Oil pump rebuild

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Be careful when lapping. The difference between loose and tight can be just a few swipes on the sandpaper. If you go too far, you're screwed.
 
Be careful when lapping. The difference between loose and tight can be just a few swipes on the sandpaper. If you go too far, you're screwed.
You are not screwed, your next step is to thin the gears, the difficult one is integral to the driven shaft but not insurmountable. Checking often does stop you going too far. I like it a bit tight, I them mount it a lathe and feed it with oil while running it at low revs, this frees the pump off enough.
 
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Thin the gears, maybe with a milling machine? Right...
Check often is right, especially when you get close.
 
Thin the gears, maybe with a milling machine? Right...
Emery cloth works but as its harder material it will take longer to remove the same thickness than off the body and end plates, in a fully equipped workshop it would be done on a surface grinder with magnetic table taking tenth's of a thou off each pass. Milling machine tooling would not be up to the task.
 
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The X ring is size 012 in buna shore 70, you need an 1/2" end mill. The X ring is .070" cross section, its compressed by both the shaft and OD of the slot so the extra 0.020" depth of the 0.090" slot takes the side expansion of the X ring.

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kommando,
If I understand you correctly, you are stating that the 1/2" end mill is used to create a counterbore 0.090" deep. Am I correct?
 
If I understand you correctly, you are stating that the 1/2" end mill is used to create a counterbore 0.090" deep. Am I correct?
Yes, same as AMR, I just use the X ring equivalent to the O ring they use.

Oil pump rebuild
 
Installing an O- or X-ring will give the shafts - especially the driven shaft - less support. The pump is a poor design to start with, and by this mod it gets even poorer. Have you considered that the angular pendulum motion of the driven shaft may increase? It's counteracted by small hydrostatic forces at the feed side, but is this sufficient? How well are the bearing seats of both shafts lubricated? Why are the sealing rings not installed at the scavenge side of the housing instead? I am curious to see a close examination of a pump with the AMR modification and some mileage on it.

-Knut
 
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Installing an O- or X-ring will give the shafts - especially the driven shaft - less support. The pump is a poor design to start with, and by this mod it gets even poorer. Have you considered that the angular pendulum motion of the driven shaft may increase? It's counteracted by small hydrostatic forces at the feed side, but is this sufficient? How well are the bearing seats of both shafts lubricated? Why are the sealing rings not installed at the scavenge side of the housing instead? I am curious to see a close examination of a pump with the AMR modification and some mileage on it.

-Knut
Knut brings up an excellent point. Perhaps part of the issue for those who have wet sumping issues is excessive clearance and/or a rough surface on the bearing surface for the shaft in the oil pump housing. Another possible fix if you have excessive clearance would be to machine the pump body, then fit and ream a bushing to tighten up the shaft to body clearance?
 
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