Welding rotor bolt pattern

[tonyorlo]

What's everyone's opinion on welding up a bolt pattern on a rotor and re drilling? I have a new set of Chevy/ford pattern rotors and need them to be Porsche. I have a friend that can drill them out for me. I have no problem welding them up. What do you guys think? Bad idea?

[Ol'fogasaurus]

I've never seen or heard of it being done. I would think that heat warping would be something you would have to consider as well as compatable welding materials.

I seem to remember someone plugging the holes then redrilling them but I think they were either pressed in or screwed in the plugs. That was a long time ago and with the newer materials I am not sure about the welding bit though.

Lee

[aircooledtechguy]

I've never heard of doing this (welding them up). Probably because welding on anything cast is not a fun proposition. It's usually full of inclusions, voids among other impurities that are detrimental to the welding process.

[Marc]

What I've done successfully was to plug the existing holes with sections of lugbolts slightly shorter than the thickness of the rotor/drum (hacksaw a slot in one end so they can be turned in with a screwdriver to the desired depth) and then use a buzz-box welder with high-nickel-content rod (such as "Super Missile Weld") to fill in the ends...grind the outer surface flush, and you have a "blank" rotor that can then be redrilled/spot-faced for press-in studs. This technique might also work if you plan to redrill for screw-in studs or lugbolts...that I've never done.

Most Porsche rims have huge backspace and require the use of spacers to correct the offset; you can buy commercially-made adapters from Ford or Chev PCD to 5x130mm - they're spendy, but not much more so than good bolt-on Porsche spacers - so if your rims are going to need thick spacers anyway, you might consider simply purchasing quality adapters to accomplish both ends.

Classiest/less labor-intensive approach, of course, would to simply buy the 5x130 (or blank) rotors needed to do yours right and hope you can peddle the old ones to defray some of the cost...

[tonyorlo]

That was my original plan, sell the old ones that I bought, but I don't think I'm going to be able to sell them for a decent price. They are new rotors. I've read many people talk about it, but never seen any success stories. The cookie cutters should bolt up with no spacers.

I've stick welded cast a few times with nickle rod, and have had luck doing so, so I'm not too worried about that. My neighbor has a lathe and a mill, so I have that side covered. This route will actually be the cheapest for me. I'm relieved to hear that someone actually did it with success. I will most likely do what you did, but I have press in stud type rotors. I may use a copper back, and make a few passes to fill it in.

[Dale M.]

I would only consider press in studs with this sort of modification....

Dale

[5.0 Chero]

sorry misread post did not see you said dual pattern rotors if they are hats you may be able to get the 5 on 5 Porsche above the ford 5 on 4.5 but it will be close if the rotors are hub-centric you should not have any problems with out plugin them

I have swapped patterns on one piece rotors from 5 on 5 big gm to ford 5 on 4.5 by milling off the press in studs and re-drilling the new pattern for press in studs then fly cutting the back side so the new press in stud head just clears the old stud head this way it helps old in the old stud/plug sorry I do not have any pictures as this was years ago when there were not a lot of options for aftermarket disc brake swaps

[tonyorlo]

Well I bought a set of rotors with the correct pattern. I have a feeling I won't be able to sell the first set I bought, so eventually I'll weld them up and drill them out.

I'm going to drill out my fronts, how did you lay out the pattern when you drilled yours out? I bought a wheel adapter with both patterns and was going to use it to transfer the new pattern.