AndreyT

I like these DTSwiss QR skewers with re-positionable handle. However, as I just found out, it is quite easy to strip the thread in the external nut by overtightening the handle. The axle is steel, while the nut is apparently aluminum, meaning that the nut's thread gets stripped, while the axle thread remains OK. Naturally, I'd expect DT Swiss to sell replacement nuts for these skewers, but I can't seem to be able to find them anywhere. Does anyone by any chance know what aftermarket skewer nuts might fit the threads on the basic steel-axle DTSwiss QR skewers?

wsteve464

If you can't find a new part you may be able to put a stainless steel helicoil insert in the original nut if it is a standard thread, kind of a pain but doable.

HillRider

All of the several brands of skewers I'm familiar with are threaded M5x0.8 so the nut from nearly any other skewer should work as a replacement.

mpetry912 

I think the part the OP is talking about is threaded differently than a typical skewer end piece. You might try buying another one off ebay, however if this is an easy part to strip the one you buy may also be compromised.

Finding an open stock part to replace your stripped one may not be possible.

Mark Petry
Bainbridge Island, WA USA

AndreyT

I expected it to be that way too. However, the nut from my original skewer (for Specialized TriCross) definitely refuses to screw onto DT Swiss thread

AndreyT

Interesting. Careful comparison and some measurements actually show that both my original skewer and DT Swiss one do indeed have M5x0.8 threads, exactly as you said. However, the reason the old nut does not want to go onto the DT Swiss skewer is that DT Swiss thread seems to be too "shallow". The groove in the thread is not as deep as it is on my old skewer. Strange.

I took a M5x0.8 die and just chased the thread on the DT Swiss skewer. It did some cutting, but no cross-threading of any kind. Now my DT Swiss skewer is compatible with third-party M5x0.8 nuts.

Is this a known property of DT Swiss skewers? Or just a bad specimen?

HillRider

I expect your particular skewer was poorly machined and perhaps that is why the original nut stripped. You rethreading should make it work properly.

WizardOfBoz

I'm guessing bad specimen. As you know, modern fastener threads are almost universally rolled, not cut. This gives strong threads, faster and for less cost. But just as threading dies and single-point threading tools (that are used on lathes) wear, so do the roller dies used to roll thread. So I suspect that old DT let the die wear down, or had the rolling machine out of spec. So your thread "root diameter" was too big.

This shouldn't be a problem, as you have a SS skewer and an aluminum nut, so the nut is the weak point.

Nice fix.

AndreyT

In this case, I believe, they made it weaker than it could have been. My rear spacing is 135mm. The skewer in question is sold as 135mm skewer. However, on my bicycle the skewer rod proves to be a bit too short: the threaded end of the skewer uses only about 10mm of the nut thread. The total "depth" of the nut thread is about 15mm. Considering how soft-ish that nut is, failure to engage 1/3 of the available thread is a major contributing factor to such problems





At the same time, the front 100mm skewer is a perfect fit: when tightened down the end of the skewer rod is even with the outer end of the nut, i.e the whole available thread is used.

HillRider

That 10 mm of thread engagement is plenty. The skewer is threaded in two diameters of the male threads and there is no benefit to more. Your bike appears to have thick dropouts and that's probably why the skewer doesn't thread in full depth.

WizardOfBoz

Hillrider, you've stated a rule of thumb that some may not know of. That is, for male and female threaded parts of like materials, more than one diameter of thread engagement doesn't give you appreciably more strength. It's why nuts are only about 1 diameter deep (that is, a nut for an M10 bolt is about 10mm thick). This rule works for most standard applications.

But it's for like materials. Here, the skewer is likely steel or stainless steel and the "nut" is aluminum alloy. Even on the old Campy skewers, where both skewer and nut were steel, the skewer protruded a mm or so IIRC. I'm wondering if a longer skewer QR might allow the OP to avoid stripping another nut? Is there a rule-of-thumb for unlike materials?

HillRider

I don't think it will matter. The OP's original problem wasn't from inadequate thread engagement, it was from poorly machined threads on the skewer that damaged the nut. Now that he's corrected it a new nut, whatever its material, should work fine with the thread engagement he has.

WizardOfBoz

Yeah, good point, that sounds right. Agree - the OP should be fine.

Given that material came off when the OP chased the threads with a die, I'm guessing a work die/improper force setting on the thread roller. So the skewer thread root had too large a diameter and the crest had too small a diameter. The skewer root then crushed the ID thread crests on the nut. After that, there was no material on either the nut or skewer to hold the nut on. It's still not optimal - the rolling process is supposed to raise up the crest (OD of skewer threads) and depress the root (the "minimum diameter"). Chasing the threads with a die only cuts the roots - doesn't raise the crest. So the chased threads are really only partial diameter. But it probably will work.

You'd expect better from DT, for what they charge. This is threading 101. No QC, apparently. Could have come loose when the OP graunched down on the pedals to accelerate or climb.

Mad Honk 

AndreT ,
How much of the measurement shown is the plastic cap on the actual metal ? If you have 10mm of insertion of your 5mm skewer, it should hold just fine.
JMHO, Smiles, MH