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Discussion Starter #1
So just back from a 700 mile trip and noticed some sea page at the FD, see pic. We are planning a longer trip in a couple of weeks and wonder if things will just get worse?
 

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From that location, it can be one of two things. The transmission output shaft is leaking or the FD input shaft seal is leaking. This does not look like the classic crown bearing failure as that would be leaking from the big seal under the rear wheel all over. No, this will not get any better so I hope you are able to take care of it before your trip.

Pulling the final drive may give you the direction you need to go. If you see a trail of oil running down the inside of the swing arm then it is likely the trans output shaft. If not, then it could be the FD input shaft seal or possibly the nut is loose on the pinion shaft allowing the seal sleeve to ride up and leak.
 

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Discussion Starter #3
From that location, it can be one of two things. The transmission output shaft is leaking or the FD input shaft seal is leaking. This does not look like the classic crown bearing failure as that would be leaking from the big seal under the rear wheel all over. No, this will not get any better so I hope you are able to take care of it before your trip.

Pulling the final drive may give you the direction you need to go. If you see a trail of oil running down the inside of the swing arm then it is likely the trans output shaft. If not, then it could be the FD input shaft seal or possibly the nut is loose on the pinion shaft allowing the seal sleeve to ride up and leak.
Wow, quick reply! That is what I thought so it looks like I need to shut it down for the season until these items are addressed. Just when I thought all was good to go.... bummer!
 

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Also take a look at the rear brake line. Mine line developed a leak and it looked like the FD was leaking.
 

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Discussion Starter #5
Also take a look at the rear brake line. Mine line developed a leak and it looked like the FD was leaking.
Just replaced those with Spielers...
 

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2005 K1200LT
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Clean the area up real good with a degreaser, then loosen the clamp and pull the boot back from the swing arm. That will tell you a lot when you look in there. I had some oil there a while back and it turned out to be decomposed grease from my new pivots that can be externally greased. I know you won't be that lucky but at least you will know how bad the leak is by how much oil is pooled in there.
 

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Wow, quick reply! That is what I thought so it looks like I need to shut it down for the season until these items are addressed. Just when I thought all was good to go.... bummer!
If you know what you are doing, it is a couple hours work for either of those seals. The output shaft is easier than the pinion seal even though it requires pulling the swing arm. To tighten the pinion nut, you have to have a jig to lock the crown wheel in place as it is one of those high torque nuts plus you need a non hardening sealer for the threads of the castle nut and a castle nut socket. The FD pinion seal is in the castle nut itself so, although requiring some special tools, it isn't difficult. The Trans output shaft is more troublesome as there is an oil hole just beyond the seal lip and if you seat it only a tiny bit too deep, it will leak like a faucet. Ask me how I know. You can see the oil hole in this picture and a properly seated seal just flush with the housing. Actually I think it is only recessed 50 thousandths based on Scouter-50's tool drawings but flush will work just fine. You can also see the castle nut with the seal in it along with the sleeve that can leak if the nut is loose. Removing the pinion is not necessary for if the seal is leaking but cleaning the sealant off the housing threads can be difficult but not impossible just making sure any debris doesn't find its way into the bearings.
 

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Discussion Starter #8
Clean the area up real good with a degreaser, then loosen the clamp and pull the boot back from the swing arm. That will tell you a lot when you look in there. I had some oil there a while back and it turned out to be decomposed grease from my new pivots that can be externally greased. I know you won't be that lucky but at least you will know how bad the leak is by how much oil is pooled in there.
Thanks John, I have been keeping an eye on this as there was less than a teaspoon of oil at the boot when I first got the bike 2 years ago. It has been fine since but yesterday’s two-up fully loaded long ride may have been the true test.
 

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Discussion Starter #9 (Edited)
If you know what you are doing, it is a couple hours work for either of those seals. The output shaft is easier than the pinion seal even though it requires pulling the swing arm. To tighten the pinion nut, you have to have a jig to lock the crown wheel in place as it is one of those high torque nuts plus you need a non hardening sealer for the threads of the castle nut and a castle nut socket. The FD pinion seal is in the castle nut itself so, although requiring some special tools, it isn't difficult. The Trans output shaft is more troublesome as there is an oil hole just beyond the seal lip and if you seat it only a tiny bit too deep, it will leak like a faucet. Ask me how I know. You can see the oil hole in this picture and a properly seated seal just flush with the housing. Actually I think it is only recessed 50 thousandths based on Scouter-50's tool drawings but flush will work just fine. You can also see the castle nut with the seal in it along with the sleeve that can leak if the nut is loose. Removing the pinion is not necessary for if the seal is leaking but cleaning the sealant off the housing threads can be difficult but not impossible just making sure any debris doesn't find its way into the bearings.
Thanks Gordon. I have greased splines on a similar configuration R1150GS which, as you know, requires tranny removal, but never replaced this seal. Is it only available from BMW, and how is it pulled out without special tools? The other thought is whether other seals are in need of replacing while in there this deep? Thanks again for your help.
 

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Thanks Gordon. I have greased splines on a similar configuration R1150GS which, as you know, requires tranny removal, but never replaced this seal. Is it only available from BMW, and how is it pulled out without special tools? The other thought is whether other seals are in need of replacing while in there this deep? Thanks again for your help.
You don't have to pull the transmission for the output shaft seal, only the swing arm. Seals are available from several places. The output shaft is a 25X40X6 OEM but you can use a 25X40X7and install it flush with the housing and there is plenty of room to still drive it too far in :)

Amazon sells the 25X40X7 in several flavors. Buna and I see one in Viton.

https://www.amazon.com/25X40X7-EAI-...=seal+25x40x7&qid=1562678277&s=gateway&sr=8-3

https://www.amazon.com/uxcell-Nitri...=seal+25x40x7&qid=1562678727&s=gateway&sr=8-2

The FD pinion seal is 35X47X7 and is also available on Amazon

https://www.amazon.com/Grease-35X47...s=gateway&sprefix=seal+35x47x7,aps,154&sr=8-3

https://www.amazon.com/uxcell-Auto-...s=gateway&sprefix=seal+35x47x7,aps,154&sr=8-1

The removal of the trans seal usually requires the use of a small drill and a screw to pull it out being very careful to NOT drill into the side of the case which happens often. If it is the the castle nut with the seal in it you can pry out with some effort being careful to not damage the threads on the outside and then drive in the new seal. If you were pulling the trans out, I would say do the other seals in the clutch area but that is a lot of extra work if they are not currently leaking.
 

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Discussion Starter #11
You don't have to pull the transmission for the output shaft seal, only the swing arm. Seals are available from several places. The output shaft is a 25X40X6 OEM but you can use a 25X40X7and install it flush with the housing and there is plenty of room to still drive it too far in :)

Amazon sells the 25X40X7 in several flavors. Buna and I see one in Viton.

https://www.amazon.com/25X40X7-EAI-...=seal+25x40x7&qid=1562678277&s=gateway&sr=8-3

https://www.amazon.com/uxcell-Nitri...=seal+25x40x7&qid=1562678727&s=gateway&sr=8-2

The FD pinion seal is 35X47X7 and is also available on Amazon

https://www.amazon.com/Grease-35X47...s=gateway&sprefix=seal+35x47x7,aps,154&sr=8-3

https://www.amazon.com/uxcell-Auto-...s=gateway&sprefix=seal+35x47x7,aps,154&sr=8-1

The removal of the trans seal usually requires the use of a small drill and a screw to pull it out being very careful to NOT drill into the side of the case which happens often. If it is the the castle nut with the seal in it you can pry out with some effort being careful to not damage the threads on the outside and then drive in the new seal. If you were pulling the trans out, I would say do the other seals in the clutch area but that is a lot of extra work if they are not currently leaking.
Thanks again Gordon. You are very helpful as usual!
 
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