The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: tunnelrider on February 27, 2025, 01:13:42 AM
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Hi good people of the forum, hope all is well. I've been able to not post any questions for a number of years now, while keeping an eye on the forum occasionally, and it's great to see the input is still going strong.
I've got noisy transmission (gearbox) output shaft bearings, a little bit surprisingly only 45,000 km since I put new bearings on all the shafts.
I removed my 1985 gearbox unit last time following the Clymer manual method of moving the engine and gearbox forward before unbolting the gearbox from the engine case and taking the gearbox out, leaving the swingarm in place. Although fairly straightforward to do, I found this method a little awkward, leaving the engine on wooden blocks for a month while I serviced the gearbox.
The Clymer manual has a different method of gearbox removal between years of manufacture. For 1970 - 1980 models it tells to move the swing arm back to remove the gearbox, while for 1981 models on it tells to move the engine forward. Does anybody have an inkling to why the different methods? Something to do with the flywheel on earlier models vs clutch carrier of later models?
Thanks for any tips,
Dan
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Hi !
On my sole BMW, an '82 R65, I removed the gearbox quite often (to repaint the frame, to repair a broken spring in the selection pawl, and so on...) I've followed both methods, either removing the swing arm or moving the engine.
I tend to prefer moving the engine because putting the swing arm back and adjusting it is not that easy. Add to this that tapered roller left open can gather dust and impurities and die of that...
On the contrary, moving the engine does not involve removing difficult parts (like headers) or anything else...
But of course YMMV ....
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I agree with georgesgiralt, I also tend to prefer moving the engine because putting the swingarm back and adjusting it is not that easy.
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Hey georgesgiralt, nice to hear from you again.
Thanks for your replies georgesgiralt and skyblu79, and your experiences doing the removal both ways.
Definitely sounds like moving the engine forward is the easier and preferred method of the two. But perhaps it's time I looked at the swingarm anyway?
The swingarm is one of the areas I've mostly left alone in 10 years of having the bike, aside from giving it a grease gun squeeze once every few years (which usually squeezes out straight away) and more frequent oil changes. I've felt a bit guilty of neglecting the swingarm, especially since I've taken the bike through numerous streams and small rivers over the years, and haven't ever inspected the swingarm bearings.
What are the symptoms if the swingarm's not right? I guess if the bearings are seized it would be reasonably hard to tell? If the swing arm preload is too loose, would the handling would be unsteady? I can't say I've noticed any handling problems, hence haven't gone into the swingarm, but gradual worsening may go unnoticed.
Would anybody agree it might be time I took the swingarm off, since it's a way of getting the gearbox out anyway?
Cheers
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Well, testing the swing arm bearings is the same as the steering one.
Remove the two shock and (without the rear wheel ) move it up and down. If you feel any stopping or resistance, you know the answer...
Same for the play. Grab one arm of it and pull/push on it. If it moves even the slightest, you know the answer.
Setting the preload is easier than on the steering as it is done by setting the torque as per specifications and then backing up per proper procedure.
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Ahh yeah, of course. Take the shocks and wheel off, have a play! Thanks for the tips and explaining georges, good sense to check before taking the plunge. I'll post back on what I find.
On another note, am I right to be disappointed with only 45,000km on new gearbox output shaft bearings? I'm not a particularly sympathetic or gentle rider so that may explain the wear, but I think that's not totally plausible if BMW trust the same gearbox to serve 1000cc bikes?
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I've always used the swingarm removal when removing the transmission.
One thing I found, is the socket I was using to remove the jamnut on the pin that swingarm rides on .
The standard depth socket was too wide to down to the nut .
I had a deep well socket and it just barely fit .
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I've had a standard socket machined to remove the chamfer in order for it to grab the nut properly, and reduced the external diameter on a lathe for it to go easily into the swing arm recess..
As I had to pay for the machining, it was an expensive socket and I keep it well buried into my drawer !
If you buy a very high quality socket, you'll find that the walls are thinner than cheap ones. But the steel will be harder so more difficult to remove the chamfer... And if you use a grinding tool to do so, be really slow and cool the socket very very often in order to keep the hardening .....
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I've had a standard socket machined to remove the chamfer in order for it to grab the nut properly, and reduced the external diameter on a lathe for it to go easily into the swing arm recess..
That is exactly what I did as well. That socket is dedicated to one job only and I turned it up when I had access to the required machinery.
I have a few tools dedicated to single jobs and they are invaluable when needed. Recently when I asked you about the Polish stanchions you purchased I sent them an enquiry and they never replied, so I am transferring a complete front end off one K75 to another as it is a time critical job. I needed a 24" monkey wrench to undo the tensioning nut on the steering head, so borrowed one of a mate. The next day I went and bought one for myself. Fortunately a lot of the simple specialised tools that are required for BMWs are available as aftermarket options.
I have bikes in the F, K & R ranges and I am fortunate that I have access to a large community of BMW riders locally.
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Sorry about the lack of action on checking the aswingarm, I had a breakdown last weekend on another previous repair :o, 40K km ago since I "repaired it" and got the heads all new valve guides, valve seats and valves fitted at an engine shop.
I had a look today and the left exhaust valve is stuck in the valve guide, maybe bent.I'll have to sanpaper off the edges esp. on top of the stem before trying to take it out.
Funny how things cycle 'round again. I last did these 8-10 years ago, gearbox and heads. :whip:
;D
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Ive been running a worn dimpled rocker arm on that valve for a while, was a bit noisy beforehand.
No dimples, flat surface on a rocker arm please! Yessir
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Sorry about the lack of action on checking the aswingarm, I had a breakdown last weekend on another previous repair :o, 40K km ago since I "repaired it" and got the heads all new valve guides, valve seats and valves fitted at an engine shop.
I had a look today and the left exhaust valve is stuck in the valve guide, maybe bent.I'll have to sanpaper off the edges esp. on top of the stem before trying to take it out.
Funny how things cycle 'round again. I last did these 8-10 years ago, gearbox and heads. :whip:
;D
Seized on the guide ? Lack of oil ? Wrong guide material ?
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Not 100% sure what's caused the exhaust valve to bind yet. I haven't had time to try and take it out yet. Here are some pics.
The valve doesn't look properly seated on the valve seat.
The rocker arm is a little notchy. Could this cause the valve stem to bend possibly?
I've also heard about valves 'microwelding' to the valve seats at high rpm - maybe this has something to do with it? I've had some rides over the past few years with sustained riding round 7000rpm for 10-15 min stretches. I know, I know... unsympathetic for sure. :smash:
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Did you clean the heads ? Because they look too dry to me...
The valve look bent and has suffered severe wear on the end stem. (this part is specially treated to be diamond hard, so using it implies very harsh treatment...)
My bet is to drive the valve and the valve guide out (with the valve still installed) and check the seat then either look for a new head or put a new guide and valve.
Job for a proper equipped mechanic with knowledge of what to do/how to do it...
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Yes the head and rocker arm were wiped clean of oil before taking the pics. I agree the tip of the valve stem shows some harsh treatment, and I know the rocker arm pad for pushing that valve wasn't in the best shape. Seems new rocker arms are becoming scarce and expensive on line, as demand for them increases I guess.
I've got a spare set of 1980 heads with the older type rocker arm without the plastic bush, that has a different, larger pad where it pushes down the valve stem than the later style (post 1985?) rocker arm. I've tried fitting it on the 1985 head to get rid of that worn left exhaust rocker before, but with it's larger push pad I recall there was barely any adjustment left on the adjuster nut for adjusting valve lash.
I'll probably use the spare 1980 heads and rockers if I get to the point of being ready for the road but haven't fixed the problematic valve and found a new rocker arm by then.
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IMHO, the valve stem damage was not,per se, caused by the rocker but by a seizure in the guide and, a following very hot valve which got pounded by the rocker.
The questions remains, what caused the valve to seize in it's guide ? Was it bent during installation ? Or a bad guide installation, making it not perpendicular to the guide ?
If you said that the head was properly oiled, we can rule that out.
As per the rockers, I had a couple worn and having a "step" making noise on their contact surface. A local BMW Guru restored the proper shape and hardened them back. They are still on the bike since 1999 ..... So maybe inquire with mechanics around you ....
Lastly, check if the push rod are strait and not damaged because they had a very harder job to do. Same goes for the cam operating this valve...
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Had a little time a week ago to get the valve out of the guide, it wasnt that hard to tap out with a normal hammer, after blunting down the stem tip mushrooming with sandpaper and spraying a bit of aerosol lube up and down the guide.
Turns out you are right george, the valve did bind in the guide, it seems to have built up a carbon layer on the stem, above the valve head, that interrupts the return of the valve to full seated position.
I'm thinking the valve might get hot by the extra friction of the rocker arm, attracting oil to carbonise (or stick) to the valve in the exhaust port, eventually building up the stem to where sits in the valve guide at full seat position.
The valve hasn't bent and is still straight, but I need a new valve guide, or K'insert, and sort out the rocker arm/ or find a new post 1985 one. Whether the valve can be reused, I'm not sure. It may just need the tip re-smoothed.
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Hi !
IMHO, your valve is beyond hope. The top stem is very special. Once hurt, it is dead. I bet it has lost it's hardness so wont last long if the valve is reused.
This goes also for the valve guide, because as the valve has seized into it, there had been metal removal inside the tube, and this will deter proper function with a new valve....
Your analysis is not totally correct I think. The valve seized first into the guide then the carbon build up took place because the valve stayed partially open. You where lucky because it closed enough not to hurt the piston...
Sorry to write this...
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Ah yep, makes sense to me, except I'm not sure the exhaust valve was not seated properly for long, as there was no difference in performance until the sign of obvious problem, which was a loud valve ting ting ting...
Agree, it'd worth the extra money to get a new valve also.
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Re gearbox removal.
I remove the swingarm and for the extra 5 minutes work involved I also remove the rear subframe and battery box. Nothing like having room to work comfortably I reckon.
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Re seized valve.
I think you are not looking far enough back in the failure chain.
I strongly suspect the problem is lack of oil.
A reduction in oil flow would account for both the damage to the rocker axle and the seized valve.
When all is operating correctly a very large amount of oil is pumped via the upper cylinder studs. As a rule of thumb cranking the engine over for 20secs should see around 150ml in tins positioned under the head.
If not, why not?
Static testing is really only valuable in gross terms given the cold pressure capability of the airhead piping system - but do connect a direct reading gauge in place of the warning switch.
Less than 80psi with cold oil and you have one of:-
The wrong oil
Stuffed pump
Failed pressure regulator
Stuffed bearings.
Inspection will confirm which.
If oil pressure is good then you have probably restricted oil flow up the studs - the usual reason for this is the use of too much "goop" when fitting cylinder/head. The only thing to use is minute amounts of hylomar and preferably nothing at all.
If you are lucky enough to not need oversized valve guides ( for which the only sources are OEM or make them yourself) pattern guides from Motobins are good quality and cheap.
Motobins also sell Intervalve valves, these are superior quality.ifci am correct regarding oil starvation you are going to be replacing bearings in the rockers and having the lash faces rebuilt. This will cost but you should probably have all four done.
I have assumed you didn't put the the clear shafts in upside down.
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Hey thanks Tony for your thoughts and tips on the possible cause of the valve seize, great to hear from you again too.
You're hot on the trail of georges thoughts too, about a lack of oil, so that's really helpful to start looking a bit deeper, thanks guys.
About the oil supply question, oil pressure valve and oil pump... the right cylinder valve train is pretty quiet in all situations comparatively to the left side that had the failure, so I hope the oil supply in general is sufficient but you're right, I need to get actual an reading of the oil pressure, since the engine has over 210K km on it now.
The last time I refitted the barrels I used a different engine case/barrel sealer than Hylomar, which I'd used for a couple of refits before then. it was CRC Red Gasket for high temp applications, because in the two or so refits previously using Hylomar the seal blew out pretty quickly with a fair amount of oil misting on both sides around the barrel base after long trips/ heavy use. I guess my mating surfaces aren't great but for the cost and hassle of fixing that I haven't investigated improving it correctly engineering wise.
The sealant I used did work much better than Hylomar at stopping the oil misting from the stud passages for something like five years, although it didn't stop it coming back completely.
I've always been conscious of using a sparse amount of sealant around the top stud oil passages and return down the push rod tubes, so it will be interesting to take the (now loose) barrel off to see if perhaps I have caused a blockage. I'll take up the tip on testing the actual oil pressure when I'm able to, and measuring the amount of oil dripping from the rockers.
By the clear shafts I'm thinking you mean the rocker arm shafts? Yes, I make sure I fit them with the dot facing the rocker cover side....
The head job I did just over 40K km ago involved an engine shop (of dubious experience on BMW heads) fitting new oversize valve guides and new Intervalve valves all round, plus new exhaust valves seats on both heads, supplied by me via Motobins. The punished exhaust valve is an Intervalve.
Cheers for the tip on gearbox removal also, I'll probably do the swing arm method this time, and get a socket machined as mentioned by our friends ealier by a friend with the gear.
What size socket fits the swing arm nut? (just being lazy here, I could check the Clymer manual ;))
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Hi Guys,
I've replaced sealants like Hylomar (or similar) to anaerobic products like Permabond or Loctite which do not cure in presence of air, thus preventing clogging oil passage tubes. The Permabond product I use is soluble in oil so will disappear from the oil passages if there is some on them.
Two drawbacks, though,
the first one is that the Permabond product is pink when cured and can show at the sealing line. Only a cosmetic reason here.
The last one is more annoying. Once cured it is very very hard so cleaning the surfaces after dismantling is a quite long job.
But having sealing that do not leak and resist temperature variation without risking oil starvation make the drawbacks less of a concern.
This is the product I use (but there are others on different brands ) https://www.permabond.com/wp-content/uploads/2016/04/A136_TDS.pdf
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I do not use any sealant on cylinder bases that have o-rings.
I used to use Hylomar but over time I decided that sealing the oil way was the o-ring's job. I just saw too many engines where sealant was partially blo cking the oilways. If this results in oilmost around the cylinder bases so be it, that is why God invented degreaser.
I have built 2 stroke 6 engines in the last couple of years, these have neither o-rings or a paper gasket. Instead they have an alloy plate which can be bought in several thicknesses in case you need to reduce compression. I do use Hylomar on these as if the mating surface isn't perfect they pump oil.
I am going to do another stroke 5-6 shortly and I am going to machine it for o-rings.
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I'm thinking I won't use any sealant on my next cylinder refit either, to eliminate the chance of blocking those cylinder stud oil passages..
An update after taking off the barrel: There wasn't any obvious sign of blockage possibly caused by using too much sealant. Both little o-rings had a little bit of sealant build up on the outside of the orings (see pic) but nothing more than that. Would this be enough to reduce the flow down the oil passage, maybe by squeezing the oring out of its position? I find it hard to think that would happen when its bolted up tight, as long as the orings were seated in their barrel groove ok.
BUT.. one of the oil passages was a bit drier than the other in the freshly taken out barrel (by that I mean oil sitting at the bottom of the passage). It was the oil passage on the intake side, so not the side that failed, but maybe caused a lack of oil to the rocker arm area in general?
So, my plan is to put the donor heads on, measure the oil pressure and volume of oil coming from the rockers.
Maybe a dumb question and I don't think it happens but just to be sure, the pushrods don't supply oil to the rockers do they?