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R1100RS Transmission Input Seal Leak - Questions


Jim Moore

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HI Guys,

 

Looks like my newly-installed 100K mile transmission has an input shaft seal leak. After a 100 mile test ride there is gear oil running down the seam between the engine and the tranny, and a few drops on the floor. Looks like I'll get another chance to perfect my transmission R&R technique. Yay me!

 

A quick search has led me to believe that I can pull the seal from the outside. I have a bad transmission to practice on, so I have that going for me. Any tips on pulling the old seal or installing the new one?

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Morning Jim

 

Make sure that the input shaft is not loose in the front bearing causing the seal to leak.

 

Also, after seal removal inspect the input shaft for grooving/scoring where the seal lip rides & if bad try to position the new seal to not run on the same area of the shaft.

 

I would also recommend replacing the shifter shaft seal & output shaft seal while you have the trans out, if one seal is leaking then the others might not be far behind (LOTS! easier now with the trans removed)

 

Is the trans vent plugged with old oil residue or crud?? if so then maybe that is causing your front seal to leak. (it wasn't plugged of for shipping was it???)

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Morning Jim

 

Where is the vent?--- see picture below (also look on your old trans)

 

Can I see it with the engine installed? ---sort of, as you can see from the picture it is well tucked up under air box.

 

At least you will get to the vent before needing to remove trans from engine.

 

1100s%20trans_zpstkwwyamv.jpg

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Thanks. I went out and found it on my old one.

 

As far as the input shaft, I assume No Movement = OK, Any Movement = Bad?

Edited by Jim Moore
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Morning Jim

 

I went out and found it on my old one. ---(yes, it's pretty big)

 

As far as the input shaft, I assume No Movement = OK, Any Movement = Bad?--- that pretty well covers it. Any more than very very slight movement if the fore/aft or lateral direction is bad .

 

If you suspect the vent as being plugged you might rig up a rubber stopper with a hole in it to fit the upper trans fill plug hole then use a hand pump (with a gauge on it) to lightly pressurize the trans innards. If the trans hold air pressure then the vent is plugged, if it doesn't hold air pressure that the vent is open.

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OK, the transmission is out, the input shaft bearing is bad. I have fore and aft and lateral play. I think I'm gonna be sick.

 

Here's my first thought. I have another transmission sitting here. It's bad, but it has a good input shaft bearing. What do you think of pulling the face off my bad transmission (good bearing) and putting it on my good transmission (with the bad bearing)? Does the transmission face just pull off after you heat up the two spots on the case?

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Evening Jim

 

Personally I would much rather just put a new bearing in what you have.

 

If you switch end housings then you will have measure & set up all the shaft end plays & that is a PAIN.

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I was wondering about that. Is it simply a matter of pulling off the face and replacing the bearing if I don't change anything else?

 

Evening Jim

 

Sort of--

 

You really should check the input shaft fit or end play after replacing the bearing but the chances are low that JUST a new bearing will make a lot of difference.

 

At the every least mike the bearing thickness on your old bearing & new bearing (use a micrometer not a caliper) & if the thickness is the VERY SAME then probably no need to do any further checking.

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Wish me luck. I'm goin' in!

 

Hey, DR you've been a huge help on this project and a lot of others. I have one more question if you don't mind. I think the bearing I need is item #7 on sheet 23-0753 of the max bmw fiche (link below). The part number is 23 12 2 325 518. Does that sound right?

 

Thanks again,

 

Jim

 

http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51676&rnd=07012015

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Hi DR,

 

I had another thought. As I looked around last night I realized that the bearing will be on the input shaft after I pull off the transmission face. I was picturing the bearing resting in the face itself. Now the thought occurs to me that I could pull the good input shaft out of my bad transmission and install it in the good one.

 

I hope I'm not driving you nuts with these questions. I'm really just thinking out loud here. You can probabaly tell from my questions that I really have no idea what I'm getting myself into.

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Morning Jim

 

Yes you could--BUT, then you would have to check/set the end play as there is no way to know if the case bearing bore positions are EXACTLY the same spacing on both trans cases. (one could be shimmed differently than the other)

 

The other thing is you will be putting a used (worn in) gear from one input shaft to mate with the used (worn in) intermediate shaft gear on the other. --might work just fine & might sing like a canary (you just never know)

 

On that Amazon bearing in above post?-- That should work OK but it is sold as a C-3 spec bearing (that "C-3" is bearing clearance or tightness). BMW has never published their bearing "C" spec so no real guarantee that the "C" ratings are the same. C-3 is a very common middle of the road bearing tightness spec so your OEM was probably a C-3 but that isn't anything I would bank on.

 

I think I would pull your trans apart before ordering anything as you just never know what you will find wrong inside (if one bearing is bad than maybe others are also)

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OK, the input shaft is out! I have some questions, but first, a story.

 

"Heat, heat, heat ... tap, tap, tap. Heat, heat, heat ... tap, tap, tap. Hmmm. HEAT, HEAT, HEAT! TAP, TAP, TAP! Oh look, two more bolts! And off comes the cover!"

 

First question, I have a tapered roller bearing on each end of the input shaft. The "rollers" are both very loose and wobbly. It doesn't feel right, but I don't know what it's supposed to feel like, but I assume it should be tight. Yea? No?

 

Second, as I was fiddling with getting the cover off, a ball bearing suddenly appeared out of nowhere from under the transmission. The tranny was still closed at that point. Any ideas?

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Afternoon Jim

 

Any idea on what BMW model & year that trans came out of? (sounds like you might have a pre-clean bearing trans.

 

On that bearing that suddenly appeared-- a picture would possibly help us identify it. Bearing ID, OD & thickness would also be nice.

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It came out of a 94 RS. Looking at the documentation, I think you're right, I have old-style bearings on both ends. Which leads me to another question. One of the beauties of the old style bearings was that you can pull the input shaft without pulling the other two. I think if I put a clean bearing on the bottom of the input shaft I will need to pull the other two shafts and replace them as a group. I wonder it I can find a tapered roller bearing?

 

My earlier description was bad. The mystery ball looks like a plain ol' BB.

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Afternoon Jim

 

Sure, could be from there, just look in end of shift drum when its apart to see if that ball is missing --Also see if that found ball will fit there.

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Hi Folks,

 

A few more questions, if you don't mind. First, how do you remove the selector drum. I have the shift forks out of the way, and I have the drum lined up correctly, but it won't budge.

 

Second, one of the transmissions I'm playing around with has no fewer than eight shims on top of the input shaft bearing. Plus the spacer. That seems like a lot. Yes? No?

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Evening Jim

 

On the shift drum-- do you have the pawl lined up with the recess in shift drum? If so then it should come out but you might have to turn/twist it a little as you try to remove it.

 

That does seem like a lot of shims-- are they all real thin? Maybe at assembly they were out of thicker shims & needed to use a couple of thinner ones to equal a thick.

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Yes, I have it lined up correctly. I can see the triangular cut in the bottom of the drum. I have it lined up with the pawl. It ain't budging. Like ... ain't budging with a crowbar.

 

The shim stack is over an eighth of an inch thick. Some thick, some thin. It was an M93 rebuilt with clean bearings.

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Evening Jim

 

That clean bearing conversion is probably the reason for the extra shims.

 

On the selector drum removal-- I really don't know what to tell you.

 

If ALL the shift forks are disengaged from the drum & the notch is lined up then about all I can think of is maybe trying heat on the stuck end to see if that will free it up.

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Thanks again. The thought occurs to me that all I'm really trying to do is pull the input shaft to use in another transmission. It looks to me like I can remove all three shafts without removing the selector drum. Does that sound doable?

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Morning Jim

 

Yes it does.

 

I haven't ever done it that way but as long as shift forks are swung clear of the shift drum (& stay clear of the drum) then I see no reason why the gear shafts won't come out past the drum.

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Hey, that sentence in the book from three pages ago. The one that said "Remove shifter drum retaining clip." That was a pretty important step. LOL at me again.

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Hi Jim - that BB sits in the neutral stop on top of the selector drum.

 

132481620.jpg

132559300.jpg

 

It's the last thing that goes in before the cover goes back on. And it likes to bounce across the garage floor and hide in dark corners of the garage when exposed to light. :dopeslap:

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Thanks Limecreek. Quick question. I thought it went into the hole in the transmission face, followed by the spring and the small bolt.

 

It's been a while since I had mine apart, but the ball sits on top of the drum, then the cover goes on and then the spring and retention bolt.

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OK, I'll have to keep pondering that one. Another question. How did you deal with the spring on the shifter? Do you just stuff it into the case as you push the lid into place?

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Afternoon Jim

 

If you try to put that ball on the shift drum star before assembling the trans you will have to be very sure the trans stays in neutral (very difficult to do as the roller detent will try to turn it to a gear position).

 

Sounds like a good way to have that ball fall free & roll around inside the trans as you push the housings together with sealer on the surfaces (personally I hate to pull them back apart with wet sealer applied)

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HI Guys,

 

I'm ready to put the lid on this thing. I have two questions. One of the transmissions had sealant around the seam. The other one didn't. So, sealant, or no?

 

Second, I'm not quite sure how to handle the spring arm on the shifter. The book says to "pre-load" it and shows it being pressed with a screwdriver. Do I just push it in as I close the cover? I seem to remember reading about someone doing something with a zip tie, but I'm not sure what to do. Anyone ideas?

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Morning Jim

 

I presume when you say seam that you are talking about sealer between the case half's?

 

You need something between the case half's or it will leak oil like crazy.

 

BMW calls for Loctite 573 (that is an anaerobic sealer)-- personally I use an anaerobic sealer very similar to the Loctite 573 but it isn't available to the general public (probably not any better just easier for me to obtain).

 

In the past I have also used gray Yamabond (sp) but prefer the anaerobic sealer if I have it handy.

 

On the spring-- I just push it with a long screwdriver (seems to work OK)-- there might be some better way but as a rule I don't change from something that works for me.

 

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OK, the transmission is buttoned up. The spring was a no-brainer. It just pushed into place. I used some sealant so hopefully it won't leak.

 

Note that I didn't say "it's fixed" or "it's gonna work." I have no idea. But it's been interesting.

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