Schizoid Clutch Pedal...?

[fkovalski]

I have noticed a difference in the "feel" of my clutch pedal. See sig for spec. 59K miles.



Over time I have noticed a little play (about 1") before the depressed pedal engages. Obviously, the fluid/ master/ slave assembly "automatically" takes up the adjustment due to wear.



But... I have noticed that now there is no play. It seems to engage normally when depressed but the "slack" at the beginning is no longer present. There is no play. Last week it went back to what I have felt all along and yesterday it is back to the "no play" feeling.



I do not like that I cannot physically check the clutch disc lining... but are the symptoms I describe an indication of needing replacement?



TIA.



-frank.

 

[NIsaacs]

I would guess it is your hydraulics about to give up. The master or slave cylinder or both. Common problem with these trucks.



Nick

 

[GCroyle]

Frank,



I'm not ready to point to the clutch just yet.



The only reliable indicator of the service status that I can state is measurable w/o any teardown is the pedal effort. When new, effort at the pedal = XX Lbs with the peak effort occurring at about the mid point and tapering as you complete the release stroke, pedal on the floor. As the disc gets thinner, the release load at the diaphragm spring tips gets harder to push, XX + Some increase Lbs. This would be a very subjective thing for someone to assess because you are comparing todays pedal to the pedal effort from a year or two back. All of this assumes a clutch that is not slipping, no mechanical issues of any kind, kinda like you are kicking the tires on a prospective purchase.



Hydraulics are a sneaky SOB, no two ways around it, but given choice between a cable system or hydraulic system, give me the hydraulic version.



Please check the fluid level and consider pulling the slave, leave it connected to the line and taking the boot off to look for fluid leaking, it would leave a puddle in the boot and check the master for leaks, look up from the floorboard and check where the pushrod goes into the body, look for fluid.



I have explained how we test hydraulics on TDR previously but we now have a video of how to bleed them and test them on our website via Youtube.

 

[EDankievitch]

Our trucks have an automatic slack adjuster (for lack of a better name) the hydro system does not do the adjusting like other trucks. It gets a bit tight right before it is about to adjust so as you've noticed all the free play will dissapear you'l think that the clutch is about to give out then it will adjust and all is normal again. I've had this happen a few times it seems that if you make a habbit to "hit the floor" with the peddel each time you shift it will adjust sooner and if you don't it takes longer. I've got 117800 miles on my clutch with no signs of slippage. And I do alot of towing but it's mostly highway except for those cliff like boat launch ramps up north. Hope this info helps.

 

[rbattelle]

given choice between a cable system or hydraulic system, give me the hydraulic version.

Hey Gary, can you elaborate a little? I'm just interested in your thoughts on the matter as a clutch expert.



Ryan

 

[GCroyle]

Our trucks have an automatic slack adjuster (for lack of a better name) the hydro system does not do the adjusting like other trucks. It gets a bit tight right before it is about to adjust so as you've noticed all the free play will dissapear you'l think that the clutch is about to give out then it will adjust and all is normal again. I've had this happen a few times it seems that if you make a habbit to "hit the floor" with the peddel each time you shift it will adjust sooner and if you don't it takes longer. I've got 117800 miles on my clutch with no signs of slippage. And I do alot of towing but it's mostly highway except for those cliff like boat launch ramps up north. Hope this info helps.

I disagree. I have worked on NV4500, NV5600 and a lot of G56 hydraulic systems. None of them have an automatic slack adjuster mechanism. The only automatic adjustment where something actually happens is in the G56 Original Equipment design self adjusting clutch. Possibly a better analogy is do you have any adjustment on disc brake hydraulics?



Our hydraulic systems and clutches do not have any clutch release bearing freeplay. The closest that we have is about 1/8" of master cylinder pushrod play before the M/C starts creating hydraulic pressure and actuating the slave cylinder. We have a spring in the S/C that pushes on the fork 24X7X365 creating a preload against the bearing, it turns all the time that the engine is turning.



I'm only offering this to help diagnosis clutch problems. We get frustrated at work because most techs assume systems are working correctly and are reluctant to perform a simple test that will tell quite a story in just a few minutes. Clutches, release systems and especially hydraulics DO NOT set CEL's and too frequently old school thinking "freeplay" creeps into the diagnosis of todays constant contact release systems.



Those of you that have ever worked on a Ford Ranger with the internal clutch slave cylinder and had problems bleeding them have been down that road of frustration and lost hours.





Ryan,



The industry seems to have adopted hydraulics as the preferred tool for release systems. Easy routing of lines, no need to worry about the cable path being smoothly routed. By using a Concentric Slave Cylinder (CSC) the friction of the fork and the bearing rubbing on a front bearing retainer guide tube is eliminated by a straight pushing CSC piston pressing on a release bearing. But the first hand info involves the 5. 0L Mustang self adjusting cable. The wire wears into the jackets, EXTRA friction, hard pedal, difficult to reset to new position can occur during R&R, system keeps changing as it creates a new cable path in the jacket, one very popular aftermarket option for the 5. 0L Mustang is a manual adjusting quadrant and cable to eliminate the troublesome self adjusting design.



Hydraulics, low friction, easy routing and packaging, generally long service life and if you understand bleeding procedures, easy to service.



I have assembled (many times) a dry master cylinder, line and slave cylinder and in a bench bleeding procedure bled and tested the system as a ready to install in the truck in about 6 minutes. Using only the fluid required to fill the system, no wasted DOT 3.



We have become reliant on CEL's and the codes, but we don't get them on these systems, need to use basic system knowledge, observation skills and sound practices to repair these systems.

 

[rbattelle]

Those of you that have ever worked on a Ford Ranger with the internal clutch slave cylinder and had problems bleeding them have been down that road of frustration and lost hours.

Oh man, I thought it was just me! I had a shop diagnose this as a bad pressure plate and install a new clutch!! Of course, that wasn't the problem and didn't fix anything.

Eventually, I just resolved to myself that I'd have to bleed the system every 3-6 months. I bought a vacuum bleeder specifically for this purpose. That truck made me loathe the CSC, my logic being that it's impossible to change it out without removing the entire transmission. I was happy to find out when I bought my Dodge that the slave cylinder is external.

Thanks for sharing your thoughts with us, Gary.

Ryan

 

[GCroyle]

Ryan,



PM sent.



Gary

 

[EDankievitch]

I just noticed that you had the NV5600 transmission. I have the G56 in my 05 with the factory self adjusting clutch. It responds like I had described above. Sorry for the confusion.

 

[GCroyle]

EDankievitch



Thanks for the update. The G56 uses the LuK designed Self Adjusting Clutch and Dual Mass Flywheel. It does have an internal adjustment system that one of its primary functions is to keep the diaphragm spring in the same operational position. Your role is normal driving will allow the system to do its job. I don't think you will see any DO THIS statements in your owners manual for your SAC DMF clutch. If any LuK employees would like to elaborate on its function, please do so. I'm basing the comments on what we have learned and our testing and observations.



BTW, the LuK SAC has a resetting procedure to reset the SAC to its base position if someone ever does a disc R&R and reuses the old SAC.



The only original equipment hydraulic systems that I know of (general automotive and lt. truck) that have an adjustable master cylinder are Asian applications. Just haven't looked at European to know. They use an adjustable pushrod on the M/C to position the cup seal and piston releative to the transfer port. And at rest, DOT 3 can flow back into the reservoir and then the transfer port is quickly closed upon starting the clutch release (down) stroke. Sometimes folks make these rods longer than they should be (I think trying to compensate for air in the system that they haven't discovered) and it causes a premature clutch failure because it simulates someone holding their foot on the pedal and not allowing the system to compensate for wear.



Air in clutch hydraulic systems compresses and wastes total available system travel for clutch release.

 

[CROW]

Speaking of clutch hydraulics. Has anyone found an lower cost option to the adjustable replacement offerred by South Bend. Sure that sucker is good, but it is also expensive ($325 if memory serves).

 

[fkovalski]

Gary- thanks for the information. I will need to look into this further. But may I ask a few questions before I proceed:

... As the disc gets thinner, the release load at the diaphragm spring tips gets harder to push, XX + Some increase Lbs. This would be a very subjective thing for someone to assess because you are comparing todays pedal to the pedal effort from a year or two back. ...

There is nothing subjective about what I am feeling. One day it "feels" normal... other times it has what I can only describe as "pretty darn hard" and no slack when I put my foot on the pedal. It is "right up to the top. " Later (even in the same day or trip) it will return to the other "sensation. " The sensation that I feel will "flip- flop" with neither one staing constant.

... consider pulling the slave, leave it connected to the line and taking the boot off to look for fluid leaking, it would leave a puddle in the boot and check the master for leaks, look up from the floorboard and check where the pushrod goes into the body, look for fluid...

I have yet to do this. I would ask for more information before I do any disassembly... I looked at your You Tube vids but did not see any thing specific to a Dodge. Is this removal straight forward on our trucks? I do not want to disable anything by screwing up. Can I just remove the slave, inspect and return right away? I have never looked for the slave before when under my truck. Can I assume that it is readily apparent? I can reply here once I perform this test/ inspection.



Thanks you.

-frank.

 

[GCroyle]

Frank,



The force that you need to overcome is a diaphragm spring that pivots in the clutch cover. You have the NV5600, same transmission as my truck. Your clutch is not like the G56 with it's Self Adjusting Clutch (SAC).



The only other forces that you are working against are:

1. Clutch bearings ability to slide freely on the transmission front bearing retainer. When installing our release bearings, the grease groove in the cast iron carrier MUST be full of hi temp wheel bearing grease. It is also OK to put a film on the surface that the bearing slides on.

2. Fork friction points. Ball stud pocket. Pushrod pocket. Fork "crowned contact point" that pushes on the bearing.

3. Internal hydraulic seal friction. Our Dodge hydraulics are plastic bodies with a plastic piston and cup seal.

4. Clutch pedal assy. Try popping out your pushrod pivot pin and checking it. I just checked mine this weekend, 93K and it had about . 010" wear where the pin pushes on the M/C pushrod. I flipped it 180 degrees and re-installed. The top pivot pin could be pulled and inspected also. These could be MINOR friction sources.



Now, how about some what if's.



What if the clutch bearing is not sliding as free as possible? High mileage and heat degrade the grease, friction.



What if this truck has been out in the farm fields driving in chaff? Or on caleche roads in Texas (someone please help me with the spelling) I hear the dust is like baking powder, it would cake and ag chaff could get in to the smallest places and mess with the pivot points of the clutch or the sliding release bearing. I don't know how you use it, so you'll have to tell us.



The video was setup as generic, those parts were actually 2nd Gen I think, but the slave cylinder mounts the same as seen in the video. A 13mm deep socket, 2 nuts and it comes out.



CAUTION: Do not allow anyone to push on the clutch pedal while you are doing this!



Carefully peel the boot back and have a shop rag handy, look for fluid. The piston will not pop out while you do this.



Installation. When new, these have a shipping strap that holds the pushrod in position and makes it easier to line up and such. Just make sure that the pushrod goes into the pocket in the fork, you will feel resistance as you push the fork into position. You will be compressing the spring inside the S/C at this time, creating the preload.



You can also look for fluid where the M/C pushrod comes out into the cab, carefully slide the start switch away from the M/C body and take a peek.



I might have missed it, but how do you use your truck and what is the mileage?



Good luck, I'm just offering my experience, opinion and perspective on these.

 

[fkovalski]

Installation. When new, these have a shipping strap that holds the pushrod in position and makes it easier to line up and such. Just make sure that the pushrod goes into the pocket in the fork, you will feel resistance as you push the fork into position. You will be compressing the spring inside the S/C at this time, creating the preload.

I am not able to in any way compress the pushrod not the fork. I cannot assemble this now that I have checked for leaks!#@$%!



Any Ideas?? I am dead in the water now!

BTW... there were no leaks in the s/c

 

[NIsaacs]

It takes both hands, both feet and a box of Wheaties to push the rod in! If the line is long enough, push the rod up against the front tire and PUSH. Then when it is fully compressed, hurry and bolt it up before it slowly comes back out. It might take several attempts before you succeed in not dropping nuts, bolts, wenches and swallowing your chew



Nick

 

[fkovalski]

Nick, I appreciate your description of the effort required... but in trying all that you describe if I would have had an inkling of movement then I would have been encouraged. It would not budge.



... however...



I ended up rigging a steering wheel puller to act as a "pusher" and it caused the innards of the s/c to "break" free. There was an audible "pop" and the push rod retracted smooth as butter like a scared turtle. I was able to re- assemble.

 

[GCroyle]

Internals of System

Frank,



It takes one hand to push a slave cylinder (S/C) into the bellhousing.



By design, all that is happening is that you are compressing the spring inside the S/C with the S/C piston.



The only other possible resistance point (assuming that the line has not been kinked or something) is the flow of fluid back up and into the M/C chamber AND M/C reservoir.



The M/C has a check valve in it that allows fluid to flow out of the S/C and is the return path during engagement. Then the check valve closes during the release stroke (down to floor) to release the clutch. The check valve is completely enclosed in the small black cap at the left end of the spring directly above the attachment of the line to the M/C.



If some debris or crud has the check valve closed, then I would clearly suspect that you would not be able to compress the S/C with your hand.



It might be time to replace the components if water contaminated fluid has created rust on the internal springs. If you choose to take the system completely apart and examine for crud and stuff, that's your call. I do not know of any source for individual components for these systems.



The S/C pic shows the internal components, the only part missing is the boot.



The M/C is one that I took apart and used an end mill to cut into it to show the piston seal, pushrod, fluid flow path and most interesting the location of the check valve. Notice the paperclip, the wire is touching the check valve, if I gently push on the check valve, it will open, it only has a VERY fine spring behind it.



Checking a clutch release system by compressing the S/C with your hand indicates that the internal components can be compressed and most importantly, that the fluid can flow BACK INTO the M/C. It does not necessarily mean that it is leak free or can create pressure, those are separate evaluations.



Gary

 

[fkovalski]

Gary,



Thanks for the additional information... those last 2 photos are of great help!

 

[GCroyle]

Frank,



I wish I took this pic this AM, this one shows the check valve, stem, carrier and spring. It has a sort of barbed end that it connected to the main piston with. The two paper clips show the fluid flow path in and out of the M/C and the clip that is pointed in to the M/C is touching it's check valve.



Good luck.



Gray