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Air assist clutch

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Anyone know what the service procedure is for properly adjusting an air assist clutch?  It acts like the clutch brake is bad, but its not. I read once before on here, that guys recommend installing a clutch cable and removing the air setup. I’d like to just fix what I have, but if I need to convert it to a cable setup, I can do that as well. What do you guys think? The truck that I am working on is an 08’ cxu 613 with an eaton fuller 18 spd.  Any information will be appreciated. Thank You,

Chris

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Should be an adjustable end on the air cylinder someplace. Its 35 years ago I had the white with air clutch.

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The adjustment for the clutch should be the same as a regular clutch cable type. 1/2" clearance between the clutch brake and throw out bearing. Adjust clutch brake and free travel should come out ok as long as everything is in good shape. 

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Im going to try and look at it sometime this week with the holiday coming up. The clutch has freeplay, and the clutch brake looks like its been replaced with one of the slip on jobs. However the clutch brake doesn’t seem to do its job.  Im currently driving another truck, but I have to get this figured out before I can put someone in that truck.  I’ll get back to you guys once I familiarize myself with it again. 

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Adjust the arm on the side of the trans so the clutch brake Just barely touches the bearing   NOTE if you over adjust this with that Dam Air assist it tends to break the the clutch  brake if it is aluminum!!  it will take out the timing sensor on the flywheel  and you end up with hard starting and a hard to replace sensor  to repair ! 

Just sayin!

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The truck had an automated greasing system on it. Someone has since cut the line to the throwout bearing and has put a standard zerc fitting on it. As far as hard starting, the truck does have an issue, but I assumed it had something to do with the electrical system. As you turn the key, it will crank and almost die out like the batteries are shot, but if you keep the key in the cranking position it will fire. As far as the adjustment on the clutch arm, I assume you loosen the jam nut and turn the square head bolt clockwise to give more clutch brake?  Do i have to loosen the other bolts attached to that arm?  The shaft going into the trans to the clutch release arm has a piece on it with two nuts and a type of a sliding adjustment, kind of like how you would tighten up an alternator. Im not sure if that all has to be loose before adjusting linkage, or just the jam nut and square headed nut?  I know when my buddy and I did the clutch on my peterbilt with an eaton 18spd, we used a piece of paper to get the clutch brake set. Is that how you guys do it?  I was reading on eaton’s website they mentioned using a 0.010 feeler gauge.  Im just killing some time until my assistant’s foot gets here. Thanks

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Also, i see that with the freeplay out of the equation, i should have about a half inch between the throwout bearing and the clutch brake. 

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The truck did also have problems shifting out of first and reverse at a stand still. Im hoping all of this is related to the adjustment of the linkage. The previous owner of the truck had passed away, so Im blind when it comes to the trucks history. Oh well, Im sure we’ll get to the bottom of it. 

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Well, i got the clutch brake working properly, its about the bottom 1/2” inch of the pedal, and i have about an 1-1/2” of freeplay( i don’t like much more than that).  So I guess i did it right. Im going to do a little more reading tonight, and see how she goes. Thanks

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If you used the feeler blade method it should be pretty much right on the money! I also personally  like lots of grease on the clutch brake 

this may seem odd to some however I seen way to many of these ruined by over adjustment grease on the brake hurts nothing and helps other wise you run the risk of taking  out the sensor for the flywheel!

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1 hour ago, fjh said:

If you used the feeler blade method it should be pretty much right on the money! I also personally  like lots of grease on the clutch brake 

this may seem odd to some however I seen way to many of these ruined by over adjustment grease on the brake hurts nothing and helps other wise you run the risk of taking  out the sensor for the flywheel!

Its funny you mention that. On eaton’s website i read last night that the clutch brakes are designed to operate with grease on them, and it does not negatively effect the performance. 

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