Rear Gear Set FINISHES & Quality

Engine, Trans & Driveline

  1. Moparfeind

    Moparfeind FBBO Gold Member FBBO Gold Member

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    I believe I have seen some different finishes and or coatings on rear diff gear sets. Wondering how longevity and gear noise is affected either way. Wouldn’t any coating come off in the first 500 miles? Are all gear sets on the market basically the same or are the cheap ones more brittle and prone to cracking failure etc? Are there certain standards they have to meet?
     
  2. cryplydog

    cryplydog FBBO Gold Member FBBO Gold Member

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    Micro Blue Bearings, Finishes, and Lubes have some way cool stuff.
     
  3. zyzzyx

    zyzzyx FBBO Gold Member FBBO Gold Member

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    The quality starts with the material that's being used, then the heat treatment and then the finish grinding.
    Material that's too soft is not good, nor is material that is too hard. It used to be easy to figure out what was
    good and what was junk. Now I think the best way is by word-of-mouth. The guys who race can tell you easily.
    Take A.R.P. for example. They put everything out there, they tell you what material they use in a certain app-
    lication, they tell you what the tensile strength is, and they tell you the best way to use the product. Can't beat
    that! Brand names used to mean a lot. ot so much anymore.
     
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    • Wietse

      Wietse Well-Known Member

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      Any coatings on the drive gears will obviously wear off in no-time.
      The rest of the gear faces will not wear off, but how much does the gearing need protection against corrosion while being partially submerged in lube oil?
      Only when you have water ingress these coatings will protect against any corrosion but that would normally not happen.
      Longevity and gear noise will not be affected by these coatings at all.
      Gear noise is normally a direct indication of wrong setup, although some brands are known to have some noise even when installed properly.

      I don't know what is the difference between the brands, like DoctorDiff is selling a gear set for $185,- which looks cheap compared to i.e. Yukon gear.
      Then again, assuming that DoctorDiff is selling good quality as i read a lot of positive story's about their merchandise. (It says on their website their gear manufacturer is Motive Performance (Richmond)
      Guess some folks might chime in and give some advice on good manufacturers for getting some good gears.

      The material quality standard is normally set by hardness. (i.e. according the Brinell scale)
      The gearing material is very hard, which causes it to be resistant against wear although making it more brittle. (the material will barely bend, it will crack straight away)
       
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      • Moparfeind

        Moparfeind FBBO Gold Member FBBO Gold Member

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        Looks like everyone is using 8620 steel. The best warranty I found is 2 years from Revolution Gear. Yukon is one year.

        Wondering if I should have posted this in the racers hangout area...??? .... lets see if we will get some opinions from those that are good at breaking them lol
         
      • Wietse

        Wietse Well-Known Member

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        Yup, if those mad scientists with their 800+hp engines manage not shattering them they will be good for use for us "moderate" drivers :D
        Seriously, i wonder if it would be worth spending $300 on a Yukon or Richmond gear compared to a $185 gear set from say doctordiff?
        I assume you are looking for street driven car, guess for track it might become a different choice.
         
      • Moparfeind

        Moparfeind FBBO Gold Member FBBO Gold Member

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        Was thinking the same...street application low HP maybe any gear set I bet would be fine??
         
      • Wietse

        Wietse Well-Known Member

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        I just read a few reviews of motive gears on Summit where some users state the gears are noisy.
        Maybe that is they difference in price?
        Guess a "rough" surface on the gears will increase noise while, at higher costs, could be machined smooth and cause less noise?
         
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        • Moparfeind

          Moparfeind FBBO Gold Member FBBO Gold Member

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          All about the lapping and final finishing?
           
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          • Mopar Hunter

            Mopar Hunter Well-Known Member

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            Strange has excellent gears, they have free shipping going on now.
             
          • Cranky

            Cranky Moderator Staff Member FBBO Gold Member

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            Street gears are harder than race gears for a good reason. Hard gears will break under high loads as in racing. Street gears need to last so they are harder. It's been awhile since setting up new gears but years ago I heard Richmond gears were prone to making noise. Thing is, I've never experienced that nor have I experienced gears making noise from Dr. Diff. Heck, had a 90 Dakota from the factory with a rear end that was a bit noisy but you had to listen for it. Stayed that way for 100k+ miles until the oldest kid totaled it. Imo, it's mainly due to setup. That said, I won't do a rear end using bearings made in China!!!!!! Plain and simple.
             
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            • AR67GTX

              AR67GTX Well-Known Member

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              If differential noise is a concern do not buy Richmond gears. I've gone through 2 sets and 4 set ups by a drive train mechanic and I checked all his backlash and gear pattern myself and although slightly diminished it still howls in a particular mode. They may be good for competition or something but wouldn't wish them on my worst enemy for a street driver.
               
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              • Wietse

                Wietse Well-Known Member

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                What would be a good brand for street applications?
                I want to change my rear 4.10 to a 3.55 in the near future.
                 
              • bee71

                bee71 Well-Known Member

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                For me I had a set from Yukon that were too noisy. I switched to a set from Nitro,they are much quieter. Running 3:23's.
                 
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                • Wietse

                  Wietse Well-Known Member

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                  Thx, they ship international as well so i can get a set from them!
                   
                • Cranky

                  Cranky Moderator Staff Member FBBO Gold Member

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                  Never had that problem with Richmond gears but I don't go by pattern. Instead, I have an old setup tool that checks the pinion depth with a dial indicator. After the using it for the first several times in the 80's and seemingly not getting a good looking pattern and then testing the new set up in my own car, I quit checking the pattern and trusted the tool from then on.
                   
                • Wietse

                  Wietse Well-Known Member

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                  Where are you looking for with that tool Cranky?
                  Gear back lash? That is normally the biggest killer for gear drives when it becomes excessive.
                  Also using a heavier oil could help reduce the gear noise.
                   
                • AR67GTX

                  AR67GTX Well-Known Member

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                  I think my mechanic had that same tool also - don't remember all the details but I remember him saying it was a Mopar shop tool he picked somewhere years ago. Seems like it takes some of the trial and error out of coming up with the right shims but I have a 489 with a crush sleeve so I may be kind of fuzzy on some of the details.
                   
                • Cranky

                  Cranky Moderator Staff Member FBBO Gold Member

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                  Pinion depth....another indicator is used for setting back lash and checked in 4 places. Also, the carrier flange where the ring bolts to is also checked for run out.
                   
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                  • john-9

                    john-9 Member

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                    If you have a 489 case buy US Gear ring and pinion -- made in the USA -- excellent gear sets --- ( Not US Standard Gear ) --- from the factory they run a gear pattern with marking compound on the gears -- this gives you the correct gear pattern to achieve when setting up the gears.
                    Motive Gear is another premium gear set ---and have gears sets for the 741 , 742 and 489 cases
                     
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