The reason they get mangled is due to using the wrong driver. Philips head fasteners are designed to "cam out" once you go past a certain amount of torque. The shoulder angle of a JIS driver is different than a standard Phillips driver. JIS fasteners are not designed to cam out, but using a Philips driver on them will almost always strip them if they are in there real tight.
Not all of us are "ham - fisted characters," some of us have had the unfortunate luck of aquiring a bike with already mangled fasteners from some PO.
The same can also be said about Allen heads. Using a correct bit/driver can nearly eliminate the possibility of stripping the head. If you don't have Allen keys with the octagonal ball-shaped end, I suggest that you invest in some. You multiply the area of contact of the bit/key/driver significantly when using these types of Allen drivers.
Just my $ 0.02
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EDIT : JIS fasteners are quite easy to identify if the head isn't already destroyed. They look just like a Philips head screw, but they will always have a small dot • stamped right next to the cross pattern in the head. Don't use a Philips driver on these!
Last edited by DieselKrampus; 06-28-2019 at 09:36 AM.
I also highly recommend the Vessel Impacta JIS screwdrivers (also avail. on Ebay) - they are one of the best tools you'll ever own. The Vessel impact driver I bought in 1971 for working on my first bike (CL 160) still works great.
Two tips that work for me- try tightening the fastener first- just a tiny bit- before trying to loosen, especially bolts, but be very careful with the smaller diameter ones- and use 6 point wrenches and sockets with little or no wear (new?). No more than an 1/32 turn CW! Also, try using a large drift and hammer to 'reshape' or re-flatten the face of the buggered screw heads to sort of renew the cross head pattern. This seems also to break free the stuck threads. In other words, you're 'impacting' the screw (or bolt) slightly inwards without adding torque. I've been able to use a fair amount of force without doing any damage. And, of course, a good penetrating fluid , given time, can work wonders.
Here in the states we have a great vendor called McMaster-Carr. Amazing source for hard-to-find stuff, not just fasteners.
Another edit- Frequently, none of the threads themselves are seized at all but the head of the fastener (and underlying washer) is corroded and 'welded' to it's mating surface- common with dissimilar metals.
Last edited by Twowheelrich; 06-28-2019 at 12:56 PM. Reason: overlooked typos drive me nuts
1968 CL 175
1991 KLR 250
MSC - www.mscdirect.com, McMaster Carr, www.mcmaster.com, and Fastenal, www.fastenal.com are all excellent sources of fasteners and machine tools that I use for my day job but also have come in handy when trying to find metric screws for motorcycles. TwoWheelRich is right, McMaster is best for that hard to find stuff.
1966 CB450-K0, 1966 CB450-K0 (two project bikes), 1973 CL450-K5 (project), 1965 CA102, 1977 CB400F, 1981 SR500, 1995 Ducati M900, 1993 Seca II, 1953 Condor A580-1, 1967 BSA B44VR (project), 1954 Gilera Saturno Sport & 1953 Gilera Saturno Piuma works bike
Common motor collective sells a whole kit of Allen wrench screws specific for any Honda.
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