Hoping someone may be able to save me some extra work before I pull the transmission out of my truck, in case there's something I'm missing.

The linkage on my clutch mechanism was tight -- essentially no free play. The clutch worked ok, but would release as soon as you touched the pedal.

I inspected the release rod (bullet) and it was tight against the throwout fork. I backed it off the release rod to create some freeplay, which seemed to go ok. But after driving the truck just a few miles, the clutch linkage was tight again, and now the clutch was slipping pretty bad. I checked the release rod, and it was tight against the throwout fork again.

Also, I noticed that now I can feel some vibration in the clutch pedal while the clutch is released (but with the throwout bearing apparently at least touching the clutch cover), but the vibration goes away as soon as I push on the clutch pedal.

Anyone have any suspicions what might be going bad? I suspect the clutch disk is somewhat worn, but why would the linkage tighten back up again after I loosened it?

 

Welcome to the forums.

When the disc wears(gets thinner), the lever tips actually pivot UP, which would take away your freeplay. Apparenlty the disc is worn to the point that the pressure plate is no longer clamping it, and the levers are at their highest position. When you take it apart, you'll notice the action of the levers as you unbolt the pressure plate.

 

Motor mounts? Clutch shaft bushings? If you are feeling vibration, most likely something inside is worn out. Maybe you can have a helper cycle the clutch while you lay under the truck and observe. Don't forget to block the wheels.

 

Thanks, I'll look at those things. Just seems weird to me that the clutch has been functional for some time (but with little/no freeplay), then when I finally loosen the linkage (and verify freeplay) the linkage tightens back up after just a few miles, so much so that now the clutch is slipping. Something must be coming apart.

I didn't notice anything obvious with the any of the external things (equalizer, bushings, etc). I guess I'll just have to pull the tranny out, put in a clutch kit, and inspect all the other stuff (throwout fork, trunnion, etc).

 

Pay very close attention to the nylon bushings, cuz if you don't, bad things will occur, if they haven't already.

2) C1AA-7543-A .. Equalizer (Z) Bar Nylon Bushings / Available from Ford/repop sellers.

The bushings crack apart/disintigrate, the equalizer bar wobbles, rides directly on the clutch pivots. Eventually the clutch pivot studs that the bushings ride on, snap off.
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2) COAZ-7526-B .. Clutch Release Rod Nylon Bushings / Reproduced, available from repop sellers.

The clutch release rod has two 90 degree ends, routes from the clutch pedal bellcrank thru the toeboard to the equalizer bar. On each end is one of these bushings.

The bushings crack apart/disintigrate, the 90 degree ends begin to crack, eventually snap off. Clutch pedal drops to the floor, as it's no longer connected to the equalizer bar.

When this occurs, you aren't going anywhere!
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1967/72 F100/350: The clutch release rod is composed of two parts: DOTZ-7521-C .. 3 29/32" long rod, one end is threaded & DOTZ-7A504-A .. 2 27/32" long pointed Extension, looks like a bullet.

The extension has no threads, slips over the end of the threaded rod and is double nutted in place. What happens: The clutch goes out of adjustment, the extension falls off...onto the road.

 

Thanks for the warnings. I ordered all 4 bushings, and the vertical rod with the 90 deg ends. Even if those turn out not to be the problem, I might as well replace them while I'm in there.

 

Just wondering, you DID tighten the jam nut on the adjuster when you adjusted it, didn't you?

 

I certainly did. I understand what you're asking -- could the adjustable lower release rod have lengthened itself, and taken up the freeplay? I don't think that happened. I definitely put two wrenches on there and tightened them against each other.

But you get what I'm struggling with here:

- The clutch had no freeplay and the adjustable release rod was tight between the equalizer and the throwout fork.

- I loosened (shortened) the release rod so that it wasn't bound up, and verified freeplay in the clutch pedal.

- After driving the truck just a few miles the freeplay is gone, the clutch is now slipping, and the release rod is bound up again. Also, I now have the slight pulsation in the clutch pedal that goes away if you push it in.

I guess my next move could be to loosen the release rod again and see what happens.

 

The logical assumption all the evidence leads me to is the lining is going going gone on the clutch disc. Have you pulled the dust cover and took a look inside?

 

Yeah, that does seem to be the logical answer. By dust cover do you mean the boot around the throwout fork, or is there something else I can pull off to have a look? I did pull the boot off the throwout fork, but it was hard to get a good angle on it to see anything telling.

 

Isn't there a tin cover on the bottom of the bell housing that can be removed?

 

OP hasn't mentioned the engine size, but if it's an FE engine: C3AZ-6366-A .. Bellhousing Dust Cover / 1963/76 all.

240/300 I-6: C4TZ-7564-A .. Bellhousing Dust Cover (same: 1964/78 330/361/391 FT's).

302: Not shown or listed.

 

Originally it was a 240/6, but the PO installed a 300 long block at some point.

Either way, it would use the 10 spline, 1-1/16" shaft clutch disk, right? Some sites list a 10" clutch disk and others 11". Not sure which is right. Also I see some pressure plates are the 3 finger type, and others have numerous fingers. If anyone has a suggestion for a type/brand to order, I'd love to hear it.

Going to try to pull the dust cover off tonight, and see if I can see what's going on.

I really appreciate all the info.

 

Some 240's use the same flywheel as a 300. Some 240's use a different flywheel, as it all depends on the size of the clutch.

1965/74 F100/350 =

C8TZ-6375-A (replaced C5TZ-6375-M) .. 240 Flywheel-Use with 10" clutch / (6) 5/16" -18 pressure plate attaching holes on a 11 3/8" bolt circle.

C5TZ-6375-N .. 240/300 Flywheel-Use with 11" clutch / (6) 5/16" -18 pressure plate attaching holes on a 12 3/8" bolt circle.

Both: "3 finger" pressure plates. FoMoCo didn't use 'diaphragm' (multi-fingered) pressure plates on the trucks.

 

I tried to remove the sheet metal cover at the bottom of the bell housing, but it looks like the upper part is sandwiched between the bellhousing and the block, so it won't come off until I split the tranny and the motor.

Everything's disconnected and the gearbox is ready to come out as soon as I can arrange for a tranny jack, so I'll know what's going on soon.