Bolt by front wheel snapped when tightening?

[hypophthalmus]

I was installing the front wheel when one of the two bolts on the fork snapped off while I was tightening it. My torque wrench was set to 30 N-m and worked fine for the axle bolt, but it never clicked. I was adapting from 1/2" to 1/4". Could this have something to do with it? I don't understand why this happened.

[zombie]

I don't understand any of your post. If it never clicked it never could have worked fine.

Most torque wrenches can be calibrated, and should be. I would look into that before trusting it. Snap on dealers usually know the process

[hypophthalmus]

I mean it's working fine except for the two little bolts on the fork.

[zombie]

Those little bolts are rated in INCH lbs, and not FOOT lbs.
That may be where you got lost.

Try this program for conversions. I have used it for years.

http://joshmadison.com/convert-for-windows/

[hypophthalmus]

But... the manual says 29-35 newton meters for them.

[zombie]

You mean the guy that had an apple fall on his head, and invented gravity? William Tell shot the apple off, and told him to sit, and shut it! I also think DaVincii's David was a model of william tell's son pointing, and laughing at Newton.

I don't know what to tell you... You need a 1/4" drive torque wrench for those tiny bolts. A 1/2 inch drive is nowhere near sensitive enough no matter what the ratings on the scale say.Truth be told I don't own a torque wrench. I trust my experience much more than I trust a hunk of steel.

Nuts, and bolts are really not application specific for torque values. They are size specific (with very few exceptions)
I'd just get a 1/4" drive ratchet, and snug the bolts down.

[MaryK]

I use a 3/8" drive torque wrench.  I agree that the 1/2" drive is much too big for almost all motorcycle operations,

[frugalangler]

Truth be told I don't own a torque wrench. I trust my experience much more than I trust a hunk of steel.

If you are not as experienced as zombie, or don't trust your wrist then Harbor Freight sells a decent 1/4" torque wrench (I wouldn't use it if I were a professional wrencher, but for the scooterist it's quite adequate and cost effective). Just never torque to spec the first time, sneak up on it - I do 50%, 75%, THEN a line width below spec (I like a little safety factor).

You'd be surprised how many spark plugs I've changed that were over torqued, I've watched mechanics install them w/ a 1/2" drive ratchet with a good grunt, I know they were over by quite a bit. One of the reasons I've chosen to do most of my own wrenching, if it gets screwed up it's gonna be my fault doing the work, not my fault choosing a lousy 'mechanic' or shop.

[zombie]

Cabbich!

[frugalangler]

Cabbich!

I think you mean "capisce" or "kapish"? (Italian meaning 'Understand')

[zombie]

KayoPectate! (Italian for "thanks")

[hypophthalmus]

Well, I replaced the bolts. This time I used a smaller torque wrench that only goes up to 24 N-m... but as I approached that, it felt like it was going to be to tight. I left it at what the wrench claims is 18 N-m. Much lower than what the manual says (29-35 N-m), but my brain is telling me that if I tighten it much more it's going to snap.

Maybe this was a misprint in the manual? It also gives a standard torque value of 7-11 N-m for 6mm socket head bolts, and I found another site saying 9. Maybe I should actually loosen these...

[hypophthalmus]

Okay, I loosened them and tightening them by feel, and 11 was just barely past there. I'd say the manual is wrong.

[zombie]

Maybe this was a misprint in the manual? It also gives a standard torque value of 7-11 N-m for 6mm socket head bolts, and I found another site saying 9. Maybe I should actually loosen these...

There's your problem brother. It's NOT the head size... It's the THREAD size. You are going 2-3 times the value.
Now we are all happy again.