The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: baffle on April 16, 2013, 04:15:37 PM
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I have asked a question on a UK forum but not found anyone who has seen the symptom my bike has. The bike is a 1980 R65. I have had the bike a few years and always I had a bad change 3rd to 2nd when bike was hot. So I decided to strip bike and while sorting transmission get frame etc blasted and powder coated. This is the first time I have stripped gear box/clutch on this bike. On taking transmission apart, one bearing (input shaft ball bearing) was a little rough but not that bad, and other bearings seemed OK to me. On taking clutch apart, it is clear that the input shaft has been bearing on the pressure plate and worn a recess in it - perhaps 0.1mm deep. Has anyone seen this kind of wear before? thanks
Picture of pressure plate here: (https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi742.photobucket.com%2Falbums%2Fxx67%2Fmattbeamish%2Fpressureplateall.jpg&hash=767249a74d45d7d9cb1f208005b4d03176339a1a) (http://s742.photobucket.com/user/mattbeamish/media/pressureplateall.jpg.html)
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Can't recall my 80 R65 or my 75 R90 pressure plates looking like that when I had them off.
Don
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I usually put a dot of anti-sieze on the end of the pushrod when assembling, but that doesn't do much.
What it looks like is that the clutch pushrod is grinding it's way into the pressure plate. My guess is the bike was run with no clutch freeplay, or the clutch throwout bearing is shot. The pushrod would be running tight against the plate and trying to weld itself to the plate : )
New pushrod, new plate, new throwout bearing assembly.
My guess.
-Armen
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The earlier, 'heavy' style clutch assembly used a different length pushrod, I think, than the later "carrier" assembly units did (1980+). I am not 100% sure of this, but there are different part numbers. Maybe it could be possible that someone fitted the wrong pushrod or pushrod assembly for the clutch in the bike?
The cut-over date in manufacture would be Sept 1980, I believe. One can look at the microfiche online in several places, such as MAX BMW here in the states - probably also on motobins.
http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51897
OR - perhaps the clutch has been misadjusted at the lever at the back of the transmission (or cable length) so that it doesn't retract all the way/far enough and is dragging (or the spring in the throwout piston is worn out/compressed)?
I haven't seen this specific problem before either, and my bike is a 1982 with the later style clutch, so I am just offering up possible suggestions to look at.
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I'm not familiar with the first generation bikes pressure plate and clutch assembly, it's very different from the second generation bikes .
The plate that shown, is it the plate that goes up against the flywheel, or is this plate that goes on last after the clutch disc is installed ?????
Again I'm not familiar with this setup, but I think the clutch disc may have been installed backwards and the hub of the clutch disc is in contact with the pressure plate .
How does the clutch disc hub surface look, worn and bright ????
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Bob you may be right about the clutch disc. I think I have an old will look when I get home and see if there a difference.
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The operating arm on the back of the gearbox should have an external return spring between the gearbox endcover and the arm. Did yours have that spring ?
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Thanks for all suggestions.
Clutch was Installed correctly I think - I have the fiche in book form so can check this ok. This is the clutch plate that is separated from flywheel by clutch spring. The external spring was present. The clutch is worn with clear wear ridges on both pressure ring and pressure plate. I could get these faced and get a new clutch plate. It has been suggested that once gearbox is back together and clutch back on I attempt to measure if there is clearance between shaft and clutch (that's gonna be fun!). If no clearance might be crankshaft endfloat prob? But bike wasn't bad before I stripped it - would I know about too much crankshaft endfloat? I had done maybe 7000 miles on her.
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Just thinking out loud here, any chance the transmission you have is a second generation transmission ?
There were differences the first and second generation transmissions, I think the input shafts were one of the main differences .
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Went and found the old clutch disc from my R90. One side is just under size of what the disc material in thickness which would go next to the pressure plate. The other side is 1/4 to 3/8 in hight. I don't think you could bolt the clutch part back together if the disc was put in backwards. Bob thinking on the input shaft may be the problem I think the newer clutch assy. used and longer input shaft.
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Transmission is older style serial Z057199. Push rod has felt ring. Would input shaft from later box fit in old box? Thanks.
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Take the clutch disc and compare the OD to the wear pattern on the plate. If the wear pattern shows a larger area than the actual clutch friction disc, then the clutch wasn't centered properly (clutch pilot tool needed) when it was installed. This could have caused the wear pattern you see because the clutch pushrod would be hitting the inner pressure plate off center.
-Armen
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Yes it can. There are 2 shafts depending on the clutch assy the back has. One for bikes up to 9-80 and the other for bikes from 9-80 to 3-85. The bikes made from 3-85 and on have a larger dia. shaft.
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Diameter of wear = same as friction disc dia (158mm). Nice idea but think was centred....Am going to find out more about the 2 shafts. Think my bike was registered may 1980. Thanks
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Look for the built date on the data plate. Do you know if the transmission had any work or was replaced.
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Don't know if any work done on transmission and 12 previous owners. My input shaft is 180.93mm long. Any comparison dimensions? The diameter for the push rod is 8.57mm at piston end and 9mm at clutch end.
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Armen,
I don't get the disk not being centered ?
The clutch disk goes on spines with very few play on the gearbox input shaft, and the gearbox body is centered on the engine body. so I doubt you can mount the whole if the disk is not centered properly in it's mechanism.
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There is enough slop in the trans mounting holes to allow the trans to mount up even if the clutch disc isn't perfectly centered. When I'm doing a clutch job, I always put an allen wrench in the alternator rotor and turn the motor a few times with the trans mounting bolts finger tight. If I goofed and the clutch disc isn't perfectly centered, I can see/feel the trans moving.
-Armen
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The input shaft is about 24 mm long on the early transmissions, and from 1981, it is about 19 mm long
The above is from Snowbum's site. Will have t assume the length he is given is the splines only. I have a extra trans apart and the input shaft measure the same you have and the splines are 19 mm. I knew the shafts were not the same there just opposit off what I though.
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The spline section on mine is 25mm shoulder to end. Has anyone got a loose input shaft from an early transmission and a wernier caliper? Is it impossible that there was a batch of bad machining as my spine section is maybe 1mm too long ( as elsewhere this is reported as 24mm)? Thanks.
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That pressure plate looks pretty worn out to me. Maybe it's so far recessed the clutch hub was rubbing?
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Yes it is worn - 0.5mm ridge maybe. The compression ring also has a similar though less pronounced ridge. The clutch disc is 5mm. Would not the hub rubbing due to wear would be seen commonly? The clearance between shaft and hub must be very tight. Thanks for thoughts.
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Just compared shaft with 2 others at Phil Hawksley's. Any differences minimal. Must be clutch - will look to renew the clutch fully. Thanks for all responses.
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With wear like that to the pressure plates, my assumption is the clutch disc was replaced last time, but not the plates. With new plates you could probably continue with the same clutch disc - it's only half worn. But that's a tough one to justify when everything else is new. Besides, clutch discs tend to wear unevenly - more on the outer edge than at the center.
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I started my annual servicing of my R90 last night. Pulled the transmission and looked up throught the clutch splines and did not see any wear on my pressure plate the you have in you pictures. The input splines sticking out of the trans are 24MM. I have replace the clutch disc a few times and have had the throw out bearing go but was able to still use the pressure plate that came with my bike.
Don
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Thanks for thoughts. New clutch for a 78-80 R65 is big cost now - just had a quote - £372 for all the bits from one of the UK suppliers (that's $567 for you guys), with pressure ring twice cost of one for later R65s. Is a cheapskate option to get ring and plate faced, and get a friction disc made up a bit over thickness - there is a specialist clutch and brake re-lining unit near me, who might be able to do it, but perhaps I am just playing with fire, and putting off the inevitable.
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I had the clutch disc relined, and both the pressure plate and pressure ring trued up .
The shop did a horrible machining job on the plates, I should have left them alone .
If by chance you so go this route, the first problem that may arise, is that you can't get the cable adjusted correctly, the adjustment bolt at the back of the transmission will be in all the way and you still don't have the proper adjustment .
You need to get a longer bolt, but at the same time, too long of a bolt won't fit the clearance you have between the clutch arm and the swing arm .
You may need to remove the clutch arm from the back of the transmission get the bolt threaded into the arm and then reinstall the arm on the transmission .