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What's reasoning for hub-centric vs lug-centric wheels ?
(I found those terms on a Chevy performance forum... )
I grew up in the fifties when life was simple.
Dad's old '46 Plymouth wheels had a big hole in the center to clear the hub and the tapered lug bolts pulled the wheel into final alignment. Lug-Centric?
My 92 Oldsmobile wheels have a center hole, with five flat spots radially aligned with the lugs. These flats extend maybe 0.020 inside periphery of what would be otherwise a perfectly round hole with clearance for the hub. The flats slide over the hub with a mild friction fit.
I assume those are to center the wheel perhaps more precisely than the lugs would, particularly were the lug nuts tightened unevenly or one left off. Hub-Centric?
Well, that's a nice idea for the factory guy
but after a couple of winters out west in ice & snow country the metal parts rust and those flats grab the hub with a vise- like grip because rust expands
meaning
when you get a flat tire you cannot change it because the wheel won't come off the hub without a sledge hammer.
So it's a terrible idea for the vehicle owner .
Today i took a wire brush to the hubs,treated the rust with phosphoric acid, applied liberal anti-sieze compound (copper Fel-Pro_)
then i took a grinder and removed those flats from the wheel's center hole.
The wheel now slides over the hub with comfortable wobble-room, ~0.030.
Have i violated some fundamental law of Automotive Engineering ?
It struck me that the zero clearance hub fit might be to prevent movement should somebody forget to tighten his lugnuts; thereby postponing when the wheel works its way off.
Thanks,
old jim
(I found those terms on a Chevy performance forum... )
I grew up in the fifties when life was simple.
Dad's old '46 Plymouth wheels had a big hole in the center to clear the hub and the tapered lug bolts pulled the wheel into final alignment. Lug-Centric?
My 92 Oldsmobile wheels have a center hole, with five flat spots radially aligned with the lugs. These flats extend maybe 0.020 inside periphery of what would be otherwise a perfectly round hole with clearance for the hub. The flats slide over the hub with a mild friction fit.
I assume those are to center the wheel perhaps more precisely than the lugs would, particularly were the lug nuts tightened unevenly or one left off. Hub-Centric?
Well, that's a nice idea for the factory guy
but after a couple of winters out west in ice & snow country the metal parts rust and those flats grab the hub with a vise- like grip because rust expands
meaning
when you get a flat tire you cannot change it because the wheel won't come off the hub without a sledge hammer.
So it's a terrible idea for the vehicle owner .
Today i took a wire brush to the hubs,treated the rust with phosphoric acid, applied liberal anti-sieze compound (copper Fel-Pro_)
then i took a grinder and removed those flats from the wheel's center hole.
The wheel now slides over the hub with comfortable wobble-room, ~0.030.
Have i violated some fundamental law of Automotive Engineering ?
It struck me that the zero clearance hub fit might be to prevent movement should somebody forget to tighten his lugnuts; thereby postponing when the wheel works its way off.
Thanks,
old jim