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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: ccarlsonnh on June 02, 2013, 09:44:40 PM
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My (excellent) mechanic did a clutch spline lube on the bike, including new clutch cable, and, afterwards, could not get any freeplay at the hand lever. Has had the transmission and clutch out 4 times and all is properly installed. He can't figure out what is going on nor can I. Only thing he can suggest right now is to replace the clutch rod and throwout bearing assembly as that's about all he can think of that might help. So, any thoughts on this? I can only imagine that he is very frustrated with this bike. And, he's done many spline lubes on these k-bikes so it's not that this is something new to him. Has never seen anything like it before. Any thoughts much appreciated!
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There is a specific procedure for setting clutch cable free play.
Even more so if your bike has the side stand retraction associated with the clutch lever.
I've not worked on one that has that SS retraction, so if yours has it I can't help you much.
Replacing the cable should necessitate proper adjustment as the new one won't be "stretched" like the old one.
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greetings ccarlsonnh...
if it were me i would put the moto on the center stand and remove the cable from the bottom lever #7... then tie a piece of something to the bottom lever #7 where you can simulate pulling in the clutch...
start it up and gas it with pressure on the shift lever and coax it into 1st... then i would work the clutch lever up and down trying to figger whats going on by sound feel and watching the back wheel...
did you get #4 back in there...
(http://www.realoem.com/bmw/diagrams/j/w/5.png)
j o
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Thanks, Scott. Yep, the specific adjustment procedure has been followed precisely several times. Can't get any free play at all.
There is a specific procedure for setting clutch cable free play.
Even more so if your bike has the side stand retraction associated with the clutch lever.
I've not worked on one that has that SS retraction, so if yours has it I can't help you much.
Replacing the cable should necessitate proper adjustment as the new one won't be "stretched" like the old one.
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Thanks, Johnny! Yes, #4 is in there. Clutch disengages fine and engages fine but there is no free play at all when engaged. Almost seems like the cable is too short but it is exactly the same as the old one that worked fine. Thanks again.
greetings ccarlsonnh...
if it were me i would put the moto on the center stand and remove the cable from the bottom lever #7... then tie a piece of something to the bottom lever #7 where you can simulate pulling in the clutch...
start it up and gas it with pressure on the shift lever and coax it into 1st... then i would work the clutch lever up and down trying to figger whats going on by sound feel and watching the back wheel...
did you get #4 back in there...
j o
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It's possible to put the #3 thing in backwards, but you've probably checked that.
If you loosen #9 + 10 all the way temporarily, can you adjust the cable so that #7 barely doesn't hit the muffler when released AND you have a little free-play in the hand lever? If so, do that and then tighten the screw and lock it.
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yes, #3 is in correctly. Mechanic has the parts coming in this wee so, after those are installed, we'll see what happens. I'll be happy if we can at least get a minimum amount of freeplay at the lever even if below spec. If that's the case will use your suggestion!
It's possible to put the #3 thing in backwards, but you've probably checked that.
If you loosen #9 + 10 all the way temporarily, can you adjust the cable so that #7 barely doesn't hit the muffler when released AND you have a little free-play in the hand lever? If so, do that and then tighten the screw and lock it.
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I had a problem very similar to this. I could not disengage the clutch, unless I adjusted it waaay "tight" (and then it would slip while on the road).
After much fiddling and taking the transmission out a couple of times, I resolved that it was the spring (comparing it to a new spring pretty much confirmed what the problem was). If you mechanic has a new spring for comparison, you might try that. My old was was not as "high" when measured laying on a flat surface and the "small" end (end towards the rod) was not "flush" like the new spring.
It is worth a check if you've exhausted everything else.
And by "spring" I mean the pressure pate. Apologies for not being clear.
Tom
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Your mechanic probably knows this but just in case, the "free play" at the clutch handle bar lever for the k75 is listed as only 1.5mm-2.5mm. as opposed to 3.5mm-4.5mm for the 100's and 1100's
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You know, I had my transmission off this weekend to tighten the grub screw, and I never checked the clutch freeplay when I reassembled it. Rode around for 80 miles today and nothing fell apart.
So I just went and checked and I have zero freeplay too. Doh!
I just loosened the #9/10 way up and disconnected the clutch cable from #7. That #7 lever has about .5mm play before it hits the muffler. I never dissected the bits where the clutch rod fits in the rear of the transmission during my service this weekend.
I won't have time to work on my bike for a couple of weeks, so I'm looking forward to reading your solution!
I wonder how much easy movement #7 has on other K75's with the cable disconnected.
Why is clutch lever free play necessary anyway? As long as the clutch rod is not depressed at all when the lever is released things should be good, right?
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Will definitely post once we get this thing figured out. The problem with zero freeplay is that you don't know for sure that the clutch is fully engaged or if there is a bit of pressure still on the spring. Also, as the disk wears, freeplay decreases which, if there is little to none to begin with, is a bad thing.
You know, I had my transmission off this weekend to tighten the grub screw, and I never checked the clutch freeplay when I reassembled it. Rode around for 80 miles today and nothing fell apart.
So I just went and checked and I have zero freeplay too. Doh!
I just loosened the #9/10 way up and disconnected the clutch cable from #7. That #7 lever has about .5mm play before it hits the muffler. I never dissected the bits where the clutch rod fits in the rear of the transmission during my service this weekend.
I won't have time to work on my bike for a couple of weeks, so I'm looking forward to reading your solution!
I wonder how much easy movement #7 has on other K75's with the cable disconnected.
Why is clutch lever free play necessary anyway? As long as the clutch rod is not depressed at all when the lever is released things should be good, right?
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If I can get some time this weekend I plan to remove the boot, spring and piston and make sure they're all seating properly.
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did you guys checked the clutch lever at the handlebar side and reset the adjust nut there first? Just curious. When I had my gearbox out, I messes with that nut and couldn't get any free play at first until I returned the setting back. Sometimes also the cable at the handlebar end snags and causes the length of be off and adjustment becomes difficult.
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I had same issue needed to adjust at handlebar end then it was fine.
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Today I removed the muffler and rear wheel and disconnected the clutch cable from the release lever. Removed the rubber boot and spring.
At rest, the piston sticks out of the transmission about 3/8" which is how it looks in the Clymer photos. I removed the piston. The bearings in the piston spin easily and smoothly.
I can grab the clutch rod with pliers and slide it in and out 1/8" easily which I think illustrates that it is not depressing the clutch spring on the other end. I started the engine in neutral and the clutch rod spins.
Removed the clutch cable from the hand lever and inspected the hand lever to make sure there was nothing in the tube limiting the cable.
Reconnected the clutch cable on both ends, hand lever adjusting screw inserted all the way, and, with the piston but without the spring and boot installed I can see that the clutch lever is barely touching the piston without any squeezing of the hand lever. So there is absolutely no way to get any free play in the hand lever.
Putting it all back together now.
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Thanks for the update Tim. Sounds pretty much what my mechanic experienced with my bike. Just doesn't seem right. Anyway, he should have the new puck and rod by now so will be putting those in and we will see if that makes any difference. I really don't see how it would but, then again, I'm no mechanic! Will update this thread as things progress (or not).
Today I removed the muffler and rear wheel and disconnected the clutch cable from the release lever. Removed the rubber boot and spring.
At rest, the piston sticks out of the transmission about 3/8" which is how it looks in the Clymer photos. I removed the piston. The bearings in the piston spin easily and smoothly.
I can grab the clutch rod with pliers and slide it in and out 1/8" easily which I think illustrates that it is not depressing the clutch spring on the other end. I started the engine in neutral and the clutch rod spins.
Removed the clutch cable from the hand lever and inspected the hand lever to make sure there was nothing in the tube limiting the cable.
Reconnected the clutch cable on both ends, hand lever adjusting screw inserted all the way, and, with the piston but without the spring and boot installed I can see that the clutch lever is barely touching the piston without any squeezing of the hand lever. So there is absolutely no way to get any free play in the hand lever.
Putting it all back together now.
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Here's a measurement for a spare clutch cable I have which I used on the RT handlebars. I'm using a shorter cable with C-bars now. The cable housing is different depending on the bars, but the exposed inner cable length should be consistent. If your cable is off the bike, you might consider comparing it to this measurement and maybe we'll learn something.
According to the clutch adjustment procedure we're supposed to have 75mm from the absolute end of the cable to the beginning of the metal sleeve. I have almost 90mm now. If I were to adjust to 75mm I would be able to dial in the free play at the hand lever but my clutch piston and rod would constantly be applying pressure to the clutch spring disk even when the hand grip is released.
Anybody know if that's okay?
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If I were to adjust to 75mm I would be able to dial in the free play at the hand lever...
Wait - That doesn't make sense, does it? :dunno2:
Any luck, Carl?
I've been working on the Maine coast since the weekend and haven't been able to mess with bike. Eager to get home and ride!
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Well, mechanic replaced throwout bearing and clutch rod which made no difference. He was able to get free play by fiddling with the cable length at the transmission end. So, everything now works with adequate free play but the adjustment at the transmission end isn't as it's supposed to be according to spec. He couldn't come up with any reason for this. He will be working on a couple more K75s in the next 2 weeks and will be taking a hard look at those to see if anything sheds light on this situation. In the meantime, I'm riding and planning a trip down the Blue Ridge Parkway next week :riding:
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If I were to adjust to 75mm I would be able to dial in the free play at the hand lever but my clutch piston and rod would constantly be applying pressure to the clutch spring disk even when the hand grip is released.
Anybody know if that's okay?
It seems to me that, if you have free play, then there shouldn't be any pressure on the clutch rod. It's when you begin to feel resistance that the spring disk is being pressured. If anyone knows this to be wrong, please let us know... thanks!
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... as the disk wears, freeplay decreases...
Wouldn't freeplay increase with a worn disk since the pushrod would need to be depressed more to reach the clutch spring?
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since the pushrod would need to be depressed more to reach the clutch spring?
As the friction disk wears, the spring moves closer to the pushrod.
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since the pushrod would need to be depressed more to reach the clutch spring?
As the friction disk wears, the spring moves closer to the pushrod.
+1
The spring is behind the friction plate on our K's.
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FYI - Looking for answers to this on the MOA forum (http://www.bmwmoa.org/forum/showthread.php?69031-No-Clutch-Freeplay-on-K75) too.
I pulled the transmission and the clutch pack today.
Push rod is perfectly straight.
Friction disk is 5mm thick. I mounted the friction disk by itself on the transmission input splines and spun it. It does not show any signs of being warped or disfigured.
The image of the throw-out bearing / piston is with the piston fully inserted on the installed transmission.
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... as the disk wears, freeplay decreases...
Wouldn't freeplay increase with a worn disk since the pushrod would need to be depressed more to reach the clutch spring?
I don't believe so. As the disk wears, the spring, which is in constant contact with the disk when engaged, moves back toward the rear of the transmission thus requiring less movement of the clutch rod to depress the spring. At least that's how it looks to me in examining the parts fiche. Others' thoughts?
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... as the disk wears, freeplay decreases...
Wouldn't freeplay increase with a worn disk since the pushrod would need to be depressed more to reach the clutch spring?
I don't believe so. As the disk wears, the spring, which is in constant contact with the disk when engaged, moves back toward the rear of the transmission thus requiring less movement of the clutch rod to depress the spring. At least that's how it looks to me in examining the parts fiche. Others' thoughts?
Agree.
I also notice in the pictures that the pushrod has a shoulder on it so it will only travel so far rearward upon "release" or "relaxed" position. Even as the friction disk will wear, and the spring pressure plate moves closer to the pushrod and transmission, eventually the spring will start to depress against the rod/shoulder and the friction disk will start slipping.
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I'm guessing that my best solution is to replace the clutch pack. My pressure plates are a little worn and the friction disk is approaching its service limit. Not sure if a new spring would help.
The Motobins price for all that plus bolts and washers is about $300 US which is considerably less than US dealer prices.
Not too excited about another day-long strip-down though :(
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Replaced the clutch pack. Problem Solved.
Plenty of room on clutch cable to adjust properly now. All the new parts measured about the same as the old except the friction disk which was .7mm thicker.
Hope this is the last time I have the transmission off for a looooong time.
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Glad you finally got that straightened out! Was your original clutch disc still within spec? Mine is well within spec with only 30K miles or so on the bike. I did 2000 miles on it over the past week and all seems to be OK so just going to keep riding it for now!
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The disc I replaced was scored and very smooth but still 4.9mm thick. New disc was 5.6mm thick.
New disc is a different design and had rivits and no channels like the old.
(the old disc pictured here is not the exact one I had but looks similar)
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Posted a pic of the clutch disc I removed from my bike over on the MOA forum and it was immediately recognized as a non-K75 disc.
Doh!
Just goes to show you that you never quite know what you're getting when you buy a used bike. I put 25k miles on this clutch and who knows how many mile the previous owner did on it. Brand name says "Surflex"; no part number.
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Weird. I had my transmission out this week and had no issues. Only thing I can think of is maybe you have the clutch cable in the wrong spot in the slot on the transmission. The cable needs to nest in the rear part (closer to the tire).
I adjusted mine exactly as described in this video. Needed nearly no adjustment when I put it together.
http://youtu.be/gBW4D2jDw2A (http://youtu.be/gBW4D2jDw2A)
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Tim, maybe that disk you removed was a VW car disk. They are reported to be interchangeable, I've not seen one so who really knows for sure.
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Just thought I'd mention that I LOVE getting into the historical "Motobrick Workshop" threads and finding things that are going to help me with my upcoming clutch pack replacement.
Now where did I leave that 30 mm socket? :threadjacked