Powr-Lok swap questions in 741 case.

Transmission and Drivetrain Tech

  1. my5thmopar

    my5thmopar Life Long MOPAR Owner FABO Gold Member

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    This is my first rebuild on an 8 3/4. I've done 7.25, 8.25 and newer corporate diffs. I have the tools for this operation. I'm installing Dr. Diff Powr-Lok, carrier bearings, pinion seal and inner axle seals. I am using OEM type bearings. I'm keeping the same gear set.

    Is there anything else I should replace? I didn't plan on replacing axle or pinion bearings since they turn smoothly.
    Does swapping the carrier effect the the pattern?
     
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    • RustyRatRod

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

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      Generally, as long as the carrier is a good quality unit, the pattern will be "close". Consider yourself lucky if you don't have to adjust it at all....but I think that's askin a lot.
       
    • 69B-Cuda

      69B-Cuda Well-Known Member

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      you are not disturbing the pinion depth so, you should be fine setting the backlash correct and checking the pattern. I have done a few that way. You may check the pattern before you pull it apart, take some good pics, and compare once you get it all back together.
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      Measure your backlash before you remove the old carrier.

      Since you're replacing the front seal you will have the Yoke off so go ahead and take your pinion out and inspect the bearings an the races just to make sure they're good.
       
    • my5thmopar

      my5thmopar Life Long MOPAR Owner FABO Gold Member

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      I took the carrier apart tonight. Pinion bearing and cups nice condition and turn smoothly. I'm on the fence about replacing them since it seems unnecessary. What ya think? The pinion seem a little loose but, the FSM says 0-15. The pattern looked ok but, I didn't a good reading. My technique as probably off. Any tips where to put the pry bar to get a good pattern? The backlash was .004 but, I am using an old Craftsman jeweled dial indicator. It might be off but, It did seem tight. Thanks Craig
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      If they are the original bearing replace them now while you have it apart.
      4 is to tight. I would have thought 8 or more being used.
      I use a bar or long screwdriver between the carrier and the case.
       
    • 69B-Cuda

      69B-Cuda Well-Known Member

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      yep, it is a good idea to replace the pinion bearings while out if you don't know when they were last changed. (Although I have run used ones before as well.) The pinion takes more load and spins faster than the carrier bearings. If running 3.55 gears, the pinion spins 3.55 times for each one revolution of the carrier bearings so, faster and more revs puts more wear and tear on it (more heat as well).
       
    • oldkimmer

      oldkimmer FABO Gold Member FABO Gold Member

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      U mean when turning that the pinion that there isn’t much preload. That’s ok as the bearings are used. But as mentioned u r already in there so u may as well change them. Then everything is new. Kim
       
    • my5thmopar

      my5thmopar Life Long MOPAR Owner FABO Gold Member

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      Correct. That's what I figured. The bearings have been changed. It appears someone rebuilt this diff in the past. I guess it makes sense to change them again. I don't have a press but, I do have a bearing separator somewhere. I hope the ring gear and carrier bearings will be easy. I have a hot oil bath that can heat them to 400 degree if needed and put the suregrip in the freezer. The FSM shows the pinion bearing being hammered on. The heat/cold method should work for this too. My first 8 3/4 but, it seems easier than the other diffs I've done. I'll soon find out. Thanks
       
    • pt70

      pt70 Well-Known Member

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      If the rear end was quiet before, then I'd just do the minimum. Clean out the banjo, replace the inner axle seals, leave the outer seals alone if the backing plates are semi dry, clean and repack the axle bearings.

      Make a holding fixture for the carrier assy. A 1/4'' thick piece of steel, long enough to clamp to a bench, drill 2 holes for the top 2 carrier bolt holes. Mount it yoke side down. Mark the end caps with a prick punch [they have to stay in their original positions]. Back off the adjuster. Bearing races must be kept together with their bearings. Remove the differential assy. Remove the yoke. take out the pinion assy. Clean the pinion assy. Check the bearing races for pitting or unusual wear. If good, assemble pinion using kerosene or light spray oil. Replace pinion yoke seal first. Torque yoke nut. The pinion should rotate smoothly. If so, remove the pinion assy., oil the bearings with diff. lube, and hide it under a clean rag.

      Clean the carrier and diff. assy. oil the diff. bearings with kerosene. Install the diff. bearings and snug up the caps. Preload the bearings a little. Spin the diff. If nice and smooth, remove diff. Oil all bearings with diff. lube but leave ring and pinion gear teeth dry for pattern check.

      I'm not familiar with the power-lock.
       
    • my5thmopar

      my5thmopar Life Long MOPAR Owner FABO Gold Member

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      I replaced the pinion, carrier bearings and races. I’ve got about 24-26 on preload, 6-7 on backlash. These are used gears. Here is the coast side since I’ve never had any luck with drive side. I think it looks pretty good. What ya think. Craig

      B95BF48D-7682-4AC0-AB76-FD223780D47C.jpeg

      5D838993-C391-43E0-A64A-910132F21348.jpeg
       
    • oldkimmer

      oldkimmer FABO Gold Member FABO Gold Member

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      Looks ok to me. What’s the drive side look like? Kim
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      Is that 24-26 with the seal installed?
       
    • my5thmopar

      my5thmopar Life Long MOPAR Owner FABO Gold Member

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      The same as before I took it apart. Here is the after and it looks like a nice worn in pattern. Kind of hard to get a good pattern on used gears. Maybe there’s another way to check. I’ve done several installs so I’m not new to this.

      No seal installed yet.

      611F61B0-22EB-442D-BBDA-2916027A18DF.jpeg

      8D1035EA-69BB-4699-96BF-3256B0D91F1D.jpeg
       
    • oldkimmer

      oldkimmer FABO Gold Member FABO Gold Member

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      R u putting pressure on the crown gear? Looks good to go. Kim
       
    • my5thmopar

      my5thmopar Life Long MOPAR Owner FABO Gold Member

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      Yes between case and outside edge of ring gear. Not the backside by bolts. Craig
       
    • oldkimmer

      oldkimmer FABO Gold Member FABO Gold Member

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      If that’s how it was b4 ur golden. Kim
       
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