I have a 79 F250 4x4 - 351m/np435/205. I've recently put a new Centerforce II clutch in it and rebuilt the engine. I bought the truck in non-running condition so I don't know if it had this problem before I put it back together.

When I step down on the clutch, there is a normal amount of pressure as I collapse the clutch diaphram, and at about a 1-1/2" from the floor, the diaphram is collapsed and the pedal pressure is much lighter. This all seems normal, but, when I let up on a the clutch pedal, while it is in that light pressure zone, the pedal comes up like it's binding or sticking. It comes up but in little gittery steps until the pressure of the diaphram comes in. (Highly technical description, I know. ) Once the pressure of the diaphram comes in, the pressure overcomes the "stickiness" and the pedal feels fine.

If the problem was just pedal feel, I wouldn't worry about it, but it's causing me to overshoot the start of the clutch engagement and the sudden shock to the driveline is not pleasant.

I've checked all the linkage and nothing is binding. The cab mount bushings are new. I have replaced the nylon equalizer bar bushings. It sits nice and level. I've also double checked that the clutch fork is correctly mounted to the pivot.

This is leading me to think that the plastic clutch pedal assembly bushings may be worn out or broken after 27 years. Any other ideas? Is the big spring under the dash under pressure and difficult to remove?

Thanks for the help.

 

Anything that feels different or make s a new squeek is easy for me to notice and so, do something about, right away, since I bought mine new. The biggest single advantage IMO.

(snipped description of an obvious clutch linkage problem)

Replace those anyway! You got a new clutch do it all the way, pretend your old pickup is a girl and you want to go to homebase?

"when you don't know what's wrong, go over everything and make sure it's right, even if it's only slightly related" -Jack Duncan, Tucson RR Signal Maintainer (deceased)

That way of doing things has cleared up more intermittant trouble than you can shake a stick at.

I went through my clutch lever system years ago and removed all sources of play and roughness that I could. Drilled and brass-bushed the two crank arms etc. When I bought the nylon bushings from Ford I got a spare set they are easy to get still, I recognize them right away, like when I see them in that silly packaged red "help!" stuff.

That spring's a pain with what I have to work with anyway... "9 inch Klein Line Pliers" and the sucker is supposed to have nylon bearing surfaces on both ends but they gave out like 15 years ago. As soon as I hear a squeek from that spring... I oil it. Want to figure out something better than that, just haven't decided which way to go there yet.

Tell us what you figure out and what you did to conquered that freekin spring.

A vast majority of the thinking when it comes to a problem is... most guys want to know -exactly- what it is and -correct only that-. :/

Do you shoot dove and quail on the wing with your centerfire rifle or do you use a shotgun?

And... "if it ain't broke don't fix it"

That always sounded like a zero maintenance approach to me. :/

In over 31 years my '75 F150 has never broken down on me and left me stranded, anywhere, EVER!

Alvin in AZ

 

Well I decided not to conquer that spring. Although the Ford shop manual says to take wire and tie up the spring as it is in it's installed compression and then remove it.

I took a real close look at the linkage and saw that as I pushed the pedal down the eualizer bar was traveling slightly side-to-side... And in doing so it was trying to slide the clutch rod out of the clutch pedal assembly. It was pulling it up against the retaining pin and the pin was dragging, binding, catching... so I adjusted the equalizer bar to set the angle parallel to the clutch pedel rather than perpendicular to the frame. Basically, i set the equalizer bar a little "crooked" - maybe 1/8" - just a little and that corrected the angles.

Then I put a washer between the equalizer bar and the pin, and another one between the clutch pedal arm and the pin. That was the rod is not pulling sideways and it has a little more bearing surface than against those pins.

After all is said and done, the clutch works great.

 

Cool one, Frank!

I got thin steel washers and "wave type spring washers" oilite brass bearings or whatever it took to remove the play from my clutch crank sytem and trottle crank system.

There's a bunch of stuff about my pickup that's better than new. Believe it?

Alvin in AZ

 

It's a good idea to replace the plastic bushings on either side of the clutch pedal in the pedestal. If they wear through they hog out an egg shaped hole in the pressed in pedestal bushings and then you need a new pedestal which is a pain. To replace the spring under the dash, take it and compress it in your vise, then wrap both sides with safety wire, install it, then cut the wire.