Can we talk about "center bore" for a minute?

Tires and Wheels (Mopar Hubcaps Too)

  1. MRGTX

    MRGTX Well-Known Member

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    When laboring over wheel choices, it seems like most of us spend our time hunting down wheels that have the right diameter/width/backspace that we need. We're also often looking for wheels that light enough...and meet some kind of price criteria. This is a tough enough combination to find but then we throw center bore into the mix and it becomes a bit more complex.

    For example, swapping on SN95 (1994-2004) Mustang wheels (and maybe still is) a popular mod. In particular, the 2001-2004 "Bullitt" style wheels are a common and nice looking wheel that folks have used with good results. With the right tires and maybe a spacer, these wheels can be made to work. What's not immediately obvious is that the center bore isn't big enough...and using these wheels requires a trip to a machine shop before they'll fit.

    How often do you guys run into the problem with center bore fitment?
    How do you know if a wheel with too small of a center bore can be safely machined without significantly compromising the structure of the wheel?

    Wheel-Fitment-02.jpg
     
  2. YY1

    YY1 Well-Known Member

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    Been an issue for a loong time.

    "back in the day", most guys knew that even though both were 5 on 4 1/2 pattern, you could use Mopar wheels on a ford but not ford wheels on a Mopar...unless they were Magnum 500 style or similar, which had no center bore.
     
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    • TX9 340 Plymouth

      TX9 340 Plymouth Member

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      I ran into the opposite issue with a set of aftermarket wheels. I put a set of American Racing Torq Thrusts on my B body. The wheels have a very large center bore, probably larger than any vehicle has. I needed to get a set of hub centric rings. I’m certainly not an expert but I think this is generally the case with aftermarket wheels today.


      Another thing to watch out for is wheel stud length when swapping to a set of aluminum wheels. The centers of the Torq Thrust is much thicker than the OE steel wheels. Make sure there’s enough thread engagement with the lug nuts.


      (1).JPG (2).JPG (3).JPG (4).JPG (5).JPG GorillaCatalog2016_Page_43.jpg
       
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      • toolmanmike

        toolmanmike FABO Staff Staff Member FABO Gold Member

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        Thanks for that information. I have a pair of Wheel Vintiques Rallys on the rear of my Swinger. The center hole is bigger than the axle. Just the lug nuts keeping things centered. Those rings are the answer to that problem. I never knew they were available. Thanks again.
         
      • Kern Dog

        Kern Dog Well-Known Member

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        Mopar Action magazine tech guru Rick Ehrenberg is a HUGE proponent of proper hubcentric wheels. He has an engineering background and is often driven by sound theory.
        I can appreciate that, but....
        Even the factory has shipped out vehicles with NON huncentric wheels, the Magnum/Road wheels are one example. TRUCKS, specifically 4 wheel drives are another. I hear time and time again how the lug nuts are designed for clamping force, not to be confused with "shear" but what is heavier than a long bed 4wd? Every 75-79 4wd Dodge truck had front hubs with a large castle nut and NO hub ring to support a wheel center. I own one. The rears have the ring cast/forged into the rear axle flange though.
        Back to cars:
        I have used both types and have had no problems with wheel shimmy or failure.
         
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        • YY1

          YY1 Well-Known Member

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          Agree.

          It's not really a "problem".

          Either it's centered, or it's not. Doesn't matter how.
           
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          • 72bluNblu

            72bluNblu FABO Gold Member FABO Gold Member

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            Rick Ehrenberg has foisted absolute garbage info on the Mopar community on several occasions, while giving the appearance of having sound theory that he can't (and hasn't even tried) to back up. His radically incorrect position on the FMJ spindles is one of these, he was just flat out wrong about the suspension geometry back when he wrote that "Disk-O-Tech" article and has never bothered to actually check his claims with actual testing. Other magazines have provided data to show the FMJ spindles are not only perfectly acceptable, but an improvement in some situations. Real engineers back up their claims with data, not hot air. He even had an easy opportunity to retract some of his erroneous claims when he did his latest rear disk brake article in the resurrected Mopar Action, but instead he patted himself on the back for writing such an awesome article. How many people missed out on factory disk brake upgrades because they passed up a perfectly useable FMJ disk set up because of his BS?

            Ehrenberg's approach that the factory engineers were always right is outdated and frequently puts him at odds with actual data. The technology has changed dramatically, and a lot of what the factory engineers did then (and do now) was for cost saving, not because it was the best possible solution. He's also fully wrong about green bearings. While I myself prefer tapered bearings, the fear mongering he's done with his platform is inaccurate and terribly misguided.

            Lug centric wheels have been around for decades, and plenty of cars and trucks come straight from the factory like that. If you tighten your 60° lug nuts in a star pattern like you're supposed to the wheel will end up centered. Hub centric makes things a little easier, but a plastic hub centric ring probably isn't nearly as great as a lot of people think they are. Both my Challenger and my Duster are lug centric, I've never had an issue with either.

            And yes, the center bore is frequently an issue. Most aftermarket wheels have a 73.1mm bore, which is big enough for stock Mopar Hubs. The problem is that a lot of aftermarket wheels also have smaller wheel caps, so, from the mounting surface of the wheel to the wheel cap they taper down. The Mopar hubs are quite deep, so, depending on the wheel they may actually have to protrude through to the front face. That's how my Enkei RPF1's were. They have a 73.1mm bore on the back, which was fine, but they tapered down to a 65mm cap and the hub wouldn't go through. So I had them bored to 73.1mm all the way through and used a different set of caps. Whether or not there's enough material there depends a little on the design of the rim, but with a 5x4.5" pattern most rims should have enough meat to go out to 73.1mm.
             
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            • Kern Dog

              Kern Dog Well-Known Member

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              I am not ready to throw R/E under the bus. I do agree that he has a couple of viewpoints that have not been 100% or that are more of an opinion but he has made sense far more than not.
              I agree that the A/B and FMJ knuckles are both fine for street use. I am also fine with the aforementioned lug-centric wheel topic. I do agree completely in his opinion against the crop of front end suspension and steering kits that eliminate torsion bars. His theories make total sense in that regard.
              He knows electrical stuff in regards to ignition, factory gauges, fuel senders, factory based drive train and brake systems, etc.
              I have aftermarket wheels on my 70 Charger. The hubs do clear but the wheel center caps are a bit tight, as Blue/blu wrote. Good point made there.
               
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              • jos51700

                jos51700 Well-Known Member

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                Having seen wheels that aren't hub centric run off center, I'll only run them with centering rings.

                And as an engineer, I've yet to see Rick write anything that wasn't sound engineering (not that I've read every word he's written).
                Whether you like or agree with his statements or not, his engineering ethics and principle are solid.
                 
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                • pishta

                  pishta I know I'm right....

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                  Chevy on a 5 on 4! Custom turned brass ring......had to be hub-centric as the Centerlines use a shoulder lug nut.

                  i14535-jpg.jpg
                   
                • Tooljunkie

                  Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                  My 80 power wagon has run oversize center wheels for 20 years. For 5 years or more it had a winch,plow,hydraulic pump and a 4D battery ahead of the front wheels. Never had problems. Other than shocks and leaf springs giving up.
                   
                • Trojmn

                  Trojmn Well-Known Member

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                  I had the end of the hub turned down. I figured, at the time, it was easier to do (brake lathe) at the time and only have to do the fronts and i felt better about it than ruining the wheels. Rears on on a 1" bolt on spacer.
                   
                • 72bluNblu

                  72bluNblu FABO Gold Member FABO Gold Member

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                  Never said he was wrong about everything, I actually agree wholeheartedly with him about coilover conversions, disk brake dust shields, and quite a few suspension related topics. I love the Green Brick build, it was one of the inspirations for my Duster build. But on several occasions he has taken up positions and made claims that are just flat out false. For someone with his knowledge and resources, not to mention his influence, that's totally unacceptable in my opinion.

                  It's not about liking his statements, I don't care whether he agrees with me or not about anything. The fact of the matter is that he has, on more than one occasion, made claims that were just flat out factually false. The claims he made about ball joint overangling and the suspension geometry changes that would be induced by using FMJ spindles on an A-body were false when he made them. Had he bothered to actually check the suspension geometry changes instead of just going full Chicken Little, he would have known this. Mopar Muscle did in fact plot out the suspension geometry changes between the 73-76 A and 73+ B/R/FMJ spindles later and in doing so proved Ehrenberg's claims to be false- he was just speculating with no data to prove anything either way. And yet, even years after being proven wrong, Ehrenberg has continued to push his unsupported claims. In the rear disk brake upgrade he wrote up in the August 2018 Mopar Action he took a total victory lap on that old article, completely glossing over the non-existent spindle issue he made such a big deal out of and still not adding the FMJ spindles to the list of spindle swaps that work.

                  Same for green bearings. I understand that the first generation of green bearings had some issues, and that people did in fact have problems with them. But he still straight up harasses anyone that suggests using the new green bearings for anything other than drag racing, which is nonsense. You can check his sensationalist claims in the "tech topics" in the Mopar Action from Aug. 2018, he tells a guy to have his "friend" sign a waiver if he's going to use them. It's ridiculous. Again, I myself prefer the original tapered bearing set ups. But the new (and by new I mean now decades old) green bearing design has been proven to hold up just fine in street applications. And the simple fact of the matter is that there are millions of cars on the road that used sealed ball bearing style wheel bearings, because they're used on a great many new cars at both the front hubs and rear axle.

                  I get that people make mistakes and no one is perfect, I screw things up all the time. And I don't care if we share the same opinions or not. But if he keeps pushing bad information out there after it's been shown to be bad then you can't say his ethics and principles are solid. Those aren't matters of opinion, the facts show him to be wrong in those cases. I don't care if he still recommends the tapered bearings, I do too. But to imply the green bearings are unsafe is BS. Same with the FMJ spindles. If he prefers to keep the stock geometry and recommends that, great, there's justification for that. But that doesn't mean the FMJ spindles are unsafe and can't be used, or that they aren't in fact better for some applications- because they are.

                  Good point, those shouldered lug nut style wheels should be hubcentric. Never liked those things, but that's just my opinion.

                  I also like the metal hub centric ring. If you think you need one, that's what should be used. The plastic ones can absolutely be deformed, they're not going to stop the wheel from being off center. It would take doing something silly, like fully torquing the lugs out of sequence, but if you did that a plastic ring wouldn't stop the rim from moving off center. And if you do torque the 60° conical lugs as they're supposed to be, the wheel should be centered.
                   
                • pishta

                  pishta I know I'm right....

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                  I liked the fact that I could be a hair off on the hand drill (!) and still get a good torque on the drum. No conical acorns allowed on these shoulder lug nut rims.

                  Question: Why do the Mopar rear axles have that strange inset?
                   
                • 67Dart273

                  67Dart273 Well-Known Member

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                  I've used a similar argument. Many of the vehicles I've owned had "different" wheels and certainly were not "hub centric"
                   
                • MRGTX

                  MRGTX Well-Known Member

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                  So an engineering degree actually hurts a person's credibility on engineering-related matters?
                   
                  Last edited: Feb 14, 2019
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                  • YY1

                    YY1 Well-Known Member

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                    Antone who has worked as or with an engineer should agree that engineers can be "funny".

                    I am not a degreed engineer, but I've held several positions titled "engineer".

                    Most engineers I know get stuck on what is absolutely 100% technically correct, and can and do loose sight of what simply works.

                    This certainly explains the wild goose chase of finding the holy grail combination of cherry picked parts necessary to assemble the "Disc o tech" brake conversion.

                    How many cars have been and are on the road for decades with "lug centric" wheels?

                    Hundreds of thousands?
                     
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                    • Mike69cuda

                      Mike69cuda 64 is the new 17 FABO Gold Member

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                      Having spent my whole career as an engineer, I can tell you it is no different than any other profession. I work in a place with hundreds of other engineers. Many are some of the smartest people I have ever met. Some are nitwits that cant hook up jumper cables on their own. Just about like any other job. Just because you have an education in a field doesn’t mean you are good at it.
                       
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                      • 69_340_GTS

                        69_340_GTS Well-Known Member

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                        That's what happens when you go putting mongrel (Ford) parts on a Mopar!
                         
                      • MRGTX

                        MRGTX Well-Known Member

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                        LOL... in fairness, The wheels are probably made by Enkei or some other supplier, no exclusive to Furd.
                         
                      • mopowers

                        mopowers Well-Known Member

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                        I work with many other scientists and engineers as well and couldn't agree with this post more.
                         
                      • 69_340_GTS

                        69_340_GTS Well-Known Member

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                        Yes, however they are made to Ford's specs. Ford center holes have almost always been too small to fit on a Mopar. I recall trying to put '65 Galaxie 500 wheels on my '70 Road Runner back around 45 years ago. Nope... center bores were too small. Got some 3/8" thick wheel spacers, and then they went on... "lug-centric", never had a problem with them.
                         
                      • 66fs

                        66fs Well-Known Member

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                        Hub centric is easy. Closest tolerance to true center. Lug centric, not so much. 5 holes in the wheel concentric to what center? And 5 holes in the hub concentric to what center? However you are running a rubber air filled tire. How fast are you going to run and how well is everything balanced?
                         
                      • 69_340_GTS

                        69_340_GTS Well-Known Member

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                        Well, one would hope that the bolt holes and center hole were produced to some kind of tight tolerance during manufacturing, on both the axles and on the wheels. Actually, I've seen how modern aluminum wheels are machined. The lathe that turns them has the lug hole drilling tool in it. While the wheel is still chucked in the turning jaws/fixture, the lug holes are put in. True-position of those lug holes is probably so close you don't even need to bother measuring it. You have probably a dozen or so things that will add up to a huge tolerance stack if you want to start worrying about them. Like, what's the runout of those wheel bearings? Or the tire runout or roundness?
                         
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                        • MRGTX

                          MRGTX Well-Known Member

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                          Good points.
                          However, I think we could make a case that modern Ford wheels are closer to classic Mopar wheels than modern Mopar wheels are. At least the Ford wheels have the 5x4.5 bolt pattern. :)

                          Speaking of hubcentric wheels, I know some guys get away with running modern 5x114.5 Charger/Challenger wheels because they're "close enough." This is where tolerances might start to stack up in a bad way.
                           
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