Leak at transmission speedometer cable connection

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gwittman

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I have a leak from the transmission speedometer cable connection. I looked in my BMW blue repair manual and the only section I can find that mentions this area is under "Speedometer pinion-Removal and fitting". The instructions are:
Detach speedometer shaft.
Remove bush and speedometer pinion.
Check string seal.
It has a picture showing removal of the bolt that holds the speedometer cable and housing to the transmission. I had already removed the speedometer cable and housing and what I removed looks different than what is shown in the picture. It appears I still need to remove the bush and pinion which must be what they are showing. I have no idea where this string seal is. Can anyone give me some insight on the process of replacing this string seal? The transmission is the original ZF that came with my 70 2800CS.
 
I got the bush and pinion out. The bush has an O-ring on the outside and is wedged in there pretty good. It took a little force to get it out. Then, of course, the pinion just fell out.
Dave, I think you are right about the typo. The seal inside the bush appears to be an O-ring with some kind of metal spring. I have not gotten it out yet but a sharp thin probe should be able to lift it and remove it from the groove it appears to be sitting in.
The O-ring on the outside of the bush looks to be in good condition, so I doubt that it where the leak is coming from. The internal seal seems to be fairly loose against the pinion shaft and is probably worn out from all those miles of rotating over the years. I am sure that is the source of the leak . I will try Mesa Performance to see if they can find a 'spring seal' replacement.
 
If you go into real oem e24 section early years there are 2 different seals shown one is just an O ring for the 265/5 transmission for approx $3 the other is for the 265/6 trans and is a $14 seal I found these under the E24 euro 1981 year transmission section individual parts so these apply to the 5 speeds. My thought is since the same pinion is used in the 4 speeds as the 5 speeds, maybe they might cross?? Just a thought
 
to be absolutely sure it wont leakw/ the new oring
sometimes i just find one thats close to orig like ac seals cheap a have a big bag of them
used a few on my e34 top heater hoses the snap in type
use a bit of weatherstrip adhesive
i do that when i dont want to fool with it anymore.
 
To remove the spring seal there is a tiny hole next to it, I simply destroyed the old seal with a small drill bit.
 
I got it fixed and for anyone interested, that seal is still available from BMW. I got mine through Mesa Performance and it cost $25. I probably could have found it cheaper but I like to support Jim whenever I can because he is a reliable 'go to' for Coupes and is just a few blocks from me. It looks like the part number is 24 21 1 200 139. It is not an O-ring, it is basically a very small lip seal with a metal outer.

Getting the old seal out was the biggest problem. The seal is pressed in and I could not get a small hook to pull it out. Chris's hint was a great help. I was afraid to use a drill bit because of the risk of damaging something. That small hole appears to be there to help lubricate the gear shaft and seal. My seal was just barely visible in that hole so I just took a pin the size of the hole and tap it moderately hard. That bent the metal outer inward and reduced the diameter of the metal. I reached in with a hook again and it pulled right out.

I wanted to make sure I could get the new seal passed the slot for the bolt that holds the bushing in place. I used various size pins to check it and found there was a couple burs at that slot. I used a dremmel with sand paper and was able to eliminate the burrs. I still had to open that are a little so the seal would freely pass the slot before it became a press fit. I used a pin about 0.001" smaller than the press fit area diameter. I wanted to make sure I didn't collapse the seals metal housing. With light pressure in an arbor press. that pin pushed the seal in nicely until I could feel it bottom out. I checked the oiling hole and the seal was in the same place as the old one. There is a O- ring on the outside of the bushing and I replaced it too. The old one was still in good condition but replacing was good insurance of not having to go back in there anytime soon. I topped the transmission off with oil and it is ready to go.
 
I performed this task about 6 years ago on my E3. I do recall getting the specs from RealOem and then matching it. X-section and ID/OD was enough to match. Bought a batch of 5 for 10 bucks, sent one to a Forum member, the other three, they are somewhere.
 
Of course, when I tried to remove the tiny shaft seal, I ruined the circled part below, which is not available anywhere.

:(

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