High clutch pedal effort

Daniel McCurdy

Full Access Member
Joined
May 8, 2020
Posts
339
Reaction score
50
Location
Evarts KY
I know its an old truck but the clutch pedal effort seems unusually high. It takes most of what my leg can do to get it to the floor and holding it down for more than a couple seconds my leg is on fire. I replaced all the pedal bushings did the heim joint mod and replaced the hydraulics and bench bled them so there is definitely no air in the system. It makes some insane vibration sounds when at low rpm in first or second, its possible its already been converted to a smf. When trying to take off in reverse the whole trucks shakes very aggresivly it also does this when starting in 2nd, it does do it in first but not as bad. I usually take off in 2nd as first is very low with 4.10. I dont know if this issue is related but its also difficult to get into gear, 1st is very difficult, if i take off in first 2nd will grind very easiely, when shifting up 3rd is very difficult to get into, it doesnt grind it just hits a wall it doesnt want to go past, its almost like the clutch isnt fully disengaging. 4th and 5th are the only gears that seem to be fine.
 

Black dawg

Registered User
Joined
Jan 9, 2006
Posts
3,995
Reaction score
703
Location
sw mt
If you can get some oil where the throwout bearing slides on the transmission, it will get much better.
 

Daniel McCurdy

Full Access Member
Joined
May 8, 2020
Posts
339
Reaction score
50
Location
Evarts KY
will the access port on the bottom give me enough room or do i have to go in from the clutch fork side
 

Black dawg

Registered User
Joined
Jan 9, 2006
Posts
3,995
Reaction score
703
Location
sw mt
Usually if you pull the shift fork boot you can see good enough to get a little oil in there
 

u2slow

bilge rat
Joined
May 8, 2007
Posts
1,817
Reaction score
814
Location
PNW
A coating of grease on the input snout, fork, and contact points for the release bearing is critical for smooth action and low effort.

On an old truck where the clutch has lasted a long time, the grease can harden and gum-up.
 

u2slow

bilge rat
Joined
May 8, 2007
Posts
1,817
Reaction score
814
Location
PNW
I might try something more like penetrating oil or fluid film. Half the battle is making the goo thats in there soft again. Should notice a change quick if it does the trick.

Be careful because you don't want slippy stuff on the friction faces.
 

Farmer Rock

just a fella' without a 10mm socket
Joined
Oct 27, 2020
Posts
1,423
Reaction score
1,313
Location
Glen Rock,PA
Be careful because you don't want slippy stuff on the friction faces.
X2 on that.

For the record, a stock zf5 clutch should be almost as soft and easy as a car. If you have a south bend clutch, that's a little different.
Take a good look see at the clutch fork, where the slave rod sits in. A few of my trucks had those joints wore through the other side completely. You can lose a couple inches of clutch travel that way.
Most likely, your throw out bearing has seen better days.

Rocks
 

asmith

Full Access Member
Joined
Jan 28, 2012
Posts
664
Reaction score
204
Location
Atascadero, Ca
I am dealing with something similar right now. my clutch has always been on the stiffer side, but i have a southbend clutch. But mine just started acting up and for the last few days it has been hard to get into gear. First is almost impossible. I have to push so hard i feel like I am going to bend the shifter. reverse is the same. 2,3 and 4th are not as bad but much harder than what they used to be. I am 99% certain the clutch on mine is not disengaging all the way. doing some digging today I found a lot of slop in the pedal bracket. the pivoting bar that the pedals swing on has wallowed out the hole it rides in and flops around. I think this is taking up enough travel of the pedals to not allow the clutch to disengage fully. It is at least something to take a peak at as its very easy to get to.
 

Farmer Rock

just a fella' without a 10mm socket
Joined
Oct 27, 2020
Posts
1,423
Reaction score
1,313
Location
Glen Rock,PA
When I fixed the clutch pedal on my 87, I ground off the pin on the pivot arm and punched it out. Welded a 3/8 bolt in the hole and used a steel 3/8 bushing that fit the eye perfectly. I was going crazy trying to bleed the clutch because it wasn't coming up all the way.bturns out I bled it right the first time, but the bushings were gone so it lost 3 inches of travel. I've had my share of clutch problems,lol.


Rock
 

ROCK HARVEY

Full Access Member
Joined
Oct 3, 2021
Posts
417
Reaction score
372
Location
Dayton OH
Those bushings in the pedal bracket are replaceable, but it’s a pain to get the bracket out of the truck. You may have to use a welder to build up the steel again if the holes have become egg-shaped, or buy a new bracket if you prefer. There are some good YouTube videos out there. When my truck gets to that point I’ll modify the bracket to use oilite (oil-impregnate bronze) bushings instead of the plastic.
 

Black dawg

Registered User
Joined
Jan 9, 2006
Posts
3,995
Reaction score
703
Location
sw mt
I got some spray white lithium grease will that work
like mentioned, something more oil like would work better. Any grease that was put on the throwout bearing or shaft tends to attract dirt and clutch lining dust, and harden over time. What you are trying to do is soften that. It works best if you can get some oil behind the bearing and then run the clutch pedal a few times.
 

Daniel McCurdy

Full Access Member
Joined
May 8, 2020
Posts
339
Reaction score
50
Location
Evarts KY
I ordered a new clutch fork if that doesn't do it the only things that'll be left is the pivot ball, clutch/flywheel, and the throwout bearing. Everything else will have been replaced. When I do the clutch lever I'll try and spray the input shaft down to clean it and throw some new grease on it
 

jrollf

Full Access Member
Joined
Oct 25, 2008
Posts
285
Reaction score
226
Location
Houston, TX
I had a really stiff clutch for a couple years and chased it like you are doing... then one day I pressed the clutch to be greeted by a "bang" and couldn't disengage the clutch anymore.

Tore it down to find 3 of the release fingers on the pressure plate broke. Put in a new clutch and pressure plate and imediately noticed the pedal was much easier to push.

All that to say your pressure plate may be going bad.
 

Forum statistics

Threads
91,217
Posts
1,128,479
Members
24,045
Latest member
Ramtough01

Members online

Top