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
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
spline wear will do that...
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
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
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
Time for Allison.
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
Quote from: bevans6 on October 01, 2016, 09:29:03 AM
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
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.
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
I think I remember that they require a special short version model or something.
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?
Fred did his MCI 5 last year , (aka) Fredward here on the board
Wasn't there a guy up in Northern NV that did it also?
Don Fairchild did Lin's MCI 5
Thanks! I found the Fredward threads, back in 2014. Very interesting. It seems the plate that replaces the flywheel and the SAE 1 to SAE 2 spacer ring are the hard to find items, but the transmission itself is not so hard. The driveshaft seems to end up around a foot long?
Brian
The drop ring is not hard to find they used those on trucks with the 10 speed transmissions the spacer is the tough one
Quote from: bevans6 on October 03, 2016, 09:03:44 AM... The driveshaft seems to end up around a foot long?
Brian
On a Gillig low-floor transit, it's 13" long (splined slider pushed all the way in). so a foot isn't out of the range of possibilities.
What exactly is the spacer? I imagine a ring of aluminum around an inch thick, some specific depth (I recall 15/16" mentioned at one point, I think) and with holes drilled through for all of the many 3/8" bolts that hold the transmission to the rear cover of the engine. Is the flex-plate/flywheel hard to find?
No just find a flex plate with a starter ring gear the 600 series are not on the transmissions torque converter like a 740 but you can change that if you choose too,not worth the trouble IMO
Something worth noting is that it is sort of standard to remove the engine to get the transmission out. However, that is not totally necessary if you want to avoid it (at least with the Allison 647/644. There is a cross member under that transmission that will not allow you to just drop it, but that cross member can be cut which would allow you to drop the transmission. I had the central part of that member cut out and replaced as bolt in. I only did it to be able to remove the pan for service. However, when my 647 needed to be removed for a problem, they were able to remove my bolt-in cross piece and drop that transmission.
I had told Fredward about this, but he said that his 5a did not have the cross member there at all. Apparently, a previous owner had just cut it out completely. Although I would be uncomfortable with doing that, I do not think that he ever noticed any structural issues from the modification.
An automatic transmission will transform your bus to a coach!
I had told Fredward about this, but he said that his 5a did not have the cross member there at all. Apparently, a previous owner had just cut it out completely. Although I would be uncomfortable with doing that, I do not think that he ever noticed any structural issues from the modification.
An automatic transmission will transform your bus to a coach!
[/quote]
I don't think all the 5's had a cross member when I did mine in 88 it had no cross member and not a sign of 1 ever being there either
There were many versions, so it is quite possible that they were not in all of them. What would be confusing then would be the claim that the engine had to come out to get to remove transmission.
Quote from: Lin on October 03, 2016, 05:15:08 PM
There were many versions, so it is quite possible that they were not in all of them. What would be confusing then would be the claim that the engine had to come out to get to remove transmission.
It is easier to roll the engine out to do transmission or clutch work on 5 IMO
When United did my transmission, they estimate if they had to remove that engine was substantially higher. Of course, removing transmissions is just routine for them.
Are these the adaptors and spacers required? http://www.phxgrp.com/single.htm (http://www.phxgrp.com/single.htm)
Does anyone know the depth of the SAE 1 spacer? At this point I plan to fully investigate the do-ability of putting a MT647 in my "coach", make some calls to guys in the HD truck business to get some leads.
Brian
Quote from: bevans6 on October 04, 2016, 04:30:49 AM
Are these the adaptors and spacers required? http://www.phxgrp.com/single.htm (http://www.phxgrp.com/single.htm)
Does anyone know the depth of the SAE 1 spacer? At this point I plan to fully investigate the do-ability of putting a MT647 in my "coach", make some calls to guys in the HD truck business to get some leads.
Brian
Brian, it appears that your two stock choices on the website are
Pt No. Engine Trans Offset
26-00334* SAE 1 - SAE 2 0.0� (in steel)
26-00309 SAE 1 - SAE 2 1.0� (aluminum)
The issue of "offset" hasn't been discussed before and I don't know what to make of the odd characters in their chart. Their website indicates a willingness to do special orders so it would be my guess that if you called and asked, they know exactly what you need and can give you an expected delivery date and cost. I'm also not sure about the choice between steel and aluminum but I'm sure that Clifford can advise.
Quote from: Oonrahnjay on October 04, 2016, 05:23:12 AM
I don't know what to make of the odd characters in their chart.
encryption ?
proprietary ?
pay to see ?
???
Quote from: Oonrahnjay on October 04, 2016, 05:23:12 AMI don't know what to make of the odd characters in their chart.
Quote from: eagle19952 on October 04, 2016, 08:26:03 AM
encryption ?
proprietary ?
pay to see ? ???
I went back and looked at the website - that's the way that the items were listed there, too. I dunno ...
The � thing is just where a character in the original document wasn't recognised or couldn't be converted to ascii. In other contexts it might have been a character (an umlaut or somesuch) from another language that didn't have a direct equivalent, but presumably in this case it was an engineering unit of some sort (I'm guessing - I haven't looked at the document)
Jeremy
(Edit: ASCII is the system by which characters are converted to numbers so that they can be understood in binary)