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Discussion Topic:
Columbia Overdrive Axle
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Daisy |
11-30-2011 @ 12:26 PM
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Member
Posts: 31
Joined: May 2010
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I was checking to see if the plunger in the vacuum canister Would operate with a little bit of air from my compressor, before Starting assembly of the Columbia. The plunger lifted all the way up when air was shot into top Hose port. When I placed the compressor line onto the other port, Air was leaking out from the gasket, and the plunger would not return Inside the canister base. I took the 4 bolts and (new) gasket out And dissembled the unit. I placed a straight edge across the plane of Base, and there is a slight void between the holes which would not allow a good Seal. It appears that 2 of the 4 planes are slightly warped. Can these be Flattened in a vise? Or tapped down with a hammer?Any suggestions Would be greatly appreciated.
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Stroker |
11-30-2011 @ 2:29 PM
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Senior
Posts: 1460
Joined: Oct 2009
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Well Daisy, I hope your "little bit of air" wasn't under very much pressure, or you, or likely someone before you may have sprung the ears on the case just testing it. First off, the gasketed interface was designed to seal under vacuum, and was not designed to contain pressure, hence the 4-little screws holding it together. Secondly, if you convert the maximum vacuum attainable at sea level, it won't be over about 14 psi. If you applied say a modest 90 psi to the canister that translates to about 1100 pounds of force trying to separate the canister from the shifter assembly. You can probably gently tap the ears back with a body hammer(I wouldn't use a vise however). You may then need to lap the open end dead flat using a piece of plate glass with some wet or dry sandpaper bonded to it, much as we do with carburetor bodies. Most folk don't have a good vacuum source installed in their shop. I used to do vacuum-forming, so I still have a big ol' Gast pump. Compressed air is a good way to destroy items meant to operate on vacuum, such as windshield wiper motors. Your vacuum canister has a cross sectional area of about 12-1/2 square inches. So if you apply a modest 90 psi to the vacuum port, you are applying roughly a 1/2 ton load to those 4-little ears, which were only designed to hold the assembly together, and apply a small shifting force to the yoke. If you used a regulator, and only applied 30 psi, it still amounts to over 300 pounds, which it wasn't designed to handle.
This message was edited by Stroker on 11-30-11 @ 2:48 PM
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Daisy |
11-30-2011 @ 4:31 PM
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Member
Posts: 31
Joined: May 2010
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Thank you. Will try the sandpaper and glass. The air pressure we tested with was minimal. Thank you again your information is invaluable
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Stroker |
12-03-2011 @ 6:13 PM
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Senior
Posts: 1460
Joined: Oct 2009
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Daisy: I "tromped" rather hard regarding applying air to the canister. I would like to hear how you are progressing though. I am planning on re-installing my Columbia, (I still have all the original controls in place), but it's been many decades since I took it out. Thus, I am looking to your experiences as a "refresher course". Please keep us posted. Dan
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supereal |
12-03-2011 @ 7:49 PM
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Senior
Posts: 6819
Joined: Oct 2009
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One of the weak links in the Columbia axle system is the vacuum shift canister. The seal, usually leather, dries out and prevents the shifter from working well, if at all. Having that canister, as well as the soft metal parts of the axle, gone over by an expert is advised.
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Daisy |
12-05-2011 @ 3:38 PM
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Member
Posts: 31
Joined: May 2010
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the columbia or right side is in place. a Question on the left side of the axle; Do you know what the Torque specs for left axle to ring gear bolts, And torque specs for cap bolts to banjo rearend.? Have not found these specs in the manuals.
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Daisy |
12-05-2011 @ 3:40 PM
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Member
Posts: 31
Joined: May 2010
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The brass or soft metal has been replaced. the cannister moves well. what are we looking for? anything before we complete the installation?
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