The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: tunnelrider on October 12, 2018, 06:28:55 AM
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Hi everyone,
Symptom is a weeping swing arm / final drive join. It's not coming from the drain plug or filler plug.
Should I use gasket sealant when I replace this gasket? I ask this because some BMW gaskets don't require any sealant. The new gasket is from Motobins.
If there's likely to be another reason for the weeping please ignore my naivety.
Thanks in advance for any information.
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Hello,
I've dismantled this part of the bile in order to powder coat the whole swing arm (and frame..).
The final drive had been put back with the plain paper gasket without anything and no leaks.
I used the proper torque to assemble the drive.
Hope this helps.
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BMW Engineers would have coniptions at the idea of you putting sealant on that gasket.
The reason is that the crushed thickness of that gasket has been carefully calculated so that the correct dimensions of the swing arm are maintained and the rear axle is true relative to the frame of the bike.
Or at least this is how it was explained to me by a now departed guru of all things BMW.
The reality is that this is another case of BMW stressing out to ensure a solution to a non problem. i would happily use a thin smear of a non-hardening jointing compound such as Hylomar and be confident the wheel alignment would not be affected.
BUT, if you clean the joint faces and use a new gasket, and then tighten the bolts to the correct torque, you don't need jointing compound.
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just make sure the axle is installed and snugged up be for you tighten the 4 bolts
to make sure the axle bores are in line when you tighten the 4 bolts
Yes use some gasket sealer sparingly and use the gasket
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Interesting job. Has posed more questions for me than the one answer for the leak, about how the whole swing arm and final drive set up works, considering the amount of abuse it gets. It was leaking from a sharp edge on the final drive face wearing through the gasket, not sure how that got there. Kinda looked like it'd copped a sharp stone from the side at the join (could be me), or a screw driver to pry open from the side (def not me). First thing -
On the twinshock final drive shock mount, what should be protecting the final drive housing from the shock absorber? A washer of some sort? Mine's got nothing currently.
Not sure if the Motobins gasket is as thick at the paper gasket on there before.
- This could lead to a new wear pattern on the coupling splines, not the end of the world as they have a lot of life left. On taking the diff off, the shaft/ rear drive coupling splines were wet with oil and otherwise clean. Black mark in the middle of the swing arm female splines from the drive splines.
Clymer says lube the splines on reinstall so I dutifully lubed the splines on the swing arm and drive couplings with high moly but wonder how long that stays on for considering the area is full of gear oil, does it get hot and it all goes out in the next oil change?
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Not sure what has happened here but something got screwed up after this post. Some sort of date stamp didn't match up in a quote, or something. I couldn't really figure out what was causing this so I just deleted the replies starting where the error occurred.
Sorry...
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Hi everyone, just resurrecting this topic to ask a couple of things - I think I managed to see in the error message before that a thin washer sits between the rear drive and shock absorber on the shock mount?
Also would anyone know how long high % Moly paste would stay on the drive shaft/rear drive coupling splines in the presence of the swing arm oil? I followed the Clymer instructions putting that on but now wonder if it would turn into a nice grinding oil mix for any bearings the swing arm oil might lube?
Cheers in advance for any info.
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If you wheel drive splines are getting gear oil on them
(the splines between the wheel and final drive)
Unfortunately you need to repair the gear oil leak
It may be just the outer seal
But being that the splines are full of oil more than likely it is the inner seal
It isn't a really difficult job if you heat the housing up with a heat gun
The bushing #1 and bearing #3 will fall out
Then you can change the seal #2
Heat the housing back up and reinstall the bushing and bearing
(You do have a heat gun don't you every air head owner has a heat gun ;))
of course the final drive really needs to come back off
The part that will make you curse is removing the gasket from the housing >:(
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As far as spline lube normally you just clean and lube it every tire change
about 7000 miles or 11000 km
also replacing the O'ring on the brake shaft is a good idea
I use a quad ring instead of the O'ring
They last a lot longer 8-)
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(You do have a heat gun don't you every air head owner has a heat gun ;-))
of course the final drive really needs to come back off
The part that will make you curse is removing the gasket from the housing >:(
:) of course I've got a heat gun and used it many times since! Thanks for the reply and diagram Mrclubike, sorry for my misleading post as I've already repaired the weep, it was just a matter of replacing the ripped paper gasket and smoothing out the nick that caused it.
Yep that gasket >:( I had to go through the tunnel to buy a spray can of gasket remover, not cheap that stuff, cost $35! By then of course I'd already spent an hour getting half of it off but the spray worked a treat and it only took another 30min to get the rest of it off, including the PIA areas by the studs. Still got 3/4 of the spray left.
It looks from the diagram the inner seal #2 you have highlighted would stop swing arm oil from contaminating the large final drive bearing. Is that the seal that holds the swing arm oil from entering the final drive?
Thanks
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The two seals arrowed respectively keep oil from the final drive housing from contaminating the outside world and your brakes.
If oil is getting into your final drive housing from the swingarm you have a different problem, and one that can be a bit expensive to fix. When you take the final drive off the bike there is a coupler that transmits drive from the driveshaft to the final drive - the "concave" part of the coupler is in the swingarm and the "convex" part sticks out of the front of the final drive and looks a bit like a gear.
If oil is getting past the seal in the nose of the final drive there are two choices - a "bodge' that actually works, or do the job properly.
The bodge consists of stuffing as much heavy axle grease as you can into the swingarm side of the coupler - don't be bashful get as much as you can in there. The grease will prevent, or at least greatly delay the migration of oil from the shaft to the final drive - this bodge has been working for around 15 years on the wife's R65/80 and stood up to a trip from here to Darwin and back. Best of all if the bodge fails and oil starts migrating again, for the price of one gasket and some grease you can simply do it again.
Fixing it properly is not a difficult job but requires special tools. You need a means of locking the ring gear in the final drive. The first one of these I did, I simply fed a piece of rag into the crown and pinon gears till they jammed and then removed the nut securing the input side of the coupler with an impact wrench.
Please do not do this as you run a good risk of blowing the pinon shaft out of its lower bearing mount - congratulations, you just bought a new final drive if you do that.
Next you need the special tool to remove the bearing and seal carrier - this was covered recently in a discussion in another thread and someone said they had bought an off-the-shelf driver a lot cheaper than even the imitation special tools made by Cycleworks LLC.
Here are some pictures of the tools needed.
if you do this job, give the age of even the youngest twin shock R65 I would change ALL the bearings, which means you have a further expense of buying a pack of shims for setting the crown/pinon mesh (big hint, buy the same brand bearings as came out and you mostly need only minor shim changes if in fact any at all.
The little bearing that carries the rear of the pinion shaft is a known "bear" to remove sometimes, in fact sometimes the only way it can be removed is by spark erosion - take money.
Done right you are rewarded with a final drive that should run trouble free for at least another 35 years or more.
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Thanks Tony for the wonderfully detailed know how, hopefully I never have to look further into the rear drive. ;D If I do I now know where to look first ;-).... I'm lucky enough to report that every time I've replaced my swing arm oil there's been the same amount in there as I put in. My questions are simply based on how far the swing arm oil travels and whether lubing the drive shaft female/ rear diff male coupling splines with moly paste might damage any bearings. I find it hard to believe the moly paste would stay on the splines for long... But I'm just guessing sorry, have no research into the matter available.
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Moly paste goes on the gearbox input splines.
Heavy axle grease goes on the rear wheel drive dogs
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Heavy axle grease goes on the rear wheel drive dogs
Sorry Tony, just need a bit of clarifying - by rear wheel drive dogs you mean the coupling I just replaced the gasket on? S**t I better change the oil a couple times then. My bad.
Cheers
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Yes, grease goes in there. There isn''t enough Starbraughs in the world!
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I'm not saying that Molypaste will not work in the coupler, but you would need three or four tubes of the stuff to get the amount I'm talking about in there.
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Heavy axle grease goes on the rear wheel drive dogs
Sorry Tony, just need a bit of clarifying - by rear wheel drive dogs you mean the coupling I just replaced the gasket on? S**t I better change the oil a couple times then. My bad.
Cheers
The splines between the drive shaft and final drive input shaft Do not need grease
they are lubricated by the gear oil in the drive shaft housing
this oil also lubricates the universal joint at the trans end of the drive shaft
The Rear Wheel drive dogs are the splines between the rear wheel and the final drive
They are lubricated by High Molly or heavy grease as Tony states
The transmission input splines are on the front of the transmission and has the friction plate of the clutch sliding on it and it need to be greased with high Molly every 20,000 miles
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rear end lube
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The splines between the drive shaft and final drive input shaft Do not need grease
they are lubricated by the gear oil in the drive shaft housing
this oil also lubricates the universal joint at the trans end of the drive shaft
Except where trans oil migrates past the seal on the pinon shaft of the final drive.
This can be a problem even with the seal in good condition - the BMW service bulletin on the topic says to pack the coupler with axle grease.
It also works a treat for failed seals if you do not have the $s or tools to do a proper fix.
I'd be interested in how you caption your photos by the way.
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Thanks Tony for the wonderfully detailed know how, hopefully I never have to look further into the rear drive. ;D If I do I now know where to look first ;-).... I'm lucky enough to report that every time I've replaced my swing arm oil there's been the same amount in there as I put in. My questions are simply based on how far the swing arm oil travels and whether lubing the drive shaft female/ rear diff male coupling splines with moly paste might damage any bearings. I find it hard to believe the moly paste would stay on the splines for long... But I'm just guessing sorry, have no research into the matter available.
Molly paste was not needed on the splines in the drive shaft housing
As far as I know the molly grease will not harm a thing in there
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I caption my photos and snips with FastStone Image Viewer 6.4
It is free
http://www.faststone.org/
https://en.wikipedia.org/wiki/FastStone_Image_Viewer
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Thanks for your replies Tony and Mrclubike, I feel more at ease with the molypaste being in there. I'll still dump the swing arm oil a couple of times though I think.
I moly'ed my transmission input shaft splines 25K km ago when I put new bearings in the trans, I'll probably wait until the clutch feels grabby before doing it again. What's the best way to reveal the trans input shaft splines? I recall reading something like taking the swing arm off the frame and pull the swing arm and trans to the rear? I moved the engine forward when I removed the trans and left the swing arm in place.
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To spline lube the quickest way to do it is to release the swingarm bearings, the shocks and the brake actuating arm. Then remove the aircleaner and undo the gearbox mounting bolts. You can then move the entire gearbox/swingarm/rear wheel etc rearwards enough to get a toothbrush in to furstly clean and then lube the splines.
Fun times.
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To spline lube the quickest way to do it is to release the swingarm bearings, the shocks and the brake actuating arm. Then remove the aircleaner and undo the gearbox mounting bolts. You can then move the entire gearbox/swingarm/rear wheel etc rearwards enough to get a toothbrush in to furstly clean and then lube the splines.
Fun times.
That's the way I do it although I found I need a rope pulling back on the rear wheel to maintain the gap. Perhaps that's because I left the shocks attached. Don't remember exactly.
Yikes, on checking, I haven't done it since 2008. Must have been good moly grease because the gear change is still fine.
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Yikes, on checking, I haven't done it since 2008. Must have been good moly grease because the gear change is still fine.
I think useage has a bit to do with it. At the current rate of utilization of the wifes R65/80 and my R65 I'd reckon that every decade or so will be just fine. I've also switched to yearly oil and filter changes on both bikes - hers in the last year has done less than 300miles, mine around 900.