to brake system with the clutch the pedal. The presence of the valve might make this master difficult to bleed by gravity.

The 2nd generation master with the reservoir in the middle has no valves in it. There is a port that is open to the reservoir when the clutch pedal is up. When the pedal is depressed, a lip seal slides past this port so the compressed fluid cannot flow back to the reservoir. My experience with this master is it is difficult to impossible to bleed with the pedal. I have used a Mity-Vac on the slave bleeder to pull fluid through. I've not tried gravity bleeding but I can see how it would work with this master.

The 2nd generation master can be replaced by the first generation master. I just takes a little bending of the tubing. IMHO the 2nd generation was not a reliability improvement, it was just a way to cut cost.

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

stevep914

JUL 28, 01:22 PM

Ok, I’ve calmed down a bit since yesterday. Elevated the nose of the car drivers side, and gravity bled- filled 2 feet of clear hose with fluid with no air bubbles evident at all. I then pushed the pushrod back into the slave, and no air bubbles there either. Pumped the clutch pedal about 200 times without the car running, and the pedal stays firm. Pushrod travel is at least 1and 1/4 inches. The 200 times on the pedal would approximate my driving time, where at the end I would lose the pedal. I am assuming the clutch operates whether the engine is running or not. Looking at the pedal and banjo, the pedal seems to come up to the stops with the banjo attached. I did notice some play in the connection where the banjo goes on the pedal. One other thing: I believe my pedal is aluminum, not steel it has an interesting twist in it. Not knowing what anything other than mine looks like, and assuming a bent pedal would provide a consistant problem, I don’t know if this is a contributing factor. Anyone able to post a picture of a normal clutch pedal I could compare mine to? I know many have converted to a steel pedal when the stock one bent. Again, would a bent pedal not offer a consistant problem other than a sporadic one like mine? Next step for me, I guess, would be to run the engine, and do another 200 shifts parked, and see if the problem occurs. So far I have made no real changes, since yesterday’s problem, other than another complete bleed. Steve

olejoedad

JUL 28, 02:23 PM

It's not the pedal arm that bends, it's the bracket that the banjo attaches to.
The bracket should be parallel to the pedal arm when viewed from the side and front.