Stripped my Through Axle Fork Threads

SmooveP

SmooveP

Well-Known Member
Yeah, the fork, not the axle. %$#@!.
It's a Sarma carbon fatbike fork, 135mm hub spacing. I ordered a new one, but it could take awhile as they ship from China or Siberia. In the meantime, I'm looking for a hack that will let me get back on the bike. I've seen other fat TA forks where the axle threads into a nut (vs. the "dropout" like mine), so I'm thinking I could use an axle like that if it's long enough. It would have to protrude through the dropout far enough to put the nut on it. Any shop guys or regular humans have one of these they could sell me? Of the 3 shops I tried, none stock any kind of TA.

In theory, a helicoil could work, but I'm not sure the right size exists. Has anyone done this?

My other more involved hack is to try threading the inside hole of the hollow axle and using a bolt and washer to secure it. Not sure about the wisdom of this approach. Can you tap threads into (presumably) hardened aluminum? Will the existing hole correspond to a standard bolt size? Will I break my face when it fails?
 
extremedave

extremedave

Well-Known Member
Team MTBNJ Halter's
I'm still thinking about the problem (nothing good comes to mind so far) but if anyone makes QR adaptors for the hub you're welcome to borrow my stock Mukluk fork for a while. Long as you like orange, and steel, and straight steerer.

Are the threads like boogered, or flat gone? Pics?
 
extremedave

extremedave

Well-Known Member
Team MTBNJ Halter's
The only decent idea I have is to drill and thread the outside end of the axle and tighten the assembly up from the outside. This could kill you too.
 
extremedave

extremedave

Well-Known Member
Team MTBNJ Halter's
You'll probably need a kit, that tap is pretty good sized unless you can borrow one somewhere.
 
Karate Monkey

Karate Monkey

Well-Known Member
Call a local machine shop, if you have one. Helicoils that big are best done by a shop, anyway, as the bits/taps that size are prohibitively expensive, not to mention the importance of the threads being perpendicular with the dropout face.

A new fork might be cheaper if you're not buddies with the machinist....

I wouldn't try to thread the through-axle for another bolt, they're usually sized to have just enough material to safely tighten.
 
michael.su

michael.su

JORBA Board Member/Chapter Leader
JORBA.ORG
fidodie said:
gotta go helicoil - they make them for spark plugs, so they do size up.

@michael.su, what say you.
@graveyardman67

can you just get the one fork lower?
Click to expand...
Gotta figure out what the thread size and pitch is. If it's really 15mm you may be screwed as that's not a standard size. Don't ask me why, it's a metric thing. They skip some sizes...
I can go check my thru axle thread for diameter but I don't have a pitch gauge at home, I'll have to take it to work and check tomorrow. Unless someone happens to know off hand what the thread is?
Threading from the outside may save it. Again, wondering if the threads are really completely gone or just boogered.
 
RSAmerica

RSAmerica

Well-Known Member
Drill out the fork to a 15mm thru hole and get a 110mm Boost fox Kabolt (or 15 mm high strength Allen bolt) and correct size Nyloc Self locking nut and spacers as need. Torque to 17 NM like the spec on the Fox Kabolt.

http://www.jensonusa.com/!WLIB6Oey9...mpaign=shopping_us&pt_keyword=&gclid=CPK3ys3-

image.jpeg
 
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SmooveP

SmooveP

Well-Known Member
wschruba said:
Call a local machine shop, if you have one. Helicoils that big are best done by a shop, anyway, as the bits/taps that size are prohibitively expensive, not to mention the importance of the threads being perpendicular with the dropout face.

A new fork might be cheaper if you're not buddies with the machinist....

I wouldn't try to thread the through-axle for another bolt, they're usually sized to have just enough material to safely tighten.
Click to expand...
I put a caliper on the threads. Looks like they're 14mm, probably metric fine pitch. The hole in the end of the axle is exactly 7mm and at least 3 inches deep. Recommended drill bit for an 8mm tap is 6.9mm, so pretty close. I may try tapping it for an 8mm bolt. It just needs to tide me over until the new fork gets here.
 
SmooveP

SmooveP

Well-Known Member
jdog said:
Try threading it in from the outside. It may work
Click to expand...
Oh, it threads in, but it's so loose you can almost pull it out.

Blair said:
For the rest of us so we know what not to do, how do you strip a thru axle?
Click to expand...
I don't know. I'm not the ham-fisted type, and it never felt like I was forcing it. I'm new to TA's so it's possible I cranked it down too much. It's a cam-action style, and I treated it like a QR. Too much? The axle looks like it's hardened and anodized after it was threaded, but the dropout looks like soft aluminum. The threads on the axle look perfect. Could be an inferior product, but there are not lots of choices in carbon fatbike forks with 450mm A/C. If I had the choice, I'd get a fork that uses a replaceable nut on the end of the TA. Or go back to QR (but you know, QR sux, sez everyone on the interwebz).

mattybfat said:
http://www.mtbnj.com/forum/threads/carbon-fat-fork-and-i9-front-hub.39342/
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Saw that, briefly considered it. Wrong A/C length. Would probably work, but might jack up front end too much for my liking.

RSAmerica said:
Drill out the fork to a 15mm thru hole and get a 110mm Boost fox Kabolt (or 15 mm high strength Allen bolt) and correct size Nyloc Self locking nut and spacers as need. Torque to 17 NM like the spec on the Fox Kabolt.

http://www.jensonusa.com/!WLIB6Oey9...mpaign=shopping_us&pt_keyword=&gclid=CPK3ys3-

View attachment 34711
Click to expand...
Nice try, but too short. My hub is 135mm.
 
Patrick

Patrick

Overthinking the draft from the basement already
Staff member
i'll take it on as a project when you get the new one, if it is helicoilable :cool:-
wasn't thinking about a rigid when first posted. we know some people that could help.
 
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