Jason From The Island of Kauai Gets Nitro 4.88 Gears |
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(61 BIG pics loading) |
MAY 10 2014 |
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Jasons 1993 Toyota pickup has 210,000 miles and it looks like it ran low recently on gear oil and the 488 gears are now toast. After some email exchanges, a package from JT's arrives. |
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Nitro 488 29 spline ring/pinion...29 spline multi-drilled flange....master install kit. |
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Because of where Jason is and the cost of sending a 65 pound 3rd to me, it was decided to use a core that I happen to have. So, I have a solid collar, a basic core, and a basic 2 pinion differential case for this project. |
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The large rear pinion race is tough to press in sometimes. The trick is to get it started straight so I use a "bubble"...... |
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...and make sure the bubble placement is the same before I apply pressure from the press. |
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Save your old races. They come in handy for pushing bearings in place. |
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The race goes down a long way. If a chisel was being used, it's very easy to think you have the race bottomed out when it's not. |
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The small front race is more straight forward....just use some old bearing parts and a hammer to tap tap it fully in place. |
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Front(outer)race is verified in 100%. |
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.080" is the 1st choice for this Nitro gear set. |
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Press the big bearing on with the Harbor Freight press. |
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Installing the pinion assembly is a straight forward operation with the right tools. |
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For this paint check, 18 in/lb is aok. |
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Now to prep the case end. |
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The carrier bearings did not press on as tight as I wanted so #638 retaining compound is employed on both sides. |
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The course file found no burrs or high spots on either mating surface. |
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The ring was a tight fit but I was able to get it to seat down with the lead filled plastic hammer. |
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Red loctite on all 10 ring gear bolts. |
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75 ft/lbs. |
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I use extreme care when aligning the bearing caps...it's too easy to damage the threads. |
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Dial in some sort of bearing pre-load while guiding the backlash in the .008" zone. |
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DRIVE----very near centered and appears to be "exact depth" but I think we can go for that "slight deep" look with a little thicker shim. |
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COAST----centered. |
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Now to push the pinion assembly out. |
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Remove the bearing... |
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...and substitute this .083" shim in place of the 080. |
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Press the bearing on. |
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Use the electric impact to gently nudge the pre-load to about 10~20 in/lb. |
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Another paint check...hmmm, didn't move hardly at all in terms of a deeper look. |
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COAST---not much change. |
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I didn't make a big enough change by adding only .003"....this pinion shim is .0885" and, doing the math, is an additional .0055" deeper. |
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Now this is much better. Has the deep look...slight favoring of the toe. |
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COAST---depth looks slightly deep and favors the heel ever so lightly. |
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Not a very good pic of the pinion...again. |
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Now to remove the pinion again but this time to install the solid collar. On the first try, I had 7 in/lb PPL with a .026" shim on the solid collar. |
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This is the splashguard designed for the 27 spline pinions...and this is the fatter 29 spline pinion. |
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By using a "half round" type of metal file, enough material can be removed in about 4 minutes to make a proper fit. |
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90311-41009 OEM pinion seal will be used on this 29 spline pinion. |
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This homemade tool will knock the seal down evenly and fully. |
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Gear oil is applied to all contact surfaces to prevent a dry start-up condition and to minimize the drag of the rubber when I check the final PPL value. |
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I used to apply a red Loctite to the pinion threads.... |
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....but, after much thought, decided it was not needed and possibly a hindrance. I have already deformed/destroyed one 30 mm socket because I did not use an anti-seize compound on the threads to help reduce the spiral thread resistance. |
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After tightening the 30mm nut as much as the electric impact would allow, the torque wrench was employed to tweak the ppl to its final desired value of 10 inch/pounds start torque. |
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Once the nut is dinged it will never loosen up on its own. |
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75 ft/lbs on all 4 bearing cap bolts. |
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Backlash is dialed in and carrier bearing preload is nudged in place by tightening the adjuster wheels 1 notch at a time. |
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I am measuring 14 in/lb start torque here. That's the force required to turn both the pinion and ring gear. That means my pinion preload is still 10 in/lb and, doing the math, the carrier bearing preload is 4. |
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The lock tabs can now be secured....blue loctite(medium strength).... |
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....and 10 inch/pounds. |
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One final paint check and the drive side looks slight deep and a slight favoring of the toe. Excellent. |
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Coast looks pretty good, too. Deepish look and favoring the heel a little. |
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A snap shot of my assembly notes. |
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And, since this was going USPS to Hawaii which has a weight limit of 70 pounds max, a light but strong rectangular box was created. Cut in half.... |
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....and slide them together to make a super duty box. |