So I am looking at it seriously. I've found a rebuilt MT-644 a few hours away, no price yet, and the guy said his tech was asking all the right questions for how to make this bolt up actually bolt up. He said they specialize, to an extent, in old stuff and have a lot of adaptors, flex-plate to flywheel, sae to sae and such, on their old cores. So I am feeling good about this so far.
Questions -
What does a rebuilt MT644 cost?
if I have a choice of torque converter, which one do I want and why?
What diameter ring gear and tooth count on the flex-plate?
Is the 8V-71 crank flange an SAE standard of any kind?
I asked if it could have a yoke output rather than flange, this mentioned in Fred's old thread. What specification of yoke would I ask for? If you have a yoke on the output of a transmission do you have bolt on caps for the U-joint, or press fit?
Various points about dropping the front of the engine, raising the rear of the engine. I have almost zero clearance over the engine in my install, since I have a custom turbo blower top. I designed and built the turbo install, so I can do it again, but I would rather not. Can I get the angle and clearance by say dropping the front a quarter inch and raising the rear a quarter inch, rather than just raising the rear?
What do I do about a shifter? Is it a cable deal?
Thanks, Brian
I sold my rebuilt MT643 for roughly $1000 Canuck bux about 4 years ago now. I say "roughly" because I took it as a credit toward work that the shop did on another vehicle. So an actual cash value was probably more like $800.
Give me a shout and I'll send the aftercooler when you get close
For the shifter Brian I would use a Stone Bennett 40 ft of air line and cable run anywhere you want to run it.
I put one in and Love it. Idiot proof.:)
Clifford - Ha! I thought we had forgotten about that whole thing. I haven't forgotten I owe you for shipping charges, so please don't you forget!.. I am starting to pull the engine package out probably tomorrow, so maybe the aftercooler is going to be part of the project!
Any new comments on my list?
Brian
I think it was mentioned in Fred's thread, but just in case-- the 640 shifter is different than the 740 shifter. I learned that by assuming that were the same, so if you are going mechanical make sure you get the right one. Also, the shift lever on the transmission that attaches to the cable is slightly different. I the transmission I bought had the 740 lever on it. We were able to re-drill it though to get it to hit the shift points correctly. If you need it, I could probably give you the measurements when the time comes.
Brian, Yes you want a yoke output to save on length. On mine the caps of the u joint bolt on from the ends. Tom
Lot of people just use a Hurst or Mr.Gasket shiftier for a shift tower on the 600 series
Whats a Stone Bennet shifter run cost wise Aprox for a MT 644 Air type
Dave
Quote from: Dave5Cs on October 05, 2016, 06:23:20 PM
Whats a Stone Bennet shifter run cost wise Aprox for a MT 644 Air type
Dave
New from United $ 2500.00 ???
Just my opinion, but the MT644 is a bit lacking in capacity to put behind a turbo 8V-71. An HT740 would be more appropriate-course probably too long though for an MC-5. Good Luck, TomC
The shop just called and said that while they have a rebuilt 644 on the shelf, they can upgrade it to 647 specs for $500 extra. Apparently the case is the same and they have the internals available. What do you think? Does this sound right?
Brian
The 647 spec would be better for you with the tank engine
Yes the 647 is rated to 950lb/ft torque-very close to what your engine puts out-smart choice. Good Luck, TomC
Link to my driveshaft thread, to keep this all together.
http://www.busconversions.com/bbs/index.php?topic=31148.0 (http://www.busconversions.com/bbs/index.php?topic=31148.0)
Brian
The supplier I am talking to has a off-the-shelf SAE-1 to SAE-2 adaptor ring that has a built in 1" offset spacer. Is that what I am looking for, or would I need an additional spacer ring? I guess I won't be able to tell for sure unless I also have the flex plate and the crankshaft adaptor, then I could expect to be able to measure from the bellhousing flange to the flex plate and know how deep I need to be at.
Clifford or anyone, do you have or know where I might find a flex place with SAE-1 ring gear and the crank flange adaptor to suit?
Brian
Well, an update of sorts. After delays from not being able to get the driveshaft out, a semi-hurricane and around 30 hours of blackout/no power over two days, and me just plain working slow and taking a day or two off, I pulled the engine out this afternoon. I used a pallet truck and built a wooden framework to pick up the rear bellhousing where the engine mounts bolt on, and the front lip of the engine where the oil pan bolts on. Tomorrow I'll take the transmission off and have a look-see at the clutch to see if I can find anything obvious wrong with it. I suspect the friction facings on the discs are what is causing the dragging. I am off to Fredericton, New Brunswick (a four hour drive one-way) to pick up my new MT-647 on Thursday next week. My new flex plate is on order, they are installing a short yoke instead of the flange plate, they found a steel SAE 2 to SAE 1 adaptor, and I'll be able to start measuring and fussing to figure out if I need a spacer and what crank adaptor I'll have to make. After that I can trial fit it so I can measure so they can shorten and rebuild my driveshaft. Then I have to measure for a modulator cable and start to figure out a shifter, get a transmission cooler and filter, and all the stuff that nickle and dimes you to death. Anyone has parts to offer, I am happy to try to make a deal!
Brian
Starting fresh like you are with an automatic transmission, I would look for a Stone Bennett control pad up front to activate electric or pneumatic solenoids at the transmission. A cable shifter is fine if well lubricated, but, at least in my bus, the shift tower is in the way of getting in and out of the seat. It would be better on the left side if you go with a cable system. And I would cool the transmission with its own dedicated cooler, to avoid putting heat into the engine coolant. Although it sounds like you already got that figured out.
Have fun.
JC
JC agree with you as far as it always is in the way on the right or as we say PITA if you know what I mean. :D
Dave5Cs
Has anyone ever adapted the manual shift lever as a shifter? I hate to throw away stuff that's good, and there it is... I was thinking of hooking a push/pull cable up to the shift rod in the engine bay. Probably a stupid idea, but there you go. Initial examination shows no cracks in anything anywhere, my bus has a cross-member which earlier buses did not and there may be other reinforcements. I am worried about transmission clearance over the cross-member though.
Brian
You could probably get a shifter assy from city bus junk yard. Morse makes cables that will outlast your coach and almost friction free. You will need to accurately measure.Oh, and also check with school bus junk yard. They've been using automatics in many of them for some time. Some shifters are on the left of driver.
Would it be possible to get a longer cable and then move the shifter to the other side and have it reach?
Dave5Cs
Brian, the PO used the original lever and rod on my 5A when he put in the 644. ;D
LOL the dash switch for a Stone/Bennet is the way to go I have used the Stone for over 20 years.
Brian I am trying to find you a couple of lock up valves to send in your care package,you are not going to like the 647 just locking up in 3rd and 4th gear it makes the Jake even more useless
my Allison has the shift lever is on the left. i like it.
Probably a good reason not too :)
I have moved a couple to the left side, people with seats that swivel prefer it on the left it cleans the floor area up
I took the transmission off this morning, and strongly suspect spline wear as the reason for the dragging clutch. Visible wear where the discs ride against the spline, the wear area is .015" smaller than the unworn section of spline. Everything else looked reasonably fresh, finger height was good, disc thickness was .420", visible grinding marks on the pressure plate from when it was blanchard ground, and the other friction surfaces looked clean. Just a tiny bit of bluing from heat in a few small sections. I had used grease on the splines, now not sure if that was a bad idea or not.
Brian
i have often suspected metal fatigue/age contributes to splines "off set" and wear.
just a fact of life.
are you still going to go with the allison ?
Yep. My knees are going, so sometimes I can't drive the clutch for very long. Getting an new input shaft for a Spicer is a bit of a long shot. I have another used input shaft but it was outside for a year or so and is a bit corroded.
Brian
Well, even working as slow as I do (I tend to mosey on out around 10:30 am, lunch from 12 - 2 pm, and nap time at 4 pm... ;D ) I pulled the engine and split the tranny off on the weekend. Number one trick, remembered from troubles last time, was to level the bus side to side and front to rear so the engine cradle was as level and plumb as possible so that when I picked up the engine it cleared the rails evenly. Pulled it out with little drama, pulled the transmission off, clutch and flywheel. Looks like input shaft spline wear is the most likely culprit, there is visible wear on the drive side of the splines from the clutch discs. All the rest of the clutch looks almost new, there are still blanchard grind marks on the pressure plate, the other friction surfaces look perfect, and the discs only have .020" wear from new spec. I put new throw-out bearing and pilot bearing last time, so they have less than 10K on them. Anyway, I know how you all like pictures... ;D
If you look closely at the picture of my shop, you can see her looking out of the window on the right. I wanted to give her a window so she wouldn't get bored this winter... :o
Brian
What size is your garage? (Shop)
That one is about 48 by 65 on the main floor, but there are three other rooms. I have another one about 40 by 65 with a 11 ft by 45 foot parking pad and a 16 foot tall door, and the rest is wooden floor, I have it set up as a wood shop and usually the bus parks in there. It's pad is tractionized, not smooth, so the pallet truck doesn't roll as well. And I have a 28 by 32 heated garage. Lots of shop, it used to be a fiberglass fishing boat factory (Nova Scotia is all about the fishing boats). It also has about three acres of park-like grounds, half treed and half mown, no neighbours, and a two century old farm house... :)
nice garages Brian
sure is nice to have more sq feet in garages then in the house ( just do not tell the wife )
dave
Nice, but too cold for this Florida boy. Still nice.
Geez, I'da brought the engine stand down to you, if I knew you were messing with this!!
Another lovely bus upgrade/maintenance adventure documented.
happy coaching!
buswarrior
For posterity and science, 10 hours, 725 Km and $6925 (Canadian bucks) later I have a freshly rebuilt MT 647 in my shop, complete with flex plate, the correct steel adaptor/spacer, a new neutral switch, reverse switch, shift cable kit and yoke output. All that I have to make is the crank adaptor, which is really just a spacer, and get the driveshaft shortened. I have a copy of the official Allison 71 series installation kit diagram, with all dimensions and part numbers, which is a bonus. The flex plate is going to be delivered in a few weeks, it's a brand new order from Allison in the US. I haven't decided what to do for a shifter yet. If I can use the original shift lever I expect I will do so, just to be ornery.
Brian
I know this is boring but I figure two years from now the next guy is going to try to put an automatic in a MC-5 and might just appreciate this detail of info...
Just unpacked everything and did my measuring to see what will fit. It sure helps to have a copy of the official Allison drawing (No. AS-04-200, probably any Allison dealer would have that drawing) that shows exactly how this is supposed to fit together. First things first, do I have the correct SAE 1 to SAE 2 adaptor, and by luck, foresight or skill on the part of the tech who found it in the used pile, I indeed do. It is Allison part number 6881378, it has 12 bolts on both bolt circles (SAE 1 has 24 bolts, they skip half the 7/16" bolts) and critically is offset by 0.886" - 0.906" (range of acceptable offset) to put the SAE 2 flange the correct distance from the bellhousing, so no additional spacer is needed. There are new offset adaptor rings available with a 1" offset that could be made to work.
This means I need to make a steel crank hub adaptor that has a 1.7" pilot hole for the pilot on the transmission torque converter, has a register for the ID of the flex plate center hole, a register for the OD of the crank flange, and a thickness of 0.720". This adaptor will perfectly locate the torque converter with respect to the crankshaft, and make sure the flex plate is also centered on the crank shaft. The flex plate is bolted to the crank hub by the normal crank/flywheel bolts. So far, so good! Next I am going to hang the transmission on the engine and slide it in to measure for the driveshaft.
Another big weather event forecast for this weekend so I may take a few day off to enjoy the probably power outage and blackout...
Brian
Brian, thanks for the clear and complete writeup -- yes, this should be of great help to the next person undertaking this task. But one question, please; I understand "thickness" as applied to a "spacer" but what is "offset" as applied to an "adapter"?? Thanks, BH
Offset is the distance between the SAE-2 flange on the transmission and the face of the SAE-1 flange on the adaptor ring. The adaptor is basically 0.9" thick so it spaces the transmission back away from the engine by that much distance. Other write-ups (Fredwards) have referenced a zero offset adaptor, which is certainly available, and a 1" spacer ring. Clifford has referenced a 15/16" spacer in the same thread. This adaptor is kind of all-in-one made specifically for this job - putting an Allison 644/7 or 654 on a Detroit 71 series engine. The MT-643 has a different torque converter and would need a different adaptor. The point and purpose of the adaptor is two-fold - one is the obvious adapt SAE-2 transmission to SAE-1 bellhousing, but second and very critical is space out the transmission so the torque converter bolts up perfectly to the flex plate.
Brian
So anyone with a MC-5 knows that the engine is set at an angle in the bay. Actually two angles - it's about 15 degrees off the center line of the bus and it's about 5 degrees off level. This lets the driveshaft point up and over the rear axle and at the flange on the drop box. So my engine is setting on it's little dolly square with the wheels and legs of the dolly, so it rolls to and fro aligned with the engine centerline. So when I offered it up to the engine bay rails it starts off perfectly aligned and by the time the engine is in the bay by two feet it's horribly off center. It only takes me four tries before I realize that I have to reposition the engine on the dolly so the dolly legs are aligned with the cradle rails and not the engine. Can you say "doofus"? ;D I'll reposition it tomorrow.
Brian
Quote from: bevans6 on October 21, 2016, 08:17:58 AMOffset is the distance between the SAE-2 flange on the transmission and the face of the SAE-1 flange on the adaptor ring. ...
Brian
Thanks!