Screw extraction method

[Ryland3210]

Even using heat and shock, I managed to bugger up one of the screws on the rear wheel housing without budging it.

 

I didn't have an impact screw driver handy, nor an easy way to make a slot in the head. Besides, I worried about removing material near the diameter of the thread. These screws are only M6's.

 

Instead, I used a Dremel tool with a small diameter cylindrical burr (like an end mill) to machine the head into a hexagon. Then I ground the chamfers off the end of a cheap Taiwanese 9 mm socket so it would get as much engagement with the hex as possible. Finally, I hammered the socket onto the screw and had no trouble ratcheting it off. This procedure took about 20 minutes.

 

The trick is to get the angles of the hexagon right, and end up with a standard socket size. I guess I was pretty lucky that my 9mm socket ended up being a press fit. Then again, both the screw and socket weren't the hardest steel in the world. Here's a picture of the screw and socket:

 

[richard100t]

I had trouble with one of those screws & I think I dremeled two sides on it. Then instead of the socket I used vise grips. I forget where this other crap soft bolt was but I ended up using the dremel to take the head off the bolt & once the piece was free I just grabbed the remaining thread with pliers & viola.

Theres lots of soft steel bolts around the clip ons (just a warning )

[Ryland3210]

I had trouble with one of those screws & I think I dremeled two sides on it. Then instead of the socket I used vise grips. I forget where this other crap soft bolt was but I ended up using the dremel to take the head off the bolt & once the piece was free I just grabbed the remaining thread with pliers & viola.

Theres lots of soft steel bolts around the clip ons (just a warning )

 

I had considered the visegrips alternative, but on my bike, the steel stamping this screw holds down is very thin. Had the head been taken off, there would have been no more than about 0.040" left. The screw was so tight (having been Loctited), I had no confidence I would be able to get the screw out that way. Dremeling flats for the visegrips would have been more likely to succeed, but in this situation, the steel stamping has a feature that would have prevented my visegrips from rotating the full 360 degrees. I knew from taking out the other five, that there would be a battle all the way out. Hence the decision to go with the hexagon/socket combination.

 

I had a similar challenge taking the rotor off the hub (I switched from the 5.5 inch wheel to the 4.5"). Five screws came out, but the sixth started to deform as I attempted to loosen it with the metric key. No room to machine flats in this case where the screw heads are countersunk. With soft screws, I'm concerned that an impact driver might destroy the screws. In this case, I ground down a 1/4" Allen key to an interference fit with the screw's socket and hammered it in. That worked fine. As Greg suggested elsewhere, I used copper based anti-seize on the threads to prevent galvanic corrosion of the aluminum and Schnorr lockwashers. These are actually called springs by Schnorr. They are hard stainless steel Belleville washers with serrations.

[macguzzi]

another way is to find the nearest torx size hammer in and remove, these screws would be ok if they hadnt made them from cheese

[Ryland3210]

another way is to find the nearest torx size hammer in and remove, these screws would be ok if they hadnt made them from cheese

 

Tried that. Either to big or too small for the M6's. Might have worked on the rotor screws, but I didn't try that method.

[Ryland3210]

Anything is possible with touchy hex-key cap screws, but the downward driving force of the manual (hammer) driven impact driver usually preserves the head enough to keep a good bite. A well-fitting (Snap-On) socket is imperative also. I bought a good impact driver after owning several used/neglected Japanese bikes (mainly the Yamaha) laden with stripped, cheap Phillips head screws. It removed them every time.

 

I use a thin coating of good old fashioned wheel bearing grease for steel fasteners and Permatex Anti-Seize for alloy stuff. The grease stays around pretty well.

 

A spring washer to me has always been a split, opened flat washer, but what I call a star washer is not cut, and has serrations. The star washers I typically see on the smaller hex-key screws.

 

When used on Phillips head screws, the downward force of a manual (hammer driven) impact driver is a vital factor. Another method I have used with success on both Phillips and slot head screws is either leaning on the screw driver while turning it by the handle (or shaft if it's square) with pliers or a wrench. An old fashioned drilling brace is even better. I don't see that the downward force helps in the case of a socket head, and does not provide for any "feel" as to whether the head is rotating or the key or socket is stripping before too much damage is done.

 

I first saw the serrated lockwashers on imported German equipment I was adding computer controlled metal injection systems to in the 80's. The Schnorr washers add the Belleville spring advantage to the serrations.