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Author Topic: mci driveshaft angle Help  (Read 991 times)
rayshound
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« on: December 17, 2006, 08:32:20 PM »

I would like to know if anyone knows for sure if the driveshaft will lay in the "U" in the middle of the tag axle? I have installed a S-60 with a HT-748 transmission which is basically a electric HT-740 in size, same demensions. I kept the same driveshaft & distance and the engine is mounted on rails just like the 8v-71. The big difference is I had a industrial machine shop that works on suspensions on big rigs take my old banjo housing (rearend housing) and cut the punkin flange off and weld a flange for a meritor punkin (late model rockwell) 2.69 ratio. It was all machined and line bored etc and is perfect. The problem comes in that the punkin (meritor) was the back rearend out of a 18 wheeler. It is correct weight rating etc but the propeller shaft is off center since it was the back rearend of the truck. So now if I line my transmission/engine to the rearend propeller shaft it is off center of the tag axle (U) spot. I have the suspension set at 3 1/2" from frame bumper to axle pedistil stop just as mci requires. I have plenty of space and upper to lower travel of drive shaft is same as when built. I don't know if travel of rear end will ever try to drop the driveshaft into the (U) spot on tag. If it does I'm in big trouble. Any suggestions? For the driveshaft  to go all the way into the "U" spot the height would have to go really high past the length of the air bags.... correct?Huh   Thanks Ray
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John E. Smith
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« Reply #1 on: December 17, 2006, 08:51:17 PM »

Let me make sure I understand your configuration... you took the back pumpkin, which (when still on the truck) is on the top side.  In installing it as a "roll-over" unit in your MCI, it is now on the bottom side -- right?  If that is the case, I wouldn't take bets on it not hitting the tag's drop-center anytime the drive tires drop into a dip or depression.  If you cross a moderately deep culvert or ditch, you run the risk of the drive shaft "bottoming out" on the tag axle's drop center -- if I am envisioning your configuration right.

What you could do, since there is more than enough room ABOVE the tag's center section (open air all the way to the underside of the floor), is have the center 18-inches or so cut out and turned over so that the tag is above the drive shaft.  Make sure that the shop puts sleeves inside the tube before welding it back in place.

Since the MCI engine cradle design is so easy to pull (I pulled the engine out of an MC-9 in 3 hours a few weeks ago), this would be a "one day" solution, and would cure any worries about the drive shaft having enough clearance.

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John E. Smith
rayshound
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« Reply #2 on: December 17, 2006, 09:06:41 PM »

John;
   Almost correct. In the truck the first rearend big punkin with more than 1 speed. second rearend driven out of the back of first rearend so the second rearend pinion is off center. . The second punkin was low in the truck. When "rolled over" the pinion (yoke) is now high. When looking at the s-60 rotate clockwise and the wheels go foward, thank goodness. Ray
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John E. Smith
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« Reply #3 on: December 17, 2006, 09:40:34 PM »

OK, I had it backwards... heck, you're in good shape, then!  The tag is a drop-center, so you should have all kinds of room for the driveshaft to move.  You might want to modify the fiber panel that seals the engine/ transmission compartment (comes up from the tag to the bottom of the floor) with a longer slot so the driveshaft has plenty of room for up/ down motion -- but that is the only possible problem I can see.
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John E. Smith
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« Reply #4 on: December 17, 2006, 09:46:58 PM »

BTW, Ray, this is the same configuration my Thomas has.  It uses a regular rear end, but they rolled it over to eliminate the need for a reverse pinion.  Will make it alot easier when I go to replace it (it has a 6.17 ratio right now -- 57 mph tops!) for better cruising.

I plan to use a different Eaton 23k rear end and just flip it end-over-end, then point the yoke to the rear -- if I can find one with the same size axle housing, I won't even need to re-locate brake chambers!  I want to change it out for a 3.55 ratio -- good for about 80 mph while keeping some measure of grade-ability.
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John E. Smith
rayshound
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« Reply #5 on: December 17, 2006, 10:39:28 PM »

Thanks again John, With the 2.69 ratio rearend I 'm hoping to have both good start ability and top end. Lots of torque and hp. 12.7L with 470hp. The machine shop did a really nice job. They usually do repairs like replacing bent axle tubes etc, when I asked them if they could put in a later model punkin in my old housing they said sure no problem how much money do you have? Actually I bought the complete rearend out of a 2001 I believe it was a Volvo. It had speed sensors, unimount hubs and all metric. The machine shop cut the punkin front mounting flange and welded onto my old housing. They got me two metric splined axles and used my old hubs, bearings, brakes etc. They had to fill in and retap the axle flange mounting bolts as the mci axle had 10 mounting bolts and the new metric meritor had 8. I have right at 2K invested in buying the truck rearend and having the machine work done. They delivered it back to me assembled and ready to go. I disasembled it to inspect. The axles pulled out easy and assembly rotates freely. A lot of work but a far cry less than a B500 allison. Ray
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