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R1150RT FD Problems and More


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I have been suspecting that my pivot bearings are N/G for a while and proceeded to pull the rubber boot off the final drive assembly to have 3/4 ounce of tranny fluid come out, which indicates a bad seal. On top of that, when I drained the FD oil, it did have sharp flecks of metallic thingies in there. I suspect they are from the crown bearing. I have a sneaky feeling I have quit a few things to replace. Where do I find all the tools and parts to do the seals, etc? I will more than likely be shipping the FD out for the crown bearing replacement and I will remove the remainder of the drive assembly and clutch to access the transmission rear input shaft seal. Has anyone done this before? Tips, tools etc required? I do have a video on the clutch replacement however, it does not discuss all the goodies I will need.

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That 3/4 ounce of gear oil in the boot is pretty normal on about any 1100/1150 final drive. It (is) coming from the pinion seal but chances are you will get about the same amount even if a new seal is installed and you are using a 75WXX synthetic gear oil. Some even have it seep a little using conventional gear oil.



On doing that pinion seal yourself. It "does" take some special tools and special know how. I have done a few using homemade tools but I also have a basic small machine shop at my disposal. I guess my thoughts on the pinion seal are: if you are asking how to do it you probably should have it professionally done. That pinion seal isn’t an easy do-it-yourself unless you are fluent in adapting and making tools as you go forward.


On the other hand the crown bearing isn’t than difficult to do at home, but again you will need some precision measuring tools, and setting the bearing preload will have to be done without using the special BMW tooling. If you want to attempt the crown bearing yourself there is a couple of good write ups in the archives here giving you a few alternate ways of setting the bearing preload. There are also a couple of links to other web sites showing somewhat of a do-it-yourself crown bearing install (hopefully someone will post you a link to it (I have my own way & precision tools so do it a bit differently)


On your tool question: you can buy some but that kind of takes the economy out of doing it yourself. Most that are effective you have to make yourself, seals & bearings can be bought from BMW or taken to a bearing house and matched up. Lately I have found the bearings to be cheaper from BMW -like- (Chicago BMW at discount) than from the bearing houses like Detroit ball or an auto parts store.


I guess I don’t understand why you want to remove the clutch to do a transmission seal on either end of the trans. You need to remove the clutch for an engine rear main seal but not any trans seals.



Edit for: My spelling sucks

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Thanks Dirtrider. I had opened that boot about 10k miles ago and did find about the same amount of oil in there. I feel better now that you said that is pretty normal. Okay, so now I will be concentrating on the pinion bearings and replace them with the bushings I rcvd from Rubber Chicken. That does not worry me much as I have the tools and parts for that job. Concerning the crown bearings, I don't have the tools etc to preload them properly, so they will be shipped out for the work, no biggie. My big concern was why I had that oil in the boot, getting way into the bike for seal replacement is a considerably bigger job with a LOT more work and time involved. I believe that most of us would prefer not to have a job like that looming in the future, riding is certainly a more desirable activity by far. How much oil will you or others typically find in that boot and how often do you check it? Due to the loss of oil, the transmission oil level will have to be checked more frequently, I would think.

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The oil usually comes from the FD not the transmission. To check, shine a light up the shaft tunnel and see if the bottom is wet - if it is, the rear seal needs replacing - relatively simple with just the swingarm needing to be removed. If the tunnel is dry, it is the FD input seal weeping. I normally get about a desert spoon's worth of oil in there between services, with no discernible drop in the FD oil level (or the tranny for that matter).



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How much oil will you or others typically find in that boot and how often do you check it? Due to the loss of oil, the transmission oil level will have to be checked more frequently, I would think.



Afternoon GO1150RT


You are now talking transmission. We are talking rear boot back by the final drive here correct? If you look in the rear control housing and can’t see any oil coming down from the front then that oil is coming from the pinion seal on the rear final drive.


Sometime you will get a trans output seal leaking but usually that oil in the ear boot is from the final drive pinion seal.


On the pinion seal leaking amount. That seems to vary by bike, how many miles ridden, how long stored in one spot, etc.

My old 1100 would seep about ½ ounce to maybe an ounce or so during winter storage. Then would go all summer without any leakage at all (conventional gear oil). I switched over to 75w140 synthetic gear oil and then always found a little oil in the boot. Later I switched back to a conventional 90 weight gear oil and no more seepage during the summer but still a little over winter storage. Don’t think I am blaming the synthetic part of the gear oil as that had nothing to do with it. It’s just that most synthetic gear oil is blended for better fuel economy in modern vehicles so has less seal conditioner blended in to reduce seal drag.


I’m sure you will some postings here telling of no leakages and others telling of about what you are getting for leakage.


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I drained the fluid from the FD and found flecks of very shinny metallic flakes, like from the race or surface of a ball bearing. So that is probably the crown bearing. I do not see any fluid running down the tube to the boot so that is probably coming from the FD too. I'll yank the FD and send it of to Rubber Chicken Racing and have it fixed and when returned give it a shot. I did try to attract the metallic flakes with a magnet and they did not cling to the magnet. Makes me wonder if the flecks came from the crush washer since it was really marred up. I think before I do anything, I'll retop off the fluids, take it for a 100 mile ride and re-examine everything again to see if the condition repeats.

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Evening GO1150RT


The real test of those metal flakes is to run them between your fingers. If they feel smooth to the fingers that usually isn’t a bad sign. On the other hand if they feel sharp to the fingers you have internal problems (usually the bearing ball separator on the crown bearing)


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Clive Liddell

Hi Go1150RT,


On my Oilhead bikes the amount of oil weeping reduced and eventually seems to have stopped when I "filled" the final drive a tad lower than the bottom of the threads. There is a shiney surface a couple of mm below the bottom of the threads and I place the oil level on this surface.


At 10000km intervals I use 2x500ml of GL5 oil, fill the gearbox and use the balance in the final drive. I find that this usually just brings the FD level to the shiney surface.

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Just to reiterate, when that FD rubber boot is opened up and you find oil, check that it isn't coming from the gearbox end. If it is from the Final Drive, then an awful lot of these bikes do (dependant on how they are ridden, how hot the ambient conditions are, how overfull the FD was etc etc). Oil in that area is 'normal and not to be worried about unless it is masses of the stuff and is draining the FD or causing a safety risk if it floods out onto the rear wheel/brake.


Onto what you have found coming out of the FD. If it looks grey and solid, just check that it isn't really sharp metalic parts, oftern it looks much worse than it is, but in actual fact that goop is often (again) 'normal'.

However, if it is sharp and gritty, that is NOT 'normal' and should be investigated further.



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