The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: raygun on June 17, 2007, 08:18:18 PM
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Ok, the final gear is out, the paralever is out, the gearbox is out and the splines both input shaft and clutch plate look perfect. So what could be causing the grinding slip? It is not the splines. Is it the driveshaft? Is it the bevel gear at the final drive? or would it be in the gearbox? Again it would slip consistently in all gears. You could accelerate gently without it slipping but if you twist the throttle some it would slip with a ratcheting sounding grind. Please help. Ray
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Look at the final drive to wheel splines, although I would suspect if they were worn completely off you wouldn't move at all - period! There are some splines where the driveshaft fits to the final drive but don't reckon I've ever heard of anybody ever stripping them.
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Justin, those points look good and the final feels tight. I'm wondering if it isn't in the driveline. Maybe the shock absorbing cam or the splines on the shaft. The driveline lube had the most gray matter of the 3 lubes. I'm hoping it is not the gearbox. The lube there looked very clean with just some very fine particles and one sliver.
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Well, that was a blow to our credibility!!
Might well be the shock absorber spring on the gearbox input shaft in the box gone south . Not unheard of for them to break. Haven't heard of the input shaft main splines (inside the gearbox) shearing, but hey, anything is possible. Another thing could be the actual shock absorber cam, when I overhauled my spare box from a '79 R65, one of the cam lobes was worn excessively, and the corresponding lobe on the main cog was partly broken and had another crack forming, so there's a possibility.
Bill...................;-)
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Bill, I thought the '79 had the solid driveshaft - so much for thinking! I'm out of ideas. :P I never had any credibility anyway so no damage done...
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I was talking about the shock absorber on the input shaft (now edited), though the '79 R65 on was the first of the models to have the Cardan driveshaft, probably BMW was testing it on them before giving it to the bigger models.
Bill.......................;-)
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The driveshaft definetly has the spring behind the female splines. I built a tool today to press the shaft and release the retaining clip. I'm headed out to do it noew, will keep you posted.
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Ok, to recap, pulled gearbox, input splines and clutch plate spines are perfect. Pressed the drive line and removed the circlip and disassembled, and it all looks like new. Disassembled clutch and checked pressure spring and clutch plate, it is all good. The only 2 things that have not been inspected internally are the final gear and the tranny. Both feel fine when hand operated. Checked the tranny thru all gears and it is very smooth. The final gear is tight and smooth. It has to be in the final gear or the tranny though, because everything else has been inspected and checks out with no wear or damage. Has anyone took the final gear or tranny apart? If so lead me in the process please. Ray
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I think Bill has had a tranny torn down, not for the faint of heart from what I hear...
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I haven't taken apart my gearbox, and you've taken apart all the other bits that I've
ever looked into, so I'm afraid that I am at a loss to give you any additional advice/info.
Personally, I was thinking that maybe the diaphragm spring might be weak or hanging
up and not pushing against the clutch plate sufficiently. If that isn't the case, and the spring in
the driveshaft checked out good, perhaps you may be in need of a tranny rebuilding specialist.
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I second the clutch parts idea. The springs do wear, so maybe it's not pushing hard enough to get good clutch engagement. You did remove all the clutch parts?
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I think Bill has had a tranny torn down, not for the faint of heart from what I hear...
Yep, done several now (very successfully by the way!!) and not as hard as your own self limitations will have you believe. You do need at least one special tool, but can be made at home. Below is a link to a very easily followed site that I used when I first repaired a box on a friends bike after he dropped an output shaft bearing. Since then I've done another couple of boxes for friends, and another spare for myself and have one on the bench at the moment for my 90/6. You will easily see in one of the photo's the shock spring and cams on the input shaft I alluded to earlier.
http://homepage.sunrise.ch/mysunrise/joerg.hau/mot/gearbox.htm
I see you have posted on Boxerworks, you may get some more ideas there, but we have been known to have a bit of fun as well, so maybe expect a bit of thread degradation.
Bill................;-)
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Thanks Bill, I'm going to have to make a couple of tools and then I'll tear into it.
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A worn throwout bearing piston would allow the clutch to slip. Had to replace mine a few years back.
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Ok, I got the tranny cover off and pulled the input shaft. "Lo and behold" there was the gear wheel with both its ears knocked off. And it looked about as sad as me when this big ol' boy tried to knock my ears off. I kept mine. Well any way it is nice to have gotten to the root of the problem. I owe a debt of gratitude to the many folks on the web that helped see me threw it. THANKS ;)
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I think we all learn something with these community diagnosis sessions - sort of
like the Socratic method cafe's that are opening up here and there, for people who
want to have an educational discussion !
I'm adding this to my growing treasure trove of useful bits of motorcycle troubleshooting knowledge !
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Some pics of the offending part would be nice for the archives...
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there is a pic at this link that looks identical to the one I pulled.
http://www.largiader.com/tech/airtrans/
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http://homepage.sunrise.ch/mysunrise/joerg.hau/mot/gearbox.htm
Good web page is Jorges I followed his note pulling down the bimbo's box. Just got to to put it back together once I saved some pennys up :)
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G'day Ray, Last week I finished rebuilding the gearbox on my '86 R65 (new bearings, seals and springs). I've never had a gearbox apart before but with Joerg's page (which was mentioned elsewhere), Clymer's manual and advice from people who had actually looked inside a gearbox before the job went surprisingly well.
Except........there was some evidence of a bearing spinning in its housing in the rear cover so I was advised to used one of the Loctite products to hold the bearing in place. With the cover heated with a hot-air gun, shims in place and all looking good I put the cover on. About halfway on the Loctite grabbed. It certainly wasn't going to come off again so there was nothing to do but to keep going and try to pull it down with the 8 screws around the edge. I wouldn't have believed it but it is quite possible to snap that rear cover clean in half. It was even, I was tightening in the approved criss-cross fashion and I wasn't really leaning on the Allen keys. With no warning it just went 'snap'. The two halves came off again quite easily.
Luckily a second-hand cover was cheap ($88, Munich Motors) and on the second attempt (no Loctite) it all went together smoothly. The gearbox is now fabulous to use. I would advise against using any bearing retainer-type product when re-assembling.
Cheers,
Another Ray
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I would most totally concur Ray, don't use any bearing retaining compound on any of the bearings in the box, your adviser was wrong. Those bearings do move slightly in their bores when everything heats up and helps them find their natural centres, even with shimming. Sometimes the galling marks (black marking) in the alloy bores are from that movement. Unless the bearing falls into the bore with little or no effort, install it as is.
BTW, where in Oz are you? You mention getting a spare back plate from Munich's, and though I know they mailorder, it seems like you had it all done in a very short time so do you live local? I live only a couple of K from Munich's.
Bill.......................;-)
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G'day Bill,
I'm in sunny Beechworth in North East Victoria about 40km south of Albury. I'm pretty impressed with Munich Motors (hello Bruce) and, indeed, Australia Post. Generally three days from ordering to arrival at the Post Office here. Sometimes two. Not bad for about 3,500km. Most parcels cost $9 postage.
For what it's worth - the gearbox overhaul kit they sell includes all six bearings, all seals, the nylon selector roller and all the selector springs for about $330.
Cheers
Ray