Why do xzn bolts exist?

[bbob203]

Tracked down the cornwell tool truck getting a proper quality bit and have 4 new xzn bolts on order. seems m7x1.25tx25mm  with a socket or torx head are non attainable..

[CRSMP5]

The problem I find with the triple square is that the torque is applied to the points, which works fine when the fastener is new, but when it is corroded or dirty it doesn't make good contact. The axle bolts are hard to tap in securely with a hammer because of their location. An allen bit applies torque to the flats of the hexagon which I think are less likely to strip, especially if the tool is not perfectly seated in the hole.

ask older air cooled people.. they were allens...


biggest point here.. no dirt.. inside tranny... maybe little oil at bottom for hydro lock effect.. but they do not rust even..

henc my worry on tool.. and telling him that next time you ever see this hit it with a hammer will save time..

[92EcoDiesel Jetta]

From an engineering standpoint, XZN head has 12 points to transmit torque compared to 8 of the torx and 6 of the allen, thus the XZN is less likely to strip. You need a quality driver bit no matter the type of head.

[theman53]

I could get them but the boss would want you to order box quantity. I don't know what that is but I would guess minimum of 100.

[Toby]

From an engineering standpoint, XZN head has 12 points to transmit torque compared to 8 of the torx and 6 of the allen, thus the XZN is less likely to strip. You need a quality driver bit no matter the type of head.

Are you kidding me? 12 tiny points are better than 6 larger ones? Perhaps you might explain why the 12 point crap strips aboutv1/3 of the time with a (Snap-On bit) and I can't remember that last time I stripped an Allen head fastener. This nis the problem with most engineers: They have more faith in calcs than actual performance. If your calcs say yes and life says no, you better refigure your calcs.

[745 turbogreasel]

I've broke more than a dozen head bolts, and only stripped one(from trying to drive it t an angle).
More splines is always stronger.

[8v-of-fury]

Snap-on is nothing to write home about lol. Not anymore anyway.

 

Perhaps you might explain why the 12 point crap strips aboutv1/3 of the time with a (Snap-On bit) and I can't remember that last time I stripped an Allen head fastener.

Well if you stripped the fastener.. likely it was a substandard bolt you were taking out.

[TylerDurden]

This is torx, but XZN has similar properties.

[Toby]

Well if you stripped the fastener.. likely it was a substandard bolt you were taking out.

You are correct there. All of the dozens that I have stripped were substandard factory VW bolts. They are always a cause for concern when you have to take them out when changing a motor or a trans. The Allen head bolts never are. In other words, it is remarkable when I get all 12 of the 12 point axle flange bolts out without problems. Just as remarkable when I have trouble with the Allen head bolts.

[theman53]

The other part of the equation is the bit has less strength behind it than the Hex key does. Also if the grain of the metal in a torx fastener is questionable as Toby has said happens a ton then the points are more easily rounded and easier to strip than a similar socket head cap screw *Allen* as some call them. The triple square and double hex I have found worse yet when you get a sub par batch of metal in them.

[burn_your_money]

Well if you stripped the fastener.. likely it was a substandard bolt you were taking out.

You are correct there. All of the dozens that I have stripped were substandard factory VW bolts. They are always a cause for concern when you have to take them out when changing a motor or a trans. The Allen head bolts never are. In other words, it is remarkable when I get all 12 of the 12 point axle flange bolts out without problems. Just as remarkable when I have trouble with the Allen head bolts.

I find that very interesting, because it is 100% opposite to the issue I have when working on the exact same engines.

[libbydiesel]

I cannot remember a single time that I have ever stripped an xzn bolt in almost 20+ years of working on VWs.  I have, however broken a couple of the heads off.  I was working with a friend removing the bumper cover from his '99 Golf last night and he broke the head off one of the torx.  Stripping allens is not exactly common, but I can certainly recall quite a few.  Almost every allen that I have stripped, I have then removed by pounding in the tightest fitting XZN bit to remove it...  hmmm....  I wonder why that always works.

[92EcoDiesel Jetta]

it is remarkable when I get all 12 of the 12 point axle flange bolts out without problems. Just as remarkable when I have trouble with the Allen head bolts.

 As I remember, you must have each xzn in the right spot at 6 o'clock to get a straight shot with the bit. If the bit is not straight it will strip the bolt. Also those axle flange bolts are in a pretty dirty spot and must be cleaned out first.

[burn_your_money]

Anywhere from 11-1 o'clock works well with long enough extensions. I rarely clean them out, I just hammer the bit in there and hit it with the impact.