Clutch pedal goes to floor

[Kaegi]

Yesterday I crawled under the M and, as I rotated the engine, I started to back out the bolts holding
the pressure plate. Just a few turns at a time. After several rotations of the bolts, the pressure
plated moved off of the fly wheel surface about a 1/4 to 3/8 of an inch. At the same time the
fingers on the pressure plate were moving out towards the throw out bearing.
Now the clutch pedal and the throw out bearing only had to move slightly to engage the fingers
on the pressure plate. The clutch pedal travel was near normal. Looking throught the holes in the
pressure plate housing, it appears that the "fat" part of the hub on the clutch disk is facing
towards the transmission. Not enough room to see the front side of the disk.
Obviously I can't leave the bolts on the pressure place loose. When I re-tightened the the bolts
the problem of excessive pedal travel returned.
Any more thoughts on the above?

I think you just need to adjust the linkage. can you pos a pic of the linkage?

[8543bob]

GOOD MORNING, I had the engine out of my "M" about two years ago, While out I noticed that the clutch disc was worn down to the rivits, but I had good clutch before I removed the engine. I repalced the clutch disc before putting the engine back in the "M". It did not require a linkage adjustment. Just a statment on my observation, Dont know if it will help you.
GOOD LUCK BOB

[m37jarhead]

The old disc was maybe about 1/2 worn or less. Fingers appear to be all on the same level. Pedal play was also normal prior to dis-assembly and the
unit worked fine. Linkage, keyways and clevases are good. Replaced the link pins with new. Now almost no play in the linkage now.
When eyeballing the forks, I see that the forks are approx. 40 degrees off high center before the throw out bearing comes into contact
with the fingers on the pressure plate. The tips of the forks are what's pushing the bearing forward instead of the flat surface on the forks.
This does not seem right to me.
Thanks for all the tips. I'll try to yank the tranny next week for a closer look-see.
Will advise my findings................

[m37jarhead]

Thanks for the tips Paul, see my PM to you.

[MSeriesRebuild]

Yesterday I crawled under the M and, as I rotated the engine, I started to back out the bolts holding
the pressure plate. Just a few turns at a time. After several rotations of the bolts, the pressure
plated moved off of the fly wheel surface about a 1/4 to 3/8 of an inch. At the same time the
fingers on the pressure plate were moving out towards the throw out bearing.
Now the clutch pedal and the throw out bearing only had to move slightly to engage the fingers
on the pressure plate. The clutch pedal travel was near normal. Looking throught the holes in the
pressure plate housing, it appears that the "fat" part of the hub on the clutch disk is facing
towards the transmission. Not enough room to see the front side of the disk.
Obviously I can't leave the bolts on the pressure place loose. When I re-tightened the the bolts
the problem of excessive pedal travel returned.
Any more thoughts on the above?

Based on what you have stated as fact in the above post; I'm inclined to agree with Kaegi; ADJUST THE LINKAGE.

I don't have a 6th sense and surely I could see the issue right away if I were there to look at it; and obviously I'm not, but I have put lots of clutches in M37's. From what I read, it has out of adjustment linkage written all over it.

CERTAINLY try to adjust the linkage before you pull the trans back out. Only takes minutes, you aren't out anything if that doesn't cure it, but you are out at least a couple of hours of hard labor if you pull the trans only to find adjustment is all it takes. What you have said happened when you loosened the pressure plate bolts sounds perfect. If you don't understand how to adjust and exactly what correct adjustment accomplishes; just ask, happy to explain that to you. My thoughts are simple, you have too much clearance between the fingers and the release bearing, so you are running out of pedal travel before the clutch can release. The fact that you have said you never moved the adjustment is a dead give away also; the difference between a half worn out disc lining and a new one is very significant as to free travel adjustment.

Adjust it man; I'm thinking you will be fine afterwards!!

[m37jarhead]

Charles: Yes adjusting is the lesser of the two evils. I'll adjust the linkage tomorrow and report back.
Thanks for the guidance. It's been more than a little frustrating.

[8543bob]

Another thought, could you have the wrong throw-out bearing installed?? Not thick enough to engage the fingers??

[m37jarhead]

The throw out bearing, ordered from Vintage Power Wagon is an exact match to the
one that was removed. (Does not hurt to consider this issue.) Thanks for the tip.

[Kaegi]

Another thought, could you have the wrong throw-out bearing installed?? Not thick enough to engage the fingers??

I had the same thought. maybe the 2 machined surfaces where the fork makes contact are not correct. over machined? with all the overseas parts these days you never know how far off something can be made anymore. ordered a slave cylinder for a 60s civilian dodge truck and nothing was in the correct place and I had to adjust the rod. the bleeder screw had a 10 mm head! with standard threads! took that out and put in the old one. no metric wrenches go in my glove box.

[MSeriesRebuild]

Another thought, could you have the wrong throw-out bearing installed?? Not thick enough to engage the fingers??

I had the same thought. maybe the 2 machined surfaces where the fork makes contact are not correct. over machined? with all the overseas parts these days you never know how far off something can be made anymore. ordered a slave cylinder for a 60s civilian dodge truck and nothing was in the correct place and I had to adjust the rod. the bleeder screw had a 10 mm head! with standard threads! took that out and put in the old one. no metric wrenches go in my glove box.

This really is not relevant as the fork contact surfaces are not on the bearing, but on the collar. A new bearing pressed onto the original collar does nothing at all to change fork contact.

[m37jarhead]

As I suspected, adjusting the pedal did not do much good. While the pedal has normal travel now, the forks are almost horizontal by the time the bearing touches the fingers on the pressure plate. Not enough additional movement for the forks to fully depress the fingers on the pressure plate.
So, the tranny comes out tomorrow. Stayed tuned. Hopefully more info tomorrow.

[MSeriesRebuild]

As I suspected, adjusting the pedal did not do much good. While the pedal has normal travel now, the forks are almost horizontal by the time the bearing touches the fingers on the pressure plate. Not enough additional movement for the forks to fully depress the fingers on the pressure plate.
So, the tranny comes out tomorrow. Stayed tuned. Hopefully more info tomorrow.

Do you by chance have some component in the linkage that is not tight and is slipping on the shaft?

Your information you share is somewhat confusing. You speak of adjusting the pedal, I'm not sure we are on the same page at all. The clutch adjustment on an M37 rotates the shaft that goes through the frame rail. Actually the pedal itself does not change. What the shaft rotation does is change the distance between the release bearing and the fingers on the pressure plate. If the clutch fork is tilting forward to a near horizontal position and the fingers are still not depressed to the point of releasing the clutch, that sounds like you added free travel instead of taking free travel away. When the clutch will not release, you must remove free travel so the release bearing moves farther forward.

I've heard of a couple of instances over time where wrong pressure plates were installed and caused strange issues, but these have been rare although it is certainly possible that it can happen. Most new pressure plates also come with small blocks on the back side of the fingers; this is a measure to keep the fingers from coming too far back while the unit is packaged and makes installation much easier. Once the plate cover is tight against the flywheel, the blocks must be removed, did you by chance leave these in place? If so, this would prevent the fingers from moving back into a normal installed position; also they can fall down and jamb the assembly so it can not release; a long shot, yet a possibility. I've seen this happen.

[Cal_Gary]

I've never known anyone to do a finger adjustment on the M37 pressure plate-this was necessary on the deuce clutches but not any M37 I've seen.

I'm really curious to hear the diagnosis on this once the problem is identified, so please keep us in the loop.
Thanks,
Gary

[Kaegi]

Another thought, could you have the wrong throw-out bearing installed?? Not thick enough to engage the fingers??

I had the same thought. maybe the 2 machined surfaces where the fork makes contact are not correct. over machined? with all the overseas parts these days you never know how far off something can be made anymore. ordered a slave cylinder for a 60s civilian dodge truck and nothing was in the correct place and I had to adjust the rod. the bleeder screw had a 10 mm head! with standard threads! took that out and put in the old one. no metric wrenches go in my glove box.

This really is not relevant as the fork contact surfaces are not on the bearing, but on the collar. A new bearing pressed onto the original collar does nothing at all to change fork contact.

i know but thougth maybe he got a new collar that might be off. just a thought.

[MSeriesRebuild]

I've never known anyone to do a finger adjustment on the M37 pressure plate-this was necessary on the deuce clutches but not any M37 I've seen.

I'm really curious to hear the diagnosis on this once the problem is identified, so please keep us in the loop.
Thanks,
Gary

There is no finger adjustment on an M37 clutch other than what is done when the pressure plate assembly is actually set up for the application on a clutch jig; this procedure is done at the manufacturer.

I must not be doing too good on offering a proper description of the procedure here, I don't know how finger adjustment got into the mix.