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Military Vehicle Pinion Seal Replacement

Rear Axle
Locating the pinion gear and seal.

The pinion seal is the seal where the driveshaft goes into the differential. On jeeps and other military vehicles it is very common to find leaks around this seal. Darryl Bauman is an ASE Certified Auto Repair Technician with 24 years of experience, including plenty of hands-on with MVs. Here he gives a blow-by-blow description of how to replace the seal with minimum effort and no disruption of other elements of the drive train.

Before you start, you may want to drain the lube out of the differential. Draining it is not strictly necessary, but does make it less messy. Then, follow these eight steps:

Step 1: Remove the driveshaft from the differential yoke. Move it out of the way.

Step 2: Take a center punch and mark the yoke, nut and pinion shaft, placing the marks in a straight line. This will guide you when you later reassemble these parts.

Step 3: Remove the nut and yoke. A hammer is usually needed to remove the yoke once the nut is off.

Step 4: Pull and replace the seal.

Step 5: Check the yoke surface where the seal rides. If it's got a groove worn in it, you'll need a repair sleeve to put on it. Repair sleeves are available from Chicago Rawhide (CR) and other seal makers.

Step 6: Put some non- hardening sealer such as Permatex #2 on the yoke splines and re-install. Line up your punch marks from Step 2.

Step 7: Reinstall the nut and tighten until the punch marks all line up and the nut is tight. You will feel the nut tighten against the yoke first, then line up the marks.

Step 8: Refill the differential and viola! Done.

By following the above procedure, you maintain the preload on the pinion bearings. With an impact gun and some practice the whole job can be done in about 45 minutes.

If you have any questions, just drop me an e-mail.

I hope this helps,
Darryl Bauman

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