Will a Stock 489 handle 700hp?

Mopar Racers Forum

Have you had a stock 8.75, 489 hold up to 700hp while racing?

  1. Yes

    11 vote(s)
    28.2%
  2. No

    28 vote(s)
    71.8%
  1. 70DusterBob

    70DusterBob Well-Known Member

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    I have about a 650hp 408 H.P. that has a H.P. 727 behind it 2,500 stall. It is time to put a diff in. Some people are telling me a stock 489 8.75, with stock gears, race axles, stock pinion yoke, stock bearings, etc, will handle 700hp with an Automatic Trans.

    Some people are telling me I need this pumpkin for it:

    Mopar 8 3/4" (8.75) 489 Case Third Member

    I want the green bearings, a 3:23 ratio, 6 Helical Gear Sure Track II, w/a 1350 Yoke.

    Problem is I can get a stock pumpkin for $850, while the race pumpkin with the above features is $1,425. Don't get me wrong, I am not out to pinch penny. What I don't want to do is spend the money on a race pumpkin when a stock one will do. If the stock will not do, I will definitely buy the race pumpkin. No Problemo! I have heard a lot of different answers.

    Members who have experimented in this area will prove most helpful. I need to know what your experience was.
     
  2. 1Badcolt

    1Badcolt Well-Known Member

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    700 HP [ WOW ] Mongo Like !!!
     
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    • RustyRatRod

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

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      Yeah as long as you don't try to hook up.
       
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      • toolmanmike

        toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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        Strange S60
         
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        • j par

          j par Well-hung Member

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          Stock 489 case.. spool, 475hp, 4 speed, very sticky tires... Where there's a will there's a way...
          20151128_141857.jpg
          That same 4.10 - 8 3/4 ring gear next to the replacement D60 - 4.10 ring gear...
          20160116_111102.jpg
          Haven't given the rear end another thought since...
          My experience...
           
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          • 70aarcuda

            70aarcuda Master Hoader of SBM FABO Gold Member

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            The ring gear in a 8 3/4 rear is the weakest link.....if you are racing...sooner or later it will eat teeth.....
             
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            • A body

              A body SLO-KID

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              Have you had a stock 8.75, 489 hold up to 700hp while racing?

              no.... because I removed it and upgraded
               
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              • TheGrateRonzini

                TheGrateRonzini FABO Gold Member FABO Gold Member

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                As stated above. You are good til you hook. Then you start breaking stuff. If you are boiling the tires every time you give it gas, that’s not usually a problem. But big sticky tires leaving at high RPM will make quick work of it.
                 
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                • 33IMP

                  33IMP Well-Known Member

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                  Yes, a stock 489 will live just fine.......as long as you never, EVER put good tires on it. Put hard-ass T/A radials on it, it will live forever. Especially if you continue to use a no-stall-speed converter, and no gear in the back.
                  There is NO way i would spend $1500 on a 8 3/4 center, if i had 700 hp. A new strange 60 is only about $700 (?) more, and you can turn your 8 3/4 before you break it, to recoup some of the cost of the 60. But if you keep that nothing converter, you probably wont need one.
                  .
                  ..
                   
                  Last edited: Oct 19, 2020
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                  • j par

                    j par Well-hung Member

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                    As a side note I had $1,200 total into my 8 3/4 that blew up and $1,200 total into the Dana 60 that now reside underneath the Duster..
                     
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                    • Jadaharabi

                      Jadaharabi FABO Gold Member FABO Gold Member

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                      Buy a dana from Dr Diff. 1977 489 with 4.56 gears in a 340 6 pac 69 4sp Dart, (12.20 et)split the crush sleeve like a laser cut it.
                       
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                      • 33IMP

                        33IMP Well-Known Member

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                        I will also bet that you will hate your car with a big horspower small block, and no converter and no gear. If i had a 650 horse smallblock, 4000 to 4500 converter, and 3.91 gear would be a minimum.
                        (Just the opinion of a guy with a 550hp big block with a 5000 stall, 3.91 on the street).
                        Edit: this post is completely irrelevant, if you made 650 with a blower, a turbo, or nitrous, i assumed n/a, and you know what happens when you assume!
                         
                      • flyfish

                        flyfish C8H18+N2O = :-D

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                        I'm confused on many fronts....why do you want 3.23 gears and a 2500 converter behind a "650hp" engine (I can't think of any).

                        Also, how did you come up with "650hp"?.....kinda smells like a big scoop of Hotrod magazine, lack of sleep and a "3/4 race cam" = 650hp?!?!?!?
                         
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                        • 70DusterBob

                          70DusterBob Well-Known Member

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                          Thanks, the way you put that is kinda funny, I hope you were trying to be funny and serious at the same time. See further all-in-one reply farther down.
                           
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                          • 70DusterBob

                            70DusterBob Well-Known Member

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                            It is not for a strictly race car. It is a street/strip car. I only have race radials on it so I can drive it on the street.

                            I am working on a project that I can't mention that will boost the hp from 500 to about 625, (I'm hoping) 650 is for room and I want it to be able to hold 700hp because I don't want to come "ANYWHERE NEAR" the breaking point! Hooking up with slicks is what one of my friend said about breaking a diff. I don't think I will be hooking up, but I am concerned about low end torque. Is that much of a factor if I don't hook up off the line but say 50 feet down the track or so? I don't know for sure where it will hook but just guestimating.
                             
                          • fratzog lover

                            fratzog lover Well-Known Member

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                            The lower(numerically) you go, the more stress on the ring gear. 3.23 or 2.76 will break before a 3.91 or 4.10
                             
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                            • 70DusterBob

                              70DusterBob Well-Known Member

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                              Hey Mike,

                              I appreciate the lead, but very Dana that Strange makes is an S60, could you be more specific? I will call them when they open to see what they can recommend for me, but like the saying goes, better safe than sorry. If you know of a particular Dana they sell, please let me know. Thanks
                               
                            • Ottmundr

                              Ottmundr 68 Fastback

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                              Just get the s60 from Dr. Diff like mentioned above.
                              and you may want to re-think that torque converter and the highway gears.
                              and go back and look at the pictures jpar put up.

                              Or, just say fuckit and get a trailer because you're gonna need it when you do destroy that 8 3/4, just like that printer in Office Space.
                               
                            • 70DusterBob

                              70DusterBob Well-Known Member

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                              I don't want to race all the time. Should have mentioned that. It is a street/strip car, I only want to test improvements that I make on the strip, but it will mainly be a highway car since I don't drive it in the city if I can at all help it. I understand the lower the # of the gear ratio, the more stress they take. But it is hard to baby a car and race it at the same time, I need an all around diff that will hold under track conditions. The engine makes 500hp, but I plan on adding to that. Dana sounds like the way to go.

                              Thanks
                               
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                              • fratzog lover

                                fratzog lover Well-Known Member

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                                It's a shame we all cant have a GV overdrive. They cost a wee bit of money!
                                 
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                                • B3422w5

                                  B3422w5 Well-Known Member

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                                  Sounds like a torque storm type thing you have going on.
                                  The rear needs swapped with any “ real” power
                                   
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                                  • 70DusterBob

                                    70DusterBob Well-Known Member

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                                    Looking at Dr Diff S60, the options are limited, I can't get Race Axles and go without a spool which I don't want. I want the Trac-Lock, but is the Trac-Lock going to hold up under track conditions? Also the Pro-Gears need a Spool, which I don't want, but I want strong gears, will the stock gears hold up under race conditions as long as I don't hook up with slicks?

                                    So, w/o the race axles, without the spool, with the trac-lock, stock Dana Gears, will be about $2,500 after taxes. Someone above said they found one for $1,200. I'm guessing that was used?
                                     
                                  • 70DusterBob

                                    70DusterBob Well-Known Member

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                                    I heard that!!!
                                     
                                  • 33IMP

                                    33IMP Well-Known Member

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                                    Slicks can spin a little at the strip, and still recover and post a decent time. Drag radials only work well as a dead hook. If they spin, the only way they recover is to completely chop power ( also, NOT good in first gear for your 727), therefor drag radials are HARDER on the drivetrain than slicks!
                                    The $1200 dana above was built from a truck dana that probably had thicker axle tubes and floater axles. So, it was narrowed, had new axle ends installed, new custom axles, and an unknown gear and suregrip, or spool, installed. Thats how to save half the cost of a new strange (dr diff) 60.
                                    Just about any guts in a 60 will live forever behind a small block. I personally would choose a 35 spline clutch suregrip. They have gone billions of miles in trucks. I dont trust the gear style, i have heard too many complaints.
                                     
                                    Last edited: Oct 19, 2020
                                  • 70DusterBob

                                    70DusterBob Well-Known Member

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                                    Where did you get your $1,200 Dana??? Dr Diff and Strange want like 2X that... Yikes!
                                     
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