throwout bearing to fingers gap?

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Kllrbee

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Adjusting fork rod due to pedal not returning all the way up. Thought it might be somewhere in the linkage, but I disconnected and checked everything with no binding. Started adjusting the rod to put bearing closer to fingers and that seems to be what was causing it. Huge difference. So how close do I need to be? Right now, Im about .050. Seems awfully close, but bearing spins freely.
Thanks
 
Theres about an inch in the pedal.
Im referring to the gap when taking off inspection cover and putting a feeler gauge between TO bearing and fingers.
I know its some give and take to get it where it needs to be. Just thought someone with more experience might have a nice ballpark number they could throw out there. Thanks.
 
Adjusting fork rod due to pedal not returning all the way up. Thought it might be somewhere in the linkage, but I disconnected and checked everything with no binding. Started adjusting the rod to put bearing closer to fingers and that seems to be what was causing it. Huge difference. So how close do I need to be? Right now, Im about .050. Seems awfully close, but bearing spins freely.
Thanks
.050" is pretty close, but as long as it's not touching pressure plate fingers you should be good. Is the fork and all of the linkage original and/or correct?
 
Not original.
Correct....doubtful.
This started life as a /6 auto. So somebody down the line did there own mounting of the Z bar, etc. Its not a /6 setup from what I can tell. But, as I said, I disengaged the pedal rod and adjustment rod and checked the Zbar and pedal assembly for binding. All good there.
Honestly, Im sure it was just pretty far out of adjustment. Seems ok now. I only checked at idle though. Ill have to see what it does with some RPMs tomorrow.
IF...its not that, the next thing Ill try will be to remove the over center spring, but Im more of the belief that just helps downward pressure, not return. Not going to go there though....dont want to open up a can o worms.
 
My memory is that a Borg and Beck clutch needs about .080 plate departure clearance, while diaphragm only needs (and should be limited to) .035. However, haven't been able to confirm that online, and this web site

The Novak Guide to Clutches, Linkages & Bellhousings for Jeep® Conversions

says different:

As stated above, the diaphragm type clutch takes slightly less travel to release and requires about .030 total air gap when released. The coil spring type [i.e., Borg & Beck] requires about .040 to .050 total air gap when released. Air gap is the clearance between the clutch disc, flywheel, and pressure plate with the clutch released. A total air gap of .050 will measure .025 between each side of the disc.

Too little departure clearance and your clutch will not fully disengage when you push the pedal all the way down. Too much departure clearance and the fingers on a Borg & Beck clutch will hit the clutch disc, or, on a diaphragm clutch, you'll over compress the spring and it may not come back

If you're running a non-stock clutch, I'd get the departure gap where it's supposed to be and let the clutch pedal fall where it may. If you don't like a low pedal, you can always modify the clutch stop (above the clutch pedal) or even bolt something to the floor under the pedal to reduce travel, which will put the pedal higher when you adjust for correct departure clearance.

As for clearance between the throwout bearing and whatever it pushes against when clutch is disengaged, all you need is enough clearance that it doesn't touch when the clutch is engaged - keeping in mind that whatever clearance you have there will decrease as the clutch disc wears.
 
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Many moons ago, I set up my stock 1970 4 speed clutch with .040 clutch plate separation and 1" in the pedal. I've driven the car over a decade since then.
 
Most service manuals say 1/2"-3/4" free travel, regardless of clutch "gap". What does your factory service manual say?
 
I would look really closely at all the linkage, while a helper steps on the clutch pedal over and over again. There may be unwanted "play" in the linkage due to wear, bad parts, bad geometry, improper assembly, whatever. Extra "play" translates into wasted motion which means abnormal or inefficient clutch application.
Bad geometry may be a result of bad alignment of the pivot "balls", bent z-bar levers, cracked lever welds, whatever.
 
Most service manuals say 1/2"-3/4" free travel, regardless of clutch "gap". What does your factory service manual say?

FSM says 5/32s free play measured at end of fork results in 1" pedal travel. But that doesnt answer the question of gap between TO bearing and fingers. I have the FSM and I refer to it always before I ask here. My question was answered above by 65 Cuda. Basically close enough as to where it doesnt touch when engaged, keeping in mind wear over time. Thats good enough for me.

I would look really closely at all the linkage, while a helper steps on the clutch pedal over and over again. There may be unwanted "play" in the linkage due to wear, bad parts, bad geometry, improper assembly, whatever. Extra "play" translates into wasted motion which means abnormal or inefficient clutch application.
Bad geometry may be a result of bad alignment of the pivot "balls", bent z-bar levers, cracked lever welds, whatever.

This got me thinking. Even though I unhooked the rods and tested for binding, I figured it might be a good idea to remove Z bar for inspection. All good there. Inspected bearings and seals, cleaned it up and regreased. I also checked that all linkage, parts, etc is correct for my setup. I compared with various info from Brewers and it is. The only thing that looks a little off is an alignment issue where the ball stud attaches to fender. Kind of pulls the ball stud so that its not exactly straight, making the whole shaft slightly crooked. I guess Ill shim it with something to get it straight, but it still wasnt binding there before, so I dont think was the issue either. It was good to remove the shaft regardless so I could see how the bearings and seals where holding up.
I still think fork adjustment did the trick. Unfortunately, I havent had a chance to go for a drive to check. My work keeps calling me in. Double time and a half OT!!! :usflag:
 
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FSM says 5/32s free play measured at end of fork results in 1" pedal travel. But that doesnt answer the question of gap between TO bearing and fingers. I have the FSM and I refer to it always before I ask here. My question was answered above by 65 Cuda. Basically close enough as to where it doesnt touch when engaged, keeping in mind wear over time. Thats good enough for me.



This got me thinking. Even though I unhooked the rods and tested for binding, I figured it might be a good idea to remove Z bar for inspection. All good there. Inspected bearings and seals, cleaned it up and regreased. I also checked that all linkage, parts, etc is correct for my setup. I compared with various info from Brewers and it is. The only thing that looks a little off is an alignment issue where the ball stud attaches to fender. Kind of pulls the ball stud so that its not exactly straight, making the whole shaft slightly crooked. I guess Ill shim it with something to get it straight, but it still wasnt binding there before, so I dont think was the issue either. It was good to remove the shaft regardless so I could see how the bearings and seals where holding up.
I still think fork adjustment did the trick. Unfortunately, I havent had a chance to go for a drive to check. My work keeps calling me in. Double time and a half OT!!! :usflag:

What I was gettin at is, since the FSM doesn't cover "THAT" and it does cover free travel, the clutch disc falls into place when everything else is adjusted properly.
 
Long time ago, while my 65 Barracuda still had its original 273, one arm of the Z-bar tore partly away from the shaft. Since I had zero mechanical experience at the time, I let a local shop sorta straighten it out and re-weld the arm. But they didn't get it in the right place. Clutch pedal ended up being maybe halfway to the floor when released. OK, I sez, I'll just adjust the clutch until I get the pedal where it's supposed to be. Problem now was that the clutch was still partly disengaged even when my foot was off the pedal. Can you say "major clutch slippage?" Ended up ruining that clutch. So I replaced the clutch and the Z bar with new. Before installing the Z bar, I took it to a better shop that welded reinforcements to the arms of the Z bar. Must have worked, because even after I replaced the factory clutch with a Weber whose pressure would kill my left knee, that reinforced Z bar lasted until I replaced the whole clutch/flywheel assembly and Z bar with 340 stuff. OK, now nothing was original, Z bar and its arms were not in exactly the same place, and the arms weren't the same length. With the pedal height set to factory specs, the departure clearance (as I recall, been a long time) was no longer correct. After some research (not so easy in those pre-internet days), I found out what the release gap was supposed to be, set it first, then figured out what I needed to get the pedal at the right height. Understand I was still quite the novice. Anyway, I ended up moving the pivot at the top of the clutch pedal, which put everything more or less correct.

So my point in #7 above is that setting the pedal gap is satisfactory if you have all original stuff in good shape. But in any other circumstances, setting that alone to factory specs won't guarantee you'll end up where you need to be.
 
you start throwing fast shifts and you're likely to tear the lever from the z-bar tube. And that can happen with stock PP spring pressure. You put in a heavier PP and all bets are off.
 
Adjusting fork rod due to pedal not returning all the way up. Thought it might be somewhere in the linkage, but I disconnected and checked everything with no binding. Started adjusting the rod to put bearing closer to fingers and that seems to be what was causing it. Huge difference. So how close do I need to be? Right now, Im about .050. Seems awfully close, but bearing spins freely.
Thanks
.050 is pretty close. I adjust mine around 1/8" or so, cycle the clutch a few times and recheck. I ruined a clutch by adjusting just the pedal freeplay. The bearing was riding on the pp fingers and it seized. Never again. I always adjust the air gap and never a issue.
 
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With my helper pushing the pedal to the floor, I can get a .026 feeler gauge between disk and flywheel.
 
With my helper pushing the pedal to the floor, I can get a .026 feeler gauge between disk and flywheel.

Diaphragm clutch? If so, that's really close to what you need. If Borg & Beck, not. Either way I'd adjust it until you get the recommended clearance and see if your throwout bearing is still not touching the release fingers (B&B) or spring (diaphragm) when your foot is off the pedal. If it is touching, you might need a longer fork to give you enough travel to get sufficient plate departure while still keeping clearance enough for the throwout bearing. Or you could lengthen one of the Z bar arms.
 
Yes Diaphragm. Actually, I was just able to go for a drive...finally. Its perfect, I think I found the sweet spot. Shifts easily into all gears at various RPMs and into reverse with just the slightest nudge.
I will still shim the fender ball stud to get it perfectly straight, but I think it was just backed off out of adjustment to far on the rod.

Thanks for the info guys.
 
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