Slip Yoke Seal and Transfer Case Replacement

Replacing the slip yoke seal on your truck or SUV is a pretty easy job if you’re used to working around driveline components.  If you’re not, let’s start by talking about how driveshafts work!

What is a Slip Yoke Seal?

The slip yoke is the part of your driveshaft that connects the driveshaft to the output shaft on your transfer case or transmission.  The slip yoke seal is the seal that allows that yoke to move in and out while still keeping the transmission or transfer case fluid sealed inside.  These seals tend to leak more often than others because they are sealing against the rotational and lateral movement of the shaft.

Due to the relatively short life of these seals, many trucks and SUVs use a fixed yoke.  Since your driveshaft still needs to get longer and shorter as your rear axle moves up and down there still needs to be a slip joint somewhere.  Vehicles with a fixed yoke will incorporate this slip joint into the driveshaft.  While this allows your yoke seal to last longer, it makes your driveshaft much more expensive.  With this type of driveshaft, there also isn’t any worry of the slip yoke slipping all the way out of the transfer case so this is often the choice of off-road vehicles looking to maintain maximum reliability in sticky situations.

You’ll notice in the video above that this Xterra has a cap at the end of the yoke which was leaking.  Many yokes are designed this way to save manufacturing costs but they do add an extra leak point.  If you’ve got oil slung under your vehicle but the seal in your transfer case or transmission isn’t leaking, then this is probably your leak point.  Luckily a little bit of sealant can keep you leak free!

Once you’ve got your driveshaft off, we do recommend going ahead and replacing that seal in your transmission or transfer case as it will most likely get damaged when you remove your driveshaft.  Also, it’s an inexpensive part and it’s quick to replace once you’ve gotten your driveshaft out.  Also, it’s a great idea to inspect and possibly replace your u-joints while you’re here.  For a more comprehensive description of u-joint replacement, check out our Live Leak Free Under the Hood video about that!

Helpful Hints

-Using an impact gun on driveshaft mounting bolts can save a lot of time and busted knuckles!

-Be very careful when you’re pulling the driveshaft out of the transfer case or transmission, you may be able to save your seal!

-Have a drain pan ready as a little fluid always comes out when you remove the slip yoke.

-Clean the sealing area on the driveshaft before reinstalling it.  Check the seal area for wear or pitting and use a shaft repair sleeve if it’s necessary

-If your u-joints have grease fittings, squeeze a little new grease in after you’ve got the driveshaft reinstalled

-Don’t forget to subscribe to the Live Leak Free channel for more great Under the Hood videos!