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Tightened clutch = drag in RA axis of GM-8

 

I recently decided to tear down my GM8 for cleaning and re-lubing for the first time and, what I thought was a lubrication issue has turned into what could possibly be another case of shaft misalignment, although I have yet to completely wrap my head around what I am seeing...


On the RA axis, I am getting drag as the clutch is tightened and have found clear witness marks on the RA shaft that confirm what is happening. On the RA shaft, directly adjacent to the outer (lower) bearing race are the noted marks (I have loaded three photos in album labeled photon_trap) where the ID of the bearing or maybe the outer race is coming in contact with the shaft resulting in considerable drag.


I could remove a few thousandths of an inch from the shaft but not fully understanding why this is happening (other than a better design might have provided a shoulder for the bearing ID to ride on like at the other end)

I am very hesitant to do that. I see no gap around any of the bearing block to center section interfaces (will not accept .0015 feeler gauge)


Also, I have been using the "improved" wave washer position between the knob and aluminum spacer and have removed the wave washer completely with the same result. It seems the rotation of the clutch knob is somehow forcing the bearing to one side until it contacts the shaft. I have also noticed minor witness marks on the shoulder on the worm end of the shaft from the bearing/race ID, no where as severe as those pictured - more like wear marks, probably normal.


In searching, I have found others to have similar symptoms but I am not sure my situation is the same --

Any insight is appreciated


Jeff
 

...ok, so I will respond to my own post, maybe for the aid of future generations...
Although I could not see or detect any gapping between the bearing housings and center section as others have noted, I found a couple appropriately sized sockets and a fairly heavy mallet and gave it all I dared. (sort of damaging the surfaces) It seems to have eliminated a lot of what I was experiencing.?
?
?However, curious as I am, I took the RA center housing assy to work and put it on the surface plate to discover that, end to end, there is a .004" difference (call it out? of parallel) across a 2 inch diameter surface. Being less than thrilled at this finding, I dug up an old arbor press, plenty big enough to fit the assembly and sockets so I have a go when I get chance, fingers crossed.

J
 

Jeff,?

You might take another look at the bearing housings.? Get a set of feeler gauges and test the gap.? ?It only took 5 thousandths to wreak havoc on my DEC axis.? 5 thousandths might be tough to gauge with your naked eye.??

Eric
 

Thanks Eric.

I could not get it to take a .0015 feeler gauge anywhere, and I held it up to a bright light - no gap visible FWIW.
I do have .0010 shim stock at work I could try, IDK, that .004 has to come from somewhere!?

Hopefully I will have time to get it on the arbor press tomorrow and see what happens?

Jeff

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