3alarmer 

Sorry to have two simultaneous threads going with
requests for mechanical information, but I think this
will be the last for a while.

I have recently purchased a 1978 or so Davidson
Signature frame built up with mostly Campagnolo
parts from that year. The guy who had it (ordered
it custom fit from Davidson's in Seattle) took reasonably
good care of it, but somehow managed over the years
to score the crank axle deeply enough that I don't
think i can just polish it out and proceed with the
same axle, which is one of those strange (to me)
Campy 68-SS-120 +1--+1.5 designations, which
I think refers to additional reach on the axle tapers?

To cut to the chase, this is such a fine frameset
(are you out there listening somewhere Davidson?),
that I have violated a longstanding rule of fix it
on the cheap and popped for a Phil Wood BB
replacement.

The woman I spoke to on the phone there
(who sounded very confident, competent, and
doubtless knows more about BB's than I could ever
hope to) assured me that my '78 crank is a JIS
taper and I ordered accordingly. I know I've got
the right cups, reach, and a good chainline on trial
installation. I'm just looking for a couple more
informed opinions as to whether I've got the correct
taper. I'd like to not trash the crank if possible
and once I've got the thing installed with threadseal
would prefer not to have to remove it.

I am ashamed to admit that I do not know how a
person measures crank taper accurately enough
to distinguish between the various incarnations that
have come up over the years.

Any advice?

Mike Larmer

cyclist2000

Sheldon Brown had a bit to say about JIS and ISO

https://www.sheldonbrown.com/bbtaper.html

See what you think.

Homebrew01

I thought it would be ISO. You could call Phil Wood back and ask a different person.

Grand Bois

He'll get the same answer.

ColonelJLloyd 

Is the spindle in the top of the photos the spindle you removed and are looking to replace? That looks like an ISO spindle to me.

The bottom pictured spindle looks to have JIS taper. Is this the BB you just order from Phil Wood?

Wherein lies your confusion?

JohnDThompson 

ISO and JIS actually use the same taper; JIS is just a little longer so the arm sits a bit further out than it would on an ISO spindle. The rings Phil uses to hold the cartridge in place allow you to alter the chainline to accommodate for such differences. You may need to thread the drive side ring in a thread or so deeper to move the arm closer to the frame if you do run into a chainline problem.

3alarmer 

Thanks to all for the incredibly pertinent
information. I'm pretty sure I got it now.

Mike

Grand Bois

I got the same answer from Phil Wood. Whatever they want to call it, ISO or JIS, I'm sure what they sell you will work. It's a common situation. I'll bet they sold hundreds.