Limited slip installation.

Transmission and Drivetrain Tech

  1. circlepilot

    circlepilot FABO Gold Member FABO Gold Member

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    (I may have the title wrong, sure grip or limited slip) One of the many individual parts that I'm working on with my build, is installing a sure grip (limited slip?) in my 8.75. When I got the rear end it had a Dr. Diff spool in it. The ring and pinion are a 4:10.
    Both the ring and pinion have very little visible wear. After installing the sure grip I set the rear end up (completely) I.A.W. the factory service manual. Never having experience with (limited slip) sure grip, (only open and locked rear ends and I have the third member on a stand.) I have some questions...How hard should it be to turn the yoke by hand? (It can be turned by hand, but it does require something more than I expected) There seems to be a "dead spot" while turning the yoke. The applied gear marker shows a correct "foot print." Lash properly set with a dial indicator and a correct pre-load on the pinion.
    Norm

    sure grip.jpg
     
    Last edited: Apr 13, 2021
  2. 70dart340

    70dart340 Well-Known Member

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    Some Mopar Purists will correct you by insisting it's "Sure grip." Limited slip smacks of GM products. If it's all torqued and shimmed correctly, It should be good. It's going to be a bit stiff until it's broken in. Don't hammer it, and check your fluid frequently. Nice job.
     
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    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      Pour or squirt some oil on the pinion bearings and then see if it turns easier.
       
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      • teringer

        teringer FABO Gold Member FABO Gold Member

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        did you check pinion run out / I have seen the yoke end bent , a sign is a leaking pinion seal . when I ran the sure grip the car would go deeper into the corner but got a little loose coming out with power transferring back between the left/right wheels, tried changing the stagger but no help because the inside track was wet and the outside dry /but if your on asphalt it might not be a problem
         
        Last edited: Apr 13, 2021
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        • SGBARRACUDA

          SGBARRACUDA ROY FABO Gold Member

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          What case do you have? New bearings? Did you set the pinion preload? Did you check backlash in 4 different places? Need more info.
           
        • oldkimmer

          oldkimmer FABO Gold Member FABO Gold Member

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          Check the rotating torque. Is it the same as b4? Did u tighten the pinion nut during the assambly? Kim
           
        • circlepilot

          circlepilot FABO Gold Member FABO Gold Member

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          It's a 489 case, new bearings and yes set the pre-load I.A.W. the service manual. Yes it was measured in four places with the dial indicator. Rear End case.jpg
           
          Last edited: Apr 13, 2021
        • SGBARRACUDA

          SGBARRACUDA ROY FABO Gold Member

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          What was your preload set at?
           
        • oldkimmer

          oldkimmer FABO Gold Member FABO Gold Member

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          Then it will be pretty stiff to turn. Did u use a new crush sleeve or use the eliminator kit? Post better pics of the pattern u got. Did u use a rag or anything to put resistance on the crown gear while turning the pinion to check the pattern? Kim
           
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          • circlepilot

            circlepilot FABO Gold Member FABO Gold Member

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            Didn't really check the rotation, prior to total disassembly. After torqueing the pinion nut, the rotation was checked with a torque wrench as instructed in the service manual. The pre-load rotation fell into the allowable limits for an original bearing..."0-15 inch pounds."
            Norm
             
          • oldkimmer

            oldkimmer FABO Gold Member FABO Gold Member

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            Says here new bearings. Not on the pinion then? Just the case ? Kim
             
          • SGBARRACUDA

            SGBARRACUDA ROY FABO Gold Member

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            Well than what was the BL set at. Usually there is some ring gear run out so you have to check it in several places and set it at a compromise number.
             
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            • circlepilot

              circlepilot FABO Gold Member FABO Gold Member

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              Right at 15 inch pounds with the original bearing.
               
            • circlepilot

              circlepilot FABO Gold Member FABO Gold Member

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              Right...original pinion bearing, the carrier bearings and cups were installed new by the PO, who installed the spool.
              Norm
               
            • circlepilot

              circlepilot FABO Gold Member FABO Gold Member

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              I tried to average it at about .007...Book says .008 is the max after everything is torqued.
               
            • oldkimmer

              oldkimmer FABO Gold Member FABO Gold Member

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              I would be at .010 with a 4.10 ratio. Kim
               
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              • mderoy340

                mderoy340 Well-Known Member

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                Factory or aftermarket gear? If Richmond BL setting is ecthed on the ring gear (normally .010). Move the BL to .010 and check rotation. If the tight spot goes away and you know for sure the bearings and races are good more than likely the runout of the carrier is out of limits. I always check the runout on unkown carriers. People beat the ring gears off with hammers instead of using heat to get old ring gears off. A good machine shop can cut the carrier to zero runout.
                 
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                • circlepilot

                  circlepilot FABO Gold Member FABO Gold Member

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                  Thanks, I'll look at that. With all of the help here and with all of the advice, I've gotten...I'm going to go back and check everything again, one more time, before loaded it into the banjo. Thanks to everyone for their input.
                  Norm
                   
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                  • 73smallblock

                    73smallblock Well-Known Member

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                    Is the pinion rubbing the limited slip? It looks like something it's rubbing right above where you can see the springs in your picture.
                     
                  • oldkimmer

                    oldkimmer FABO Gold Member FABO Gold Member

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                    Probably the pinion nut came loose at 1 time. Kim
                     
                  • RustyRatRod

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

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                    If it has any backlash at all, you're probably good. I have an old friend WL Kitchens in Warner Robins, Georgia whose a renowned old drag racer all over the southeast. He used to set them all up at zero backlash and let um "wear it in". I never saw him have a failure. lol Although I'm sure he probably should have. He's deep in his eighties now, but still races on occasion.
                     
                    Last edited: Apr 18, 2021
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                    • circlepilot

                      circlepilot FABO Gold Member FABO Gold Member

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                      You know I never noticed that until you mentioned it. The chunk is down in the shop, but I went back and looked at my picture and blew it up. First thing tomorrow, I'll check it out. It sure does look like pinion gear marks.
                      Thanks
                      Norm
                       
                    • SGBARRACUDA

                      SGBARRACUDA ROY FABO Gold Member

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                      That is not unusual to see witness marks on a cone style SG. I have seen them much worse than that. Seems to be a more common occurrence in the 489 case that uses a crush sleeve. That happens when the pinion nut comes loose and the pinion gear leaves those marks on the case.
                       
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                      • RustyRatRod

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

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                        Yup, that's a very common issue and it comes from the pinion nut backing off. My guess is, it's not happening now, but it sure is worth checking out.
                         
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                        • circlepilot

                          circlepilot FABO Gold Member FABO Gold Member

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                          Just now had the chance to get out a reply...Those marks, must of been there when I got the sure-grip. I just never noticed them before. Cleaning it up and oiling the hell out of everything, enhanced the marks. I checked and there is no contact being made between the sure-grip and the pinion, ran it through a full 360 degrees. Thanks to all for the "heads up."
                          Norm
                           
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