Yukon Gear Axle Seal For 9.5in GM

Stop Gear Oil Loss at the Axle Tube — Precision Fit for GM 9.5-Inch Differentials

The YMS3747 is a Yukon Mighty Seal rear axle seal engineered to the exact dimensional requirements of the GM 9.5-inch rear differential. A leaking axle seal is one of the most common causes of rear end gear oil loss on these platforms, and a worn or hardened seal allows gear lube to escape past the axle shaft and can contaminate the brake shoes or pads on the same side. The YMS3747 restores the factory sealing surface with a precision-fit design that seats correctly the first time, preventing the off-center installation that causes early failure on lesser seals.

The YMS3747 services one side of the axle. Order two to replace both sides at the same time, which is the recommended practice whenever the axle shafts are removed. Sold individually.

Key Features

• Precision OEM Fit — engineered to GM 9.5-inch axle dimensions
• Yukon Mighty Seal Construction — latest seal design for long service life
• Prevents Brake Contamination — seals gear oil away from brake components
• Sold Individually — order two for both sides
• 1 Year Warranty — against manufacturing defects

What's Included

• 1x Yukon Mighty Seal rear axle seal (one side)

Vehicle Fitment

Frequently Asked Questions

What is the difference between a pinion seal and an axle seal?
A pinion seal sits at the nose of the differential where the driveshaft yoke connects to the pinion gear. An axle seal sits at the outer end of the axle tube, where the axle shaft exits the housing toward the wheel hub. This is an axle seal. Both seal types retain gear oil inside the differential, but they are different components with different dimensions and replacement procedures.

Why does this seal service only one side?
Each axle shaft has its own seal at the outboard end of the axle tube. They are separate, individual seals and are sold that way. Because both sides typically wear at similar rates, replacing both at the same time when the axle shafts are already removed is the most practical approach. Order two seals to service both sides in a single job.

What does a leaking axle seal look like?
Gear oil will appear on the inner face of the wheel or brake drum, often accompanied by a burnt gear oil smell from the brakes. You may also see a wet residue along the bottom of the axle tube near the wheel hub. If the leak is severe enough, brake performance can be affected by gear oil contamination of the friction material.

Should I replace the axle bearing at the same time as the axle seal?
It is good practice. The axle bearing and seal occupy the same location at the end of the axle tube, and accessing one requires the same disassembly as the other. If there is any roughness, play, or noise in the bearing, replacing it at the same time avoids returning to the job shortly after. Inspect the bearing carefully while the axle shaft is out.

Does the GM 9.5-inch axle use C-clips or a retainer plate to retain the axle shaft?
The GM 9.5-inch semi-float rear uses a retainer plate bolted to the axle flange. The axle shaft is retained by the bearing and retainer plate rather than a C-clip, so the differential cover does not need to be removed for axle shaft service. Access the retainer plate bolts from behind the brake backing plate.

What warranty applies to this axle seal?
This seal is covered by a 1-year warranty from Yukon Gear against manufacturing defects. Under the Magnuson-Moss Warranty Act, installing this aftermarket seal does not void your vehicle manufacturer's drivetrain warranty on unrelated components.

Will this fit the Hummer H2?
Yes. The 2003-2009 Hummer H2 was built on the GMT800 platform and shares the GM 9.5-inch rear axle assembly with the Silverado and Yukon-based vehicles of the same era. This seal fits the H2 rear axle seal application as shown in the fitment table.

Can gear oil contaminate my brakes through a leaking axle seal?
Yes. If an axle seal fails and gear oil migrates outward along the axle shaft, it can reach the brake drum or rotor surface and contaminate the friction material. This reduces braking effectiveness and can cause pulling or grabbing. A failed axle seal should be addressed promptly, and brake components should be inspected for contamination at the same time.

What gear oil should I use after replacing the seal?
The GM 9.5-inch differential uses 75W-90 GL-5 gear oil. Full synthetic is recommended for extended service intervals. If a limited-slip unit is installed, add the correct friction modifier per the differential manufacturer's specification.

Installation Notes

• Raise the vehicle and support safely on jack stands. Remove the wheel and brake drum or rotor.
• Remove the retainer plate bolts from behind the brake backing plate and slide out the axle shaft carefully.
• Inspect the axle shaft journal surface for scoring or grooves that would cause premature seal failure on the new part.
• Remove the old seal using a seal pick or slide hammer with seal attachment. Do not damage the axle tube bore.
• Clean the seal bore thoroughly and inspect for damage.
• Apply a light film of clean gear oil to the seal lip of the new YMS3747 seal.
• Drive the new seal squarely into the bore using a properly sized seal driver. A driver that contacts only the outer edge of the seal prevents deforming the lip.
• Reinstall the axle shaft, retainer plate bolts, brake components, and wheel.
• Check the differential fluid level and top off as needed.
• Road test and verify no leaks after the first drive.

California Prop 65 Warning

WARNING: This product can expose you to chemicals including lead and lead compounds, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.