Posted: Wed Apr 08, 2020 5:40 am Post subject: Yet another clutch alignment question
I am trying to assemble my clutch linkage and the problem that I think I have is that my freeplay is 'all the way to the floor'. I have the body off so I'm basing this on making a cardboard template of the toe area and placing it on the frame to get an vague sense of where the pedal actually is lining up - so it's entirely possible that I'm going down a blind alley.
I've seen multiple posts about this topic (of clutch pedal free play), as well as reference to paragraph 191 in TM 9-8014 for pedal freeplay, however I've only seen one pic and it doesn't have a notation about what position it references.
The pic from Wes' album that I'm looking at:
Pic of my clutch pedal when it's in what I believe is roughly 'as high as the floor will allow it to get' - note the cardboard template showing floor (I think) - also note that the arm of the clutch z-tube that is attached to the clevis is at about 10 o'clock or so, and this seems to roughly correspond to the pic in Wes' album:
Next is a pic of the position I need to put the pedal at when the throwout bearing first makes contact with the pressure plate fingers - note that this appears to be right around 'at the floor' and also note that the clevis connection arm is close to 12 o'clock position:
As for questions I've seen asked in other threads:
I have done all installation.
New linkage cable from clevis to ball end - I can't compare to the old one as it was entirely rusted through in two separate pieces.
New throwout bearing
New clutch kit (on Rock Auto it was listed as for 1960 CJ5 from M-Pact, and included clutch disk, throwout bearing, pilot bushing and pressure plate). When installing the pressure plate, I made a gauge as per TM9 - to 27/32" - the pressure plate fingers were much higher than this and I had to adjust them down quite a bit to get to 27/32".
Rod from pedal to z-tube is what I had on hand, it looks to be the 10 3/4 one or at least close to that dimension.
New z-tube from Midwest Military - it's snug, not a lot of wobbling. The holes in the arms on this are definitely different distance from axis of the one that I took out.
Engine and transmission are replacements - not what was in it when I got the pile-o-parts. _________________ Tundra (really my name, not my truck)
I forgot to mention - the clevis adjustment is tightened all the way down and it seems to me I need that cable to end up shorter than it currently is.
My question for others is this - in a normally working setup, is the arm at the bellcrank end of the ztube in the 12 o'clock position when the throwout bearing hits the fingers (which means I have an issue between the clevis and the pedal) or is it in a materially different position (which would mean my issue is somewhere between the clevis and the flywheel)? _________________ Tundra (really my name, not my truck)
I've seen multiple posts about this topic (of clutch pedal free play), as well as reference to paragraph 191 in TM 9-8014 for pedal freeplay, however I've only seen one pic and it doesn't have a notation about what position it references.
This should explain where the free play is measured:
My question for others is this - in a normally working setup, is the arm at the bellcrank end of the ztube in the 12 o'clock position when the throwout bearing hits the fingers (which means I have an issue between the clevis and the pedal) or is it in a materially different position (which would mean my issue is somewhere between the clevis and the flywheel)?
You must keep in mind that Willys used several different cross tubes with different arm angles on some of them. So you must first determine if your clutch cross tube is a correct M38A1 tube?
Also do keep in mind that the cross tube can be installed both ways (left to right) !!!! Which changes the throw angle relationship off.
Quote:
As for questions I've seen asked in other threads:
I have done all installation.
New linkage cable from clevis to ball end - I can't compare to the old one as it was entirely rusted through in two separate pieces.
New throwout bearing
New clutch kit (on Rock Auto it was listed as for 1960 CJ5 from M-Pact, and included clutch disk, throwout bearing, pilot bushing and pressure plate). When installing the pressure plate, I made a gauge as per TM9 - to 27/32" - the pressure plate fingers were much higher than this and I had to adjust them down quite a bit to get to 27/32".
Rod from pedal to z-tube is what I had on hand, it looks to be the 10 3/4 one or at least close to that dimension.
New z-tube from Midwest Military - it's snug, not a lot of wobbling. The holes in the arms on this are definitely different distance from axis of the one that I took out.
You need to finish your homework by going thru the 1960 CJ5 Parts manual and confirming each of the non-M38A1 parts you installed are listed in the manual for the jeep they belong in by the same part number as your M38A1's parts manual.
As for the reference to MWO ORD G1-W88:
To summarize: Most likely you have your clutch cross tube installed reversed. Contributing factors may be your parts substitutions which still need to have their compatibility confirmed by comparing part numbers to original M38A1 parts numbers. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
my z tube from above - I think it's oriented correctly, but open to correction.
I don't have a CJ5 parts manual at this time, so a definite answer to this may need to wait until I can get one, but Crown Automotive online catalog lists the J0804746 as correct for both CJ5 55-71 and M38A1. I understand the isn't the same as getting the part from the Willys parts book.
I'm less certain as I'm digging that the clutch release cable and the z-tube are correct. Midwest Military (where I got both) shows the same part # for both M38 and M38A1 (630068 for tube, 8328129 for cable) - however my parts manual for M38A1 lists the tube (they call it 'lever') as 7372823. The cable does have the same part # 8328129.
So I wonder if anyone can confirm that part #630068 is the same as 7372823? If not, it's certainly possible that I just have the wrong part and need to replace it.
It seems that the wrong cable length could be adapted for in some circumstances by using the adjustment from the modification that Wes listed, but if the mounting hole locations are different in the z-tube then that would seem to be harder to adapt to (without just getting the right tube).
For reference for this M38A1 restoration, I'm going for 'motor pool', so in this area functional is critical (which I believe I don't have at this point) but precise part number match (in and of itself) is not critical for me. _________________ Tundra (really my name, not my truck)
There are significant differences in the three critical parts (Cable, Rod and Shaft) used in the Willys lineup of Jeeps.
Here's the result of my own research:
Quote:
So I wonder if anyone can confirm that part #630068 is the same as 7372823? If not, it's certainly possible that I just have the wrong part and need to replace it.
Actually the 630068 is the WO# for the fulcrum in the bell housing that the fork pivots on. You got off one line in your scan of the manual.
Joined: May 30, 2014 Posts: 3444 Location: Texas Hill Country
Posted: Thu Apr 09, 2020 5:20 pm Post subject:
The part numbers for the M units look the same.
You mentioned the shaft you took out looked different than the one John supplied. Can you elaborate?
Also, I keep kicking something over in the back of my mind about a fulcrum lever not being seated correctly giving someone fits on here. Maybe look in the inspection hole and make sure it’s sitting where it’s supposed to be.
This is a good one. These vehicles aren’t brain surgery, but you have to put the right parts together the right way....
I believe the clutch cable is seated properly in the release fork but I'm also open to correction on this - and the fork seems to pivot nicely on it's stud and press the throwout bearing retainer and bearing properly against the pressure plate fingers:
The new clutch cable is (rough measurement from ball to end of threaded portion, not including the clevis, made while the cable is still in the bellhousing, so it's got an extra dose of 'rough') about 11.25" long.
Comparing the old z-tube to the new one:
The new one the arms are 180 degrees from each other (by eye, not by measurement)
The old one the arms are definitely not 180 degrees from each other (not sure if it's obvious in this pic or not)
The old one was installed wrong way around (the clevis is both corroded and powdercoated in place and unable to be removed without some work so serves as a witness to the way the old one was installed) as seen in this comparison between the two:
Additionally the centerline of the holes in the arms are definitely different.
The hole in the arm appears to be right around 5/16" (based on putting the shank of a 5/16" drill bit in the hole)
Measuring with a digital caliper over painted surface, the old and new tubes both appear to be very close to the same size diameter - 0.891" for old (powdercoated), 0.885" for new (painted) - I'd hazard that these are close enough to the same.
I then measured with the caliper the gap between the drill bit and the tube (note that this is not actually measuring 'center to center' - but I'll provide my calculation of that dimension for each measurement below)
For the old tube, at the end where the clevis is: 0.53" (+0.315/2 + 0.891/2 gives 1.133" center to center +/- measurement error)
old tube, frame end: 0.797" (+0.315/2 + 0.891/2 gives 1.4" center to center +/- measurement error)
For the new tube, at the end where the clevis is: 1.388" (+0.32/2 + 0.885/2 gives 1.9905" center to center +/- measurement error - so realistically, probably 2")
new tube, at the frame end: 1.02" (+0.32/2 + 0.885/2 gives 1.6225" center to center +/- measurement error)
My conclusion on this - the old tube is not the same as the new one. Since I got this as a pile of parts, what I don't know is if it ever drove with the old tube or if it was put in as a replacement some point before the project was abandoned.
I've asked John at Midwest Military what part number the z-tube that I got from him is patterned after (he is selling a new manufactured part, not NOS - and his web page has the #630068 but at this point I'm assuming that's unintentionally the wrong # - I selected not by the number but by the name & photo on his web store).
Ultimately, if I'm understanding the mechanism of the linkage here, the ratio of the center-to-center for the two arms is what is critical to determining the distance the the clutch cable will pull and in turn how much it will pull the release fork. How far the clevis is screwed down on the thread determines 'starting point' but the ratio of the arms determines how far from 'start to end' (of the range of motion of the release fork). If I do the mod to the clutch rod that Wes listed, I could adjust the 'starting point', but the only way to adjust the 'start to end' range is to go to a different z-tube (and installing the z-tube backwards is also effectively inverting the ratio of the two arms, so 'just like' going to a different tube). _________________ Tundra (really my name, not my truck)
I know you have an M38A1 and I have an M38 but the engine block, bell housing, transmission should be the same based on serial number changes for the sealed bell housing which I guess you have since you have the boot on the clutch cable. The 740 and the 758 parts manuals call for the same cable for the sealed bell housing and for the same cable assemble for the sealed bell housing. Each manual has a listing for each.
In any case I listed the two clutch cables in the 740 parts manual that are for the sealed bell housing and the ones for the 758 parts manual that has two listings.
The 740 parts manual shows the following numbers for the clutch cable
CABLE, control lever (used on engines after serial
No. 74419)
TRU-SA4126 or WO-805935
Ord Part # 8328129
And
CABLE, control, w/SEAL, assy (used on engines after serial No. 74419)
WO-807488
From the 758 parts manual
cable control lever, flexible steel
TRU-SA4126 or WO-805935
Ord Part # 8328129
and
CABLE, control, w/SEAL, assy
WO-807488
I have a early M38 so it has a non sealed bell housing so I don’t know what the difference in the length of the cables for the sealed and non sealed bell housing but common sense (if applicable here) would suggest they are the same length.
I have the old clutch cable from my non sealed bell housing M38 and from the ball to the end of the threaded portion it is 10.5 inches.
To muddy the water I have another clutch cable that appears new and I don't know where or why I acquired it. It might have been in the extra parts I got with the jeep. It is 11.5 inches.
If I lay both of these side by side, balls aligned, the ball to the the beginning of the threaded portion is within a .25 in , the big difference is the threads on the longer one start after the threads on the shorter. So if I had used the longer one it would not have enough threads to tighten it enough, but there is room for more threads.
I looked on another parts web site and they listed the clutch cable for the M38 and M38 as 11 inches long, part # 640124. (note this is the same part number for the M38 with the non sealed bell housing that I have)
I don't know if any of this is helpful to you or not in short it appears from the parts manuals for the m38 and the m38A1 the cables and the cables with seal assembly are the same. I think from what you have said, assuming your clutch control tube is correct and installed correctly that you need a clutch control cable 10.5 inches long or more threads on the one that you rough measure at 11.5 inches.
I can send pictures of the two cables I have if it would be of any help to you. _________________ R G Mutchler
M274A5
M-38 MC13312
http://willysmjeeps.com/v2/modules.php?set_albumName=rgmutchler&op=modload&name=gallery&file=index&include=view_album.php
Heard back from John at Midwest Military - he says that the z-tube that I have is patterned on Ordnance number 7372823 which matches my parts listing for the M38A1.
rgmutchler - the cable I have is Ord part # 8328129
I do have the yoke tightened down as far as it will go - making the effective length of the cable as short as possible - tomorrow I will try moving the yoke to the other end of the it's range of adjustment. I think I effectively need the cable shorter not longer; but it's simple enough to test that theory by adjusting it longer to see. _________________ Tundra (really my name, not my truck)
I moved the clevis to the furthest end and it definitely makes the problem worse not better.
I then looked again at the modification Wes posted - and what I notice is that they call for the length of the replacement rod that goes between the two pivot tubes to be 10.5", so I'm inferring from that that the normal rod, Ord # 7372836 is nominally 10.5" center to center. I remeasured the rod I have and it's 11.25" - definitely not 10.5" center to center. Since my old z tube is definitely different from the correct one, I think it's reasonable to question if the rod I have (which was on the M38A1 when I got it in disassembled form) is correct.
I do like the idea of this rod being a double-sheer setup with the two clevises so I believe that's the route I'm going to go unless someone can identify that 7372836 really should be 11.25". _________________ Tundra (really my name, not my truck)
Joined: May 30, 2014 Posts: 3444 Location: Texas Hill Country
Posted: Sat Apr 11, 2020 10:41 am Post subject:
Hi T,
I have a new in package WO-805935 cable.
It is 11-1/2" from the outer end of the ball to the end of the threads.
That does not include the clevis at all.
I think that is a fair place to take a measurement from.
My takeoff rod (clevis both ends as per the mod) is 10-1/2" from the center of the pins on each end.
I would suggest you locate a nearby M38 that runs and drives well and compare your three critical parts (Cross shaft, left hand push rod and right side cable) to that M38's critical parts. I know we have several members in NH.
I'd offer a direct comparison but I have not got my current M38's engine installed to provide any quality assembled photos with dimensions. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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