An oft quoted statement is that modern cars have tighter tolerances, machining is much more precise now, etc, etc. As some of the regulars know, I I disagree with that premise. Ultra-precision might be had on a Bugatti Veyron but on a garden variety Ford Taurus, Toyota Camry, or Chevy Malibu, etc that will not happen.
Using crankshaft oil clearances and end play for an example due to that being the starting point for an engine assembly I will state that if one tore down any modern car that had never been started one would find that bearing oil clearances, end play, etc will vary a bit; all within spec, but varying.
I’m in the middle of an engine building SNAFU that I WILL resolve and this involves main bearings from a very reputable manufacturer. I might add that this manufacturer is gargantuan, worldwide, and they actually produce many types of engine parts, gaskets, suspension components, and so on for many different car manufacturers along with the aftermarket.
So here’s my question for those who think modern cars and manufacturing are extremely precise and this is in regards to main bearings although the principle carries over to every other part on the car.
What would you consider the maximum deviation, variance, or tolerance (hundred thousandths, ten thousandths, thousandths, etc) to be when comparing main bearing shells?
Just some food for thought and yes, I’ve omitted the details behind the current SNAFU for the time being. Anyway, I’m just curious about opinons on a +/- deviation.
and will weigh in later.