Replace Shift Selector Seal

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On the Topic of Replacing the Selector Shaft Seal without dropping the valve body

seems like this is a pretty common problem, although the first time I had ever read about it was this weekend. There are some decent videos that use a special tool to remove the seal from above, and I found at least one write up of somebody who dropped the valve body and pushed the seal out from below, I did neither. Well, I wanted to use the tool, and I thought I found it at Napa for $8.99, but it ended up being the GM version which absolutely will not work.

Time to complete: less than an hour (not including time seal spent in the freezer prior to getting started)

tools needed:
* 12mm socket
* 7/16" socket
* various picks & flathead screwdrivers
* tiny bit of grease
* Transmission selector seal

Autozone had this as part #8609 but Napa had it as # 8017. I went with the Napa part, but the AZ one looked identical.


Step 0: put your new seal in the freezer.

Step 1: DONT drain the pan, don’t remove the front driveshaft, don’t disconnect the cooler lines. I mean, you can drain the pan, but it isn't absolutely necessary. If you're going to drain the fluid it probably means you removed the pan. At that point it might just be easier to drop the valve body as well. My goal was to NOT drop the valve body, although it's not as scary as it sounds.

Step 2: I already had my skid plate dropped for other repairs, but it’s absolutely possible to do this repair with the skid pate on. But it’s probably easier without it.

Step 3: remove the 2 bolts holding the cable brackets. The top bracket was 7/16” and the bottom bracket is 12mm. Because of course. It was really hard to get a good pic of this, but the pink arrow is the 7/16” and the blue is 12mm. They’re on opposite sides, but each bolt has a square but on the other end that holds it in place for you.

View attachment 266095

Step 4: slide both brackets off the selector switch. I had to do some gentle prying with a flathead screwdriver to get them to slide off. There was a lot of gunk up there, even after liberal use of brake kleen.

The picture isn’t great, but both brackets are on the shaft, and they only go back on one way. The top one can be flipped toward the rear & out of your way. Step 5 deals with the other one.

View attachment 266097

Step 5: also not completely necessary, but probably helpful was moving the shifter cable out of the way. On the rear of the bracket is a metal ring with expanding fingers on it to keep it in the bracket. Squeeze with pliers and it will pull through.

View attachment 266099

Step 6: remove the seal. This is where the tool would come in handy. But instead I started in with a pick and got some of the inner metal lip to pry up. I was as careful as I could be to not mar up the shaft. You should be even more careful.

Once I had it sufficiently f’d, I used a small flathead screwdriver and was able to get the entire seal out of the seat. It didn’t take long, but early in it seemed futile. Maybe this took 10 minutes? Probably not even.

Once you take the seal out, you start to get more ATF bleeding into the seal seat. I had a paper towel in there to absorb as much as possible before taking it out at the last second to put the new seal in. Maybe it doesn’t matter, IDK.

View attachment 266108

Step 7: put the new seal in. If you left it in the freezer long enough, it will help it go in easier. You’ll also need an appropriately sized socket as your driver. That fancy tool comes with one, but if you own a TJ and can’t improvise a seal driver....

Seal driver requirements:
* same outer diameter as the metal portion of the seal
* inner diameter big enough to slip over the shaft
* long enough that the upper tip of the shaft does not extend through the driver
* not so tall that you can’t bang on it from above.

for me, it was a 21mm 1/2” drive socket from Autozone. Had it been maybe 2mm shorter I would’ve had to use a deep drive and that would’ve been harder.

sorry, no pics of this part of the process, but it’s the easiest to figure out once you get to this point.

anyway, get your seal out of the freezer, grease the inner lip (I used some red grease, ATF will probably work too), slide the seal over the shaft (it will be snug), and slide your driver over the shaft & onto the seal. CAREFULLY and with great patience tap the driver as uniformly as possible to drive the seal into the seat nice and straight like. You’ll want it to be flush with the surrounding area, keep tapping until it is.

I used a 4 lb sledge and just lightly tapped it. Don’t worry, mine went in a little crooked, too. You can see it fully seated in the mirror

View attachment 266109

Step 8a: put it all back together. Pull the forward cable back through the retaining bracket till it seats. Then slide the selector cable bracket over the shaft. There is a flat spot on the back of the shaft that only allows it to go on one way.
Then feed the 12mm bolt back through and put the square bolt into the notch and tighten back up.

Step 8b: put the upper bracket back on. There are 2 pieces the tip of the shaft will feed through. The bottom part will fit through in any orientation. Then rotate the bracket so that the flat part of the upper shaft will fit through the upper part of the bracket. This took a little bit of patience, but once I finally had it in place it slid right on.
Put the 7/16” both through, square nut into the notch, and tighten down.

step 9: crack a celebratory Coors light, dry everything up, and wrap a paper towel around the area. Pray it doesn’t turn red.

There are other ways to do it, that was how I did it. This job ended up being much easier than I expected. The moral of the story is that if you have a leak that appears to be at the transmission pan, take your time and be 9000% certain it's not actually from this seal, especially if the problem arose after the car had sat for some time.
 
Since I just completed this a few minutes ago, here are my tips.

1. Getting out the old one is a bastard. It could take 5 minutes, it could take 60 minutes. You will absolutely mangle the old one getting it out. Expect that.
2. For getting a deep socket to drive in the new seal, make sure to get one that lines up with the outside diameter of the new seal. I went with a 7/8" deep socket and I think I might have slightly bent the inner metal while driving in the new seal. If I had a socket that was exactly the same diameter as the seal, or slightly under, I wouldn't have that concern.
3. The trans cooler line will get in the way of driving in the new seal. I used a piece of scrap wood (1x2) and wedged it between the bell housing and the cooler lines to push the lines out of the way. It actually worked pretty well, but I still hit the lines with my 3 pound sledge a few times. They are tough.
4. Use a heavy hammer. I used a 3 pound hand sledge hammer to drive in the new seal.

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Right now, I have the seal seated. I have sprayed everything with brake cleaner, and I'm waiting for that to dry. I'm going to let it sit for several hours to make sure there are no more leaks. Then, I'll put the skid back on, drive it around, and top off the ATF.
 
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Does that seal only press in or does it have some type C-clip that goes in after it’s installed? Just curious.
 
After doing this last night, I checked this morning and there is no leak. Hopefully I won't see a puddle of red fluid under my Jeep for a long time.
 
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That's fantastic. Nicely done, sir. You've already topped off the ATF? If so, it would already be leaking if it weren't sealing so I think you're good to go.
 
I haven't topped it off yet, but I'll do that soon. Whenever I popped the seal the other day, it was still leaking so I know that fluid was still above the level of the seal.
 
I haven't topped it off yet, but I'll do that soon. Whenever I popped the seal the other day, it was still leaking so I know that fluid was still above the level of the seal.

One thing I would love to understand is at what level within the trans case does the fluid sit at when the vehicle is off/cold? Particularly because if you remove the dipstick with it full of fluid youl'l learn the hard way that the fluid level is well above where the dipstick seals. But the selector shaft is roughly at the same hight as the dipstick seal, so why doesnt it just pour out when you remove that seal? And even ignoring that aspect, if there is enough for it to come out of the selector shaft hole, why does it only seep out and not rush out? For it to seep out at all would seem to imply that the overall level is above the height of the hole, but a basic knowledge of University Physics 1 would suggest that it would flow out quickly to equalize the pressure difference.

But what do I know.
 
You can't get a good seal with metal on metal. That's the purpose of the shift shaft seal. However, the tolerance between the metal pieces of that mechanism are pretty tight and therefore not that much fluid leaks out. I had the seal off of my Jeep for almost 24 hours and the catch basin under the trans had 0.5-1 quart of fluid in it. So, the physics within the transmission are pushing the fluid down and out, but because the "hole" in the shift shaft is pretty small, and the pressure behind it isn't that high, the rate that the fluid leaks out is pretty small. Once enough fluid leaked out that it got below the level of the "hole" in the shift shaft, it would then stop leaking.
 
Freezing it did not work for me and after fighting it for hours, ruining two seals I decided a “special tool” was needed.

I built this brace so that it holds center on the drain pan edges and carries the load of the c-clamp on the bolts. Dandy PVC nipple ground to fit the seal attached to a piece of pipe I had laying around, it clears the shift shaft and now I can knock this project out in about 5 minutes (after the old seal is removed). The c-clamp presses the new seal in straight and perfect.

I’ve done a few for others now and it works awesome.

PS- photo was taken with a transmission on the bench after the fact for a better view, the c-clamp and tool work great with the trans in the vehicle.

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