zf5 clutch linkage creating hard shifting

[kladd]

this is not directly bump related. or maybe it is cause i am using a zf-5 in my '71 hiboy/4bt conversion...

the truck in question is my '97 f350 powerstroke. years ago it started shifting hard. turned out there was not much throw in the slave cylinder. i put a new bushing on the pin that connects the master push rod to the pedal and it was fixed. a year ago i repeated the experience. hard to believe 1/16" of throw makes so much difference.

dealer told me i needed a new clutch/flywheel/pressure plate the first time it happened. huge $$$ so i passed and i dont even think that would help.

now again its shifting as hard as ever. but bushing seems pretty tight this time. have i just been compensating for a deteriorating master or slave cylinder? if so which?

i sure wish i could just lengthen the pushrod by spinning it.

anyone else have such a problem. everyone i know with a powerstroke has an automatic.

thanks!
kevin

[averagef250]

Kevin, this is a common problem on the newer Fords. It's either in the clutch itself, not sure why they do this, but the big organic diesel clutches sometimes don't like to release fully when hot. If it only does it hot, I'd suspect the clutch/pressure plate. Or it's in the pedal assembly/master.

The bushings in the clutch pivot wear out and the joints were the pedal attaches to the pivot rod and the arm that pushes the master pushrod get sloppy.

You can fix it two ways- Pull everything out and replace it with new. The whole entire pedal assembly brand new from Ford is under $150. Or you can pull it out, either replace the bushings or switch them around so the good ones are where the bad ones were, etc. and then pull the pedal and pivot arm to remove all the slop in the opposite direction they are being pushed when you push in the clutch pedal and put a few tack welds on the joints.

There really never is much slop at all in these things, but a little goes a really long way. After going through it you'll notice a night and day difference in how the pedal feels and the clutch works.

One other thing I've encountered is a truck that recently had a shop replace the steering column. They forgot to tighten two bolts up in the dash that let the pedal assembly deflect.

[kladd]

hey dustin.

i'm back. thanks for taking the time to respond so thoroughly!

your explanation about the problem with ford diesel clutches sticking might explain why the dealer was so hot to change out the clutch years ago, despite there appearing to be lots of life left in it.

however i am convinced the problem is the sloppy clutch pedal linkage as you suggest. problem seems unaffected by temp.

fixing the bushing between pedal and pushrod fixed it (again) 10k miles ago, and that bushing looks good still. so some other aspect of the linkage is now worn i bet. i get at least 1 inch of pedal travel before the slop is taken up and the pushrod starts moving.

i'm sick of this crap and am going to try to fabricate an adjustable pushrod. some tubing, threaded rod, a couple nuts, and some welding. then i can manually lengthen the rod as the bushings deteriorate. even if down to metal on metal at least i should be able to shift!

on another front, just bought a clutch pack from cap for my 4bt/zf5/71f250 project. vendor is rhino. any opinions on them?

thanks!
kevin

[averagef250]

The Ford diesels do not use dual mass flywheels because they are clanky. They use dual mass because they use an aluminum transmission. ALL diesels have the same issues with gear clatter at low RPM with a manual transmission. With an iron cased transmission you just can't hear it. Iron absorbs the sound, aluminum amplifies it. The dual mass turns the rapid positive and negative accleration of the crank throughout it's rotation into a smooth rotation.

Dual mass are expensive and problematic. I don't touch them, I only replace them with repsets. Conversion kits that eliminate the dual mass flywheel. You'll hear the gear clatter, but it isn't that bad.

[kladd]

i thot it might be useful to someone someday to post my results.

after further examination i decided it was not so easy to make the pushrod from pedal to master adjustable because the rod runs thru the clutch switch, so much so that there is little rod left in the clear.

i took the pedal assembly apart, ground down the weld for the pivot pin on the pedal assembly, punched it out, filled the hole with mig weld. then drilled a new hole 2mm closer to the master. this affectively lengthed the rod by 2mm. reassembled with new bushing kit i already had and the slave travel increased from about 400 thousands to over 500.

truck shifts great now and i have more margin for bushing wear. we shall see if i ever have to replace bushings again.

kevin