Factory disc brake rotor question

Brakes for your Classic Mopar

  1. 4spdragtop

    4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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    Continuing on the front end of our 69, I have 4 factory rotors I was going to have turned to see if they are ok. Costs $30 per rotor. I dont want to spend $60 on the pr without hubs if they are pooched. Couple questions...the ones without the hubs do they look like the hubs were removed properly? Swedging has been mentioned before.
    Also I have hubs from my front drum brakes, will they work for factory disc?
    Thanks all.

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    Last edited: Feb 2, 2021
  2. 4spdragtop

    4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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    Found a bag of 10 factory (appear to be) wheel studs. They slide right in the rotor that had hub removed. Would a couple tack welds on each stud be good?
    If I can, I will use the hubs from my front drums?

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    • Dana67Dart

      Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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      Since the order is stud, rotor, hub, wheel, nut. I do not see any reason to tack the studs and rotors together.

      Tacking might introduce a failure point as well.
       
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      • Professor Fate

        Professor Fate Push the button, Max...

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        I don't have a definitive answer for you, but I doubt if the drum hubs would work. Are they from 9 or 10 inch drums?
        I assume they look identical to you, since you're asking. Make darn sure all the critical measurements match, then look up the bearing and seal sets for each application and see if they match... you may get lucky, but I'd be skeptical.
        The studs I wouldn't worry about- the rotor gets sandwiched between the head of the stud, and the knurling locks into the hub. It should slide through the rotor.
         
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        • 340sFastback

          340sFastback Well-Known Member

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          Rock Auto is showing new rotors for $17 so you might want to look into new ones (no hubs just the rotors). And no need to weld on the stud. Like others have said once wheel is bolted down it all gets squeezed together.
           
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          • MoparLeo

            MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FABO Gold Member

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            You will need to thoroughly clean, preferably sand blast the assemblies and then get out your dial calipers and start to measure things. Not always best to rely on someone else for your info. The 2 piece were factory swaged for a reason. Not good to just recommend that it will be ok for someone else not to do it. Like you, this is just my opinion.
            There is a reason that the factory changed to a 1 piece rotor just a few years later. Less brake vibration problems and stronger assembly. They are very economical. Also if you are trying to keep it "original" you will need left hand studs on one side which are fairly difficult to find right now.
            Question, are you doing a conversion or does your car have disc brakes right now ? If not you will need much more than a set of rotors.
            DISC-O-TECH: Stop on a dime
             
            Last edited: Feb 2, 2021
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            • 67Dart273

              67Dart273 FABO Gold Member FABO Gold Member

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              Steve do NOT worry about swedging those. As long as the hub and the rotor present a flat surface--and you can remove any burrs with file, etc, just stick the studs in and stack them together. If possible I would TURN THEM ON THE HUB. If they are not tight (swedged) I would assemble them, use washers / whatever and snug them down to the hub with upside-down lug nuts.

              I have a rotor/ drum lathe. Too damn bad you ain't close. By the way you can safely turn those
              (big fat double thick rotors) a LONG ways past the toss dimension if you can get someone to do so.

              I can not answer, though on the mismatched hubs/ rotors working.
               
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              • RustyRatRod

                RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                I've never seen any rotors that were swedged on. All of them I've taken apart only had the splines holding the rotors to the hubs. Once the wheel's on it caint go anywhere, anyway.
                 
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                • 4spdragtop

                  4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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                  I bought a fairly complete factory disc brake setup. Came with pair of spare rotors that have the hub removed. I also found a bag with used KH wheel studs.
                  7/16" fine thread. They appear to match the other studs that are still attached to the other hub/rotor.
                  So I go to drop the stud in the rotor and it slips right in? No press needed?
                  The reason for the question about tack weld on the back was we had to do that to a rear stud on the 67. Spun a stud, so there was no way to get the tire off. 2 man job, 1 to hold stud from spinning and another to get wheel nut off. Make sense? Hope I explained it properly.
                  If I encounter any of those fn LH wheel studs, they will be replaced pronto. I've ordered Timken bearings for them. Timken SET2, and Timken SET6 are the #'s. $11 each, pretty good.
                  Seal is also a Timken, crosses from a National # I got off here #6840S. $17!! each damned seal!
                  Front drums appear to be 10". I wont ever use them. They will go with the car if it sells. I havent done a lot of research but I thought I read the hubs will swap between disc and drum?
                  I'm gonna blast the other empty rotors for a look see.
                  Oh and found another pair of hubs, not sure what from? KH stamped in them.
                  Thanks again

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                  Last edited: Feb 2, 2021
                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  Are you saying there's no press on the new rotors or the old ones? Either way, no there's reallyno need for a press fit there. The rotors center on the hubs, nit the studs, so you're good there. When the wheel is tightened down, you've got a rotor sammich. They ain't goin anywhere. The only real reason Chrysler swedged rotors and drums on was to keep them in place goin down the assembly line. There really was no other reason for it.
                   
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                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                    Also Steve, that COULD be an aftermarket rotor, even though it's rusted up. They've never stopped being available new. AFAIK, new aftermarket replacement rotors have never been swedge fit, but slip fit.
                     
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                    • 4spdragtop

                      4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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                      Everything I got is used Rob, no new stuff. I see now the splines run into the hub, stick out of the rotor a tad. I've read several threads about swedging.
                      Studs slip right into rotor that I sandblasted some. Shoulder I'm pointing at is a nice fit, but no press needed. Now to go into the hubs, I would say I will need a press.
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                    • RustyRatRod

                      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                      Oh yeah. They press into the hubs. I'm banking that's a replacement rotor, because factory rotor stud holes were small enough the splines would press in them as well. I would install the new studs put it all together and let it ride. No need to swedge anything.
                       
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                      • Professor Fate

                        Professor Fate Push the button, Max...

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                        Then all is as it should be.
                         
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                        • hemi71x

                          hemi71x FABO Gold Member FABO Gold Member

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                          This has been hashed out numerous times in the past.
                          DISC hubs, and DRUM hubs are NOT the same, and do not interchange.
                          If they did, Disc hubs would not be as expensive as they are, to purchase, in this day and age.
                           
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                          • CFD244

                            CFD244 These pretzels are making me thirsty. FABO Gold Member

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                            What is the discard and normal thickness on those rotors. My KH look fairly thin, an there is no discard info on them?
                             
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                            • mvh

                              mvh FABO Gold Member FABO Gold Member

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                              Hmmm, I can't believe those are the right studs. Either that or the holes are all egged out. I recently replaced my rotors, and they were a tough pull to get them apart, and an even tougher one to seat them again. They should be a TIGHT fit. People are saying "oh, it doesn't matter when it's all tightened down", but you don't want the studs spinning, or falling out on the road when you go to change a tire.

                              The minimum thickness dimension is stamped into the rim — usually hard to read because of the rust. Don't recall it offhand.

                              You can buy new slotted cross drilled rotors for these, for about $70/pair. Hardly worth monkeying with ancient dubious ones.
                               
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                              • 67Dart273

                                67Dart273 FABO Gold Member FABO Gold Member

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                                I don't know about KH the 73/ later ones I've seen have been marked on the casting. I would not be afraid to turn them another 80 at least. They are nice and thick. The thing to watch for (and you could drill a small 1/8 inspection hole) is the web that connects the rotor faces to the inner hub section. If the tool gets back in there it can thin that out.

                                Also do some measurements to show what the pads would be "worse case" and figure how far the pistons will extend. If they are no where near "popping out" of the bores you are OK

                                Years and YEARS ago I had a Shethead roommate for awhile who had an 80-something Courier. One night he came liming to the house, I saw him "idle up." Turns out he'd worn the pads clear down to metal and the rotor about 1/3 the way through, and one piston and just blown right outta there!!!
                                 
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                                • RustyRatRod

                                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                                  You don't get it. The studs press into the hub. I'm betting that's an aftermarket rotor he has. They are all a slip fit. The way the factory did it, the studs pressed into both the hub and the rotor. It doesn't matter if the rotor isn't a press fit with the stud, because they are pressed into the hub FIRST.
                                   
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                                  • hemi71x

                                    hemi71x FABO Gold Member FABO Gold Member

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                                    .780
                                     
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                                    • RustyRatRod

                                      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                                      Right and none of the new rotors will accept a press fit stud. They are all a slip fit, because the studs press into the hub, then the rotor slips over the whole assembly.
                                       
                                    • 4spdragtop

                                      4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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                                      The loose studs appear to be old original KH. I'll look for new good ones. Hopefully.
                                      I'll haul them to machine shop for skinning.
                                       
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                                      • 4spdragtop

                                        4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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                                        Gonna leave the pair with hubs together and get them turned for sure, hopefully they are good. A pair of rotors bought and shipped is $130- 140 Cdn. Thats buying from Rock Auto or Summit. If I were to buy local it would be more than that. Ones with hubs gotta be worth a $60 gamble. Does anyone recognize what these extra hubs are from? You can see KH on the left one in pic.
                                        Thanks
                                        Steve
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                                      • RustyRatRod

                                        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                                        What bolt pattern are the extra hubs? 4" Wanna sell um?
                                         
                                      • 4spdragtop

                                        4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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                                        Not sure on the size and not ready to sell just yet. They may be drum brake, I dont know.
                                        I'll measure tomorrow
                                         
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