DIY: Front Differential Pinion Seal Replacement

Recently I noticed a small oil leak coming from my front differential, I figured it was the pinion seal so I called a few places and was quoted $800-$900 for a crush type bushing and $200-300 for a solid bushing. Since my truck had been re-geared I knew it had a solid bushing installed.

I didn't have the right tools to complete the job so I contemplated whether paying to have it changed or do it myself. The second option seemed like a better choice so I decided to buy the tools instead.

After researching for a solid 2 weeks I decided to pull the trigger. As a side note, the clowns on YouTube were not much help with instructions for the repair.

Tools:
- 14mm wrenches and sockets
- 3/8 in. drive ratchet
- 30mm impact socket
- 5mm hex bit socket
- Impact wrench
- Seal puller
- Steering wheel puller
- Torque wrench
- Crescent wrench
- Rubber mallet
- Ball peen hammer
- Center punch

Misc:
- 80w-90 Amsoil gear oil (2 quarts)
- Retainer bracket
- Aluminum bar
- Marking Paint
- Gray automotive RTV
- Rubber safe PTFE grease
- Red Loctite
- Toyota OEM pinion seal part #90311-41009

Step 1
-Remove the front differential filler plug with a 5mm hex bit socket. Be sure to remove the filler plug first. If you cannot remove the plug stop now and don’t proceed to step 2. You will need to remove the plug somehow or take it to a shop for removal.

Step 2
- Make sure to scribe a line across the drive shaft and the pinion flange so that it goes back on in the exact same location. The last thing you want is to add drive shaft vibration. Remove the (4) 14mm front drive shaft bolts.



Step 2
- Move front drive shaft to one side.



Step 3
- Un-stake the pinion nut



- Here is the pinion nut un-staked.



Step 4
- Paint a line across the pinion shaft, pinion nut and flange. Also add a retainer bracket to the flange to keep it from rotating while removing the nut.



Step 5
- Remove the pinion nut with an impact wrench and a 30mm socket. The Bostitch made quick work of the nut. I highly recommend this impact wrench for the price, it has plenty of good reviews, model BTMT72391.



- Here is the pinion nut removed.



Step 6

-Remove the pinion flange with a steering wheel puller.



- Here you can see where the seal was leaking gear oil.



Step 7

-Remove the front differential drain plug with a 5mm hex bit socket and drain all gear oil. (sorry no pictures)

Step 8

-Remove the pinion seal, be careful not to damage the pinion spline teeth.





- Here is what the differential looks like with the seal removed. You can see oil slinger from this view.



- Here are the two seals side by side. The one that came with the Nitro master kit feels like a harder compound with less elastic memory than the Toyota version.





- Here is the part number from Toyota. I recommend you use the Toyota OEM pinion seals if you decide to re-gear your truck. The one from Nitro only had about 1000 miles of use over the last 3 years.



Step 9

- Lube the new seal with rubber safe grease, be sure to add grease to the recessed area of the new seal where it will contact the pinion flange and the outside diameter surface where it contacts the differential.

- Also make sure to pack grease around the small spring on the backside of the seal. This will help prevent the spring from popping off when seating the new seal. (sorry no pictures)

Step 10

- Install the new seal on the differential, you can begin pressing it on by hand. Make sure that it goes on evenly. You will want to make sure the seal is seated all the way to just below the inside shoulder as shown by the yellow arrow in the picture below.



- I used a flat piece of aluminum bar stock to lightly tap on the seal until it was seated, see picture below.



Step 11

- Inspect the pinion flange for wear. If you notice a recessed step where the seal contacts the flange you will need a new flange, see picture below.



Step 12

- Add a small bead of RTV sealant to the flange as outlined by the red circle in the picture below. Also be sure to add a small coating of grease to the remaining teeth on the opposite side of the flange.




Step 13

- Install the flange onto the pinion shaft. Be sure to line up the two marks you painted on earlier. Tap on the flange with a rubber mallet and try to seat as far as possible.

Step 14

- Install the retainer bracket to the flange again to keep it from rotating. Next install pinion nut, add a few drops of Red Loctite to the threads and tighten with your impact wrench. Be sure to tighten just enough so that the painted marks all line up.

Step 15

- Stake the pinion nut with a punch and a ball peen hammer.

Step 16

- Install your front drive shaft and torque the 4 bolts to 65 ft/lbs. Be sure to line up the scribe marks you made earlier.

Step 17

- Install the lower drain plug on the front differential and torque to 48 ft/lbs with a 5mm hex bit socket.

Step 18

- Make sure the truck is level and fill the front differential with 80w-90 gear oil, approximately 1.59 quarts or until it starts to run out of the fill hole.

Step 19

- Install the filler plug on the front differential and torque to 29 ft/lbs with a 5mm hex bit socket.

Step 20
- Crack open an ice cold beer and enjoy it you’re done.

RJM

 

Have you ever replaced the pinion seal on the rear differential???

 

The rear is still holding up well so I havent replaced it yet. It should be the same procedure but easier since the flange will not rotate freely with the tires on the ground.

RJM

 

Awesome info and great detail. Much obliged.

 

Great write up! Would this be the same for a transfer case output seal?

 

DOes that part number for the pinion seal work for 2019 Tacomas?

 

Anyone know what the torque is on the pinion nut? The front diff has crush washers so don’t want to over torque.

 

Really late replay but I just used nail polish to mark the pinion nut to get it back to where it was before I removed it.

-RJM

 

My issue was it came loose and didn’t get a chance to find The previous measurement. Happened a few more times so I’m going with a solid spacer to not worry about preload so much.

 

Great write up .
The picture in step 12 showing the pinion flange groove where the seal rides can be fixed with a speedy sleeve .
Measure the thickness of the pinion shaft and call a machine shop for the proper size speedy sleeve . Using loc tite , press the sleeve on .Speedy sleeves go on very easy and cost about 30 bucks .
This will save you from purchasing a new pinion flange $$$$$$$$.
In some cases , there is enough room for a metal clad seal with 2 sealing surfaces and 2 garter springs that can eliminate pinion flange leaks if a single seal cant do the job well enough .

 

could you not have engaged 4wd, put the front tires on the ground then torqued the nut?