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Rear Pinion Seal Replacement.

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#1 HBHRacing



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Posted 10 September 2004 - 01:10 PM

This article will guide you in replacing your warn out and leaking pinion seal.

Some are hesitant to touch anything on the rear end of a car, but the truth is that it is a very basic and easy repair and should only take about an hour to complete.

What you will need:
Jack and jack stands.
Basic hand tools
Seal puller
1 ¼ Inch socket
Impact gun if available.
Drain pan
New seal
Gear oil
Limited slip additive if applicable

Securing the car.

Always use jack stand or similar equipment to secure your car. Never trust your life on a jack alone. They do fail and can trap you under your car before you have a chance to move. While changing your pinion seal it would be a great time to switch out the old gear oil. For this reason when you lift the car you want it to be level. I like to use a set of drive on ramps for the front. This is a fast way of getting off the ground. Then you can jack up the rear and place jack stands under each axle tube. Once the car is safely secure we can move on to dis-assembly.

Removing the drive shaft.

There are 4 bolts holding the drive shaft to the rear pinion flange. Simply remove the 4 bolts and remove the shaft. You might have to lightly pry behind the U joint to release it from the yoke. Pay close attention to make sure that the U joint bearing cups do not fall off. Once the shaft is out of the rear pinion yoke use tape to secure the Bearing cups from falling out. When you pull the drive shaft out from the transmission you might get some transmission fluid coming out of the tail shaft. You can either place a drip pan under the transmission or you can get a plug that will stick into the transmission to avoid leaks. Only a small amount should drip out.

Removing the rear pinion yoke.

The rear pinion yoke, also named the companion flange is secured to the pinion gear and holds the drive shaft U joint. In order to maintain proper torque specs you must take a few steps before dis-assembly. Start by using a paint pen or marker to make a straight line extending from the center of the pinion shaft, down over the nut, washer and companion flange. This will be your reference mark. Now count the number of exposed threads on the pinion shaft that extends past the nut and record this for later.

Now you can use your 1-¼ socket to remove the pinion nut. If needed you can hold onto the flange with a large pair of channel lock pliers or similar. Once the nut is off remove the washer and place both aside. The companion flange should now easily pull away from the rear. You might need to LIGHTLY tap on the back of the flange with a piece of wood or a rubber mallet. Do not use a hammer. Once the flange is removed you will probably lose some gear oil so have your drip pan ready.

Replacing the seal.

Now that the companion flange is out of the way the seal is exposed. To remove the seal use a seal puller to hook behind the seal. Use caution not to nick the pinion shaft, bearing or seal-mating surface. There are several types of seal puller that can be used. It might take some time to get the seal out. Once the seal is out allow the oil to drain and clean the seal surface thoroughly.

Once the surface is clean you can install the new seal. There are many seal installation kits available that will make this job a lot easier. If you do not have one then you can still install the seal with a simple hammer. Be extremely careful not to damage the seal. Work slowly and lightly until the seal starts. Then simply finish installing the seal until it’s flush.

Installing the yoke.

The yoke now simply slide back on in it’s original location. Once on replace the washer and the nut. This is the part that a lot of people care afraid of. Installing the nut too lose can cause failure, and installing it too tight can cause whine. But it’s very easy to do correctly. Simply tighten the nut until the mark lines up and the same number of threads is exposed. Now go just a small amount past the mark. That’s all there is to it.

Installing the drive shaft.

Simply slide the slip yoke into the transmission and carefully place the U joint into the cups being careful again to not disturb the bearing cups. Once in place replace the hold downs and bolts and tighten to 14 foot-pounds

Once you get the car back on the ground you are ready to enjoy leak free driving.

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