Clutch Release Cable |
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sean
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Posted: 01 Jan. 2009 at 4:01pm |
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Group 11-02 : Clutch Control Parts
Part No. 640124 : CABLE, clutch control Here's a great case of Willys using one part number for 2 different parts. This may be why some run into problems with clutch release after replacing this cable. Photos will enlarge. top: p/n 640124, 10 1/4" long, after s/n 12315 The service bulletin referencing the change: Sean |
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samcj2a
Member Sponsor Member x 5 Joined: 21 Oct. 2006 Location: Arlington, VA Status: Offline Points: 8549 |
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That seems to be a pretty significant issue for the DIYer not having access to service bulletins and also having the stated combination of parts. Thanks for posting that one. Now, if only I can remember it is here when the time comes to deal with any clutch issues.
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sean
Moderator Group Sponsor Member Joined: 20 July 2005 Location: North Idaho Status: Offline Points: 7388 |
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Sam:
Considering that 3 inter-related parts changed w/in a short time span, there's 8 possible combinations of cable, lever shaft & clutch disc. Certainly, not all combos can be compatible. Reference to "relocating" the lever hole to 1 13/32" w/out mentioning the original spec makes me wonder if cable travel was increased or decreased. Sean |
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Bob W
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samcj2a
Member Sponsor Member x 5 Joined: 21 Oct. 2006 Location: Arlington, VA Status: Offline Points: 8549 |
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Thanks, Bob.
Sean, unless I'm not visualizing these parts correctly, I think that the cable travel is increased with the cable attached to the control lever at a greater distance from the fulcrum, or pviot point, with the same amount of pedal travel resulting in more movement of the cable and the clutch pressure plate levers and a quicker engagment or disengagement. Edited by samcj2a - 04 Jan. 2009 at 10:41pm |
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Jeff
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to add to the dilemma, I have also found that after replacing a clutch, I had to change my clutch rod to a shorter one. This change was due a lack of adjustment available in the cable. From what I have read, over the years there has been changes made to the clutch assemblies which necessitates changes in the rod.
Jeff Edited by Jeff - 06 Jan. 2009 at 12:22am |
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sean
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Excellent Bob, thank you!
Interesting that there's no mention of the shorter cable in this earlier bulletin though. Sam, I'm reading it differently. Cable travel should be reduced. Original hole at 1 5/8" (= 1 20/32"), new hole at 1 13/32", makes shorter moment arm. Sean Edited by sean - 05 Jan. 2009 at 3:05pm |
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samcj2a
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Sean yes, I must have been comparing 10/16 to 13/32.
I wonder if there is something missing still. They say the pedal pressure is unchanged which would be true if the leverage that the pedal has is reduced since the clutch plate pressure is reduced. That is consistent with the shorter moment. What does not seem intuitive to me is that shorter cable travel would fix the problem that they say was found to be the result of the the driver failing to depress the clutch pedal all the way. With that being the root cause, they would want to increase the cable travel, at least on the surface of it. OTOH, they have not told us in this bulletin what changes were made to the pressure plate. (They did heavy up the driven plate's hub, but I don't take that as compensating for not enough pedal travel.) I assume there were no changes to the pressure plate assembly. Here is what I think the explanation is: Since the moment on the "pedal rod end" was reduced, the same amount of pedal movement will, in fact, result in greater movement of the cable, not less, and that is consistent with the pedal's having less leverage and requiring the pressure plate springs to require less force to release the clutch at the pressure plate, not the pedal.
When I first replied, I did not reread the bulletin you posted that started this, and I was visualizing the cable rod end moment as being longer which would have resulted in longer cable travel by virtue of my mental lapse on the moment's being increased. The fix I incorrectly visualized could not be implemented because there probably is not enough metal at the end of the cable end lever. I think the only reason they tell you to braze up the original hole is so there is no opportunity to use the wrong hole.
Anyway, I think that my current explanation is correct. As always, though, I stand ready to be corrected! Edited by samcj2a - 06 Jan. 2009 at 3:58pm |
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sean
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Sam:
Per Bobs bulletin #765, paragraph 4: "clutch assembly (aka pressure plate) .... exerts a pressure of 1015 lbs instead of 1250 lbs". I'll have to spend some time analyzing it, but it seems Willys was in trial-and-error mode to "field fix" a design flaw, trying first one thing, then another!
Sean |
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samcj2a
Member Sponsor Member x 5 Joined: 21 Oct. 2006 Location: Arlington, VA Status: Offline Points: 8549 |
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Sean, Until we know what changes were made to the "Clutch Assembly", we may not know the full story. I will purse the terminology question, but since the word "assembly" is used, I think that the "assembly" included the pressure plate, the fingers, the springs and whatever other fasteners and parts are needed to put it together. I think that the most important change was the change to the springs to reduce the force that was required to release the clutch (as indicated in your bulletin). My bet is no other changes to that assembly were required.
A key point in my post was that the cable travel was, in fact, increased. I think that both of us were intially misunderstanding that the moment that we now both understand to be reduced was at the cable end of the control rod and levers as opposed to where it actually was, at the pedal end of the control rod. Given that the moment was reduced at the pedal end, the conclusion must be that the cable travel was increased for the same amount of pedal travel. Further, the changes that I described all all consistent with a fix to the problem that was described. Reduced cable travel would not accomplish a fix as far as I can see.
Edited by samcj2a - 06 Jan. 2009 at 4:24pm |
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sean
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Sam:
Get's even more complicated now, w/16 possible combinations of cable, lever, pressure plate & clutch disc! Sean |
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samcj2a
Member Sponsor Member x 5 Joined: 21 Oct. 2006 Location: Arlington, VA Status: Offline Points: 8549 |
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I suppose another solution is to just push the clutch to the floor! At least I'll be on notice to pay more attention to what is going on when I disassemble my clutch for whatever reason. I did finally look at your parts list to and did see that the springs were the only thing to change. In looking at that list for all three editions of the list, I was reminded that the supplier of the later clutch assembly was Auburn. I recall seeing the mention of more than one vender from what I recall was either a service manual or a mechanics manual that I had back in the day. I don't recall the name of the vendor of the original clutch. Do you? |
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lowenuf
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original pressure plate manufacturer was Auburn, and original clutch disc was Borg & Beck :)
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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