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Ring and pinion installation

A ring and pinion project for the performance enthusiast

Nic Conley - October 10, 2011 10:00 AM

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Randy’s Ring and Pinion supplied us with Yukon’s 3.73 gear set, Dura-Grip locking differential, and a complete bearing set, including axle bearings and seals. Quality products and at a great price.

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After the rear wheels and brake drums were taken off, the driveshaft was disconnected. Then, the rear differential cover is popped off and the fluid drained.

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This pin holds the axle shafts apart in the case, and must be removed to get them out. It is held in by the bolt as it seats in the hole through the shaft.

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After that, the C-clips pull right out, allowing the axles to slide out easily.

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The differential retaining caps come off next and then the differential case should come out. Sometimes it takes a little persuasion to get it to pop out.

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Make sure the caps and side shims are kept in order. They must go back on the same side when reassembled.

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The pinion yoke will have to be removed with an impact gun and the pinion can then be slid out from inside the housing.

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A slide hammer is used to remove the axle bearings from the housing.

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Once the inside of the housing is clean, new pinion bearing races are tapped in.

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As you can see, the pinion gear from the original 2.56 ratio is HUGE!

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The inner bearing is removed from the pinion, revealing the pinion depth shim that we must use on our initial setup. The shim and new bearing are installed, coated with a light oil before being placed into the housing. A crush collar is used to achieve the correct pinion bearing preload. It usually takes between 200 and 300 lbs-ft to crush the sleeve, but the preload can’t exceed 20 lbs-in.

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Yukon’s Dura-Grip differential is a great street/strip unit with lots of holding power.

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The new ring gear is installed using new bolts and thread locking compound. Then, the new carrier bearings are installed on the differential.

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Using the original preload shims, the differential unit is slid back into the housing. The carrier cap bolts are torqued to specs.

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The backlash is checked. It should be .006 to .010-inch

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Marking compound is used to ensure a correct pattern on the ring gear, denoting the proper pinion depth and backlash. If the pattern isn’t right, the shim under the pinion bearing must be changed. Sometimes, it takes several tries to get it right. Once the pattern is correct, the cap bolt torque is double-checked.

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Next, the new axle bearings are pushed in, using the old bearing to tap them in. Then, new axle seals are tapped in.

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The axles are reinstalled, along with the C-clips and retaining pin.

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The rear cover is replaced. The unit is topped off with new fluid, along with four ounces of posi additive or “friction modifier”.

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When looking to get more of your muscle car’s power to the wheels, nothing achieves it quite like swapping in a lower ring and pinion gear set. The lower ratio (higher number) multiplies the leverage your horsepower has on the tires.

This will make probably the biggest improvement in your car’s performance, as far as your “seat of the pants” meter goes. A simple gear swap can literally feel like adding 50 horsepower or more.

Our project is a GM 8¼-inch rear axle, but keep in mind that almost all GM ( as well as Ford and Chrysler) rear axles utilize this very same process. The steps would be exactly the same for all 10-bolts, 12-bolts, and even the little 7½-inch rear ends found in GM cars and light trucks from the early ’70s to present day.

Our parts source decision was an easy one. One call to Randy’s Ring and Pinion in Everett, Washington, netted us with everything we needed, in quick and wallet-friendly fashion. Randy’s uses quality Yukon gears, differentials and bearings in everything they build. The guys at Performance Solutions in Boise, Idaho, are well-schooled in all types of high performance upgrades, and handled the entire rebuild.

This particular axle is in a 1970 Chevelle sporting a brand new custom-built 383 small block, but the performance was anything but stellar. The lackluster acceleration was due to the extremely high 2.56 gear ratio. Sure, the car would cruise down the freeway at just over idle rpm, but anyone with a good set of sneakers would beat it across an intersection on foot! We decided on 3.73s to get things hopping, along with a Yukon locking differential to keep power going to both wheels.

Our kit also included a full set of bearings, seals and gaskets, plus any type of preload shims that we might require. Something to remember is that we also had to make a significant speedometer gear change as well. Otherwise the indicated speed on the speedometer was over 20 mph off! The difference was night and day, and the Chevelle has that much-needed punch to live up to its muscle car heritage.

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