Clutch linkage adjustments
 

I've searched the forums but haven't found exactly what I'm looking for.

Just took delivery of a 71 C20 4 speed manual with 55k miles. I must push the pedal to the floor for engagement and I can't even get it to engage into reverse without a harsh grind. Sometimes I get a smooth 2-4 gears.

I looked at the linkage adjustment in the manual and the nuts are already at the far end of the rod. Under the dash there appears to be some slop between the push rod and the pedal assembly but nothing too bad.

What are my next steps? Am I missing something? Am I probably looking at a worn clutch? Any other tests?

Thanks!

Re: Clutch linkage adjustments
 

What kind of freeplay do you get at the pedal when start to push down on it? What I mean by that is the distance the pedal travels before it feels like it is starting to push on something heavy?

Re: Clutch linkage adjustments
 

several inches. about half way depressed

Re: Clutch linkage adjustments
 

Sounds like someone used the wrong throw out bearing. They should have used a long one.
You can replace the rod with the lock nuts on it with a longer piece of ready rod (aka all thread) to get your freeplay shortened up. Ready rod should be available at a parts or hardware store.

Re: Clutch linkage adjustments
 

Did you check the oil in the trans?
Low or no oil can make shifts hard too.

Re: Clutch linkage adjustments
 

Thanks guys. Will check the tranny fluid today.

Unlikely to be the wrong throwout bearing as the truck is almost 100% stock and I doubt its been changed at 55k miles.

Re: Clutch linkage adjustments
 

Don't count on it not being the wrong tob.
Try the ready rod.

Re: Clutch linkage adjustments
 

Look for something bent,

Also, does the throw out fork look like it it coming straight out of the bell housing (perpendicular to the frame), or is it angled back?

Re: Clutch linkage adjustments
 

any idea on the diameter of the lower clutch rod?

Re: Clutch linkage adjustments
 

No, but you'd want at least 3/8 inch to be strong enough. Get some new lock nuts with it too.

Re: Clutch linkage adjustments
 

Thanks for all the help

1. Gear oil was topped up
2. it all looks bent to me :) See pics
3. Will try a new threaded rod but it looks like there's not much room. Maybe 1.5" until it hits exhaust.
4. Tranny is IDd as an NP435

Here are some pictures that should help the forum help me. Thanks again!
https://www.dropbox.com/s/q0al3med8e..._6663.JPG?dl=0
https://www.dropbox.com/s/6vjdsgt312..._6664.JPG?dl=0

Re: Clutch linkage adjustments
 

Check the portion of the linkage that goes through the firewall. I had a bent one of these (not sure the name) on a '69 that made the clutch feel like it was going out. Replaced it and all was well.

Re: Clutch linkage adjustments
 

Consider moving the wedge to the notch closest to the bell housing, it will travel less distance to release clutch. I'm Not certain there should be a spring hooked to the end of the rod, acting to disengage the clutch. I bet someone with arthritis added the spring and moved the wedge to the outter position, to make it easier to push the clutch in. Bruce
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Re: Clutch linkage adjustments
 

The other interesting thing that occurs is that when I depress the clutch pedal slowly with will "stick" half way down without really acting much on the fork.

Re: Clutch linkage adjustments
 

Ah. This combined with the clutch staying 1/2 depressed makes sense! Will give it a try. Many thanks!

Re: Clutch linkage adjustments
 

That tells me the rod is bent going through the floor. The sticking you feel is the rod pushing on the edge of the hole in the firewall.

Re: Clutch linkage adjustments
 

Get someone to step on the clutch while you watch to see how far the end of the fork moves back. It shouldn't move more than an inch until the tob contacts the clutch fingers.

Re: Clutch linkage adjustments
 

No, there is no sticking at the firewall. It certainly isn't straight though. And there is so much slop at both connections of the down rod that I can jiggle it. Even when the clutch is stuck at its half depressed state.

Re: Clutch linkage adjustments
 

Good call. That gave me the length I needed to be able to shift smoothly and get it into reverse. Pedal needs to be on the floor though!

Re: Clutch linkage adjustments
 

Time for a new return spring, if there is no firewall interference. The old spring has likely given it up to the ghost.
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Re: Clutch linkage adjustments
 

Look for cracks on the base of the arms of the Z-bar. They can start to bend, making your clutch action screwy. Then suddenly break off, leaving you with a stuck clutch -- usually in rush hour traffic.

Re: Clutch linkage adjustments
 

will do, thanks for the tip. Anyone know where I can buy NOS or aftermarket linkage in case I want it?

Re: Clutch linkage adjustments
 

Certainly check the rod that comes through the firewall.
Even if it's slighty bent it will reduce the travel.

The hard part is knowing "how" how bent it's supposed to be since they allready have a curve to them.

Also if it's bent it can throw off the movements and bind up.

Re: Clutch linkage adjustments
 

Ah, found the upper here. Now I'm wondering if I should just upgrade the whole set to spherical. Has anyone done this?

http://www.lmctruck.com/icatalog/cb/full.aspx?Page=152

Re: Clutch linkage adjustments
 

any chance you are missing the spacer thing on the clutch fork side of the rod?

*edit, saw it was there in the photo