Problem with C4 cams -- uncentered axles


Original Post
AaronMana · · Unknown Hometown · Joined Sep 2015 · Points: 0

I've encountered a problem with several Black Diamond C4 cams, where the two cam axles are not centered on the stem. In the attached photo, you can see that the cam lobes on the left are scrunched up together, while the ones on the right have a lot of wiggle room; there's about an 1/8"-1/4" displacement of the cam axles to the right. The axles are not loose, they both have the same displacement, and looked like this brand new.

Of the twelve C4 cams I've purchased in the past year, four of them have had this problem. The first time I encountered this issue, I sent a photo to the supplier and they very emphatically said that this is defective and should not be climbed on. They could be exaggerating of course (they have liability to worry about), but from an engineering perspective I have to agree; the lengthening of the axles on one side means that those portions of the axle will generate a lot more torque on the stem when loaded. I would assume that BD tests cams whose axles are properly centered, so the performance of a cam with this defect is an unknown element.

Has anybody else noticed this type of defect in C4s or any other type of cam? If it's widespread, it could be symptomatic of a quality-control issue at the BD factory.

Brand new C4 0.5 showing cam axles that are off center.

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,500

It's not a problem, it's part of the design. The cams have play built into the axle length so they don't bind. If you want, you can center them, but it's not necessary.

Further, you should always contact the manufacturer with questions before you accuse them of being negligent in any way. More often than not, they will address it by either explaining the reason for the design such as your question, or conduct an internal investigation if there is a legitimate issue. If they don't know about potential issues, they can't fix them, so always contact them if you have any concerns.

AaronMana · · Unknown Hometown · Joined Sep 2015 · Points: 0
John Wilder wrote:It's not a problem, it's part of the design. The cams have play built into the axle length so they don't bind.
You're right that they have play in them by design, but it is definitely not part of the design to have the cam axles off center. If it were, then all C4s would be like this, and they aren't.

John Wilder wrote:If you want, you can center them, but it's not necessary.
Well, I'm definitely not about to start hammering away at a cam. This is an important piece of safety equipment; if I purchase it new, then I think I'm not being unreasonable if I send back a defective piece rather than try to fix it myself.

John Wilder wrote:Further, you should always contact the manufacturer with questions before you accuse them of being negligent in any way.
I totally agree, I'm not trying to bad-mouth BD. But I DID go through the proper channels to alert BD to this issue. All assembly lines will occasionally spit out a defective widget, but it makes me worried if 1/3 of the items I've received have this problem. The point of my post is to see how wide-spread this issue is, not complain about BD.
Barrett Pauer · · Brevard, NC · Joined Apr 2013 · Points: 225

It's not a defect, it's designed to be able to do that. If it bothers you a lot just smack it on the table and it will re align

Trevor · · Cottonwood Heights, UT · Joined Jul 2006 · Points: 125

about every season since camalots have been available, there has been a thread regarding this non-issue.

here is one of many such examples:
https://www.mountainproject.com/v/bd-c4-broken/107665788#a_107665993

AaronMana · · Unknown Hometown · Joined Sep 2015 · Points: 0
Barrett Pauer wrote:It's not a defect, it's designed to be able to do that. If it bothers you a lot just smack it on the table and it will re align
Sorry I should have been more clear in my long-winded initial post. The problem is not that there is extra wiggle room between the cam lobes. The problem is that the axles are off center; the cam is NOT designed that way. The cam lobes are also NOT designed to be able to slide around through the stem holes (as I mentioned, the axles aren't loose in this cam). The point is that the internal forces on components will be very different for off-centered axles like this, compared to a piece with centered axles, and I doubt that the cams have been tested in this unknown configuration.
Barrett Pauer · · Brevard, NC · Joined Apr 2013 · Points: 225

If you search similar threads you will find this is a non-issue.

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,500

The axles aren't attached to the stem. They slide back and forth, just like the lobes on the axles. They are designed to move inside the stem, just like the lobes on the axle.

It really is part of the design.

JeffMK · · Unknown Hometown · Joined Feb 2011 · Points: 160

I posted about this in the past too. Definitely not an issue.

Previous MP Post

AaronMana · · Unknown Hometown · Joined Sep 2015 · Points: 0
Trevor wrote:about every season since camalots have been available, there has been a thread regarding this non-issue. here is one of many such examples: mountainproject.com/v/bd-c4...
Thanks for the link, Trevor. It's not clear from that post if the that cam had that problem from the beginning, or if it picked it up through use (doesn't look like a new cam, in any case). Anyways, what I'm gathering is that this is a common problem (or "feature" if you like). It could be minor, sure (though I still claim that without a dedicated and controlled test, it's impossible to conclude that it's minor). But it raises the question: from a manufacturing perspective, ensuring centered axles should be easy (other manufacturers seem to have no problem with it), so why are there C4s coming off the assembly line like this?
Eric Fjellanger · · Unknown Hometown · Joined May 2008 · Points: 830

"It could be minor, sure (though I still claim that without a dedicated and controlled test, it's impossible to conclude that it's minor)."

You're trying to talk like a cam engineer, but you aren't one. You don't have the specs for the cam that say how the axles are supposed to align and move. Why don't you contact BD and see what the engineers who designed the cam have to say about your observations?

Mike Mellenthin · · San Francisco, CA · Joined Nov 2014 · Points: 0

C4s are coming off the line like this because this is what brand spanking new totally within spec C4s are supposed to look like.

Sorry man, it's simply not a problem.

Also, your assumption that BD only pull tests centered cams is in all likelihood wrong (seeing as they ship a bunch that are not) but like other people have said, you could always ask them.

Crag Turkey · · Holladay, UT · Joined Jul 2013 · Points: 60

Not a Defect or feature, but integral to the design of the Camalot. It would significantly reduce holding power if the lobes couldn't move on a free floating axle. You can bang any of your cams and see this is the case, and don't worry about hitting it too hard. They test the hell out of those things and I'd be impressed if you were able to even scratch the cam. As others have said, if you asked the manufacture to begin with they would have told you this.

Cortney · · Golden, Colorado · Joined May 2015 · Points: 0

Actual mechanical engineer here.

"the lengthening of the axles on one side means that those portions of the axle will generate a lot more torque on the stem when loaded."

hmm, the stem actually doesn't see torque forces applied to it (unless in some gnarly horizontals, but then that rotational force wouldn't be transferred to the axles anyway. the moment would be about the edge of the horizontal with the lever arm being the length of the stem sticking out). Cams and camming angles are designed to transfer an axial load in tension to create friction against the rock surface. if anything, the axles would see torque but because the lobes are free to move about the center line of the axle, i don't think they really do.

" I would assume that BD tests cams whose axles are properly centered, so the performance of a cam with this defect is an unknown element."

Assumptions in the eng/man world are what get you as an engineer and in turn a company into trouble. I can guarantee due to the liability this company assumes that they have tested these cams in every conceivable orientation.

"Has anybody else noticed this type of defect in C4s or any other type of cam?"

yes, all of my c4s can do that. If you have any of the larger sized C4's (3-6) you can slide the stem back and forth on the axles.

So to answer your question/statement, this is in fact designed into the cams.

Again though, ask BD.

that guy named seb · · Britland · Joined Oct 2015 · Points: 0

Don't have any C4's but i can confirm this even happens with my new wild country cams they don't have as much movement as the black diamond ones appear to have (they are narrower) but it very easy to just apply a little bit of force and shift the stem to one side of the device.

Rob Warden...Space Lizard · · Between Zion, Vegas, LA, an... · Joined Dec 2011 · Points: 0

All of mine do that. Every c4 I have ever used does that. You can read center it with your palm. If you don't like it get single Axle cams with spacers. I will gladly buy what's left of your c4s

Sdm1568 · · Ca · Joined Aug 2012 · Points: 0
AaronMana wrote: This is an important piece of safety equipment; if I purchase it new, then I think I'm not being unreasonable if I send back a defective piece rather than try to fix it myself.
Just send the "Defective" cams to me and I'll properly dispose of them. Mwhahaha!
mstolorena · · Shelby, NC · Joined Sep 2016 · Points: 95

"Of the twelve C4 cams I've purchased in the past year, four of them have had this problem.”

Firmly grasp said 4 cams, press thumbs against lob. Flip. Repeat until centered.

Khoi · · Vancouver, BC · Joined Oct 2009 · Points: 0

As several posters here have already informed you it's not a defect; it is designed to do that.

AaronMana wrote: Well, I'm definitely not about to start hammering away at a cam. This is an important piece of safety equipment; if I purchase it new, then I think I'm not being unreasonable if I send back a defective piece rather than try to fix it myself.
So are nuts. You should see how hard I often have to pound on my nut tool to clean a nut placed by my old climbing mentor!

But more to the point...

Who needs a hammer? You can move all those parts around with your bare fingers. I have done that to my Camalots and many Camalots that are not mine.
Guideline #1: Don't be a jerk.

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