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Discussion Starter #1
After having a bear of a time getting my rear main seal out, using a combination of vise grips, hammers, slip-joint pliers, and other odds & ends, I went back to this forum for some advise. As richdude suggested on this thread, I switched to using a simple slide-hammer dent puller and some carefully-drilled holes for the seals on the transmission. WOW, what a difference!! :yeah: They took a fraction of the time and came out without putting up a fight at all.

I thought I'd post some photos of how it all went down.

First, here's the WRONG way to do it... Long rod with a 2" steel dowel pin inserted in a hole across the tip of the rod, vise grip clamped on to the other end so I could beat on it with a hammer. All it did was tear up the seal, as did the improvised "seal puller" tool I had tried earlier, made up of a bent nail & some vise grips:

Eventually, all of this nonsense had the seal so chewed up that I was able to get a vise grip on one of the torn up edges and yank the seal out:

Now, here is the way it worked so much better for me:

First, use a spring-loaded center punch to set a mark on the very center of the face of the seal. Easiest way is to put the mark right where one of the little depressed "dots" is. Getting a good center punch mark is critical to ensuring the drill bit doesn't wander off, where it can easily dive through the rubber part of the seal and mar either the shaft or the housing - MAJOR mistake there.

Then, use a 1/16" drill bit to slowly and carefully drill a hole through ONLY the top face of the seal. You have to be very careful that your drill chuck doesn't mar the housing bore or the shaft, especially when the drill bit breaks through the seal surface. Also, don't let your drill bit dive too far when you break through, or you'll hit the bearing behind the seal (roughly 1/4" away on the tranny seals, a bit more on the engine rear main seal).

Follow up with a 7/16" drill bit and enlarge the hole slightly. Don't try to start with the 7/16" bit or you'll wander off center and damage something. Again, be careful not to let your chuck hit the housing or let your bit dive too deep.

Once that's done, insert an appropriately-sized screw into the end of your dent puller (I got mine for under $10 at AutoZone), thread it into the hole, and a few light taps will pull the seal right out!

On the clutch (input) side of the transmission input shaft, there is a felt facing that you have to dig away before you expose the drilling surface. Again, be patient and use care so you don't gouge into the aluminum housing with your screwdriver:

I was able to get the lightly-lubricated input shaft seal on the output side of transmission (where the clutch slave cylinder goes) started just using a couple fingers - then following up with a deep well socket and a claw hammer to tap until it was seated to the proper depth (the old one was at 1.533"). No special seating drift pin required (despite claims to the contrary by both the BMW and Clymer manuals). As many have said before, don't seat this seal any deeper than the original seal, or you will seat it past a small slot cut into the seal bore, resulting in a huge leak of tranny fluid back along the clutch rod into your clutch!

On the clutch side of the input shaft, make sure you tape up the splines with electrical tape, lube the tape with oil, and the seal will slide right into place. Seat to the measured depth with a socket, as with the seal on the other end.

Hope this helps someone! It really made a huge difference for me, now replacing seals is quick & fun! (uh, that is, assuming your transmission is sitting in front of you on a workbench ;) )

6,285 Posts
Ya' know for a 5 year old kid you're pretty durned good with them tools!

Very schweet tech, Mr. Schweintechnik! ;)

And since you're an Engineer, and I'm a Commercial Hot Air Balloon Pilot - I've got a good story for you:

Ron is flying a hot air balloon and realizes he is lost. He reduces height and spots a man down below. He lowers the balloon further and shouts, "Excuse me, can you tell me where I am?"

Schweintechnik yells back: "Yes, you're in a hot air balloon, hovering 30 feet above this field. "

"You must be an engineer", says Ron.

"I am", replies Schweintechnik. "How did you know?"

"Well", says Ron, "everything you have told me is technically correct, but it's of no use to anyone."

Schweintechnik says, "You must be in management."

"I am", replies Ron, "but how did you know?"

"Well", says Schweintechnik "you don't know where you are, or where you're going, but you expect me to be able to help. You're in the same position you were before we met, but now it's my fault!"
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