The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Rick on April 10, 2015, 09:46:51 AM
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I am in the process of refurbishing a 1979 R65 and learning along the way. I am hoping someone can help with an issue that came up yesterday that has me puzzled. I recently adjusted valve clearances and used the rear wheel to turn the engine to TDC for the valve adjustments. The bike was on the center stand on a block of wood to get the rear wheel off the ground. The wheel turned as it should when bumping the engine to the timing marks with the transmission in gear. Once the valve adjustments were done and I got it buttoned back up I started the bike to see how it ran. Since the rear wheel was off the ground I decided to keep it running and run it through the gears since I haven't had a chance to ride it yet to check things out. It seemed to shift OK and took it back down to neutral and shut it off. I took the bike off of the center stand and blocks to get both wheels back on the ground and it was then that I noticed that I couldn't move the bike. It was in neutral with the engine off. Put it back on the center stand with blocks to get the rear wheel off the ground again and tried to turn the rear wheel and couldn't budge it. The neutral light is on and I am fairly certain it truly is in neutral but the rear wheel won't budge. I started the engine, put it in first gear and released the clutch and the rear wheel turns but when shut off again and back in neutral the wheel is still stuck. I couldn't find anything by searching he internet that might even give me a clue as to what happened or what might be the issue so I am hoping someone may have ideas or had run across this before. Clutch? Transmission? or ???
Thanks!
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First question I have is: After bringing the bike to TDC and setting valve clearances, did you then rotate the engine and bring up TDC to adjust the opposite cylinder?
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Yes I did rotate 360 to adjust the opposite side valves.
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With the rear wheel clear of the floor, with the engine running and the neutral light illuminated, does the rear wheel continue to rotate ??
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No Bob, it does not continue to rotate.
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The Airhead gearboxes are factory-supplied with several false neutrals. Whenever I get lazy with my shifting, I can find one.
With the engine off, try shifting through the gears and back to neutral. You may have to roll the bike fore and aft a bit. Report back.
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So there is no drive when the gearbox is in neutral but the wheel is still stuck.
That means the gearbox is selecting neutral OK. Which leaves the drive shaft, rear drive/wheel/brake assembly.
The rear brake isn't stuck on is it ?
Agave,
I realise this isn't any help at all this point but I only tried bumping the engine over once using the rear wheel and decided the shock loading was much too violent on the whole transmission system. I know lots of people use the rear wheel but I now always use an Allen key in the rotor bolt with the plugs out to make life easier. You did have the plugs out ?
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Thanks for the responses so far guys.
Montmil, I don't know if I can rock the bike back and forth enough to get it to shift through all gears because of the locked up rear wheel but will try either tonight or tomorrow and report back.
Barry, I was wondering about brake being stuck too. I did have the rear wheel off recently to put a new tire on but when put back on it turned freely and also turned OK during bumping. Maybe the brakes stuck for some reason when I ran the bike through gears with the wheel off the ground. I will check the brakes too.
Regarding bumping I have read good and bad about both ways of turning the engine over. Point taken though about the possible transmission stress due to bumping the rear wheel. The wheel was off the ground already when I did the valves so I just used the whel bump method rathr than take the front cover off. Yes the plugs were out also.
To be continued. Thanks again!
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Sounding more and more as if the rear brake is stuck "on".
First, try backing off the adjuster on the aft end of the brake rod. If the brake is indeed stuck, you will not be able to get the rear wheel off for an inspection. Maybe the brake cam has gone over-center?
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I was starting to think brakes too Monte. That was the first thing I was going to do.... see if I can get the wheel off. That will tell me if the brakes are stuck. If thats the case, then another problem... how DO I get the wheel off?
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I was starting to think brakes too Monte. That was the first thing I was going to do.... see if I can get the wheel off. That will tell me if the brakes are stuck. If thats the case, then another problem... how DO I get the wheel off?
If the brakes are truly locked onto the drum, ya ain't goona get that wheel off until they -brakes- return to their original relaxed position. After backing off the adjuster nut, check the brake arm for any movement. Perhaps a gentle plastic mallet tap in the opposite direction of the rod's pull might encourage a release.
It's going to be something simple. Brake cam over-center. Maybe a tad embarrassing, but... simple. Once free wheeling, pull the rear wheel. You're baby just may need some new shoes.
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Checking the rear brake seems to be the next thing to check, as Monte has said .
But this is really an odd situation that this happened all of a sudden .
Does the rear brake pedal move at all ???
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The rear brake pedal does move as if normally operating Bob. It is worth checking the brakes first to rule that in or out but it could be a false neutral as Monte noted earlier. If it is a false neutral though, shouldn't the rear wheel turn if the clutch is engaged no matter what? The wheel doesn't turn even with the clutch engaged with the engine not running. Very puzzling.
I appreciate the suggestions for things to take a look at.
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Does the rear wheel move at all when you have it clear of the floor and the transmission neutral indicator illuminated ??
You should have some ' free play' in the drive train, be able to move the wheel by hand maybe an inch or so in rotation, even if the tranmission is in gear .
If it is locked solid, the rear brake is looking suspect .
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I am also with the "brakes are on or something has slipped in the rear hub to cause wheel to be locked up" camp.
I use the rear wheel to turn the engine for setting valves, etc. all the time. The "shock load" of rolling the throttle on and off while running on the road will transmit much more of a shock load through the drive train and gearbox than what any human can do with their arms on a sitting still bike without knocking it off the centerstand entirely.
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Agave,
With the rear wheel off the ground (motor not running) and the clutch dis-engaged (lever pulled in) can you rotate the rear wheel with your hand in any gear?
-Mike V.
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Bob, there is no free play at all when neutral indicator is lit.
Mike V I can't rotate at all in any gear with the lever pulled in.
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Just pulled the rear wheel with no issues. It isn't the brakes hanging up the wheel.
The wheel will still turn if bike is running and in gear with wheel off the ground, but still frozen any other time. Fearing a clutch/transmission problem that I didn't originally anticipate with this bike. :(
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Agave,
I'm confused ... everything was fine, no issues until after you adjusted the valves?
Are you getting any rear wheel free-wheeling in any condition?
I'm wondering if your clutch splines / input shaft need service or your clutch plate is hung up.
-Mike V. (puzzled)
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I think we are all puzzled. I thought Bobs question about slack in the various transmission components was a good one and would nail it down a bit.
So to recap - there is no rotation possible at all even with the wheel off. You would expect at least a little free play from clearance in the meshing of the final drive gears. If that is totally non existent I really am puzzled as it would imply something seized in the final drive/rear wheel bearings.
If you can feel some free play then that moves the suspicion forward to the gearbox.
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Mike V & Barry,, I know, I figured people were getting confused.
Recap:
Had rear wheel off ground while adjusting valves. (Don't think the valve adjust has anything to do with this issue.)
After valves adjusted, started bike and ran it through the gears while rear wheel still off ground and shut engine off. Wheel turned OK.
When rear wheel was back on ground noticed that rear wheel was locked up.
No movement in wheel at all, no movement or freeplay whether engine is running and in neutral, or running in gear with clutch, or not running in neutral. Can't move it at all in either direction.
If running and put in gear with wheel off ground it does rotate, but didn't want to run it very much like that. Still stuck after running like that.
Pulled rear wheel to verify brakes not stuck.
Thats where I left it until I can dig into it starting at final drive and moving forward.
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This may not help at all, but drain the final drive, shaft / swingarm, transmission oil and see if you may get a clue there, by the condition of the oil, metal contamination .
May be able to identify the faulty component, without any extra work .
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Stuck Clutch Plate?
Agave, try this: Carefully!
With the bike securely on the centerstand and the rear wheel off the ground hold the front brake. Start the engine in first gear. Do not disengage the clutch. Run the engine up to a medium rpm and aggressively apply the rear brake with heavy foot pressure. If your clutch plate is stuck this may release it.
Try this a couple of times first then we can try the road method.
Has the bike been sitting for a while? Your valve adjustment had nothing to do with this.
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Even a stuck clutch I'd still expect to see a little backlash/play in the rear wheel rotation in one direction or the other. But maybe there isn't, or it is small enough that the owner cannot tell the difference.
Try pulling the plugs out of the cylinders, so you effectively have no engine compression to work against. Push the bike off the centerstand and just try to roll it back and forth in your garage. If you hear the wooshing of air out the spark plug holes when you push the bike then the gear box is in gear and is driving the engine. Turn the key just far enough to light up your dash lights to see if the neutral indicator is on. If it is - it is lying to you and the gearbox is really in gear. Then try pulling the clutch lever in and pushing the bike forward and back - you should have room to do this 8-10 feet in either direction ideally. If the pistons do not move while doing it this time, then your clutch is not stuck and is working OK.
You need to do some diagnostics to identify whether the problem is in the clutch, the gearbox, or further back, and this may help rule out some things.
I am wondering if this might be one of the infamous shift cam/pawl spring problems, where in it leaves the gearbox stuck in whatever gear it was in and one cannot shift out of it, regardless of the neutral switch indicator. The only way to get the gearbox out of gear again is to turn it upside down - which is usually done with taking the gearbox out of the bike, rather than flipping the whole bike upside down. Requires gearbox teardown to fix - I hope this isn't the case for the owner as it will likely run $500 to repair, but if one is unlucky enough to have it happen, you really have no choice in the matter.
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I am wondering if this might be one of the infamous shift cam/pawl spring problems, where in it leaves the gearbox stuck in whatever gear it was in and one cannot shift out of it, regardless of the neutral switch indicator. The only way to get the gearbox out of gear again is to turn it upside down - which is usually done with taking the gearbox out of the bike, rather than flipping the whole bike upside down. Requires gearbox teardown to fix - I hope this isn't the case for the owner as it will likelyrun $500 to repair, but if one is unlucky enough to have it happen, you really have no choice in the matter.
I'm thinking the same thing or maybe another internal transmission / spline problem. But want to see if we can figure this out before wrenches get involved.
maf - doesn't the broken pawl spring reflect in a loose shift lever and inability to change gears? I think Agave mentioned he could shift through the gears. I'm eagerly awaiting the resolution to this one.
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Mike-
Usually the pawl spring problem does result in a loose, but ineffective shift lever. But, maybe something else has failed instead, or it really isn't shifting through the gears and just appears that way to the owner. I am hoping for an inexpensive solution for the owner, and hoping the 'push tests with sparkplugs out' can help point us in a direction, or reduce the possibilities..
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I didn't think a pawl spring problem due to the fact it was not stuck in one gear and I have been able to shift into gears.
Couldn't do a push test with plugs removed because the wheel wouldn't roll, but that is a great suggestion to file away for future use.
I decided to remove the final drive unit. Once removed, the drive shaft can be turned easily by hand but final drive unit couldn't be turned.
I may have found the problem. The nut was very loose that holds the drive shaft spline coupling hub. I started tightening the nut down and as I did the final drive unit started to free up and turn. The more it was tightened, the more free it got. I assume this nut being loose allowed the bevel gear inside the final drive to move causing binding??? just my best guess. Now to figure out how and how much to tighten that nut and make sure everything is OK. Hopefully nothing was damaged by running briefly like this with the wheel off the ground while trying to figure out the problem.
Kind of concerned as to how and why that nut got loose and how tightening it down can affect the bevel gear mesh/backlash though.
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Check shop manual for torque requirements. Additional info can be found on Snowbum's site within the final drive sections.
Very strange issue. You might consider yourself lucky that you found the problem in your garage rather than at 70mph.
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Here's what the tool that is used to tighten the loose nut that you have .
http://www.cycleworks.net/index.php?main_page=product_info&cPath=29_33_54&products_id=325&zenid=60da9e1041ab08ca00831d29b23095fd
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Bob asked the smartest question many posts back. If there was no perceptible backlash at all when turning the rear wheel and it wasn't the brake then it had to be something to do with the final drive.
Torque setting from the BMW repair manual is is 111 lb/ft
That's a high torque figure and with the requirement for dry threads and loctite it's probable some PO didn't follow the correct method.
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I'm wondering if a previous owner had the final drive input seal replaced and the nut didn't get tightened up as it should, due to the requirement of a specialty tool, seeing as this nut has a hefty torque value, got it as tight as they could and called it good .
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Agave,
Good find - final drive was not high on my radar since it's not an often problem area.
Another good and useful thread for archival purposes. And, another important symptom to keep in our memory banks.
Keep us informed, please.
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Thanks for all the help everyone. Hopefully this can help someone in the future. Now to ensure that it is done correctly and put it all back together.
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Indeed, that was an odd one - never encountered that one before! It *was* a good thing that it loosened itself and became a jam nut while in your garage and not out on the open road!
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Absolutely... sometimes we do get lucky. I wouldn't have wanted to see what would happen out on the road with that loose nut.
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Absolutely... sometimes we do get lucky. I wouldn't have wanted to see what would happen out on the road with that loose nut.
There are already way too many loose nuts out on the roads as it is!
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FFunny%2520Pics%2FWhatCouldGoWrong_zps963567ac.jpg&hash=1ad0e37c31954a22e7331165110e3a8dc10d794d) (http://s196.photobucket.com/user/montmil/media/Funny%20Pics/WhatCouldGoWrong_zps963567ac.jpg.html)