Here recently, I had the pleasure of finding massive amounts of grit and grime all over the under chassis of my car near the rear. Upon more investigation. I seen that I had oil dripping from driveshaft yoke where it bolts to the rear pinion flange. Apparently, the excessive grit and grime was from gear oil being slung around from the pinion flange and allowing more "grit and grime" to build up.
Figured it was time to change the pinion oil seal. Points of interest
: This is not a very common seal to go bad, nor is it uncommon for it to go bad. I would rank it up there with a rear main seal, sometimes they do and sometimes they don't. Its one of those items that you may never have to change but it could happen. With that being said. If you have aftermarket gear sets in your car and you did not use a Ford branded pinion seal....well, now you have just increased your odds of having a rear pinion seal leak some day down the line. I will point out why during the install. Tools Needed: Inch Pound Torque Wrench Small Pulley Puller 12 point 12 mm Socket
...(best to have one in 1/2" drive) 1 1/16" 6 point socket
....(Yes, that's 1 inch and 1/16th) Seal removal tool
(this is completely optional but it saves a lot of time and only cost about $10.00) Ford 8.8 pinion Seal part# BR3Z-4676-A
(I highly recommend this seal, I wouldn't bother swapping it out with anything but this seal from ford. Even if you are doing a gear change...toss the seal in the gear install kit and buy one from ford or leave the factory seal in it) Paint pen or touch up paint Optional Tools Needed: Impact Gun Small Torch
I am not going to get into outlining how to raise and support the rear of your car and make sure it is secure and safe. But, you should make sure you have the car securely on Jackstands. If you don't feel safe with the way you have supported the car...redo it! BE RESPONSIBLE!
Skill Level Needed: This is not a task to take halfheartedly. You need patients and you need to fully understand what you are doing and what can be effected if you do it wrong. Plan out what you’re going to do and how you’re going to do it.
In this write up I performed a few extra task such as, changing out my rear gear oil, Installing new universal joints, and changing out my trans fluid. But, the topic of this post is the pinion seal.
*Below are the steps given in the book on how to change out the seal. I feel it is important to read this and wrap your head around what you are going to do. A few things to point out is the last step. This is the one step that gives everyone issue. It calls out to tighten the nut back down to a given "book spec" then keep tightening it down until you reach you recorded rotational torque. This is where I am going to point out....Disregard the last step! Ignore everything about a range. Your Task in this step is to put the pinion nut back on with the exact same reading....not a range....Not more and not less...The exact same as what it was before you removed it. I don't care if your rotational torque is 312.9 inch pounds....that's what you put it back at!
Book spec is a range and a very wide one. Though very light in regards to torque. A few things we are effecting when changing this seal is pinion bearing preload. This is the reason you should not change this seal if you do not fully understand what’s going on. The pinion nut that we are removing is the same nut used to set pinion bearing preload and collapse the "Crush sleeve" during a rear gear install. Many people have screwed up gear install because they could not get the pinion bearing preload correct. With this repair...We are not setting pinion preload but we are removing it and attempting to put it back where it was before we removed it so that the pinion bearing preload is the same as it was before we started.
1. Remove rear wheels and Brake Calipers
2. Mark the drive shaft and companion flange
3. Mark relationship between the pinion and companion flange
Using an inch pound torque wrench, measure and record the torque required to turn the pinion nut through several revolutions
4. Using a suitable tool to hold the pinion flange and remove the pinion nut
5. Pry out the oil seal
6. Clean the oil seal mounting surface and tap the new seal in place
7 Inspect the splines for burrs and nicks. Remove any rough area with a crocus cloth, wipe area clean
8. Install the companion flange, align the marks made during removal and tap gently with a soft faced hammer if needed.
9. Using a suitable tool, Hold the companion flange while tightening the pinion nut to the minimum torque listed in specifications (8-14 in lb) Continue tightening, take frequent rotational torque measurements, Using the inch-pound torque wrench, until the measurement recorded in step 3 is reached.
Lets get started!
As noted above, I did a few extra tings while changing the pinion oil seal. First I changed my rear gear oil. So that's what I will show here.
Remove the bolts for the rear cover. Use a flat head screw driver to pry open the rear cover and drain the fluid.
After you pry off the cover. You will want to use something to clean the mounting surface. I have a little handheld scarper that uses replaceable razor blades. Scarp the surface clear of all old gasket material and gasket sealer.
After I have the surface clean, you want to make sure you didn't leave any debris behind and you may want to reach in and drag out the left over oil in the bottom of the housing...it has a little pocket in there.
Now that you have it drained, cleaned everything...your ready to install the gasket and cover. I always use a gasket and silicone. Some just use silicone. I applied silicone to both sides of the gasket. No need to get crazy here and I always run my bead on the inside of the bolt holes as shown. Some people choose to run a bead around the bolt holes...either method is fine. I typically like to torque everything down in a star pattern or criss cross. Torque spec for the rear cover bolts are 28-38 ft lbs. But, if you don't have a torque wrench, Just run them down tight...but be careful...you can snap the heads off...so its best to use a torque wrench. At this point you can fill the rear differential back up with fluid. I didn’t because I am moving forward with changing out the pinion seal.
The differential pinion Seal.
First mark the Drive shaft and Companion flange. From the factory, your driveshaft will have a green or yellow paint on it. It may look like a dot and it may look like a strange blob of color. Your Companion Flange is suppose to have a green dot on it as well but, this can wear off in time. This is put on at the factory to help reduce vibration in your drivetrain with balancing and offsetting run-out. This needs to be lined back up. Hence, marking where it is at. Remove the 4 bolts holding your driveshaft yoke to the Companion flange. These are 12mm 12 point bolts and can be a bear to remove sometimes. I was going to try and show you how to remove it without an impact gun. Book says to slide a screw driver between the U joints to lock it while using tools to break the bolts free as seen in the picture…..but, after busting 2 sockets and 1 wrench. I tossed that idea and grabbed an impact gun. After a few minutes of that…I eventually had to grab my torch (little hand held one like in the picture) and heat the bolts then use the impact gun…Moral, these can be very hard to get off. I haven’t ever had as much trouble trying to remove these bolts before, All I can figure is…who ever did the gear install before I purchased the car had an impact gun that would run up to 500 ft lb..I don’t know but I do know…it was tough on this one. After removing the for bolts. You can slide the driveshaft into the transmission housing a little and support it up and out of the way with a jack stand. I went ahead and removed mine because I was changing Universal joints (really had no option now because I melted the grease boots on all my caps with the torch) and I was going to drain the trans fluid. Sooo, I drained the trans fluid and just pulled it out of the trans tail shaft and put it to the side.
Not going in depth on this. But, I took pictures because I was bored. Now that you have the drive shaft off and out of the way you can see the pinion nut. The first thing we want to do is check the rotational torque of the pinion nut. You want to make sure your brake calipers are unbolted and off of the rotors before doing this. I have what’s called an “I-Beam” inch pound torque wrench. This allows me to see where the needle points while I have the wrench on the pinion nut and turning it. You want to make a number of turns in one direction with the wrench. Recording the reading each time you do this. After you have the readings. You will want to mark the pinion and pinion nut for re-alignment later. I made marks on the pinion nut and companion flange for alignment then made marks on the pinion and pinion nut. I also made sure to put a mark on the companion flange spline and pinion spline that you will see later. You can only make this mark after the nut is removed and exposes the splines. Basically for me…I am putting the companion flange back on with the exact same alignment it had to the pinion…than I am going to line up my pinion nut to the alignment marks on my Companion flange. This has pros and cons…Pro is, the Companion flange has more surface area and is larger diameter. I can see it better. Con…if I don’t put the Companion flange back on in the exact location…it’s going to be all screwed up…..more room for error. But, as long as I put it back in the right location…I have a higher degree of success with alignment of the pinion nut going back where it was. You will see, I made a total of three marks using touch up paint. I wanted to make three marks that where a little offset. This will make it easier for me to know when I’m getting close to the previous location during reassembly. Inside of those paint lines I made an alignment dot. You may want to count the exposed threads on the pinion before taking the pinion nut off also. You pretty much want to do any and everything you can to make sure you know how to put this nut back on to where it was before you take it off. As you have already found out. The Nut is 1 & 1/16th”. Because I already gave up on not using an impact gun. I grabbed my impact gun and removed the nut.
Note in the picture below. Before I went to the next step, I marked the spline on the Companion flange and pinion! This is critical for the method I am using to realign everything. I used a pulley puller to remove the Companion flange after removing the pinion nut. Worked out well for me with no problems. After the Companion flange is removed you can remove the pinion seal. I used a seal removal tool (pictured below)….it’s not expensive and a lot easier than working at it with a screw driver. Just pluck it out. Here you will notice the difference between the seal I removed and the seal I purchased from ford. However changed my gear sets…put the cheap crappy seal that came with the install kit in it. You can see that the factory replacement has a seal on the outside of the seal housing and the inner seal is cupped outward rather than inward…like the one I removed.
New Ford seal on the left old seal on the right.
Installing the new seal can be a little tricky unless you have a “seal driver” handy. This is what I did. First I put my brake calipers back on my rotors and bolted them up. I didn’t bolt them up tight…I just threaded the bolts enough to allow me to apply my hand brake. After that, I went back under the car got the seal in placement. Grabbed my Companion flange, slide it on the pinion and used the pinion nut to get the seal to slide into the housing. I did not run the nut all the way down on the pinion. I just used the Companion flange to get the new seal started into the housing evenly. After I got the seal started on into the housing I removed the Companion flange and tapped lightly around the seal…working my way around tapping it down a little at a time until it was seated. Now you are ready to re-install the Companion flange and pinion nut. Grab your documented rotational torque readings and put it back together. I lined up my Companion flange to the mark I had made on the pinion spline. Then I put loctite on my pinion nut and started running it down. The book calls that you periodically check your rotational torque while tightening up your pinion nut. I tightened my pinion nut up until my marks lined back up than checked my rotational torque. This is also where it will come in handy to know how many exposed threads you had before taking the nut off. About the time I noticed the resistance of the pinion nut change and start getting tighter, I checked my threads exposed and seen it was only about a half a thread away from having the same amount of threads exposed as before. Then I looked at my alignment marks and noticed that I was only about a ¼ of a turn from having my marks lined up. So, now I know that I was where I needed to be to start lining up my marks. I still had not taken my brake calipers back off because I was using those to keep my pinion from moving. I went ahead and turned my nut until the dots had lined up perfectly on my marks I had made. After that, I removed my calipers again and checked my rotational torque with my inch pond torque wrench. It was at the same reading as before. Things to note using my method vs checking rotational torque while tightening up the nut. It didn’t matter what rotational torque was until I get the nut back where it was. If my rotational torque had been less then before…I would have ignored the marks and kept going until I reached what I had written down. If the rotational torque had been more then what I had recorded…oh well…so be it. I would have called it done and not backed it off. As I had said before, this nut was used to set the compression sleeve. The compression sleeve does not relax when pressure is taken off of it. That’s why…during a gear install…if you torque it down to far and don’t get it set right. You have to toss it and grab a new compression sleeve and start again. Same principle here. It can’t be backed off from where it was to begin with . You also can’t turn the nut down past where it was because you will be putting too much bearing pre-load on the pinion. You really don’t have to worry too much about compressing the compression sleeve, it takes a lot to compress…so, if you do compress the compression sleeve….You have really jacked things up! Again, while this can be rather simple to change. It can be very easy to screw up. And screwing it up can be detrimental to your rear end. After finishing the seal swap. Top off the rear gear oil. And put your driveshaft back in. As before you want to line the marks up on the companion flange and drive shaft. I did not use the marks I had originally put on mine. The factory mark on my Companion flange had been gone and I was just hoping who ever did the gear swap before lined it back up. But while cleaning up my Companion flange while it was off the car. I found what was left of the factory alignment dot on the backside of the flange. As it turns out. My driveshaft was off by one rotation. So I remarked everything to what the factory had and aligned it up. The driveshaft yoke to pinion flange (Driveshaft U-joint-to-pinion flange) bolts are spec’ed at 70-95 foot ponds of torque. Know, everything is finished up and ready for a test drive down the road….With luck, you will not have any weird whining sounds coming from the back and it will not explode!