Saturday, June 17, 2017

in which the specification is useless

You won't remember that, on that rainy ride up to Round Valley where I overdid it, that we went through some of the famous Brunswick Shale mud. You certainly won't know, because you weren't there, that it splashed all over, perma-staining a jersey and getting all up in the doings of the crank.

I suspect the mud got up into places it hadn't ought to be in the bottom bracket, and that's why the grinding recently developed in the bottom bracket bearing. No worry; the OEM ones are not too expensive, and they can be delivered in less that a week. AND I still have the original manual with the specs for installation. (Good thing; the manual that came with the new part didn't have torque specs.)

The new one showed up a few days ago, and I set to work putting it in. Torque the BB into the frame at 355-445 in-lbs. (which is 30-36 ft-lbs. in real money; my torque wrench isn't calibrated in inch-lbs, but it's an easy conversion). Keep it on the low side of spec; if it creaks, you can always tighten it later. Slide on the wave washer, and torque up the crank to 337-363 in-lbs (28-30 ft-lbs)...

Wait. That doesn't feel right. That's what the manual says, but the crank binds, and now the dust shell is warped.

Yeah, that edge that's peeking out in the lower center of the photo? You're not supposed to be able to see that.

Sigh. OK, UN-torque it to the point that the spacing around the wave washer looks correct. Hrmph. Wouldn't you know, the crank spins freely now.

Well, it's good enough to get a ride in this weekend... and the replacement is due on Tuesday. THAT one, I'll torque by feel.

Edit June 22, 2017: It turns out that FSA makes two models of crankset with the same name, with different methods of attachment.  None of the equivalency charts I found made the distinction... until one I found a few days ago. Now I know the difference, and I've got the CORRECT part on order. Sheesh. Saved yourselves thirty characters on that line, didn't youse?

1 comment:

  1. Jim if you're going to do more torque in the future invest in a digital one that gives all 3 scales. It will make your life better!