TC 88 Oil Pump
Road Master
Joined: Mar 2012
Posts: 1,030
Likes: 988
From: Ohio
My understanding about the dots is that HD added the dot to oil pump gyrotors that have thinner gyrotors to make room for the wave washer and spacer for the updated TC 88 pump. Facing them outward towards the cam plate is how they should be from the factory. They do not align the inner gyrotor to the outer. When disassembling you want to keep them as they were when they came out. I spray them down with brake clean, blow with air until clean and dry. Then I mark the two rotors with a paint marker making a dot so I can assemble them as they were before taking them one by one to inspect. When placing them back together, I use a small scraper to slide the paint dot off. Then oil and assemble to the pump body with the two rotors as they were when removed.
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6th Gear
Joined: May 2026
Posts: 11
Likes: 1
I didnt keep track of the rotors when I took them apart, I think one might have stayed together. I took photos as I was taking it apart, I can try and match what was there. How critical is it that they go in exactly as they came out?
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,922
Likes: 8,027
From: poway
They Gerotors are not timed. The dot simply indicates that the 2 parts are are assembled the same way, you don't get the inner reversed from the outer. You can check which way they came out by looking at the marks on the outer gerotor and the inner part of the pump for scavenge and camplate for outer.
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