12-01-2020, 02:13 AM
A Modern Lip Seal for the 1 1/8” crank A7 Engine
Part two
Machining the seal holder: Aluminum was purchased in the form of a slice of six inch diameter rod. I scribed the outer diameter of the seal holder on it and cut off the excess on the band saw so I wouldn’t have to machine it all off (and also so the blank would fit in my lathe).
5 ALUMINUM BLANK.jpg (Size: 34.02 KB / Downloads: 323)
Since the most important dimension was the one the seal pressed into this was machined first. The dimension for the hole was actually written on the seal which was 2.500” but the actual seal measured .005 larger than that as it is designed to compress and be a tight fit. I opted to make the hole about .002” larger so that I could press the seal in with my fingers rather than using a press or hammer as I didn’t want to distort the holder when installing the seal. The rest of the dimensions were standard turning procedures. The most difficult thing was holding the seal holder which required changing chuck jaws so things had to be checked with a dial test indicator to ensure concentricity. A groove was machined in the portion that locates into the bearing holder to take a small section O-Ring to seal the seal holder against oil seepage. A thin paper gasket could be used between the seal holder flange and the bearing holder but the O-Ring should render that redundant. The four bolt holes were drilled using the bearing holder to locate them by poking the same size drill as the bearing holder hole down each hole to drill through the seal holder flange.
Once installed my calculations show that there should be about 1/16” clearance between the flywheel and the retainer bolts etc.
7 CLEARANCE.JPG (Size: 37.16 KB / Downloads: 323)
I’m hoping this will function as well as the other fly wheel seal
that is sold for the I 5/16” crank.
I have not yet drawn up a mechanical drawing but hope to soon for those wishing to make a seal holder for themselves.
Stephen
