1948 - 1956 F1, F100 & Larger F-Series Trucks Discuss the Fat Fendered and Classic Ford Trucks

Slipping Clutch

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Old 05-14-2015, 04:28 PM
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Slipping Clutch

Hey Guys - Kermit is a 54 F100 with a rebuilt 272 mated to a T5. John Mummert modified the bell housing and I bought a new 11" disc and pressure plate, throwout bearing and pilot bearing from John. I had the flywheel resurfaced locally. I have about 100 miles on the truck since rebuild and the clutch has been slipping since day one. I have about 1" play in the clutch peddle with mechanical linkage and with the inspection plate off, everything looks dry and new. I would really like to exhaust all possible fixes before having to drop the trans but I'm running out of ideas. I've tried calling John but get no answer.
Anyone have similar problems? Solutions? Thanks, Ken
 
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Old 05-14-2015, 06:49 PM
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What does that one inch play at the pedal look like at between the clutch fork and the throwout bearing?
 
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Old 05-14-2015, 06:57 PM
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Is it a diaphragm clutch or Lng type (3-finger)? Can you see if the throwout is truly clear of the fingers when released?
 
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Old 05-14-2015, 07:05 PM
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And, does it slip all the time or just under full power, heavy load, fifth gear? Be aware too, that depending on what type pressure plate you have, Long, the clearance between the throwout bearing and the clutch fingers may become smaller to none at high rpm.
 
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Old 05-15-2015, 10:05 AM
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Thanks for the comments guys - On closer inspection I do see that with the pedal fully out, the rear of the throwout bearing is flush against the trans and the front is still in contact with the fingers to the point that I cannot spin the bearing. The fork still has a little play in the its' slot on the bearing assy. So the throwout bearing assy is too long? What if I loosened the trans to bell bolts and slid the trans back far enough to free up the bearing from the fingers - shouldn't take more than an 1/8". Then I could machine an aluminum shim and bolt it between the trans and bell. Would that work or am I creating more problems? Thanks, Ken
 
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Old 05-15-2015, 10:49 AM
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Check for washers or spacers under the ball nut? Lets try to keep it simple, not make any more modifications. If you move the transmission back, will you still have enough driveshaft movement?
 
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Old 05-15-2015, 12:40 PM
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I have to wonder if the PP is set up correctly. What brand is it? Lots of instances of chinese rebuilt PP's having incorrect finger height. Any way to measure their height without pulling the trans? Although I suspect you'll be pulling it anyway. Note that a too-thin disc will have the same effect.
 
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Old 05-15-2015, 01:38 PM
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Originally Posted by flattie39
Thanks for the comments guys - On closer inspection I do see that with the pedal fully out, the rear of the throwout bearing is flush against the trans and the front is still in contact with the fingers to the point that I cannot spin the bearing. The fork still has a little play in the its' slot on the bearing assy. So the throwout bearing assy is too long? What if I loosened the trans to bell bolts and slid the trans back far enough to free up the bearing from the fingers - shouldn't take more than an 1/8". Then I could machine an aluminum shim and bolt it between the trans and bell. Would that work or am I creating more problems? Thanks, Ken
Agree with Ross at this point, pull the transmission. I just verified the ball stud in my '56 parts bell housing does have a thick lock washer under it but if the TO bearing is wedged between the bearing retainer and the clutch fingers, removing the washer will not gain you anything.
 
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Old 05-15-2015, 08:19 PM
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Appreciate all thoughts. I decided to slide the trans back to see how far I would need to shim it out, having already decided that I wouldn't go more than a 1/4" shim. Well, I had to open the gap 5/16" before I could turn the TO bearing and that was with no visible clearance between the TO and the fingers. Too much. Instead I bought a short TO for an 89-91 Mustang T-5 and it's a good 1/2" shorter than the one I got from Mummert. I didn't know there was a long and short one. Of course I'll have to pull the trans to install it but that's better than jury rigging the thing. Thanks again guys and Ill let you know it turns out. Ken
 
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Old 05-16-2015, 07:46 PM
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Well, my buddy and I unhooked everything and pulled the trans back far enough to remove the long throwout bearing and install a short one. Since the short TO was much closer to the fingers I had to entend the threads on the fork adjusting rod and set the bearing surface so it barely touched the fingers with the pedal out. After hooking everything back together I tried the clutch. It worked OK but was stiff as a cob. Almost had to use both feet to disengage the clutch plate. I finally got hold of John Mummert - he had been gone all week - and he said my problem wasn't the long TO, but the long front bearing retainer on the input shaft of my 91 T5. He said the 93 and earlier T5s are supposed to have a short retainer which allows the longer TO to work like its' supposed to. I googled it and he's right - the longer TO provides more mechanical advantage. So I ordered a short retainer and will have to pull the trans again with hopefully better results. It's a lot better feeling to have a problem with a solution than without. Thanks for all your help - Ken
 
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