Interesting comment Roy!
Nachi came out with plastic cages early in the piece. They have now gone back to metal on their premium (Quest) bearings.
Plastic is ok in light duty applications. Any HD or severe applications the bearing manufacturers recommend metal cages. Given the heat of the brakes, I would & have always used metal cage bearings. In industrial applications involving heat & high loads metal cages are used.
For a 60x vac pump, a metal cage would be better. The contaminants in engine oil are also a concern to plastic.
Its a bit like using Viton O rings & seals, not mandatory, but they last much longer.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

When I was younger I worked for an old timer who taught me to raise the wheel with the tire on and gradually tighten it while spinning and stop when there is no more "rock" which you can feel quite easily by grabbing the tire at the top and bottom and "rocking" it.

Shawn, you might be interested to know that this old timer had a mine in the Dragoon mountains, if I recall Sunsites was not too far down the old 666 before they re-named it. Myself I have been working out on Ratliff Farms a bit lately, halfway between Cochise and Sunsites on Cochise Stronghold road.

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Brian
87 300Dturbo 180K #14 head still running R-12 SOLD 12/2017
02 F350 Powerstroke 180K
05 Chevy Express 1 ton w/Royal Utility box 120K
08 Infiniti FX-35 40K
15 Golf Sportwagen TDI 35K
10 Sprinter 3500 chassis with a Class A Winnebago on it. 56K