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Thread: TruTrac Install Question

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    Full Access Member Sleepertrk's Avatar
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    Default TruTrac Install Question

    So i'm really wanting a TruTrac but want to do the install myself. I'm quite capable of most mechanical repairs and mods. I've got plenty of experiance and all the tools needed but its been a long time since i have done any diff. work. My big hold up is i don't remember how to measure and set lash. I want to buy the TruTrac and install it this spring but once i swing for the TT i can't go paying somebody another several hundred in install fees. So who can give me a quick internet lash lesson? Has anybody on here done their own install? What else would be my hold up?

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    Junior Member BMF'n Titan's Avatar
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    I did the install myself, setting the lash is not that hard. I had bought the TT with the bearings and races from 4x4parts dot com. Before the install I had already pressed the bearings on and red Loctited each bolt on the TT. Bought a cheap dial indicator and mag base at Harbor Freight. After backing both axles out put the dial indicator on a tooth of the Ring gear and rock the diff back and forth so the teeth mesh with the Pinion gear. The distance the ring moves from hitting each side of the pinion gear is the lash. The tolerance is 0.0031 to 0.0051 inches or 0.08 to 0.13 mm. Record the original lash before loosening the bearing caps or side adjusters.

    Mark each bearing cap left and right and each one so you know it's top and bottom......they are line bored at the factory and have to go back exactly as found.

    Once you have the ring gear installed on the TT, install it into the diff, leave the bearing caps snug but not tight, adjust the bearing side adjusters until there is no lash at all. This means you have adjusted the ring gear (towards the right) to be fully mated with the pinion gear.

    Also remember that the side adjusters act as the beaing loaders.....this just means that you have to think about the bearings of the diff just as you do when re-packing or replacing a wheel bearing. The nut on the wheel bearing when tightened too tight locks the hub because of too much load is being placed on the bearing.....they are beveled and are being pressed into the races..........same with the diff, you want them tight so as not to have slop but don't want it too tight to jam the bearings into the races.......hope this makes sense

    Anyways now you have 0 lash with good load on the bearings, now just start backing off (loosening) the left side while tightening the right until you get the exact lash that you had originally while also getting the bearing loads correct...which basically means they are tight but not too tight and when you spin the pinion (hang the driveshaft up out of the way) everything spins smooth ........and you have the exact lash recorded before the install.

    The bearing caps are torqued to 80 foot lbs and the adjuster locks are torqed to 89 inch lbs. Recheck everything again and re-adjust if necessary......I checked and re-checked several times.

    Everything should spin smoothly from the pinion and the lash should be the same as the original once everything is torqued and you are now ready to re-install everything.
    Last edited by BMF'n Titan; 03-08-2010 at 02:03 PM.
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    Sleepertrk (03-08-2010)

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    Full Access Member Sleepertrk's Avatar
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    Hey thats exactly what i was looking for. Like i said its been awhile but everything you said at least has some meaning to me. In other words i understand. I knew it would somewhat come back to me but really wanted something to fall back on or glance at. Its gonna happen by the end of this summer for sure. I really appreciate the school lesson on lash. Thanks again.
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    Junior Member BFALCO126's Avatar
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    hey sleeper good luck with the install and let us know how it goes. i am going to get a TT one day as well and i will be installing it so let me know if you encounter any issues along the way! thanks!
    2005 TITAN XE 2WD

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