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Old 10-13-2014, 10:06 PM   #17
Tom Endy
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Join Date: May 2010
Location: Southern California
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Default Re: Evaluating rear axles

Quote:
Originally Posted by BILL WILLIAMSON View Post
Only a MAGICIAN could overfill a rear end!
Bill W.
It would be difficult to overfill the banjo on a Model A Ford on purpose because it is a fill to spill proposition.

However, there are two ways that banjos become overfilled:

The first is if the special flat washer that is used to attach the U-joint to the transmission main shaft is missing. See photo. This washer acts as a dam for oil that runs under the rear bearing along the shaft flutes. If the washer is missing or has been substituted for an ordinary flat washer the oil will continue on into the U-joint housing. It will continue past the grease seal behind the torque tube roller bearing , which is the same part number as those used in the axle housing. Oil can pass through this seal. If the seal is totally shot more oil will pass. The oil will continue down the torque tube and into the banjo.

The second is if there is a cottage industry modified Borg Warner overdrive installed. Most have a rear oil seal installed that is not an oil seal, but the same part number grease seal used in the axle housings. Oil will seep past these seals and enter the banjo.

If you have a Borg warner installed it is prudent to check the oil level in both the banjo and the overdrive about every 500 miles. If you discover the banjo is manufacturing oil it does not mean you are going to become rich. It means you will eventually starve the overdrive of oil and it will fail, and you will overfill the banjo such that oil will migrate out the axle housings and pass through the grease seals and saturate the brakes.

Tom Endy
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