Clutch dragging, not fully disengaging, when hot.

[bevans6]

1980 MC-5C, 8V-71 with the four speed Spicer.  Clutch has started dragging progressively worse when hot.  It does it when just plain hot - not overheating from abuse, but hot from the engine having been running for a few hours, and this is obviously when maneuvering through a town and into a camp site, makes it hard to get parked.  Clutch is the twin disc dry clutch, everything was inspected and looked fine when I installed with engine a round 10K km ago, along with new throw-out bearing, pilot bearing, rebuilt clutch cover (all new springs, reset finger heights, etc).  Clutch free play is adjusted per the book, linkage all seems fine, and oddly (or perhaps not oddly) the bite point where the clutch engages does not change at all, and it engages very nicely with the bite point about 3/4 of the way up the pedal movement (not near the floor at all).  It just doesn't fully disengage when hot.  Any ideas?

Brian

[luvrbus]

It's either your release fingers have came out of adjustment,pilot frozen to the shaft  or the spline has to much wear would be my guess

[eagle19952]

spline wear will do that...

[Tony LEE]

Gearbox is so free running that since there is no clutch brake to stop it, it just keeps spinning forever so either slip it into gear as you come to a halt or put up with the embarrassment of graunching it into gear each time when you are sitting at lights and your leg is too tired to hold the clutch down for a long time

[bevans6]

Well, I guess I will be pulling the engine this winter, oh well.  I just don't get the "works fine when cold, drags when hot" symptom.  It is definitely worse than the gears spinning, it gets hard to pull out of gear, and once it stalled the engine with the clutch fully down.  I think it has to do with the plates - maybe sticking on the input shaft splines, maybe something with the friction material.  I had a clutch in something else that transferred friction material onto the steel plates, and it would drag and not disengage properly.  How much do clutch discs cost, and do you replace them or have them rebuilt?  Is there a technical name for the type of clutch and flywheel setup that I have that I should use if I am calling clutch/transmission shops for work or parts?

Brian

[luvrbus]

I am sure you know that setup the disc are marked for the front and rear ,I recall from the MCI 5 last year the spiral on the front disc was with the engine rotation and the rear disc was the opposite.Check your center plate if the lugs are real worn you may need another center plate.I know they are friggn expensive for a 15" clutch        

[TomC]

Time for Allison.

[bevans6]

My health is taking some steps that make the Allison more of an option, but we'll see.  First step is take it out and look at it.  My manual has all of the critical dimensions, but if the splines on the input shaft are boogered, that will be an bit of an issue...

Brian

[luvrbus]

My health is taking some steps that make the Allison more of an option, but we'll see.  First step is take it out and look at it.  My manual has all of the critical dimensions, but if the splines on the input shaft are boogered, that will be an bit of an issue...

Brian

Luke sells a spline saver for those transmission at 1st I was a little leery of trying one but Luke convinced me to try it and they work pretty darn good and are not real expensive either   

[chessie4905]

Since you have to pull the engine to repair clutch, it would be a good time to go ahead and go to an automatic. The expense of the clutch parts may help offset the changeover costs, plus the coach will be easier to sell down the road when the time comes, as most potential buyers don't even know what a manual trans is let alone drive one. You may take a 2 to 3 mpg penalty depending on trans model that works. To me, the auto is worth it. Previously I drove a 4104 and know the difference.

[luvrbus]

Going to a automatic on a MCI 5 with a 8v71 is a very costly adventure lol it would cheaper for him to buy a 6V92 TA with a 740 Allison if he wants a automatic   

[chessie4905]

I think I remember that they require a special short version model or something.

[bevans6]

Since we're talking automatics, I recall that someone put an Allison 640 in an MC-5 a couple of years ago, and wrote about it extensively.  Does anyone recall who or can link me to that thread?

[luvrbus]

Fred did his MCI 5 last year , (aka) Fredward here on the board

[B_K]

Wasn't there a guy up in Northern NV that did it also?