Clutch Job Looming

JDToumanian said:

-- Are you sure you put the clutch disk in facing the right way? It is not reversible, there is a pressure plate side and a flywheel side.

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Check - disk in the correct orientation. I checked and double-checked this during the install. The disk actually had a sticker on one side which said "This side toward Pressure Plate." Additionally I matched the orientation of the disk I removed.

JDToumanian said:

-- Are you sure you used the correct clutch disk and pressure plate combination? The 3-puck disk must go with the 4-finger PP and the 6-puck disk must go with the 3-finger PP. It is my understanding that they are not interchangeable.

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Check - all new disk, PP, T/O bearing and input bearing. I ordered them together as a kit.

JDToumanian said:

-- I'm not sure I trust your transmission adapter (the aluminum ring the transmission bolts to)..... I'd make sure to check it. There is a procedure in the TM for checking it's concentric-ness. I probably would have replaced it when I saw the thread repair coils. It seems that if you have the correct free travel at the pedal and all the above things are correct, it's gotta be something odd like the transmission's input shaft binding in the clutch disk splines or pilot bushing. The amount of disk material and the wear to the pilot bushing could also indicate this....

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Excellent thought - I had some trouble getting the tranny in, it's totally possible it buggered up the input bearing a little and is now binding on it. I will check that and post up. It will probably be this weekend, as I am trying to get a new house ready for move-in. The timing on this is horrendous. Better though than if it would have gone on me during my 750 mile recovery

Death: I did grease the T/O bearing, and the movement along the input shaft is fine. It's just that when I depress the clutch for some reason the tranny doesn't disengage. My money (for now) is on Johns suggestion of the input shaft binding on the input bushing. I appreciate the post - always helps to have folks remind of all the different steps & parts to ensure nothing gets overlooked.

You didn't let the tranny hang by the clutch disc did you? If so you could have bent it.

Dirt

RANDYDIRT said:

You didn't let the tranny hang by the clutch disc did you? If so you could have bent it.

Dirt

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Good question! Nope, no hanging tranny. The whole operation was done with a chain hoist from above.

A'ight - quick update on this issue. I pulled the tranny again today (this time it took me a grand total of ~90mins from walking out to the driveway to the tranny sitting on the ground.)

As expected the pilot bushing is in pretty bad shape. Disk, PP and flywheel all look good. I did take a closer look at my adapter ring and confirmed that not only is every single one of the bolt holes a coil, but at least one of the coils has started backing out grrrrrrrr....

A new pilot bushing and alignment tool are already en route. Once I finished the tear down I called Boyce and ordered a new adapter ring. All my parts should be here on Tuesday, and then I'll do the reassembly.

Looking forward to it....

I need some help! I am lost on what my issue is. I received my disk alignment tool and new pilot bushing today, and reinstalled the tranny. It went in smooth and easily, literally a 10min job once I had it on the chain hoist so I am very confident it wasn't binding and there was no installation issue.

However, still the same problem. With the truck in gear and the clutch pedal fully depressed I can't spin the output shaft on the tranny by hand. If I get both hands on it, and put my weight into it I can spin it, but nothing like it is when it's in neutral. It seems like an adjustment issue, but everything is adjusted to spec.

Does anyone have a measurement/adjustment figure for the fingers on the pressure plate? I removed the tranny (again) and everything looks clean and in good shape. I am supposed to be moving this week, and need to take my truck with me!

BTW: clutch disk alignment tool - TOTALLY worth the $30 it costs at Memphis.

You didn't think to try and spin the trans while it was out of the truck(trans in gear) did you? Might not be a clutch issue. Is everything hooked up, or are you trying this with the short shaft out?

To be clear, with the trans in neutral, it spins fine, but with it in gear - but the clutch peddle is pressed - no spin?

gimpyrobb said:

You didn't think to try and spin the trans while it was out of the truck(trans in gear) did you?

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Yep, I did check to ensure it could spin while in gear outside of the truck. Tranny seems to function just fine.

gimpyrobb said:

To be clear, with the trans in neutral, it spins fine, but with it in gear - but the clutch peddle is pressed - no spin?

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EXACTLY the issue I am having. Output flange spins freely by hand while in neutral. Clutch depressed and no spin. If I get my weight on it and both hands I can turn it, but there is considerable resistance.

I've done clutch jobs on other vehicles many times, and never run into this issue before.

I checked with the vendor of the PP, and was told it shouldn't need any adjustments, but I can't think of anything else that could be causing it. It really seems like an adjustment issue, especially since I can get some rotation on the output flange with the clutch pressed if I put enough effort into it. The clutch just doesn't seem to be engaging fully.

That SUCKS!

I wouldn't mess with the adjustments on the pressure plate, it should be pre-adjusted from the factory and never need to be touched. And since the old pressure plate was exhibiting this same behavior, I think we can rule that out. But obviously something is wrong....

Since the transmission is out again, why don't you post some pics? ....Particularly of the throwout bearing end of the transmission, maybe someone will recognize something wrong there.

A strong possibility is wear, failure, or incorrect adjustment of something that you wouldn't normally expect, like the clutch pedal counter-shaft, or the fork that pushes the throwout bearing. Maybe one of these arms is slipping on it's shaft, or is not on the right spline? Or maybe the pedal itself is not high enough off the floor of the truck, thus not providing sufficient travel. (You didn't move it down to make it easier to get your foot up on the pedal, did you?) Because the root of the problem is that the throwout bearing is not moving far enough to cause the pressure plate to release the clutch disk. Are you absolutely sure all linkages and the free travel is correct? ....A very excessive amount of free travel could cause this....

The second pic compares my old throwout bearing carrier to my new one.... The little buttons that the fork pushes on were missing....

Jon

With the trans in gear you have to back drive all of the gears. What gear do you have it in when you try to rotate the output shaft? I would try putting it in 5th and see if you can spin it then if you had it in 1st before. If so you may just have a lot of drag when trying to spin all of the transmission gears.

I agree that trying to spin the transmission of the truck would have been a good test.

I did some digging around on the site and found TM 9-2815-210-34-2-2, pg 543 which gives the correct adjustment for the fingers on a 3-finger pressure plate. It says that the fingers should be 2 5/32" from the pad where the T/O bearing rests to the pp face (where the clutch disk sits - from #2 to #3 in the first pic.)

It doesn't state explicitly that this measurement is taken with the pp installed, but based on the orientation of the fingers in the drawing, I assume it is. When measured in that same location my fingers give me a whopping 1 7/8". I know it's very unlikely the manufacturer/reconditioner set them incorrectly, but that seems like a significant difference to me?

I know my adjustments are all correct in all my linkages (I checked and rechecked them all.) I think my next step is to adjust the finger heights, and reinstall the tranny and see where that puts me.

Attached are also some pics of the pp and T/O bearing as they currently sit. Please let me know if you see something grossly amiss. I am reassembling the way they came out.

Worth it to note these are not the symptoms I was having before the clutch replacement. I was having standard 'your clutch is toast' problems - hard shifts, couldn't get it into the asynchronous gears, I could hear the T/O bearing grinding, etc. This is another reason I think it's the pp, I haven't messed with anything else and it was all working before.

wbdodgeiv said:

With the trans in gear you have to back drive all of the gears.

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I am not sure what you mean by 'back drive'?

wbdodgeiv said:

I agree that trying to spin the transmission of the truck would have been a good test.

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Tranny spun freely while on the ground and out of the truck.

I still wouldn't mess with the pressure plate adjustments..... Because that's still doing the same thing as adjusting the external linkages: Changing the relative position of the throwout bearing to the pedal. I would rather assume that the factory got it right, and the linkages are wrong on the outside.

I would start with the one on the outside of the transmission. I don't have time to dig through TMs right now, but I recall there's a procedure where you push the arm until the throwout bearing contacts the PP fingers, and then measure the angle of the arm relative to the front of the transmission housing. Once that is correct (and it very well might not be since you've switched from a 4-finger to a 3-finger PP), THEN you adjust the pedal free travel by turning the clevis on the linkage.

Also, if you look on page 539 of the TM you mentioned above, you will see that the adjustment for the PP you referred to is for LDS engines which presumably go in a 5-ton with a different transmission..... And I think it's done out of the truck, "on a flat surface."

Jon

JDToumanian said:

Also, if you look on page 539 of the TM you mentioned above, you will see that the adjustment for the PP you referred to is for LDS engines which presumably go in a 5-ton with a different transmission..... And I think it's done out of the truck, "on a flat surface."

Jon

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Tks Jon - that was the piece I was missing. Couldn't figure out if the adjustment was while installed or not.

The arm adjustment you referred to is 3.5" from bellhousing to center of hole the pin goes in. I did install and measure to that with no improvement. I will reinstall again (tomorrow hopefully, if the weather lets up) and make sure everything is up to spec.

The other measurement I thought might be helpful is the distance from the arm to the bellhousing when the clutch is fully depressed. Seems like that might give me an idea if I am getting the proper amount of movement when I press the clutch in.

Two other things came to mind.....

-- Make sure the pressure plate is the correct one. Maybe they sent you one for a 5-ton multifuel? I'm not sure if they're the same or not....

-- Another possibility is 'operator error'.... Did you know that 1st gear is not synchronized? So with the engine running, if you simply push in the clutch and try to stuff it in 1st gear, it will grind. To go into 1st at a stop with the engine running, push in the clutch and then "bump" a synchronized gear.... 2nd or 3rd I usually do, and then (with the clutch still pushed in of course) it should go into first easily. The bump makes the synchros stop the gears from moving.

No offense intended by stating what may be obvious, I'm just making sure we've eliminated EVERY possibility before you mess with the PP adjustments.

......And honestly if it DOES turn out to be the PP adjustment, I'd be a bit annoyed with the manufacturer and the dealer that sold it to me. You aren't supposed to have to mess with that. The procedure in the TM is for verifying serviceability of a used PP or for adjusting it after rebuild (surface grinding). It isn't supposed to be for adjusting a NEW one...

Jon

Success! So I owe Jon a HUGE thanks on 2 counts.

First for convincing me to NOT mess with the PP finger adjustments. Turns out they were accurate despite my efforts to convince myself otherwise. Fortunately I never made any tweaks.

Second he convinced me to post up pics of the bits 'n pieces as it was apart. It was while looking at those photos I saw that my input shaft appeared ever-so-slightly mushroomed on the end. Accordingly I grabbed the flap disk and smoothed it out. I put everything back together, checked the resistance on the output flange and found it spinning smoothly!

After it was all back together I took the load of scrap that's been in the bed for the past couple of weeks to the steel yard. As I was doing the test run I thought the truck was a little more sluggish, and kind of struggling to drive. I was worried I had done something wrong. Turns out the 'little bit of scrap' I had in the back was 3000lbs! After dropping it off the truck was back to being spry and speedy (well, for a deuce.)

Tks all for your help. Good to be back on the road again, and a huge relief as I have to move tomorrow

In a lot of big rigs, its common to change the input shaft and input shaft bearing when doing a clutch job.. The old input shafts make for awesome alignment tools when you weld some sort of handle to the end, although you might have to file down any blemishes that the input shaft might have.

Alright! Good job! ......Just in time! Don't hurt your back moving......

Jon

Been following this one from the start. Glad you got your tuck fixed.