Clutch damage analysis? - K-Bikes.com - Excellence in Motion
 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 28 (permalink) Old Aug 1st, 2010, 1:02 pm Thread Starter
MIK
Senior Member
 
MIK's Avatar
 
Join Date: Mar 2006
Location: Acton, MA, USA
Posts: 187
Question Clutch damage analysis?

I have the bike stripped down now and the clutch is out (except for the clutch housing as I still need to make a tool for that). It only took me 3 days but with a lot of re-reading, picture taking and otherwise not turning wrenches time in the garage.

The clutch doesn't look contaminated, nothing leaked into the clutch.
The only 2 seals that were leaking were the one that goes into the slave cylinder pushroad (there was some transmission oil under the slave cylinder)


and output transmission seal (there was some oil in the swingarm).


And, the friction plate is still above the service limit -- 5.4mm (service limit is 4.5mm).

So the question are -- why did it slip and what should I replace? The surfaces on the cover plate and pressure plate look worn but smooth. Looks like there is some heat discoloring, but I don't know if that is abnormal and indicates need for replacement by itself. The plates(cover/pressure) surfaces are very smooth to the touch, but have some "polished" spots.



The friction plate is worn differently on different sides:
side 1:


Side 2:


What does it tell you?

Anyway, the clymer said that another reason the clutch can slip is weakness of the spring plate. I don't know how to test it, but I guess I need to replace it just in case.

The most important question for me now is -- should I replace the pressure plate and the cover plate? Opinions? Experiences?

TIA.

Max
more pics are here -> http://nedod.fomac.net/other/k12gt/clutch/
Attached Thumbnails
Click image for larger version

Name:	p7310584.jpg
Views:	35
Size:	869.7 KB
ID:	12387   Click image for larger version

Name:	p7310592.jpg
Views:	29
Size:	883.5 KB
ID:	12388   Click image for larger version

Name:	p7310594.jpg
Views:	26
Size:	872.9 KB
ID:	12389   Click image for larger version

Name:	p7310595.jpg
Views:	35
Size:	834.0 KB
ID:	12390   Click image for larger version

Name:	p7310597.jpg
Views:	36
Size:	848.5 KB
ID:	12391  

Click image for larger version

Name:	p7310606.jpg
Views:	32
Size:	826.7 KB
ID:	12392  
ipla68 likes this.
MIK is offline  
Sponsored Links
Advertisement
 
post #2 of 28 (permalink) Old Aug 1st, 2010, 5:42 pm
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
My clutch came out with even wear both sides so I'm trying to guess at your problem.

I can't think how a clutch could have got that bad without you feeling or noticing something sooner. Do you hold in the clutch a lot at stops?

The clutch disc should be fully floating both sides when it releases and when engaged the spring tension is shared both sides.

I can only think that if you get oil or clutch fluid contamination on one side, that will slip and wear more than the other.

The only other possibility is the plate splines have been jamming on the shaft which would stop it floating so it remains locked up against one side with no wear and wears down on the other. I think I'd have a good look at the splines on the shaft and plate, then check the plate can slide easily.

The heat blueing is to be expected if the clutch has been slipping badly. It's pretty difficult to determine off the bike if the springs are now soft or the pressure plates are out of true.

How can the plate be OK to the service limit if one side is worn down to the rivets? I think the service limit assumes even wear both sides and you have a very unusual problem I have never seen.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!

Last edited by voxmagna; Aug 1st, 2010 at 5:50 pm.
voxmagna is offline  
post #3 of 28 (permalink) Old Aug 2nd, 2010, 4:07 am
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
.............PS what are all those red/brown streaks on the friction material?

Has the bike been for a swim in (salt?) water?

Most friction material is impregnated with metal, usually copper/brass but sometimes steel. If the material is left in contact with another metal surface and allowed to get wet, the metal impregnation literally rusts and glues itself to the other surface of a rusted rotor or drum.

This happens frequently on cars when left standing a long time with the hand brake on, the car appears totally locked up when moved, there's a loud 'crack' from the rear, a chunk of disc or shoe friction material is ripped off and there's a grinding noise every time the brakes are used.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
voxmagna is offline  
Sponsored Links
Advertisement
 
post #4 of 28 (permalink) Old Aug 2nd, 2010, 8:58 am
Veteran
 
H96669's Avatar
 
Join Date: Jun 2009
Location: Burton, British Columbia, Canada
Posts: 1,770
Oh La La!!! Ugly looking clutch.....looks like it had been cooking for a while. You can sometimes clean the blue spots with sanding and wire brushing, but that one looks past that stage.But the pressure plate, that happened on my GS, clutch was slipping,I replaced the disk only and the next day had to replace the pressure plate, clutch was still slipping.

Could there have been just enough tranny oil seeping down from the seal at the slave to contaminate only one side of the plate....just a tought.

But anyway I did have the same leaky seals as yours and reinstalled new ones at the same depth, bench tested and.....they were still leaking. Because there is no "Seal Depth" posted anywhere I opened up my transmission to sort that out, and I do have some good pics as to why even new ones may leak again soon and where they have to be set not to leak.

Here is one, you can see how close the wear groove is from the lube hole, and it is from a transmission that had been worked on by a "Technician".........


Benelli 50cc at 14
Yamaha RD 200 at 16
Yamaha RD 350 at 17
Honda CB 750 F at 18
Honda V45 Sabre at 24
BMW K100RS at 27
BMW R100GS at 34
BMW K1200RS at 53
H96669 is offline  
post #5 of 28 (permalink) Old Aug 2nd, 2010, 9:16 am
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
Yes you hit the right point on the wear groove.

All conventional seals aim to get the minimum spring tension to seal whilst giving long life. Most rotary seals eventually wear in a groove, but may still stay sealed for many miles. But swap out the seal and position the new one across the wear groove (or oil hole!) and you have a leak disaster. I also think shaft wear increases with heat cycling on the seals which loose their soft flexibility and harden on the lips.

Sometimes, the only solution is to have the shaft metal sprayed and re-ground. On a bike that's such an expensive pig (sorry elephant) to fix, that's a worthwhile option. The newer style Teflon seals look as though they may not produce a wear groove so easily. But the funny thing is, many rush to recommend them, but if you are starting with groove wear on the shaft they probably won't ever seal. For me, Teflon types are for new or re-conditioned shafts.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
voxmagna is offline  
post #6 of 28 (permalink) Old Aug 2nd, 2010, 10:35 am Thread Starter
MIK
Senior Member
 
MIK's Avatar
 
Join Date: Mar 2006
Location: Acton, MA, USA
Posts: 187
Quote:
Originally Posted by voxmagna
.............PS what are all those red/brown streaks on the friction material?

Has the bike been for a swim in (salt?) water?
lol. Yes, those look like red/brown streaks on the friction material. And no, no swimming except for riding in heavy rain :-)

But...
* there was plenty of transmission oil on the other end (clutch slave cylinder end) of the pushrod. If oil was there it could probably get on the plates as well.

* when the clutch started to slip it was slipping only under heavy acceleration. I rode the bike home for another 40 miles after that happened, so some damage (uneven wear on the friction plate) could be done at that point. Although, the clutch felt "weak" when rolling from a stop for a month before that.

* the bike was sitting for 2 months before I got around to disassemble the clutch.
MIK is offline  
post #7 of 28 (permalink) Old Aug 2nd, 2010, 10:45 am Thread Starter
MIK
Senior Member
 
MIK's Avatar
 
Join Date: Mar 2006
Location: Acton, MA, USA
Posts: 187
Quote:
Originally Posted by H96669
looks like it had been cooking for a while. You can sometimes clean the blue spots with sanding and wire brushing, but that one looks past that stage.But the pressure plate, that happened on my GS, clutch was slipping,I replaced the disk only and the next day had to replace the pressure plate, clutch was still slipping.
All right. I made up my mind. I am replacing all those parts. BTW, the pressure plate part number has changed
http://www.realoem.com/bmw/showparts...73&hg=21&fg=05

Quote:
Originally Posted by H96669
But anyway I did have the same leaky seals as yours and reinstalled new ones at the same depth, bench tested and.....they were still leaking. Because there is no "Seal Depth" posted anywhere I opened up my transmission to sort that out, and I do have some good pics as to why even new ones may leak again soon and where they have to be set not to leak.
Oh my... I see transmission work in my future. Thanks for pointing it out. How did you bench tested the seal, BTW?
MIK is offline  
post #8 of 28 (permalink) Old Aug 2nd, 2010, 10:55 am Thread Starter
MIK
Senior Member
 
MIK's Avatar
 
Join Date: Mar 2006
Location: Acton, MA, USA
Posts: 187
BTW, for some reason, I couldn't take the pushrod out when I took the slave cylinder off. It just wouldn't come out no matter how I pulled. I thought it should have just slide out easily.


Another question, I have about installing new pressure plates with old clutch housing. The clymer tells you that those 3 parts are a balanced unit, but then they tell you that when replacing the parts, rotate them 120 deg in relation to manufacturing marks. How does that make the unit balanced and prevents vibration? ... confused...
MIK is offline  
post #9 of 28 (permalink) Old Aug 2nd, 2010, 1:48 pm
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
I'm afraid you might have passed the point of no return like I did and now can't put it back exactly as it came out. I never found these mysterious paint marks they talk about and ended up making a static balance test rig so I at least didn't get any out of balance all on one side. But then you are buying a lot of new clutch parts, so I'm curious about what you do about balance. For the record I found the new disc was well balanced (obvious I suppose) and the other parts weren't far out.

Phasing the drive lines correctly is probably a more important thing to get right. The clutch parts do have drillings in them so I conluded some balancing is already done.

Now the pushrod jamming is bad news and a possible symptom of some of your problems. The pushrod has plenty of clearance in the long bore, from memory there's at least +- 0.5mm which is why mine rattles about unless the clutch is pulled. If the pushrod jams then it can stop the clutch closing fully so you get accelerated wear. I'm not sure what comes first, heat from other problems, oil bunging up the pushrod and seizing or what. But a siezed pushrod is a clutch slave bearing and clutch plate doom with all the slippage signs. That's why I put up with the rattle which is probably what the BMW felt mod. is supposed to stop. Although many think it's to hold back leaking oil.

I know this is my rattle because I wrapped some ptfe tape around the pushrod and for the first 1K miles, clutch rattle was silent.

When you eventually get the pushrod out, roll it on a sheet of glass and check it is true. I hope you haven't got a bent shaft or bent it getting to the clutch. It's tempting when you are up to your eyes in oil and lifting gear to pull the lump rearwards and have it rest on the pilot spigot. Again from memory the rod is about 8mm dia in a 9mm hole. Should be plenty of clearance - but then it's a long hole so any warping is unacceptable.

Keep up the good work and leave nothing to chance now you know how much work is involved.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
voxmagna is offline  
post #10 of 28 (permalink) Old Aug 2nd, 2010, 2:16 pm Thread Starter
MIK
Senior Member
 
MIK's Avatar
 
Join Date: Mar 2006
Location: Acton, MA, USA
Posts: 187
Quote:
Originally Posted by voxmagna
That's why I put up with the rattle which is probably what the BMW felt mod. is supposed to stop. Although many think it's to hold back leaking oil.
I took the transmission out with the pushroad still in, so it was probably sticking in the clutch. It doesn't look bent and it already has felt on it filled with oil from the seal leak. I am getting another rod anyway since I can't trust this one.

Quote:
Originally Posted by voxmagna
Keep up the good work and leave nothing to chance now you know how much work is involved.
Thanks. I'll try. Although, I totally expect something left to chance due to limits of my experience and knowledge. One thing is for sure... it's good to have a spare bike
MIK is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the K-Bikes.com - Excellence in Motion forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Clutch problems and possible solution (with pix) JCW K12/1300R/R-Sport 16 Aug 20th, 2012 10:15 am
Clutch issues -too hard basket?? rgmrogerwilco K1200RS/GT (Classic) 9 Jan 30th, 2012 11:39 am
Clutch issues - comments please? rgmrogerwilco K1200RS/GT (Classic) 8 Mar 9th, 2009 6:06 pm
clutch cable problems!!!!!!!!!!!!!! gabriel Technical, Repair and Maintenance 1 Nov 12th, 2007 3:22 am
Clutch questions 03 K12GT tyggyr K1200RS/GT (Classic) 12 Oct 18th, 2005 2:00 pm

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome