Clutch woes 1976 R60

[opus451]

Hello All,

My bike is a 1976 R60/6.
I have my ideas of what the problem might be, but not enough experience with my bike yet to know for sure, so I throw it out to all of you.

The clutch control piston is not returning with the arm, making the clutch lever and cable of course useless.

What am I looking at here?

Thanks in advance!

Eric
Brooklyn.NYC

[Rob]

If the bike is new to you and you are having problems, you need to remove the lever and check things out.

I'm not sure how similar yours is to the '79 R65 I had, but remove the arm (mine was the PIA "E" clip type), and then the rubber boot.
The piston should pull out next. You should be able to pull it out with your fingers. If not, long-nose pliers may be needed.

On the piston is a large seal - both in diameter (20-30mm?) and in thickness. It is square section. The piston is also the throwout bearings outer race.

With that out, take your small magnet-on-a-stick and put it in there and remove the bearing and the inner race.

I know BMW went back & forth on bearing design a couple of times. I had the one with roller bearings laid out radially. I guess the ball bearing design that preceded it and followed it worked better. The roller bearings need attention. Or just carry the tools and spare with you. It's easy enough to replace and you can sure tell when you need to! Ah, the early days...


This is just one scenario. You also need to pull the gearbox and clean/examine/lube the input splines. Involved, but easy enough that an incompetent like myself could do it. You also want to check for oil leaks from the rear main seal (involves pulling the flywheel [RED ALERT! Block the crankshaft!]) and the oil pump. Make sure those cover screws are tight.

Gearbox oil has a completely different smell than crankcase oil. That would be coming from the input shaft seal.

This is also a good time to consider the neutral switch, especially if it is the newer style that mounts on the bottom rather than the rear of the gearbox.
If yours is leaking, or malfunctioning, now is the time to replace it.
The switch from the two different eras work opposite each other - NO vs. NC, so be sure to get the right one.

Or it could be something else. Like the tip of the throwout rod. It needs to be kept lubricated (every 24-36 months, depending on mileage) to keep it from deforming, along with the clutch, uh, pressure plate?
You also have to use your molybdenum grease (Honda Moly 60 is good) sparingly there and on the splines so they don't fling grease on the clutch.
DON'T put grease on the female spline teeth on the clutch. Input shaft only.

[opus451]

Thanks Rob!

I believe the piston was able to pull out the last time I looked at it, but I will investigate some as you suggest. If the pressure plate has given out, or the friction plate has gone down to nothing, would that cause the piston to either not be pushed back out, or to be pushed out as far back as it will go given the loss of friction plate thickness?

[Duane Ausherman]

Rob has given you a good, but large list.

You asked, "If the pressure plate has given out, or the friction plate has gone down to nothing, would that cause the piston to either not be pushed back out, or to be pushed out as far back as it will go given the loss of friction plate thickness?"

No, you have something that is stuck. I would start as Rob suggested. You didn't give us any history, so his suggestions are for a bike that is new to you. Check your log book to see what has been done in the past.

In a case like this, once you come to the defect, it will be obvious. That is tempting to just fix that issue and move on. If you don't have a clear long history on the bike, that would be a mistake. Go through it and be sure of everything. Take photos, inspect every part for wear etc. My site has quite an article on the clutch stuff.

[Rob]

And while the Haynes and (?) repair manuals are not perfect, they have good pictures on taking things apart and measuring clutch spring height (tension), etc.
Be suspicious of torque specs. in those books. Be suspicious of torque wrenches in general.

I do remember you from your participation on the previous Boxerworks.
What did you have then? For how long? Is this the bike you had shipped across the country to NYC?

[opus451]

Thank Duane, thanks Rob.
Good to see you guys are still well and on here.

That's right, I was asking for advice on shippers.
Which was good advice, but I opted for the adventure!

In late July, I flew to Seattle with my tools and gear, took a bus to my cousin near Mt. Baker, pulled the bike from under a tarp out in the woods (I know, abuse!), put the key in after 3 years of sitting and the battery turned over! Had water up to the top of the pipes from the deep snows. Had a rear tire and battery shipped there during previous week. Did all the things one would do and got it road worthy in 3 days. Over the next 6 days I would angle my way through Oregon down to route 80, and head East. Turned south around Kansas City and got caught in one of the worst storms I've ever seen around midnight, slept in an open air car wash stall in the middle of farm and god country, while it blew hell all around me, which was good because I was exhausted. Took 40 on into Asheville where my brother was waiting at the hostel there with his bike, and we road the Blue Ridge a while and then hit the interstate back to NYC. 4000 miles in about 6 days. Only major problem was the alternator light came on, and laid me up for about 24 hours at a truck stop west of Rawlings, Wyoming while I voltmetered everything to make sure nothing was burnt, another solid night of much needed sleep. Slept on one of those picnic tables under the lean-tos they have out there. All checked out, and it turned out to be the starter relay. I was reminded to always check the simplest possible fault first, but then again, I didn't know to look there and I think it is one of those things only experience with the old bikes will teach you. It was one of those moments where you just breath deep and feel good to be back up. I pulled the cap off and push-buttoned the thing the rest of the way. I was so anxious to get back on the road, I headed out about 2am after a few hours sleep, and eventually had to pull off not expecting the temps to dip so low, somewhere in Nebraska. I pulled off and hugged the engine for a while. Great trip all in all. Longest of my life so far. This is a damn beautiful country out there.

Actually Duane, it was yours and Snowbums sites that helped me out during my rest at that truck stop, and just getting it back on its feet the week before.

Way before the major trip, back in 2007, I pulled the engine and tranny apart and rebuilt it, with the recommended upgrades and such. Brought the bike to a mostly new starting point with its power plant at least. Splurged on a Dyna, an Omega, a new starter. Clutch looked good then, friction plate was nearly new. I did start my personal log then, so I will refer back. So after that long trip, with alot of gear on its back, all kinds of different topographies, and after the years of stop and go traffic in NYC since 2007, I don't doubt the clutch needs a good look. And I am sure plenty of dust got in the the piston area, so it being stuck has a good probability. Its about time to give the bike a thorough going over again and bring things back to spec. I will follow those steps Rob, and refer to your site Duane.

I'll try to report back as things progress.

Thanks guys!

Eric

[opus451]

Oh, and any further ideas are greatly appreciated!

[Airbear]

Great story, Opus.

Now, if the gearbox hasn't been out since 2007 it is definitely time to do so, especially given the sort of punishment you have been dishing out (NYC traffic - yikes!). As Rob says, the splines on the input shaft need a clean and grease or the clutch plate will stop sliding smoothly. And I'd be checking the clutch diaphragm plate - there's a minimum height spec, and the 'teeth' around the inner diameter can dig their way into the mating surface, making clutch operation lumpy at best.





Lots of other things to check - the throw-out bearing particularly. It's time to go in there and have a look.

Have fun.

[opus451]

I am trying to visualize and surmise.
Please correct me if I am wrong.

Clutch lever is gripped, cable pulls, clutch control arm/piston/pushrod pushes forward against pressure plate which pushes against diaphragm, releasing friction plate from contact, putting tranny in a neutral state.

Clutch lever is then released, diaphragm energy is released rearward, pushing pressure plate (along with pushrod, etc) rearward, pressure plate resting against friction plate, transferring engine power through tranny to rear drive and voila, youre flying by the seat of your pants. Or suddenly falling over in a turtle speed accident (come on...we've all been there...).

So my only very partially returning pushrod could be a worn diaphragm, yes?
can a diaphragm lose that much spring? Or is it that it has deformed the pressure plate just a few micrometers enough to be the lost return distance?

The friction plate is strong still. I know this because when I ever so gently had to slip the bike into first gear sans lever, the damn bike almost shot out from my crotch! So wouldn't the diaphragm/pressure plate be the things giving it a solid seat to tear-ass out from under me? If diaphragm was less springy or pressure plate caved, wouldn't the friction plate slip some?

Inspection of the rod shows minimal to no wear to pressure plate end, felt is looking good. Going to clean up and inspect bearing, piston/gasket, and continue the process.

Any thoughts as always are much appreciated.

[Airbear]

Eric, ok, you've given the old girl a year to think about self-repairiing. Sometimes this works, but it is rare and usually involves offerings to various gods and rituals at midnight involving the entrails of various innocent animals that haven't actually finished using them and so on.

Fortunately, in the year since my last post on this thread I have encountered a gearbox problem that may be pertinent to your case. I found it when I was preparing a new to me 1976 gearbox for installation and found that the clutch throw-out bearing would not slide smoothly in the bore in the rear of the case. The bearing had chewed a groove in the bore ...



Here's a better view after pulling the rear cover ...



And the fix. I took the cover to my local motorcycle-friendly engineer and he bored it and installed a brass sleeve with a 1mm wall thickness.



I then re-shimmed, assembled the box and happiness prevails. So, could this be a likely culprit in your case?