[email protected] (Dave Williams)
gnttype  19 Feb 1996
- -> Not always needed. Any GOOD crank grinder or speed shop can
  -> grind the rolled fillet radius for you. Beats the big bucks for a new
- A good crank shop will dress their wheel so it's rounded on the sides. That 
  will grind a radius in the area between the journal and the cheek. The more 
  radius, the stronger the intersection is.  Unfortunately, the large radii 
  aren't good for wheel life (crank grinder wheels run from 1-1/2 to 3 feet in 
  diameter, $350-$550 each).  Thrifty shops grind nice squaaaare corners.  
  There's not much you can do for a square crank. 
- The Buick was the first production application I know of for rolled fillets.  
  Buick ground the cranks close to square cornered, then used a hardened steel 
  roller, a pair of back supports, and lots of pressure to actually dent the 
  metal of the journal *down*.  It's the opposite of what a crank grinder will 
  do.  For purposes of strength, it pretty well doesn't matter whether the 
  fillet is an innie or an outie, believe it or leave it. 
- I'm not sure the rolled fillets actually gained Buick anything over a 
  conventional fillet, other than possibly a better price from their crank 
  vendor.  To the best of my knowledge there is no aftermarket source for 
  having the fillets re-rolled. 
- The problem with the rolled fillets is, once you turn the crank, it's just 
  about square shouldered again.  You'd need to go .050 or so under to get a 
  noticeable radius the other way, unless you widened the journal at the same 
  time.  And if you widen the journal, you're looking at aftermarket rods, so 
  it's cheaper just to buy a new crank. 
- A reground rolled-fillet crank will hold up for most purposes, but it will 
  never be as strong as a new one. 

[email protected] (Dave Williams)
gnttype
- Gawd, I love it when I refute my own messages...
- I dug through my shed this morning and found a pair of 2000cc SOHC Ford 
  cranks, circa 1971 or 1972, with rolled fillets.  One was turned 20/20, and 
  the roll was barely visible.  Comparing to the photos in the Buick Power 
  manual, the Buick fillets look narrower and deeper than the ones on the Ford. 
- -> A reground rolled-fillet crank will hold up for most purposes, but it
  -> will never be as strong as a new one.
- I'll qualify this:
        *if* the journal wasn't burned
        *and* you didn't grind substantially through the rolled area
        *then* it'll probably be okay
- I'd also like to interject that the presence of a few "flak grooves" in the 
  journal don't necessarily require regrinding the crank.  They don't affect 
  the load-bearing characteristics of the journal much, assuming the journal 
  is still properly round. 

[email protected] (Dave Williams)
gnttype  21 Feb 1996
- -> There is NO reason tho replace the crank if it needs to be ground.
  -> The rolled fillets will never be touched by a COMPETENT machinist!
- The fillets won't be as deep any more, but you're substantually
  correct.  And .005 to .010 shouldn't affect anything.
- I would venture the problem is not so much the grinding, as *why* the
  crank was ground.  The rolling process prestresses the fillet area,
  making it more resistant to cracking.  If the journal was burned by a
  spun bearing or severe lubrication problems, there's a good chance the
  heat would anneal the entire area, causing the rolled fillets to lose
  their stress.  So the grooves are still there, but they're no longer
  working as intended.
- -> would assume that if your crank has the fillets gone, then the
  -> machinist pulled a fast one on you and switched it with a non-turbo
  -> crank
- That's a good possibility, particularly if they happened to have a
  ground core in stock.  "Parts is parts" to most places.