what to use when welding brake discs

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My father is building some sort of contraption and needs to put disc brakes on it for some reason. To keep it cheap, he's using discs he has laying around but they aren't the right stud pattern. Anyway, he want's me to weld up the holes so he can put new ones in and open up the centre. I was going to preheat and post heat and use weldall rods (E312-17). I just wanted to see what everyone else thought would work.
Reply:I would think that welding would be a bad idea, if only for the fact that you'd probably warp the discs like crazy.  Not to mention any stress induced may crack them before installation, or worse, when he needs to stop.
Reply:I'd try tigging it with 308L stainless filler. And turn the rotor afterwards because it'll probably warp.Welding/Fab Pics: www.UtahWeld.com
Reply:Disc brakes are sooo cheap. Can't he just measure and find one that will work?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Just redrill and not worry about filing, Or go to a brake shop or repair shop and see if they have some in the scrap iron bin,Last edited by Farmerboy; 12-01-2013 at 08:58 PM.
Reply:Doesn't matter what you weld it with, it will just make it impossible to machine. Just drill the new holes and press the studs in.
Reply:Baffle him with your skills and tell him no......research what he needs and get it.  If it is some contraption that does not go on the road you can play around I guess, but even a new disc can be pretty cheap as mentioned above.
Reply:I agree with these guys.  If its not a high speed and/or heavy contraption then play around with it.  But if its critical that the contraption stops as an automobile or the like, then just purchase a new or a used one from a junk yard that can work with what you need it to.seabee78
Reply:It's certainly not going to be running fast. From what I can gather, the stud pattern is hard to come by. I told him it would likely warp or crack but he would like to see if it would work before he goes out and spends $200 on rotors.
Reply:+1 on redrill in fresh metal and not worry about filling the old holes.If you look at some of the "multi-fit" vehicle rims, they have many hole patterns drilled in them.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:If some of the new holes will overlap the original holes just tap threads in the old holes and screw a plug into them and then redrill for the new holes.  I have used pipe threads to do this as the taper will make for a tight fit.
Reply:Fab an adaptor plate out of steel, with 1 patteren on 1 side and the other on the other.Swanny
Reply:I'll tell you what, If you accurately measure the diameter of the center hole (the big one) using dial calipers, and tell me what the desired hole pattern is,I'll send you a .PDF file of a CAD drawing that you can print off, center on the big hole and tape down, then carefully center punch your bolt holes and drill. No machining required and as long as it's not some high speed application it'll work fine. If you want to try this, PM me the dimensions.Welding/Fab Pics: www.UtahWeld.com
Reply:Looks like this one could use a few beads of 6011 ... and a quick inspection of the pads – I think they might be getting thin!
Reply:How about not weld it and just clock the disc a few degrees and drill the new bolt pattern? Doesn't matter if there are a few other bolt holes in the disc hat.
Reply:It's been done now. We were going to rotate the holes but there were other holes in the way to put bolts in to pop the disc off with. Looks like it welded up ok and there doesn't appear to be any major warping. Dad going to take it into his work and cut the centre boar out and spot mark the holes to be drilled. Thanks for the help guys.