Clutch pedal

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71scamp78

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Got 73 Duster I'm working on for a friend who doesn't wrench. Its a 4 speed and the clutch pedal sits well below brake pedal so not a lot of movement. I can pull up on it and it will be about even with brake pedal where it should be. Whats the proper way to adjust it. I haven't adjusted one because all my rides never needed it lol. I know there is an adjuster under car but I don't think that would help pedal much. I assume that is to adjust the throw out bearing. Any help is appreciated
 
1753294724820.png
 
Most likely someone replaced the factory style clutch with a Diaphragm style clutch.
 
You can search here for threads that show how to remove the Over Center Spring, and then how to mount a different type of spring. The pedal will sit lower though.
 

71scamp78 said:
Shouldn't there be a return spring here.

View attachment 1716433608
Click to expand...
The "over center" spring is the huge rusting thing at the very top of your photo. Once the pedal moves far enough to get it "over center" that spring is trying to push down the pedal. The RETURN spring is a very light spring underneath, connected to the release fork somewhere. and trying to pull the fork to the front of the car which helps disengage, but is really only helping the "play"

This all only works when

The clutch parts are all correct pieces
(Read that AGAIN!!)

When the clutch disc is not terribly worn out
When the thing is adjusted properly---there is only one---on the pushrod down at the fork, which changes the pushrod length.

And when the Z bar is not only correct, the engine sitting properly on poroper mounts (not some welded in conversion mounts) but also that the Z bar is NOT DAMAGED and or rusted, causing the levers to be displaced rotationally from their proper relationship

You can see it below. AN979 on the pushrod I believe is a lock nut. If not it is the adjuster. AW483 is either the adjuster or a washer. AG412 I believe is a rubber anti rattle cushion. The RETURN SPRING is right there, FS480

IT WAS FAIRLY COMMON back in the day for guys to add a generic parts store spring to the return spring for a little more "help" in the return dept.

clutchadj.jpg
 
Last edited:
67Dart273 said:
The "over center" spring is the huge rusting thing at the very top of the photo. Once the pedal moves far enough to get it "over center" that spring is trying to push down the pedal. The RETURN spring is a very light spring underneath, connected to the release fork somewhere. and trying to pull the fork to the front of the car which helps disengage, but is really only helping the "play"

This all only works when

The clutch parts are all correct pieces
(Read that AGAIN!!)

When the clutch disc is not terribly worn out
When the thing is adjusted properly---there is only one---on the pushrod down at the fork, which changes the pushrod length.

And when the Z bar is not only correct, the engine sitting properly on poroper mounts (not some welded in conversion mounts) but also that the Z bar is NOT DAMAGED and or rusted, causing the levers to be displaced rotationally from their proper relationship

You can see it below. AN979 on the pushrod I believe is a lock nut. If not it is the adjuster. AW483 is either the adjuster or a washer. AG412 I believe is a rubber anti rattle cushion. The RETURN SPRING is right there, FS480

View attachment 1716433613
Click to expand...
All of what 67Dart273 said!
 
Well, most of that is true. The pedal doesn't need to come up all the way, most don't. Yes, that adjustment rod to the clutch fork is the adjustment. That big rusty spring is to help push a 3-finger clutch pressure plate in, not hold the pedal up. If you have a little play between between up pedal and contact to to the throwout bearing, your done.
 
CRUZE 418 said:
Well, most of that is true. The pedal doesn't need to come up all the way, most don't. Yes, that adjustment rod to the clutch fork is the adjustment. That big rusty spring is to help push a 3-finger clutch pressure plate in, not hold the pedal up. If you have a little play between between up pedal and contact to to the throwout bearing, your done.
Click to expand...
I didn't mean to imply that. I only meant that functionally when it's "over center" it tries to pull the pedal down. However you are not ever going to get free play if the pedal is not "up" on the upper end of over center. As you say, "if you have a little play"
 
I do believe the "Over Center" spring works in BOTH directions.
It assists your leg effort pushing the pedal down and compressing the pressure plate springs it was designed for (not diaphragm).

The pressure plate springs are also the "return" springs for the pedal. They push back on the pedal linkage as you lift your foot up to a point just past pedal "center" position, then the "Over Center" spring pulls the pedal up to its stop.

Leaving the OC spring on with a diaphragm can simulate "riding the clutch" as it will pull the pedal downward if not raised past pedal center. Hence, OC spring removal is the norm.
 
Daves69 said:
I do believe the "Over Center" spring works in BOTH directions.
It assists your leg effort pushing the pedal down and compressing the pressure plate springs it was designed for (not diaphragm).

The pressure plate springs are also the "return" springs for the pedal. They push back on the pedal linkage as you lift your foot up to a point just past pedal "center" position, then the "Over Center" spring pulls the pedal up to its stop.

Leaving the OC spring on with a diaphragm can simulate "riding the clutch" as it will pull the pedal downward if not raised past pedal center. Hence, OC spring removal is the norm.
Click to expand...
So i should remove the big spring?
 
71scamp78 said:
So i should remove the big spring?
Click to expand...
Yes, provided you have a diaphragm pressure plate. The pedal will not return to the up stop and likely flop a bit.
If it's a B&B style it either needs adjustment or possibly repair.
 
Before you do anything
Scoot under there and see where the fork is, relative to the frontmost edge of the window thru which it passes.
Remove the adjuster rod, then pull the fork towards the back of thre car. There should be just enough room to install the rubber boot, and not much more.
> If your fork is further back, something is wrong inside the BH.
Here are the possibilities;
Worn out clutch disc, wrong TO bearing, Wrong clutch-finger height, Wrong clutch pivot height or system, wrong fork or a bent/broken one,
> If the fork is where it is supposed to be, then the possibilities are:
too short an adjuster rod, a wrongly clocked Z-bar, the Z-bar not securely located, by the big horseshoe clip, a too short downrod, a wrong ratio pedal-box, a too short fork.
> Keep in mind, that to disconnect the engine from the transmission, you only have to push the pedal down sufficiently to get the job done. Usually, in my experience, there will still be a couple of inches under the pedal to the floor. I'm assuming you know about setting the Freeplay. Factory adjustment is 1 inch, but you can set it any amount less than that, as long as it's more than ZERO.
Less just means you gotta adjust it more often, if you do a lotta clutch-slipping.
More just means you need longer legs to get the travel.
One inch, keeps the purists off yur back.
Mine is set to almost nothing, cuz I modified the adjuster, so that I can adjust it in seconds, anywhere I find a curb to drive up on.
> If you have an A833 overdrive, you may have a Truck bellhouse, which needs special considerations to make it work in an A-body.
 
If you have a borg and beck 3 finger clutch, you will need to check the air gap to make sure it's correct. Jamie Passon recommended .060" with the pedal depressed.
 
I have a low petal. I have a diaphragm plate. I removed the over center spring and didn't notice much difference at all, so I re-installed it. My last clutch was a B&B with a low petal issue. It's always bothered me I couldn't figure it out. I'm used to the lower petal now and don't have to lift my leg with the bad knees much lol. I've got just enough free play at the throw-out bearing as not to wear that out. Obviously, I'm missing something. Anyone know of a stronger FS480 return spring? (I am my own worst enemy). Good luck and keep us posted on how you make out.
 
In my Dart, it has a Centerforce diaphragm clutch. If I had the over center spring in without any linkage hooked up and pulled the pedal to the top and let go of it, the pedal would slam right down to the floor. So in my case, the OC spring does not hold the pedal up. My free play is adjusted at the fork to bellhousing spring, that is all that counts. I don't care where my pedal ends up.
 
Kendog 170 said:
I have a low petal. I have a diaphragm plate. I removed the over center spring and didn't notice much difference at all, so I re-installed it. My last clutch was a B&B with a low petal issue. It's always bothered me I couldn't figure it out. I'm used to the lower petal now and don't have to lift my leg with the bad knees much lol. I've got just enough free play at the throw-out bearing as not to wear that out. Obviously, I'm missing something. Anyone know of a stronger FS480 return spring? (I am my own worst enemy). Good luck and keep us posted on how you make out.
Click to expand...
Ken, how much free play do you have at the throw-out bearing. What the factory recommend there?
 
Not much. Just enough so my throw-out bearing doesn't free wheel when not engaged. I didn't know about the Free FSM back when I assembled it all. I had 2 weeks to finish my car, or have it towed because I has sold my house. Got it all together and engine broke in 2 days before closing. Somethings amiss. Hopefully I have time this winter to go over a few issues I have.
 
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