SoreFeet

Why are these cranks so highly colectable if the machine work is spotty like this...Am I overly exaggerating? Is this typical of most cranks?

https://img253.imageshack.us/my.php?image=0001434qm2.jpg

CV-6 

From the angle and lighting of your picture, I cannot tell. I see normal machining marks on the arm near the spider. I see what MAY be a crack, but I cannot see it clearly. It is not unusual for them to crack at the spider, but the problem can be alleviated with judicious use of a file, if the crack has not progressed too far. I have also heard of them cracking at the pedal threads. Retake a picture at a lower angle using natural light. No flash.

Rabid Koala

+1

Here is a picture of one that definitely had a crack:

Grand Bois

Define "spotty machine work". Are you referring to the fact that the back of the spider isn't polished?

AEO

That's what I've heard of those era of campy cranks. They fixed them eventually, but people still love the design, despite the flaws.

vosyer

It appears yours did not get regular maintence - I always inspect the spiders when I buy them because of the known issue on cracking and many of the ones I have gotten have had small cracks which I have filed away. Plus I regularly inspect them and most do not have an issue again. That being said my cracks are never as bad as the ones in the pictures - I would never let them get that bad or buy ones with that size of crack.

Deanster04

The cranks look pretty "beat up" by all standards. That might have been the period when stress cracks formed a little more easily. Casting and machining. That is one of the issues of aluminum. If caught early then an judicious use of a file will help. Good luck.

buddyp

The sharp edge in that area is what mechanical engineers refer to as a "stress raiser", IOW poor design. If the crank isn't already cracked, or maybe only a tiny bit, you can save them by filing off the sharp edge as the others mentioned. The NDS has the same stress raiser but it doesn't seem to be a problem, I suppose because its less heavily loaded.

As far NR cranks being poorly made, remember anything made of aluminum that is cyclicly loaded has a finite life and the newest NR cranks are 20 years old now. From an aesthetic perpspective I think the NR/SR crank is about the nicest looking design ever and they are light too. Maybe just a wee bit underdesigned

Charles Wahl

Schoolmarm comments:
The photo above posted by Rabid Koala is not of the OP's crank spider; it's from an earlier discussion of this topic - so opinions on its condition or maintenance are not germane. Also, it's properly "stress riser" not "raiser."

RK1963

Rumors of this type of problem led me to go with Shimano 600s

Trsnrtr

I owned three NR cranks in the '80s and all developed cracks similar to the red background pic.

piwonka

yeah.
i've had a set of 151bcd cranks that were just starting to get the cracks. i traded them for some of the same cranks but different length, worse cracks. i got the dremel and files out to take care of them.
i have another set of the nr/sr road cranks and they got the same thing. so i'm gonna file and smooth that area again. gonna keep my eye on that area now.
just seems like something you gotta deal with i guess.

i hate for them to end up like this.

redtires

+1 on pretty much everyone who used the word "file" in any part of their post. I've filed many of those cranks and never had a problem once it was done. I've also done many a brevet on them once filed.

melville

And to get to the nitty gritty technical stuff--I've used a 5/32 round file, known around my house as a 'chainsaw sharpening' file. I've rescued slightly cracked cranks with it, and done it preventatively on some NOS 151 track cranks.

For those of you who deal in the Far Eastern copies of Campy stuff, yes, they copied that thin little web between the crankarm and the spider where all the trouble starts on some of them. Check your Suginos, SRs, etc. to avoid surprises.

Lew Decker

Well...Now what??? My daughter has a very nice Bertoni Specialissima - full SR Campy. The other day I saw cracks in the crank arm near the spider much like RabidKoala's earlier pic. Mine are not so bad, but they are big enough to be easily seen with 63-year-old eyes. I've already started looking for a replacement on eBay, but are the cracks serious enough to force my daughter to park the bike?

Going back to Rabid's previous pic - would it be possible to file those cracks away, or is that crank set too far gone? I really didn't want to part with the original crankset on my daughter's bike, but...

Old Fat Guy

File or Dremel the cracks away, then buff. If you are really worried, use some machinist die to see if the crack is still there.

At least that's what I've gleaned from the numerous threads I've read on the subject.

Lew Decker

Does anyone have a pic of a crank/spider that has been filed? I'd like to see the results before I crank up the right-angle grinder...

Rabid Koala

Here is a quick and dirty picture taken this evening in very poor lighting. This may not be the crank that was shown in my earlier picture, but it was filed (with a Dremel) along with all of my other Campy cranks:

piwonka

file until the cracks are gone then sand/buff the sharp edge to smoothness. you don't want a sharp edge because that is a stress riser.

norskagent

what is the verdict on my NR cranks?


close up of area of concern:

lotek 

that looks more like a gouge or scrape than a crack to my eye.
Also, I thought the cracks only occurred at the crank arm/spider junction not
on the spider itself.

marty

piwonka

yeah, that just looks like a gouge. it is highly unlikely a crack would form at that area also.

norskagent

thanks, that is very good to hear. The rest of the cranks appear fine.

poprad

No one has mentioned that a good machine shop can weld aluminum and fix cracks completely before filing.

stronglight

I'm not seeing any cracks in your photo. Perhaps a picture in natural outside lighting would help...

I hope you've adjusted the front derailleur where the cage was hitting the inside of that crankarm.