Rising Clutch Pedal

[MooseStang]

While exercising my vert today, I noticed at higher rpms that my clutch pedal was rising.    Shifting was otherwise normal.
Can anyone explain?

 

[Sheriff41]

You probably have a pressure plate with counterweights that use centrifugal forces (as RPM increases) to exert additional pressure on the clutch plate.  This counterweight action is felt in the clutch pedal.  You can add a little play in the clutch to minimize this when the clutch is released.  Any movement in the pressure plate from counterweights will just take up the play.

 

[Stanglover]

You probably have a pressure plate with counterweights that use centrifugal forces (as RPM increases) to exert additional pressure on the clutch plate.  This counterweight action is felt in the clutch pedal.  You can add a little play in the clutch to minimize this when the clutch is released.  Any movement in the pressure plate from counterweights will just take up the play.

That is probably so, but on my car with a Centerforce II clutch, I don't think I can say I've ever noticed that happen. Clutch free play is essential and needs to be set correctly. Then again, I don't ride the clutch pedal either, so my foot isn't on the pedal.to feel if it rises. Maybe I'll try that next spring when the car is "back on the road".

 

[Hemikiller]

Factory Long clutches have counterweights on the release arms. Rev the car with the clutch pedal depressed, you'll feel the change in pressure. 

 

[71ProjectJunk]

Shouldn't the clutch pedal be pushed all the way to the top by the spring under the dash so that there is no way for it to move any further? I know that when I replaced my z-bar the pedal would either stick all the to the firewall or all the way to the top, and with quite a bit of force. Only thing I can think of is that the spring on the top of the pedal is either broken or no longer there. I know that when you install a Centerforce clutch kit you are supposed to remove that spring, which pushes the pedal all the way to the pedal stop on the dash. I would guess that if that spring is no longer there, the pedal may move a bit when you accelerate and everything moves around, as there in nothing putting pressure on the pedal to remain on the pedal stop on the dash. I would guess that without that spring and enough clutch free play, you could have movement on the pedal, but it is just a guess. The only other thing I can think off is that all the bushings on the z-bar are perished, and when the car accelerates there is enough movement in it for the pedal to move, but I would still think that if the spring on top of the pedal is there, it probably would not move.

 

[Stanglover]

If the clutch has been replaced with a Diaphragm style clutch, Centerforce or whatever brand, the old assist spring designed for the factory long finger style clutches, must be removed. If it has not and a diaphragm clutch has been installed, perhaps that is the reason. I took mine out as soon as the Centerforce II was installed and I have never felt the issues described. However, I do agree that if the bushings along the linkage path are shot, then I can see that maybe causing some issues. Again going back to my set up, all the bushings were replaced with bronze oilite and the clutch arm bearing replaced with Mustang Steve's bearing kit. That alone took many pounds pressure off the left leg. 

 

[MooseStang]

Thanks for everyone's input.   I do probably need to rebuild the bar, new bushings and springs.  I'll also add that "normally" the clutch pedal about an inch below the brake pedal,  but, I can also "pop" it up about an inch above the brake pedal. 

 

[71ProjectJunk]

I can tell you all about the pop, as I have just been dealing with this same situation and I have gone through the whole clutch linkage assembly on my car. I had to change every piece of the clutch linkage, it was all junk. You have an upper clutch rod that goes from the pedal to the z-bar, then you have your z-bar and then you have the lower clutch rod. The z-bar has a connection to the frame rail and a bracket on the transmission that hold it in place with round plastic bushings. There are also 2 springs on the z-bar to help keep the lower clutch rod in place and to help clutch pedal stay up. The correct location for your clutch pedal is in the up position (where it pops out) about and inch above the brake pedal. So, being that it is not above the brake pedal and it "pops" up, it means that you have a problem with your clutch linkage.

Here is the problem, the upper clutch rod has plastic bushings at both ends it, where it connects to the clutch pedal and where it connects to the z-bar. Then you have the round plastic bushings that hold the z-bar in place, and the z-bar pivots on these bushings, and then you have the lower clutch rod which has a bracket with a bushing that connects to the z-bar. All the small plastic bushings on my parts were not there, and the parts had been running metal on metal, this damaged the upper clutch rod, the z-bar and the lower clutch rod. The holes on the z-bar were egged out and the rods were worn half way through. As for the plastic bushings that hold the z-bar in place, the one on the frame side was broken, the one on the engine side was still in one piece. Then I had the bracket that goes to the transmission which has a stud on it, where the plastic bushing goes to. Well Ford in all their stupidity, pressed in the stud to the bracket, so that stud was loose. At least this was an easy fix, I just welded the stud to the bracket so that it would not wobble in place. 

Here is a photo of the complete clutch linkage:

 

[71ProjectJunk]

After I replaced my Z-bar, my rods, all the bushings and my springs, and set the correct linkage clearance on the bottom bar, my clutch pedal would sit 1" above the brake, and it would come up and down really smoothly.  Regrettably I could not replace the lower clutch rod with the new one I had gotten as the clutch fork had a hole in it and the previous owner had put a really thick bar down there so that it would not go through the fork. I have a new fork, but I have yet to pull the transmission to replace it. 

Now, this is what I found out about the pop. After everything was working perfectly (obviously the fork and lower rod still need to be changed), I started the car and ran it, when I pressed the clutch all the way to the floor, I had the most horrible grinding noise you have ever heard, it was bad. There are a couple of things that can make that noise, but honestly it seems like the fork is hitting the pressure plate. If you only press the pedal to about an inch, inch and a half from the floor, no issue, as soon as you go beyond that, all hell breaks loose. I did not have this noise before, but everything was loose down there. I went and adjusted the lower clutch rod out until I could press the clutch all the way in with no noise, but now the pedal will not come up. Originally before I changed everything, the pedal would not come up, so I am back to where I started, lol. So, your adjustment may just be off. The clearance needed between the clutch rod and the fork is right a .200 of an inch, I know that I am now at about 1 inch clearance so that I do not get the grinding noise. As that clearance changes the angle of the bars on the Z-bar changes, and it seems that after a certain angle change, the spring that goes from the z-bar to the frame can no longer pull the pedal up. You may just be able to adjust your linkage and it may start working as it should, or maybe just changing the spring from the z-bar to the frame may do the trick. 

After I went through this, I would say that you would be lucky to not have to change most of your clutch linkage, the little plastic bushings are not the best idea in the world and as soon as they fail, and they will fail, you have metal on metal contact. If you are lucky and the bushings are still there or partially there, and the parts have not been egged out of shape, then you can just replace all the bushings, grease everything, adjust the clearances, change those 2 lower springs and be on your way. 

 

[Stanglover]

About the clutch pedal "pop". This is what I know from my own learning experience. When I bought my car back in 2008, I found a PO to the guy I bought it off, had installed a new diaphragm clutch of unknown brand. The pedal was doing exactly what you describe. This unknown brand clutch would slip badly if I jumped on it, I guess it was too weak. So, in 09, I replaced it with a Centerforce II, had the flywheel reground (very important!) and set it all up, but the "pop" was still there, in fact worse, the pedal would stay down to the floor. So I did some research and was in contact with Centerforce via email. That's when I found out that the old helper spring HAD to be removed. These were necessary for the long finger style clutches. If one replaces a clutch with a new long finger clutch, leave that spring there!! To remove this spring was not easy working from the top, dash pad removed. There is a ton of pressure on these springs, so be VERY careful removing it. I ended up cutting the damn thing out with a Dremel and cut-off disc. After this was removed, the clutch pedal worked as it should. In fact, as I'm a short ***, I needed the clutch pedal higher so I can get enough travel without being too close to the steering wheel To do this, I modified the pedal stop rubber, see attached  diagram. Oh how I wish these cars had adjustable steering columns!! 

On the noise you're getting. Not to say this might be your issue, but when my new clutch was put in by a mechanic (I have no hoist to do it myself) I was getting some noise and a bit of sticking. So we pulled the trans again to find that one of the spring clips that hold the throw-out bearing to the fork, had broken off, causing the bearing not to travel straight on the input shaft.. On the throw-out bearing, that was a new replacement style and pretty cheap looking. My solution was to buy just the bearing from a local bearing supply dealer and replace the old bearing in the original Ford cast carrier. Problem solved.

Clutch set-up.pdf
Clutch bushing sketch.pdf

 

[Hemikiller]

Thanks for everyone's input.   I do probably need to rebuild the bar, new bushings and springs.  I'll also add that "normally" the clutch pedal about an inch below the brake pedal,  but, I can also "pop" it up about an inch above the brake pedal. 

That means it's not adjusted properly, and/or your bushings and other parts are worn. 

 

[midlife]

To remove the helper spring: get it so the spring is extended as much as possible, then insert coins between the coils.  Then relax the spring back to minimum extension and it should fall right out.  Neat trick, eh?  Also works on door springs.

 

[71ProjectJunk]

To remove the helper spring: get it so the spring is extended as much as possible, then insert coins between the coils.  Then relax the spring back to minimum extension and it should fall right out.  Neat trick, eh?  Also works on door springs.

That is a really neat trick, just learned something new

 

[Stanglover]

To remove the helper spring: get it so the spring is extended as much as possible, then insert coins between the coils.  Then relax the spring back to minimum extension and it should fall right out.  Neat trick, eh?  Also works on door springs.

 I wish I'd know about that trick when I did mine. 

Actually imo, the absolute best way to do  this is to remove the entire hanger bracket and take it out, replace the stupid plastic bushings on the clutch shaft with a bearing kit, Mustang Steve's or Scott Drake. While at it do the brake pedal shaft bushings as well. Yeah, it's lot of work that is best done during a restoration.

 

[MooseStang]

Oh boy.

 

[Stanglover]

Oh boy.

Oh boy indeed. Yep, that spring is in there!! The spring on the fork to push rod is definitely not correct either.

I don't recall you saying exactly what clutch you have in the car. I'm assuming it's a diaphragm style, not the original long finger type. That's important to know. If you have the newer diaphragm clutch, that spring has to be removed and your problems will go away. However, correct set up is crucial as I'm sure you're aware. Unfortunately, these do not allow for perfect pedal height adjustment and get full travel. On mine, I have to have the pedal set as high as possible, but I still need full travel to the floor boards to ensure the clutch is fully disengaged to stop grinding the gears. It's a pity no-one has come up with a hydraulic clutch mechanism that is a direct replacement for the Z bar crappy set-up we have to use. I know there are aftermarket clutch replacement kits, both hydraulic and cable, but I don't think there is one to replace just the Z bar and linkages. That would be really nice to have! 

Good luck and let us know how it works out.

 

[MooseStang]

Sorry, I don't know the clutch type.  I'll start off by replacing the bushings and bar springs.

Any parts kit recommendations?

 

[71ProjectJunk]

Another thing, besides that spring being incorrect, is that you are missing the clutch fork dust boot:

https://www.cjponyparts.com/clutch-release-lever-dust-boot-mustang-260-289-302-351-1965-1971/p/C6OZ7513C/?year=1971&gclid=Cj0KCQiA15yNBhDTARIsAGnwe0VTxo9i3gXnFXvY3LF0xcjf3TcAsTWc4PJK5C3lSKmSFH1Yifdv4EIaAv_JEALw_wcB

Check the spring on the other size of the z-bar, that goes from the z-bar to the frame rail, that is the spring that will have the clutch pedal come up. Willing to bet that if the lower z-bar spring is incorrect, then the top one will be too. Either way you should probably replace both springs as they are cheap and they will help your clutch linkage work as it should. There is also another dust boot that goes from the upper clutch rod to the z-bar, if you are going to be dealing with all this you might as well get that one too. It is not a very important dust boot, as it is only there so that dirt and water do not go into the drivers compartment, but you might as well change it if it is bad. The dust boost for the transmission is more critical, as it will prevent dirt and water from getting to the clutch and throw out bearing. 

 

[71ProjectJunk]

Sorry, I don't know the clutch type.  I'll start off by replacing the bushings and bar springs.

Any parts kit recommendations?

Since you are missing the dust boot to the transmission you may be able to look in there and see what you have. You will either have a diaphragm pressure plate or a long style. The diaphragm has a bunch of fingers that contact the throw out bearing, and the long style only has 3 fingers that contact the throw out bearing. If you can get your phone in there and take a couple of photos with the flash on, you may just be able to see what you have.