Second snapped 142 Thru Axle in 6 months

[Ferro]

Thanks JXV. Appreciate the input.

[Ferro]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

[Headshot]

DT QRs and axles as well no doubt are pricey. I was looking at a DT screw up 135 QR and its over R400!

 

One trick i saw mentioned on another website forum - I forget which, was to buy the correct diameter bolt and cut it to the required length and then use a tool to cut the correct thread at the screw in end.

[JXV]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

Yes 1.75 is the thread pitch....corresponding to standard Metric (Coarse) thread for M12 diameter. This is the normal M12 bolt thread.

 

You could buy any M12 x 200 smooth shaft allen-head bolt and get an engineering works to cut it to length and re-thread it for you. A well equipped workshop is likely to have a die set of the correct size or a programmable lathe that can do it .

 

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[Pulse]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

A lot of the stuff on KTMs are non-standard, or rather not the most commonly used standard

[JXV]

A lot of the stuff on KTMs are non-standard, or rather not the most commonly used standard

Metric coarse is the standard for 12x142 TA. A sensible choice for this robust application where the bolt threads into alloy dropouts and could easily be cross threaded or damaged if they were finer. It needs to be able to engage easily. Downside of coarse threads is that they are deeper than fine threads and therefore reduce the shaft diameter under the threaded part.

 

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[Headshot]

you will need a tap and die kit , or at least the die part and these start at R1k 

Ouch! Only good value if you plan on breaking a few more...

[droo]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

 

I'm pretty pure that's the problem right there... that's the same pitch as the Giant one, which Mayhem said also has a problem with coming undone.

 

My guess is that the axle came loose, which then caused shear on the shaft where the hub meets the frame. Snap.

 

The standard one has a finer thread, which means more clamping force per unit torque, so it won't come undone as easily. You'll have to wind that axle up pretty tight for it to survive.

[Ferro]

i wonder if it is also not an inherent weak point right where the thread starts. Maybe the inner core should be slightly thickened around this point.

 

Thanks for the insight so far. Enjoying it very much.

 

Will definitely routinely check that the axle is still tightly engaged.

[Captain Fastbastard Mayhem]

i wonder if it is also not an inherent weak point right where the thread starts. Maybe the inner core should be slightly thickened around this point.

 

Thanks for the insight so far. Enjoying it very much.

 

Will definitely routinely check that the axle is still tightly engaged.

FWIW mine is now MOER tight. And I can put a fair bit of force on it...

 

But then it's also the Giant one, so same TP as yours. .

[BDF]

Just a thought but could the chainstay or triangle be slightly bent. This would mean that there is always pressure on the TA to bend where the thread ends. 

 

If you look at the bike from behind, I suspect that the chain side wheel insert lug will be at an ever so slight angle. i.e. the bottom of the lug will be bent toward the non-drive side just a tiny bit.

 

Just check it out.

[Ferro]

Just a thought but could the chainstay or triangle be slightly bent. This would mean that there is always pressure on the TA to bend where the thread ends. 

 

The first TA (DT Swiss) broke on my first frame. The second one (KCNC) broke on the second but identical frame. So maybe the first frame also damaged the second TA which was built over onto new frame or the KCNC was not a lekker replacement.

 

It does not seem to be a recurring issue with the frame itself as far as google shows.

 

Edit: ...unless both frames were bent.

[BDF]

The first TA (DT Swiss) broke on my first frame. The second one (KCNC) broke on the second but identical frame. So maybe the first frame also damaged the second TA which was built over onto new frame or the KCNC was not a lekker replacement.

 

It does not seem to be a recurring issue with the frame itself as far as google shows.

 

Edit: ...unless both frames were bent.

Cool. Do you fall to the right a lot? (ha ha)

[droo]

Another thought - check that the end caps on your hub are tight. If one of them is loose, the skewer will work loose, causing a shear stress on the axle, causing it to snap.

[Ferro]

Another thought - check that the end caps on your hub are tight. If one of them is loose, the skewer will work loose, causing a shear stress on the axle, causing it to snap.

 

Thanks. i will keep that in mind. I check the TA now before every ride to make sure it isn't loose.