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Replacing Ring-& Pinion Gears - Layin' Track(s)Two-Steppin' With A Peg Leg Truck From the March, 2005 issue of Mopar Muscle By Randy Bolig Photography by Randy Bolig
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Smokin' tire. It's antics... Smokin' tire. It's antics like this that get the attention of local law enforcement. Before the rear build, our Dodge would completely haze the passenger side rear tire only. Now, with the help of Randy's Ring and Pinion, our Dodge is doing the two-step on asphalt. It's a noise as recognizable as burning the tires of your car. The sound coming from the rearend announces to everyone within a one-block radius that there's a bearing going bad in your rear. First, there's the growling noise, and then, when the bearing gets really bad, it affects the backlash, and you now have a strange roar along with the growl. Our '98 Ram had both of those noises, and we knew it was time for a repair. The old Dodge has dutifully hauled the Valiant (and now the Super Bee) on several occasions, but during a recent short trip, the noise finally got to the point of unbearable. The 9 1/4-inch Dana rear in the truck is definitely not a popular rear within the aftermarket. We learned this by searching the Internet, looking for parts. Used in trucks and vans from 1994-2000 (and in passenger cars in the '70s), it rarely went bad. Like many factory axles, the Chrysler 9 1/4 is a C-clip axle, meaning the axles are prevented from moving sideways by a c-shaped clip inside the differential. While off-roaders will prefer the strength of a collar and thrust bearing-type axle, for daily street use and towing, this type of axle is more than up to the task. Raise the vehicle and safely... Raise the vehicle and safely support it. Next, loosen the differential cover and drain the gear lube. The 9 1/4 rear doesn't have a drain plug, so this can be messy. Before we started, we needed to come up with a plan. The Dodge is used mainly for daily transportation, hauling stuff and towing things. The factory had installed an open-type differential with 3.55 gears. We didn't want to lose the good fuel mileage we were already getting with the Dodge, but we did want it to tow a little easier up hills. To get everything we needed, we could have either spent an entire day calling everyone we could think of for each individual piece, or we could call one supplier and get a good deal on everything. We decided to call Randy's Ring and Pinion, and get everything from them. We knew we needed bearings and a ring-and-pinion, but what ratio should we get? The 3.55s worked well, but a little more gear could be better, right? As we drive this truck all over the eastern states, 4.10s would definitely be too much. We finally settled on a set of 3.90 gears. This would help with towing, and we may want to play now and then. Since the rear in the Dodge was an open style, we decided now would be a good time to put the power to both wheels. So we also ordered up an Auburn Limited Slip unit. While replacing a ring-and-pinion, it is a good idea to also replace all other wear items in the differential. In this case, we replaced not only the ring-and-pinion and differential, but also both wheel bearings and seals, as well as the bearings associated with the differential. When doing an install like this, it is a good idea to purchase the complete installation kit. This kit came with all the necessary ringbolts, bearings, seals, gaskets, and marking compound. Never having attempted a 9 1/4-inch rear rebuild before, we decided to take the truck to Harrell's Automotive in Lakeland, Florida. Not only does Lonnie know what he's doing, but he's also close to home.  Now remove and clean the differential...  Now remove and clean the differential cover.  Remove both rear wheels and...  Remove both rear wheels and pull the brake drums. Remove the set bolt that holds the center pin in the differential case and remove the pin.  With the center pin removed,...  With the center pin removed, either axle can be moved slightly inboard, revealing the C-clip. Remove each C-clip, and pull the axles outboard to remove them. Once removed, inspect the axle splines and bearing location for wear.  Once the axles are removed,...  Once the axles are removed, loosen the two bearing caps, which hold the side bearing races in place. Mark the caps so you replace them on the same side. Now you need to loosen the side adjusters. Instead of using shims to hold the differential side bearings in place, the Chrysler 9 1/4 axle makes use of threaded adjustment spacers in the axle tube. These adjusters look the same as those in an 8 3/4 rear.  Movement of the spacers requires...  Movement of the spacers requires a special tool. It's basically a specially shaped nut on the end of a long shaft with another nut on the other end for a socket. It reaches through the axletube to the adjuster. We got our tool from Randy's.  Lonnie made this handy tool...  Lonnie made this handy tool for holding the yoke still, so the pinion nut can be removed and replaced.  With the center section and...  With the center section and pinion gear out of the housing, we can see the pinion-bearing race had taken a beating.  Now you can remove the ring...  Now you can remove the ring gear from the differential. Even though we are using a new differential and gears...  ...this step must be done...  ...this step must be done because the tone ring under the ring gear needs to be reinstalled on the new differential for the anti-lock brakes to work. The tone ring can gently be tapped off the center section.  Using a punch, we removed...  Using a punch, we removed the pinion bearing races.  With the races out, clean...  With the races out, clean the housing up really good.  The tone ring is then placed...  The tone ring is then placed on the differential. The ring cannot just be pushed into place; it is a press fit. The ring is sandwiched between the ring gear and the differential.  To install the ring, place...  To install the ring, place it on the differential, and slowly warm the ring until it slides in place. Do not get it too hot; it only took a couple seconds to get ours warm enough to install.  Next, the ring gear can be...  Next, the ring gear can be installed on the differential. New bolts are supplied with the installation kit, and they should be used along with Lock-tite. The bolts are left-handed thread and get torqued to 115 lb-ft.  Now the differential bearings...  Now the differential bearings can be pressed onto the differential.  This is where things can get...  This is where things can get tricky. The pinion gear is shipped with a number written on it. Our number was 2.823. This number denotes the distance between the pinion gear face and the centerline of the differential.  This distance is changed by...  This distance is changed by adding or removing shims from between the pinion gear and the large inner pinion bearing.  When you remove the old pinion...  When you remove the old pinion bearing, take note how many shims are installed, and that could be a good starting point. We needed to add shims, and it took a couple tries to get it right.  Next, install the pinion bearing...  Next, install the pinion bearing races. If you don't have a race installer, a brass punch can be used; just be careful and take your time.  Slide the pinion gear into...  Slide the pinion gear into the housing. At first, until you get the pinion depth set up, you will not want to install the seal. To set the depth and bearing preload, install the pinion gear, slide the new crush sleeve and bearing in from the front, and install the yoke and nut.  Tighten the nut to approximately...  Tighten the nut to approximately 200 lb-ft to crush the sleeve and set distance for bearing preload. Next, loosen the nut until you get approximately 20-inch pounds of resistance when you spin the yoke. Make sure all bearings are coated with oil before you start to set up preload. After depth is set, remove the yoke and install the seal.  With the pinion FINALLY set...  With the pinion FINALLY set to spec, the differential can be installed. To get it close to the factory required spec, follow this procedure. Make sure adjusters are turned out so the differential can be installed. Put the differential in place, and install the bearing caps finger tight. Next, tighten the top bolt of the bearing caps to 10 lb-ft. Now adjust the driver side bearing adjuster so that there is approximately 3-6-thousands of endplay in the gears. Tighten the other side adjuster. That is the basic placement; now for setup.  Now with the dial indicator...  Now with the dial indicator attached to the rear, proper backlash can be set. Adjust the bearing adjuster on the driver's and passenger's side a little at a time until proper final backlash is set.  This should be 6-8-thousands...  This should be 6-8-thousands of an inch. Once final backlash is achieved, tighten the bearing adjusters to 75 lb-ft. and recheck backlash.  With backlash achieved, it's...  With backlash achieved, it's time to check for gear mesh pattern. White marking compound is applied to the ring gear in three different locations, and the pinion is turned to rotate the ring gear, leaving an impression in the marking compound. By reading the guidelines in the instruction manual, you can see if your pattern is acceptable or not, and adjust the pinion shims as necessary. This may take several tries to get it right, but taking the time is worth it. It took us a couple attempts.  Once backlash and the gear...  Once backlash and the gear mesh is finally set, torque the bearing caps to 100 lb-ft.  We also replaced the axle...  We also replaced the axle bearings and seal  To make sure the bearing adjusters...  To make sure the bearing adjusters stay in place, Mopar uses these little metal tabs that bolt to the caps. Next, slide the axles back into place and reinstall the C-clips and axle pin.  Reinstall the cover, and fill...  Reinstall the cover, and fill with fluid. We chose Royal Purple synthetic 75-80 Max-Gear lube. Max-Gear is recommended for automotive differentials and manual transmissions. Max-Gear is a tough, high-performance, GL-5 automotive gear oil designed to provide maximum protection to heavily loaded gears. Max-Gear also has hypoid friction modifiers for clutch or cone-style differentials already blended in the mix. This means you don't need to buy that also.
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