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Diaphram clutch pedal adjustment #2795403
07/11/20 09:49 AM
07/11/20 09:49 AM
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nd65 Offline OP
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Hey All,

When using a diaphram clutch in our old mopars what is the best method to adjust free pedal play and the pedal stop?

Thanks,
nd65

Re: Diaphram clutch pedal adjustment [Re: nd65] #2795404
07/11/20 09:58 AM
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The only adjustment is on the rod underneath. That is a variable to a lot of people. Most important thing is that the throw out bearing in not spinning when disengaged. As far as a stop there is no adjustment the over center spring pops the pedal back against the rubber stop.

Re: Diaphram clutch pedal adjustment [Re: NITROUSN] #2795407
07/11/20 10:05 AM
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nd65 Offline OP
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I recall in a Rick Ehrenberg article he said you need to install a pedal stop when switching to a diaphram clutch. He stated you can over extend and damage the clutch.

Re: Diaphram clutch pedal adjustment [Re: NITROUSN] #2795409
07/11/20 10:07 AM
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Originally Posted by NITROUSN
The only adjustment is on the rod underneath. That is a variable to a lot of people. Most important thing is that the throw out bearing in not spinning when disengaged. As far as a stop there is no adjustment the over center spring pops the pedal back against the rubber stop.

The over center spring should be removed when a diaphragm clutch is used.


In theory, there is no difference between theory and practice. In practice, there is.
Re: Diaphram clutch pedal adjustment [Re: NITROUSN] #2795413
07/11/20 10:13 AM
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I adjust by measuring the clearance between the disc and pressure plate/flywheel. I shoot for .060"" and let free plat at the pedal be what it is, after all what is important is that the disc is disengaged when the pedal is down, not how much slop there is at the pedal with it up.

Remove the clutch inspection cover, have someone floor the clutch pedal, measure the gap between the disc and flywheel, .060" is what I go for. Adjust the rod as needed to get into spec, cycle the clutch pedal a couple of times and recheck, adjust if needed and you are done.

Re: Diaphram clutch pedal adjustment [Re: nd65] #2795416
07/11/20 10:15 AM
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So your want to put a stop to prevent over engagement? You would have to devise some sort of travel limiter. Not sure why as almost all mopars had a diaphragm style clutch.

Re: Diaphram clutch pedal adjustment [Re: nd65] #2795417
07/11/20 10:18 AM
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Originally Posted by nd65
I recall in a Rick Ehrenberg article he said you need to install a pedal stop when switching to a diaphram clutch. He stated you can over extend and damage the clutch.

That style of pressure plate does have a shorter stroke so a down stop is a good idea.(actually a good idea for any clutch)
I have seen some pretty nice adjustable stops that people have fabricated. I used a chunk of 2X4 under the carpet for years. whistling


In theory, there is no difference between theory and practice. In practice, there is.
Re: Diaphram clutch pedal adjustment [Re: NITROUSN] #2795420
07/11/20 10:22 AM
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Originally Posted by NITROUSN
. Not sure why as almost all mopars had a diaphragm style clutch.

Nope runaway

Last edited by GomangoCuda; 07/11/20 10:22 AM.

In theory, there is no difference between theory and practice. In practice, there is.
Re: Diaphram clutch pedal adjustment [Re: GomangoCuda] #2795425
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Originally Posted by GomangoCuda
Originally Posted by NITROUSN
. Not sure why as almost all mopars had a diaphragm style clutch.

Nope runaway


I should correct what I was trying to say. Mopars that run a diaphragm style may or may not need the over spring or stop . Follow the manufacturers instructions.

Re: Diaphram clutch pedal adjustment [Re: nd65] #2795459
07/11/20 12:31 PM
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Determining the pedal stop's travel limit is done in combination with setting the full clutch release free play. You can adjust it so that your feeler gauge will just fit in between the pressure plate, clutch disc and flywheel when the clutch pedal is all the way on the floor. I used to start with the feeler gauge not being able to fit between the clutch disc etc when pushed all the way to the floor , and then increase the adjustment using the clutch rod until I got the desired release clearance. That way I would have the correct clearance when the pedal is fully depressed when fully on the floor.

In a lot of cases, this will mean that the clutch pedal will not come up enough for the over center spring to lift the pedal past the over center point of the spring's top-of-travel resting position. I used to have to use my toe to bring the clutch pedal the rest of the way up. This is another reason why some people remove the over center spring.

Spend the time to make sure all the connecting points in the linkage are square to each other where they connect. I have always had to straighten out linkage parts when assembling the Z-bar components.

Another trick I learned while trying to set-up my clutch release mechanism is to lubricate all the parts that contact each other with synthetic disc brake grease. It outlasts and outperforms any other lubricant that I have found and won't attack rubber or plastic.

As my old autoshop teacher used to say, the only time clutch parts wear when set-up correctly is when they are being used, so keep your foot off the pedal, hand off the shifter(to reduce wear on the shift forks and synchros) and use the clutch's "slip" as minimally as possible to reduce wear and keep the heat down in it.

I cringe when I see how much some people unnecessarily over slip and ride the clutch when they drive a manual transmission car, and learn how to heal-toe the brake and gas pedal to start moving on a hill start if you don't know how to do it yet..




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1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 3.91's (closest thing to an automatic 5 speed going)
Re: Diaphram clutch pedal adjustment [Re: Sniper] #2795470
07/11/20 12:50 PM
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Originally Posted by Sniper
I adjust by measuring the clearance between the disc and pressure plate/flywheel. I shoot for .060"" and let free plat at the pedal be what it is,


Problem with that is, if there is a lot of pedal free play you get into the over center spring which will pull the pedal down. Above works OK if the OC spring is removed.


I'm supposed to respect my elders, but its getting harder and harder for me to find one now.
Re: Diaphram clutch pedal adjustment [Re: John_Kunkel] #2795500
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nd65 Offline OP
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I appreciate the comments. The over center is removed and an adjustable pedal stop in place.

Thanks
nd65

Re: Diaphram clutch pedal adjustment [Re: John_Kunkel] #2795501
07/11/20 02:11 PM
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Originally Posted by John_Kunkel
Originally Posted by Sniper
I adjust by measuring the clearance between the disc and pressure plate/flywheel. I shoot for .060"" and let free plat at the pedal be what it is,


Problem with that is, if there is a lot of pedal free play you get into the over center spring which will pull the pedal down. Above works OK if the OC spring is removed.


The standard recommendation when running a diaphragm clutch is to remove the over center spring regardless.

Re: Diaphram clutch pedal adjustment [Re: Sniper] #2795510
07/11/20 02:34 PM
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FYI, when designing my hydraulic clutch linkage, I contacted Centerforce tech line about the Dual Friction 10.5" disc & diaphragm pressure plate.

This was their reply: "The disc will be released with an 0.030” air gap. Linear travel at the bearing is 3/8” to release. Bearing load is 500 lbs."
May be useful to someone shruggy

Re: Diaphram clutch pedal adjustment [Re: DrCharles] #2795622
07/11/20 08:50 PM
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Same .030 here. That was the recommended back in the 60's and 70's by Schieffer and Zoom on their diaphragm clutches. Much more than that would cause the pedal to stick to the floor on shifts above 6000 rpm.


July 19th should be "Drive Like Rockford Day". R.I.P. Jimmie.
Re: Diaphram clutch pedal adjustment [Re: nd65] #2795742
07/12/20 09:05 AM
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My CF has been in for years Its been beat on and still works like new,Center spring removed and just the spring for the fork.I adjust all my clutchs so that they just engane Reverse easily.Ive had to adjust y Cf once in years.Only like 1 turn or so on the rod.With a scatter shield its just about impossible to get to the disc to check clerance.Rocky


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Re: Diaphram clutch pedal adjustment [Re: GomangoCuda] #2795810
07/12/20 12:31 PM
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Originally Posted by GomangoCuda
Originally Posted by NITROUSN
The only adjustment is on the rod underneath. That is a variable to a lot of people. Most important thing is that the throw out bearing in not spinning when disengaged. As far as a stop there is no adjustment the over center spring pops the pedal back against the rubber stop.

The over center spring should be removed when a diaphragm clutch is used.

Sure like to hear the reasoning for this

Re: Diaphram clutch pedal adjustment [Re: cudaman1969] #2795814
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Originally Posted by cudaman1969
Originally Posted by GomangoCuda
Originally Posted by NITROUSN
The only adjustment is on the rod underneath. That is a variable to a lot of people. Most important thing is that the throw out bearing in not spinning when disengaged. As far as a stop there is no adjustment the over center spring pops the pedal back against the rubber stop.

The over center spring should be removed when a diaphragm clutch is used.

Sure like to hear the reasoning for this


Go read John Kunkel's post

Re: Diaphram clutch pedal adjustment [Re: cudaman1969] #2795865
07/12/20 03:12 PM
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Originally Posted by cudaman1969
Originally Posted by GomangoCuda
Originally Posted by NITROUSN
The only adjustment is on the rod underneath. That is a variable to a lot of people. Most important thing is that the throw out bearing in not spinning when disengaged. As far as a stop there is no adjustment the over center spring pops the pedal back against the rubber stop.

The over center spring should be removed when a diaphragm clutch is used.

Sure like to hear the reasoning for this


Because the over-center spring helps to bring pedal down not up. It's only needed with a 3 finger design to help your leg push down that race-style design. Generally when left in place with a diaphragm style your pedal will stay to the floor with high RPM's.

Ron

Re: Diaphram clutch pedal adjustment [Re: RJS] #2795889
07/12/20 04:02 PM
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Rio Linda, CA
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Originally Posted by RJS


Because the over-center spring helps to bring pedal down not up.


Actually it does both; at the top of the pedal travel it pulls the pedal up, after traveling over center it pulls the pedal down and reduces the leg effort.


I'm supposed to respect my elders, but its getting harder and harder for me to find one now.
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