Cameron

'91 GT

Clutch pedal will drop over night. Once I pull it up by hand, it is ok. Doesn't drop while I am driving it, or if I just sit for a few minutes (perhaps it does, but does so so slowly that it is not noticable). No sign of fluid leaks near the clutch master or slave cylinders or hoses.

It has to be air getting in somehow, doesn't it?

AO

I doubt it would be air. More likely a bad seal, but I'm no expert in this area, so I defer to those that have BTDT.

FlyingDog

By drop over night, you mean it's soft in the morning, or the pedal is on the floor? Do you have fluid near your pedal? Something to consider is too much preload or improper spring adjustment preventing the master from refilling from the resevoir except when you pull up by hand. If the pedal is on the floor in the morning, the pedal is definitely misadjusted.

Cameron

The pedal is nearer the floor, but not quite all the way down to the floor in the morning. Maybe 1/2 to 2/3 down. No fluid near the pedal or clutch master.

I am trying to do some research on this while at work. I don't have my workshop manual in front of me but saw a post about the 'overcenter helper spring'. Can someone tell me about this, please? I was hearing something that sounded like a spring stretching noise a couple of weeks ago when depressing the clutch pedal. It stopped as abruptly as it started (the sound that is).

mulik51

I have the same problem. I did play with the spring and it didn't help me, so probably it is not it. There is a "buterfly nut" on it. You can tighten it, or loosen it.
In my case it can be air becouse i have my engine apart
Very Interested in the fix...

Klim

GlenL

Keep a close eye on the brake fluid level. I'll bet some is leaking out somewhere. Might be master or slave pistons or the fittings on the black hose.

Cameron

I don't see any brake fluid loss. WTF?

FlyingDog

I hope this helps. IIRC, my spring keeps the pedal all the way up. I don't hink it could sink even if it lost fluid.

GlenL

Matt, Good point!

This is perplexing. Sounds like two failures in one.

deliriousga

Mine did the exact same thing right before the the flex hose blew off the fitting, emptied out the reservoir and no clutch. There were no signs of fluid leaking beforehand, but the 18 year old rubber couldn't take the new master cylinder.

If you changed the master or slave recently, you ought to go ahead and replace the flex hose since the pressure is higher.

I think the spring pulls the pedal to the floor making it easier to push and the fluid pushed it back up. My fluid loss caused the pedal to be on the floor.

FlyingDog

If you look at the diagram, the spring holds the pedal up until you have pushed the pedal an inch or two, then it pushes down. Basicly, it fights you until the inlet from the resevoir is covered, then it assists you.

AO

Read the words, it says the spring is designed to boost foot pressure by preloading the system thus requiring less force to disengage the clutch. Matt, you got it backwards.

GlenL

Andrew,

Looking at the diagram the helper spring should function as Matt describes. The trick is that the line of force from the spring switches from the bottom of the arc to the top. (When the spring is pushing directly at the pivot for the pedal the force will be zero.) Even though the spring is most compressed in that area, the effective lever arm is short so the net force is small.

At full-up, the spring will help hold the pedal up. I'll bet the designers intended that to give the hydraulics an unloaded position. In that position the gravity feed from the reservior will fill the system and it'll be self adjusting as the discs wear.

AO

Glen-
Agreed, it looks like it would function as Matt stated from the picture, but if you look ay the assemble below, you can see that the spring is not fixed on the other end - rather it floats once the pedal is pushed beyond the expanded length of the spring.

GlenL

Right. But when the pedal is all the way up the spring is compressed. When the pedal is pushed down it'll eventually be fully extended and not push on the pedal.