Redrilled Cobra Rotors

GMAN

GMAN

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When I picked up my cobra calipers, I got the rotors thrown in. So I decided to to take them to work and re-drill them. First I had the original wholes welded up, then I grinded them smooth. Instead of lining up the holes from the original rotors, I decided to use the Mill at work to do the job.
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I first had to use an indicator to get everything concentric.
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It's a good thing I did this, because when I tried to eyeball it, by putting the original rotors over the cobra rotors, I was off.
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I drilled mini punch holes after I got all my measurements, and then used the original rotor for reference and they lined up perfectly.
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Now I started to drill the wholes. Once I had all my calculations this part was easy.
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All done. :D
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that's interesting, but all you really need to do is grab a grinder and slot each hole slightly. the positioning is done by the center hole so the accuracy of the hole is negligible.
still cool though.
 
Actually if I had eye balled them I was going to be .10 off, and that would've ultimately sucked. This way I got to use some precision instruments, and the holes are exact.
 
Man-o man way to much work. No need to weld up old holes. You where on a machine with DRO just drive to the holes. Learn bolt hole placement use this calc. http://www.doov.com/cgi-bin/bolthole.cgi Thought you might of picked up some pointers from my write up on this. Edit it looked like you where spotting off punch marks but now looks like center drill holes. Carry on. lol
 
Right on the Mark said:
Man-o man way to much work. No need to weld up old holes. You where on a machine with DRO just drive to the holes. Learn bolt hole placement use this calc. http://www.doov.com/cgi-bin/bolthole.cgi Thought you might of picked up some pointers from my write up on this.
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Not for me. I had a lot of fun doing this. Plus I got to learn the mill. :cool: I didn't want to see 10 holes in the rotor either. :D
 
GMAN said:
Not for me. I had a lot of fun doing this. Plus I got to learn the mill. :cool: I didn't want to see 10 holes in the rotor either. :D
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Did you drive to holes using B.C. #'s? Just kinda want to hear how done to add pointers. I learned from others, I just try to help others learn.
 
You can't see the extra holes once the wheels are on, and you missed a chance to lower the unsprung weight. And I wonder if you're going to have vibrations, since you've probably affected the balance of the rotors.
 
Did you bevel the holes on the backside for the shoulder of the studs or just go big enough so they slip through?
 
A rotary table is easier..... (Especially for us that don't have a DRO on our mill) :)
 
97MarkJA said:
Did you bevel the holes on the backside for the shoulder of the studs or just go big enough so they slip through?
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+2

Also, I'd be worried about warping the rotors by welding on them. Any warping, however slight, will be quite noticeable at high speeds and while braking...
 
When I had a CRX Si back in the late 90's I put some 17" rims with 245/45's on em. I was like I put ABS on the car cause no matter how hard I stomped the brakes I couldn't get anything to lock up :rolleyes:

I put a set of Corvette Rotors on it and just drilled the 4 lug pattern in and left the 5 lug holes there. Just made a hub centric ring to make sure it was centered.

Still have those rims and wish they were 5 lug so I could throw em on the Mark :(
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All of that is done, and they fit perfectly. Incidentally I have a brand be set of drilled and slotted rotors on order. Now I have a program to run on the Okuma to run them now. This is a bit overkill, but it is valuable experience for me. I can't beat it. I get to learn on a lot of different machines.
 
2002WRXSTi said:
When I had a CRX Si back in the late 90's I put some 17" rims with 245/45's on em. I was like I put ABS on the car cause no matter how hard I stomped the brakes I couldn't get anything to lock up :rolleyes:

I put a set of Corvette Rotors on it and just drilled the 4 lug pattern in and left the 5 lug holes there. Just made a hub centric ring to make sure it was centered.
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those are giant tires for a crx. lol. dang. no wonder it needed bigger brakes.
 
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