June 24, 2018, 02:20:44 PM

Author Topic: Transmission pan access for Allison on MC5a  (Read 1142 times)

Offline Lin

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Transmission pan access for Allison on MC5a
« on: August 13, 2013, 08:41:03 AM »
Although the Allison 647 fit in nicely, there is a cross member under it that makes it impossible to remove the transmission oil pan.  For some time I had planned on cutting out a section of the member and reattaching it with tabs and bolts so it could be removed as needed.  I am having a it done now by a welder I trust.  Of course, as with many things, it is a bit more involved than I had thought.  The section has been removed and is now to be replaced with a 3" x 3/8" piece of angle steel which will bolt to extensions welded to the forward face of the of the area where the radius arms attach.

Anyway, this has made me curious about what others with Allisons in MC5's have done to make that pan removable.  Maybe I should have asked before starting!
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Offline Ed Hackenbruch

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Re: Transmission pan access for Allison on MC5a
« Reply #1 on: August 13, 2013, 03:37:30 PM »
 Lin, looks like mine may have had the same thing done to it when they put in my 644.  Can't really get a good look at it right now.  Don't know if the shop had to remove it when i had them change it over to transynd, looks like there may be a couple of inches between it and the pan, maybe they were able to slide it out of there without unbolting the cross member.
1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA

Offline Lin

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Re: Transmission pan access for Allison on MC5a
« Reply #2 on: August 13, 2013, 04:08:34 PM »
Ed, I had wondered about what you had.  Although it is possible that there are some variations between MC5's, it did seem to me that others would have this problem.  I suppose if someone had a shallower pan than mine, it would be easier to slip out.  I tried to do it with mine but could not.  That, of course, does not mean it could not be done, but I could not see how.  Anyway, if yours has bolts in the cross member, it has been modified since the original is not like that.  I looked at the work they are doing on mine a while ago, and it appears that since he is using a vertical channel to replace the original pipe and horizontal plate, it will end up a good deal forward and give much more access to the pan.  It really looks like that pan will come out relatively easily without unbolting the member.

I had become a bit concerned about the project when I realized that there was some re-engineering involved rather than just being simply remove and replace.  Hence, I was wondering how others had solved this problem.  On the positive side, even though it is much more elaborate than I had planned, the welder/mechanic doing the work is someone that did a lot of work for me before, so I have a lot of confidence in his ability.

One thing I was concerned about was whether cutting the cross member would cause the sides of the bus to separate a bit.  After all, I have no idea what could compromise monocoque integrity.  When I asked him, he said that it did relax about 1/8"!  I guess that's okay since I am still far below the 102" limit.
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Offline TomC

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Re: Transmission pan access for Allison on MC5a
« Reply #3 on: August 13, 2013, 08:21:44 PM »
Not the first bus to do this. My '77 AMGeneral has a removable cross member under the engine oil pan.  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.

Online luvrbus

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Re: Transmission pan access for Allison on MC5a
« Reply #4 on: August 13, 2013, 08:45:24 PM »
Eagles have a removable cross member  4 bolts to remove it
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Offline Lin

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Re: Transmission pan access for Allison on MC5a
« Reply #5 on: August 14, 2013, 09:56:30 AM »
Cool, so my 5a is now an Eagle hybrid.
You don't have to believe everything you think.