Bad clunk on clutch take up

[Breezerider]

My recently purchased 1980 R65 has 18k miles on it and had a very grabby clutch- let it out too fast and it would jerk my dentures out. It took some getting used to- less than 1/4" movement at the lever end is the total take up. There was a clackety noise when I shut it down or got the idle down to about 500rpm. I pulled the gearbox and found that the pressure plates were slightly grooved, more like wavy with 3-4 hot spot gall marks on both plates. The clutch had plenty of material with maybe .1" difference in outer and inner edge thickness. At $500 for a replacement, I figured this was not too pathological and put the puppy back together. A little online research told me that the clackety noise was normal and greasing the clutch splines lightly helped cut the noise down and eased shifting a little. But...

Within 100 miles of mild sport riding I heard a clunk sound as I let the clutch out and the bike got under way. Within 50 miles this grew progressively worse unless I went extremely slow on the lever. By the time I limped back home, the clunk was really loud and I could feel it in the footpegs. I have enough mechanical experience and tools to tear into the gear box if necessary, and just enough $ to get a new clutch and pressure plates, if the problem is with the clutch. Anyone have a take on these symptoms? Are there aftermarket plates that might be cheaper? Could the problem be in the shaft drive?

Walter

[willr65]

I think you need to separate the driveshaft from the gearbox to determine what is faulty. 18K for a gearbox isn't much before it breaks up!  :-?

[steve hawkins]

This thread needs to be moved to the tech section.

However, I would start by stripping the bike and looking at the following area before you dive into your gear box -

1.  Look at your drive shaft, both at the sprung coupling and at UJ.  This should be bathed in oil....but you might find wear on the UJ which should have full range of movement but not have any discernable play.  The sprung coupling might get worn/slack but not at this mileage.

2.  Final drive splines and play.  check oil for bits of metal floating in it

3.  Then look into the Gearbox.  check oil for bits of metal floating in it

As mentioned above, at this mileage you should not be having an issue.  I have a slight clunk on clutch take off on my R65, but I have more than 110,000 miles on mine, and I expect/hope to find the issue with the driveshaft.  If not, I will probably live with it as it does not seem to be getting any worse..

Steve H

[Semper Gumby]

+1 what Steve said.  Sounds like the tranny needs to be re-shimmed.  I wonder if you could put a reliable person on the bike to slowly let the clutch out while you stand on the left hand side of the bike.  You ought to be able to feel the clunk as the shaft hits home on the aft cover of the tranny.  Just a thought.  You might be able to do the same thing with the motor shut off but with first gear selected and then rock the bike back and forth with the clutch engaged.  Probably nonsense but worth a try.

But...otherwise   I would do the spline lube with the thrust bearing service.  While you have the back end apart check that the drive shaft universal joint is not loose or "notchy".  Look for Reasons like water in the oils (latte colored), metals in the oils.  Seperate the final drive from the drive shaft and make sure that the source of the clunk is not there.  Grab both ends of the drive shaft and see if it is solid and not loose (not likely).

My 1980 has ~86,000 miles (the warrenty has expired) and sofar no tranny problems.  But then I change out the oils twice a year (october and april) so I usually see and fix oil problems before they cause to much damage.

Good luck.

[nhmaf]

It might also be possible (though you MUST do the clutch arm/pushrod, throwout bearing clean, inspect and lube at the back of the transmission) that you've got a bad
diaphragm spring or runout problem with the flywheel, if you are getting strange wavy wear patterns in the clutch disk.  

While there could be a driveshaft/U-joint issue, it also merits checking the  rear drive splines (Excessive wear there can cause clunky/jerking motion) and there is
also a spring-tensioned drive shaft (mates with intermediate shaft) in the gear box that has, on rare occasions, been seen to break - actually, either the big spring that keeps
the lobes that mesh with the input shaft can break or one of the "ears" on the lobe can break off (Items 5&6).  If either of these occur, you'll generally be seeing some sort of
metal "chunks" on the drain plug of the gearbox.

I have only seen one of these break before, and it was on an R100, but not one that was "horsed around".

[Breezerider]

The shock coupler with the big spring is a weakness in early R65's- the coupler cams can break.  I'll start tearing into the gearbox this week.  Anyone have a good source for gearbox parts, particularly the later shaft and pawl upgrades?

Thanks for all the replies.  

Walter

[Ed Miller]

I thought the shock coupler was in the drive shaft, not the gear box.  Is there another one?  I don't think gear boxes were R65 specific.  I know that '81 on, they were the same as all the other airheads.

Good luck,

[Justin B.]

Item 3 is the "input shaft" and items 4-8 make up the input shock absorber.  There is also another spring-loaded hootus in the drive shaft for the ultimate in silky-smoothness!  

[steve hawkins]

BreezeRider,

I think you have also posted on Boxerworks.  As I said there, let us know your findings when you do your strip down.

We would all like to know how you get on. so do not keep it a secret.

"Knowledge is power" and all that!

Cheers

Steve H

[chewy4x4]

bump

Why the bump chewy?

[chewy4x4]

THis sounds like the noise that I have been having on my 65 so I thaught I would bring this thread back from the past as a reference.

[oldbiker]

Hello Breeze rider. Sorrry to hear about your gearbox. I had a very loud clunk in the gearbox of my `83 R65 ls last October. My problem was the spring on the spur gear on the input shaft had become weak resulting in the lobes over riding if I naccelerated or slowed down rapidly always making a loud noise. The strange thing in my case was there were no broken parts and a check on the oil from the box yielded no information. I had to strip the box and replaced the spur gear and spring. Bought the parts from Motorworks UK who were very efficient. I followed the information here on R65 Wiki. Lucky Lou has posted a very good site with plenty of pictures on 7th February 2010. I have some photos of the gear on my own post "clunk in Gearbox"last October.
I must say I am grateful to all the members that advised me at the time. I have the bike on the road now and am enjoying a smooth silky gearchange. I put the small bearing as advised by Wiki rather than the nylon roller on the selector fork. It seems to have given na more precise feel to the gear changing.
Hope you get sorted out soon and back on the road.

[montmil]

Where you been, OldBiker? No phone call, no email, not a Tweet nor a Text... not even a postcard.

We held a fine Irish wake for you and now you turn up alive! We'll be mailing the bar tab to you [smiley=beer.gif]

Monte

[oldbiker]

Monte

Hope you had a right few whiskies at my wake. The sad thing about life is we all will miss our own wake. We often say that a wake is more fun than a wedding- everyone can go and you dont have to be invited.
I have logged into the forum practically every night and enjoy all the advice and comments. In truth this is my first BMW and I have no experience of repairs other than the gearbox. The bike is running well now and I am getting plenty of enjoyment from it. I have a few BSA and a Norton Commando that keep me busy in repairs.
Hope the weather is good in Oregon for biking.
Cheers
Old biker

[chewy4x4]

New fluid and no joy. I still have the clunk I really don't want to pull that tranny bu tit seems to be becoming inevitable.