How do I adjust clutch free-play?

[jsimpson]

My clutch doesn't have much pedal. How do I adjust it?

 

[RJOL]

Don't think you can...

Don't think there is any adjustment as the clutch is hydraulicalyl operated...

 

[MikeR]

Right, you cannot adjust a hydraulic system.

 

[bighammer]

I adjusted mine. Works real well. Just takes a little patience,(actually only about an hour) a grinder and a welder.

 

[Steve Campbell]

bighammer, would you mind letting the rest of us in on the secret touch? Please

 

[bighammer]

It's just a matter of "adjusting" where the bracket is welded to your clutch pedal. If you get under the dash, you will see the whole setup. Play with it a bit and decide how much it needs to move. Then pull the "C" clip in the shaft that holds both pedals, and the master cylinder pushrod clip. Remove the pedal, grind away the welds, re-position and weld it back on.



C'mon up to Traverse, I'll do it for ya.

 

[Steve Campbell]

bighammer, thanks. I will check that out today.



I think I will pass on having you do it as, from central Idaho, that would be a long drive.

 

[jsimpson]

Not as bad a drive as it would be from South Florida!

 

[bighammer]

How or why did this get moved? I think it applies to all the 2nd generation trucks (12 and overvalved ) I hardly consider the clutch pedal a drivetrain item.

 

[Roger rodbolt]

While you can cut or adjust the clutch petal linkage under the dash it will only change the stroke and clearance to the clutch master cylinder. This distance shouldn't change enough to need to be adjusted.



Clutch free travel is typically adjusted at the clutch throwout fork on the bellhousing. This critical adjustment changes the distance between the throwout bearing and the pressure plate "arms" or "fingers" when the clutch is fully engaged. On our hydraulic clutch system there is no factory adjustment and it appears that the clutch slave cylinder holds the throwout bearing in constant contact with the pressure plate.



I ran into trouble recently after installing a custom dual disc clutch that would slip at about 700ft. lbs. Problem being there was too much pressure being applied on the throwout when clutch petal was relaxed, ie, no free play. To adjust the clearance you must remove the trans and bellhousing and grind addtional clearance in the throwout arm or reset the clutch disc or pressure plate to provide clearance. After adjusting, the clutch is holding 1300ft. lbs.



To check free travel: remove the slave cylinder and make sure there is at least 1/4 inch free play at the throwout arm.



JSimpson,

Your low pedal is most likely due to problems in the clutch hydraulics, air entrained or seal wear.



If you check the free travel as mentioned above and there is EXCESSIVE free travel you may have clutch trouble but that is unlikely.

 

[South Bend Clutch]

Roger rodbolt





I have to disagree on this one. With a hydraulic system there is not suppose to be any free play between the throw out brg. and the fingers of the pressure plate. The system is designed to run the brg. continuously but without tension. In your case the dual disc clutch would deffinately ride to high in the bell housing if the flywheel was not cut down to adjust for the distance (height). You kind of achieved the same result with what you did. Changing the master cylinder location is a great way to achieve more travel. The slave cylinder moves approximately 7/8" to 1" stock. People often think if they extend the slave rod... . they will get more travel. All that is accomplished by this procedure is that you relocate the starting possission of the of the push rod further back into the slave. it will only do what it is told to do. Just as the names say... ... . Master / Slave. If you extend the master rod then you are telling the slave to push farther. Bighammer achieved the same result by relocating the start point of the master rod on the bracket of the pedal. Very smart! What you did was also a good idea for what you were trying to accomplish.



I just wanted to clarify the facts on the subject so there would not be any misunderstandings in the future.



Sorry to butt in.



Peter

 

[jsimpson]

I wouldn't be at all surprised to find that my clutch is in need of work, but I'm just trying to get a little mnore pedal for now. I'll start by bleeding it.

 

[bighammer]

Thanks for jumping in Peter. I thought that the bearing and fork were always together. The slave and rod is not really adjustable because of the way they adjust to the fork. The answer is more push on the master. Push that bracket a CH (OK, maybe 1/8 to 1/4 inch) forward (toward floor) on the clutch pedal, and gain a bit more height in your "catch point". Mine was low before, but with my new clutch it was right on the floor. Mine was adjusted almost a 1/4" and now is in the middle of the pedal stroke. (catches at bottom 1/3, releases at top 1/3) I had my old '69 F250 adjusted that way and liked it.



On my 25 year schedule, my new 2019 truck will read my mind

 

[dan_gilson]

The reason why we have to go through all the cutting and movement is because of the piece of junk DC uses for the clutch master Cylinder. It is completely none adjustable. Both the brake and clutch masters of the RX-7 that I owned had adjustible rods and the pedal had adjustible stops. So with a little patience you could move the pedal height to just about where ever you wanted it.



My clutch is about 1. 5" above the brake and it disengauges within the 1st 2". I would much rather have it closer to the floor so that I would not have to lift my leg so faaarrr! Yah, I getting old...



I have been playing with the idea about going down to the local race shop and getting a better clutch master. Has anyone done this yet? Part # of things that worked would greatly be appreciated.

 

[bighammer]

I seem to lean towards the low-buck kind of mods. An adjustable master would be sweet. (and probably not too hard to find) I just did the quick solution to get back on the road and enjoy the rest of my weekend after my clutch install. Still very happy with it though.



Not many BOMBs are free, but it makes them sort of special (My shortened gearshift is another one)

 

[rickhans]

Even the Hyundai's I used to buy for our kids to drive had adjustable rods on the master cylinder.



There is a replacement clutch master cylinder available from NAPA. I don't have the number handy, but there was rather lengthy thread on it a few months back. Search on "NAPA". If you don't find it, post a message here and I will dig out my notes. I plan to buy one and install it. According to those who had installed it, it cut the pedal pressure in half, but was difficult to bleed the air out of. The piston is larger than the OEM master cylinder resulting in more leverage and less pressure.



Personally, I prefer the pedal up high. I have had discussions in the past about the Dodge clutch pedal problem. The swing bar angles forward instead of away from the pedal, like all other trucks I have ever seen. This prevents me from using my heel or center of my foot to depress the clutch, other wise it causes my foot to bend. After the first year I had to go to an orthopedic surgeon about my foot problem caused by the clutch.



Until I get the new cylinder to reduce pedal pressure, I depress the clutch only enough to be able to shift.

 

[jsimpson]

A larger piston in the master cylinder will INCREASE pedal effort. A smaller master cylinder will DECREASE pedal effort.

 

[GDouglas]

One thing to keep in mind concerning any clucth master cylinder mods is to avoid shutting off the makeup fluid hole that goes up to the resivoir. All brake master cylinders work the same way too. With the pedal at top travel, you want the piston to have just moved past the make up hole in the bore so that you keep the self adjust feature. If the piston never goes back past the makeup hole when you release the pedal, then the fluid that is in the resivoir will never leave into the system to be able to compensate for any aging/use of the pressure plate.



Usually when adusted right, you can look down in the resivoir as someone just barely moves the pedal and see a slight spurt back up into the resivoir. This is the small amount of fluid that is between the end of the piston and the make up hole that gets squeezed out upon initial pedal movement. When the piston passes the makeup hole, then it becomes a pressure tight arrangement and all further fluid goes straight to the slave cylinder.

 

[rickhans]

You have it backwards. The smaller the diameter, the greater the pedal pressure. What is constant is the pressure required to push in the pressure plate. As the diameter of the piston is increased, the pounds per square inch being pushed by the piston decreases.



For example, if the piston dia. is 1" (I have no idea what it really is) the surface area pushing the hyd. fluid is . 786 sq. inches. If you increase it to 2" diameter, the surface area is 3. 14 sq. inches, 4 times that of the 1". That reduces the pressure reqired to push the same pressure plate by 3/4 if all else stays the same.



Several have used the NAPA cylinder and have experienced this exact thing. On the 98. 5 it is an exact swap out for factory. There is a later model, I forget what year, where there was a slight modification required for it to bolt up.

 

[jsimpson]

Sorry, but you've still got it backwards: a larger MASTER cylinder diameter INCREASES the amount of fluid pushed per unit of stroke. That INCREASES pedal effort. Long experience at building street rods (over forty years) has verified this time and again. On the other hand, a larger SLAVE cylinder diameter will DECREASE the pedal effort and stroke.