That GD Clutch Again

[snowprick]

Following total loss of clutch (see earlier post) I had all my hydraulic fluids replaced. Now while cruising back home at a leisurely 120kph (75mph) I decided to run to the front of my group and wave good buy before I reached my exit. While in 6th I grabbed a big handful of throttle (just love the response) and the engine revs wound up rapidly with no bike speed increase. I tried again with the same result. The road was clean and dry so no wheel spin, I suspect the clutch is slipping. My bike only has 28,000 km on the clock so the clutch should still be like new. Anybody got an answer?

[CycleRob]

That clutch slave release system is not ideally designed. There is way too much spring pressure working on the tiny ball bearing embedded in the moving slave piston. All the time. Even when the clutch is engaged. My slave failed too. When the bearing eventually fails on high mileage OilHeads, the non rolling friction members overheat the piston and therefore the DOT-4 fluid behind it . . . . to the boiling point. You end up with air in the system, a damaged slave bore from the spinning piston and problems releasing the clutch. When the slave piston spins too much for too long, DOT-4 leaks past the seal, travels up the inside of the hollow input shaft that contains the clutch release pushrod, where it will eventually soak the clutch disc material. Then the clutch slips. If you remove your rubber TDC inspection cap you may see oily dampness and more importantly, the smell of steaming brake fluid. That's scenario A.

Scenario B is much better because it's easier and much cheaper to fix. That's where either the clutch lever is contacting a handguard so it's not fully releasing -or- the tiny mastercylinder bleedback hole is clogged shut. Both anomalies will give you the symptoms you have.

Whether it's A or B, you likely have a damaged $127 slave assembly (-10% discounted). You need to 1st remove the TDC cap and give it a look & smell. If that's OK, take apart the clutch M/C to clean it out. These images will help:
http://i142.photobucket.com/albums/r87/ ... ube-31.jpg
http://i142.photobucket.com/albums/r87/ ... ube-30.jpg
http://i142.photobucket.com/albums/r87/ ... ube-17.jpg
http://i142.photobucket.com/albums/r87/ ... ube-26.jpg
http://i142.photobucket.com/albums/r87/ ... ube-27.jpg
http://i142.photobucket.com/albums/r87/ ... ube-29.jpg

If you need help, PM me your home phone (not cell) and best time&day to call.

.

[gunga din]

CycleRob

Could the pressure in this sealed clutch slave chamber add stress to seals, thus causing the fluid to leak onto the clutch plate then seep into the gearbox causing gearbox seal failure? I have heard bikes having the clutch slave chamber drilled as per your suggestion have not experienced seal failure (yet).

Do you have any thoughts on this?

gunga

[snowprick]

CycleRob,

Thanks for coming to the rescue. Option A, which seems more likely given the history, looks like bad news or bad news. Currently the bike is in the shop and they are going to start work tomorrow (Monday). Armed with the information you have kindly provided I will go over there tomorrow and "assist" them.

I sense that now is the time to remove that catalytic converter and pound it into oblivion, then grind it up and throw it in a volcano somewhere. Can anyone point me to that topic. I seem to remember there was a requirement to replace it with a Y piece and fit a chip somewhere.

Thanks again CycleRob I will keep this post alive until the job is complete.

I am about 12 hours different from you so will avoid telephone contact.

[CycleRob]

snowprick,
I must'a had a senior moment . . . . I was under the mistaken idea you were in Florida. My unlimited call plan is for continental US, so I guess I won't be calling.
You should keep the CatBox, it's valuable and at worst, it can be sold.

gunga din,
There is no pressure build up in the slave chamber as it is vented thru the hollow input shaft where the release pushrod goes thru. There's only the felt band there to keep clutch dust from getting anywhere near the slave piston's exposed bore, but air can easily seep by.



When I removed my slave it was an orange/brown gunky mess!! I also was surprised at the very heavy internal spring pressure the slave piston has against the pushrod. All the time the engine is running. It seems really excessive when compared to the dozens of it's Japanese counterparts I've taken apart over the years. On a standard shift car, that same slave spring pressure is easily counteracted with your pinky finger. The 50R's slave takes 2 adult male thumbs to compress it. I even considered shortening my bike's internal slave spring, but shelved that plan for fear of wandering into some unforeseen vibration, wobbling or retention issue. Sometimes you gotta trust the German engineers . . . . except maybe when it comes to QD's, FD's, transmissions, ABS systems, and wire harnesses.

I should have shortened the %&#$ slave spring!!


.

[baltm604]

Many factors from driving style to environment can kill a clutch in 18k miles.

From persnal experience, driving 90% of the time in urban traffic, being bigger than the average rider (+300lbs), and mis-matching rpms while engine braking killed my clutch in a hurry.

Bill

[snowprick]

The clutch is oil SOAKED

Seems the engine blew a seal so I am looking for the parts now (please dont mention MAX BMW) I will also replace the clutch slave as it got overheated recently.

I am off on a four day ride on the 650 POS tomorrow so when I get back I will try and get some photos and post.

I will also look closely at my splines as I now have the opportunity. Any bets on the splines too?

[CycleRob]

snowprick,
What you think is oil might be DOT-4 fluid from the slave. It will travel forward thru the hollow input shaft and leak out on the flywheel's steel friction surface that mates with the clutch disc. Give it the smell test. A slave failure happens a lot more often than an engine rear seal failure.

[snowprick]

snowprick,
What you think is oil might be DOT-4 fluid from the slave. It will travel forward thru the hollow input shaft and leak out on the flywheel's steel friction surface that mates with the clutch disc. Give it the smell test. A slave failure happens a lot more often than an engine rear seal failure.

CycleRob,

Given the overheats that I have suffered I bet you are right but wont know till I get back from a 4-5 day ride starting in 13 hours. (a very sufferble 75 degrees today) ha ha. Just had to throw that in. Will take photos if I am back in time (still waiting for parts)

For those of you who are not familiar with engines blowing seals check this out

http://www.youtube.com/watch?v=F5HhhxbwiQQ

[snowprick]

Just got back to the Philippines after a cold and expensive trip to the UK. Dont know how you do it guys!.

My BMW dealer has opened the bike and informs me that the oil leak which toasted my clutch was GB oil. It leaked past a displaced seal behind the clutch slave cylinder. The oil worked its way along the clutch pushrod and then onto the clutch plate.

Photos were difficult today but will try again in a few days when I feel a bit better.

[Beemeridian]

11

[snowprick]

Prelim photos

[CycleRob]

snowprick,



Here's my solution to a slave piston leak that you may have already seen. It will also give me an immediate indication when my clear tubing drain pipe emits either smelly GearBox oil or tart/sweet* DOT-4 fluid. My cost of this mod = zero, using salvaged/discarded materials.

http://i142.photobucket.com/albums/r87/ ... ube-17.jpg
http://i142.photobucket.com/albums/r87/ ... ube-26.jpg
http://i142.photobucket.com/albums/r87/ ... ube-27.jpg
http://i142.photobucket.com/albums/r87/ ... ube-29.jpg

Wouldn't it be nice if BMW also integrated some similar system, of nearly insignificant cost , considering how damaging a DOT4 or GB oil leak can be on a bike usually ridden twice/triple the distance the avg bike is?? Maybe too much faith was placed in the invincibility of German Engineering.

* No, I don't taste it. I just smell it.

.

[AndyRR]

Does the transmission have to come apart to replace the seal behind the clutch slave? When I look in there, all I see is the bearing that was installed from the inside. The only other "seal" that I found was the felt ring on the clutch rod.
Also, does gear oil in the presence of the clutch slave necessarily condemn it?

[snowprick]

Does the transmission have to come apart to replace the seal behind the clutch slave? When I look in there, all I see is the bearing that was installed from the inside. The only other "seal" that I found was the felt ring on the clutch rod.
Also, does gear oil in the presence of the clutch slave necessarily condemn it?

The dealer tells me "he has a puller", as an engineer I will watch and learn. Looks like a gouge out job to me but lets wait and see.

The gear oil went further, it travelled up the pushrod and the rest you know.

[snowprick]

STILL WAITING FOR PARTS!

Good news, the splines look OK

[boxermania]

snowprick

Those splines look really good and with good contact, do notice that there is some trash on the teet and even a bit f rust so water got in there. How are the teeth on the clutch disc?

Make sure thatb the teeth on both the input shaft and the disc are clean and use a good Moly paste for lubrication...notice that I called for paste, not spray.

Looks that you are about finished......

[snowprick]

snowprick

Those splines look really good and with good contact, do notice that there is some trash on the teet and even a bit f rust so water got in there. How are the teeth on the clutch disc?

Make sure thatb the teeth on both the input shaft and the disc are clean and use a good Moly paste for lubrication...notice that I called for paste, not spray.

Looks that you are about finished......

The GB was in the paint shop at the time I took the photo. Nice opportunity to get rid of that brown stain ala QD's. If I had been doing the job myself, I would have made everything nice and clean and protected the spline before painting............ I am in the Philippines!

I drop in on the dealer regularly to try and drive things my way and have already asked for Honda Moly-60. Later I will ask for the clutch cavity to be cleaned so that they can mess up the nice paint job and so it goes on.

The clutch is toast due to oil contam.

If you ever get the sh1ts with your dealer in the US........ try living in Asia.

[snowprick]

The Good News.

Finally the parts arrive and the bike is ready for delivery to me. They replaced the clutch plate, and the slave cylinder (at my request) Cost of parts $463. Cost of labour $135. Bike will be delivered on a trailer tomorrow morning to my door. Now I can throw that gutless F650 GS POS on the lawn and get back to riding a real bike with a boxer engine.

[Sunbeemer]

...Cost of labour $135

Congratulations on getting your bike back in good running order, and pretty inexpensively (except for the parts). That's gotta be one of the benefits of living in the Phillipines!