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How To Replace A Yoke Seal

Posted in How To: Transmission Drivetrain on November 1, 2012
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If you are like us, you probably hate seeing leaks under your rig or the smell of gear oil hanging heavy in the garage air. Many times a situation like this can be traced back to a leaky yoke seal, which is a fairly common problem. We wanted to show you what exactly goes into a yoke seal replacement, so we contacted Tom Wood’s Custom Drive Shafts in Ogden, Utah ( for some pointers and headed down to Off Road Evolution in Fullerton, California, ( to show you what it takes to swap one out.

To give you a better idea of what parts are involved in a yoke seal replacement and how they interact with each other, here is a cutaway photo of a differential. As you can see, the crush sleeve (yellow), sits on the pinion and spaces the head and tail bearings. If your differential uses a solid spacer, it would replace the crush sleeve in this picture.

Replacing the yoke seal will require removing the pinion nut, which releases tension on the crush sleeve. This is important to know because the crush sleeve sets the preload between the pinion’s head and tail bearings. With not enough preload, the pinion will thrust sideways under load and destroy the ring-and-pinion gear and with too much preload the bearings can burn up and seize. Setting the crush sleeve is simply compressing it lengthwise, until it is the length required to properly preload the pinion head and tail bearings.

As an alternative to the crush sleeve, some differentials can use a solid spacer. This solid piece of machined steel is a bit shorter than a crush sleeve’s crushed length and is used in conjunction with shims. Shims bring the spacer to the correct length, allowing it to set proper bearing preload, just as a crush sleeve would. Solid spacers have several benefits over crush sleeves, such as having the ability to be reused. Also, with a solid spacer, once it is set up, it is set up for life and you won’t have to worry about over tightening the pinion nut when replacing a seal or yoke. Lastly, the solid spacer is not vulnerable to rock hits against the yoke the way a crush sleeve could be.

We began our yoke seal replacement after finding an old Dana 35 housing at Off Road Evolution. First, the pinion nut is removed and then the flange is taken off using a puller.

Because solid spacers are direct replacements for crush sleeves, you can easily set up your pinion with the right parts. Companies, such as Dynatrac (, carry solid spacers in stock for anyone wanting to make the conversion. Read on to learn more about yoke seals, crush sleeves, and solid spacers.

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