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over-center spring

Mike Szadaj

Mike Szadaj

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1968 Coronet RT. Got the z bar and all clutch linkages installed today. Car is not in running order yet. There is an over-center spring that I have not put in. When in this spring will pull on the clutch pedal toward the firewall. When installing a modern day clutch is this spring needed? Isn't the force needed much less compared to a 1968 clutch? Right now without that spring the pedal force required seems about right. I think if I installed the spring the pedal would never get off the floor. If this spring is absolutely needed, how the heck do you get it on? This thing is one HEAVY DUTY spring!
 
There are types of "modern" clutches.
Do you have a diaphragm type clutch or a Borg & Beck type?
Diaphragm type clutches (like CenterForce) will tell you in the instructions to remove the
over-center spring; if you have the B&B, you need to install it.
 
Centerforce (diaphragm) clutches don't use them. If you need to put one on stretch it out and put washers between coils.
 
It is a diaphragm type, so question answered.
moparedtn said:
Diaphragm type clutches (like CenterForce) will tell you in the instructions to remove the
over-center spring; if you have the B&B, you need to install it.
Click to expand...
What are these "instructions" that you speak of? Strange words you speak that are not in my vocabulary.
Fran Blacker said:
If you need to put one on stretch it out and put washers between coils.
Click to expand...
Great problem solver that I am sure I will use in the future.
Thanks to all,
Mike
 
Mike Szadaj said:
It is a diaphragm type, so question answered.

What are these "instructions" that you speak of? Strange words you speak that are not in my vocabulary.

Great problem solver that I am sure I will use in the future.
Thanks to all,
Mike
Click to expand...
Forgot to credit someone posted it before, don't remember who?
Edit: Moparedtn said to use washers.
 
Last edited:
B&B clutch is the 3 finger type plate and the spring is needed. To install the spring just loosen the pedal assembly from the firewall. This will allow the clutch pedal to travel down enough before hitting the floor to easily install the spring. No washers and no pinched fingers.
Diaphragm plate doesn't use the spring.
 
Tired of toeing out the last inch of pedal travel. Lots of mystery surrounding clutch operation. Little agreement on the fix. Add my lack of understanding.
 
Last edited:
I have also heard of that spring being called a clutch assist spring.
I believe I read somewhere it was there to make the clutch easier to depress for women drivers who did not like the heavy clutch pedal of manual shift cars.
I have removed mine and it causes no problems.
 
steve340 said:
I have also heard of that spring being called a clutch assist spring.
I believe I read somewhere it was there to make the clutch easier to depress for women drivers who did not like the heavy clutch pedal of manual shift cars.
I have removed mine and it causes no problems.
Click to expand...
The purpose of the over-center spring is two-fold, actually....
As its' name indicates, it assists pedal travel in either direction of the pedal from the point of clutch engagement:
a. it assists with disengaging the clutch when pedal is depressed
b. It makes sure the clutch is fully engaged (and therefore, the throwout bearing is totally clear of the pressure plate)
when the pedal is released

It's TWO - TWO - TWO springs in one!


Sorry, man, don't know what came over me there.... :rolleyes:
 
moparedtn said:
b. It makes sure the clutch is fully DISengaged (and therefore, the throwout bearing is totally clear of the pressure plate) when the pedal is released
Click to expand...

So its a good idea to replace it with a lighter spring that will bring the pedal all the way back up.
 
Stanton said:
So its a good idea to replace it with a lighter spring that will bring the pedal all the way back up.
Click to expand...
shakes head.gif
 
I Don't see you issue Moparedtn !! Without the over-center spring the pedal will only come up as far as the pressure plate pushes it. The throwout bearing will stay in contact with the PP fingers - not something you want.
 
Stanton said:
I Don't see you issue Moparedtn !! Without the over-center spring the pedal will only come up as far as the pressure plate pushes it. The throwout bearing will stay in contact with the PP fingers - not something you want.
Click to expand...
What about spring from cluch fork to bellhousing?
 
A spring is either a compression or extension spring. I do not believe it assists in either direction. It's purpose is to help depress the pedal. The pressure plate pushes the pedal back up. As Fran Blacker mentions the clutch fork spring will keep the release bearing away from the pressure plate.
The old 3 finger style clutches really push back against the clutch mechanism and the spring causes no problem. Diaphragm clutches are not so tough and you can do away with the over centre spring.
I always take those springs off now as the clutch pedal is much "freeer" and they do not seem to hang up at the top of the pedal travel and stop you getting the right freeplay.
 
Fran Blacker said:
What about spring from cluch fork to bellhousing?
Click to expand...

That spring is fine when the over center spring is present but it doesn't have near enough tension to pull the fork back and the pedal up when the over center spring is removed.
 
Stanton said:
That spring is fine when the over center spring is present but it doesn't have near enough tension to pull the fork back and the pedal up when the over center spring is removed.
Click to expand...
Mine works fine. Centerforce clutch.
 
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