Clutch disc replacement

[F14CRAZY]

Slightly unrelated in my vibration saga is the fact that the the clutch disc splines in my K75 are looking pretty bad and I suspect that they will strip out before too long. Splines on the trans input shaft still look pretty good though. No slippage and clutch action works well.

Counting that everything still looks and works fine, can I just replace the disc? Do I "have" to replace the fancy diaphragm spring along with the "cover" and the "pressure plate?" In the automotive world I feel its best to resurface brake rotors or flywheels when replacing the wearing items they come in contact with, but then again when I had the Subaru dealer replace the clutch in my Forester they showed me the flywheel and said it was fine to put back into service without turning.

Can the K75's "pressure plate" be turned?

Drake (the bike's previous owner a few years ago) likely replaced the rear main seal and all, and since I know it isn't leaking from when I lubed the splines a few months ago and also when I took the trans off to reposition the clutch components (bike is making my hands and feet numb after like 45 minutes...featured in another thread) I've become pretty familiar with tearing the bike down  :falldown:

Thanks guys.

[Motorhobo]

I only replaced the friction disk -- but to be honest I wouldn't know how to determine if the other clutch parts are worn or need replacement. The only reason I didn't even think about replacing the other clutch parts is that I couldn't afford it anyway at the time. Next spline lube I'll inspect all the clutch parts more closely.

So my humbe opinion is  -- you only really need to replace what's worn or doesn't look like it will last until the next trans spline lube. If you expect to do the spline lube 15k miles from now, then your clutch parts should last till then.

That's my on-a-budget take on it. If you miscalculate and have to replace a clutch part before the next spline  lube, c'est la vie.

[wmax351]

Pick up your clutch parts from motobins.co.uk. Even with the shipping, still a lot cheaper.


Basically, you look for scoring in the pressure plates. If the clutch disc is very (well past service limit) worn, it is more likely that the plates are scored. The surfaces should be flat still. How many miles on the bike?


I replaced them all when I did a rebuild with a new engine. I tossed the ones from the 100k bike, worn to the rivets. I kept the ones from the 30k engine, which are fine (the rebuild started out as a clutch job, when I spotted a Craigslist motor and realized mine was failing, so I put the new clutch in the new engine). If you want, I could sell you the plates from the 30k engine cheaper than whatever is on ebay: just looking to get them to someone who would use them. The disk is probably fine, but I'd replace at least that anyways.

[K75RT Keith]

Got a set I replaced at 48k sitting in my garage.  Still quite usable. 

[jacksdad1963]

Iīve asked the same question: my K1100 has done 93k miles and the clutch is starting to slip at high speed/engine revs
Im sure I donīt need to replace every single part, just wish i had the money to do so!
BUT, like lots of us, I need to know what to replace, without  blowing my cash, but also without wasting time re-doing the same job, for the sake of a few $$$! Any help much appreciated! Mike

[F14CRAZY]

I've become pretty efficient at tearing the bike down and removing the trans so I guess if I have to go back it isn't a big deal  :yow

[Motorhobo]

I think in retrospect it may have behooved me to better inform myself about how to detect wear or defect in the other clutch parts in the pack. As I said above, I only replaced the friction disk. Now about 5k miles after reassembling, it seems the clutch isn't completely disengaging when I pull in the clutch lever.

Symptom is: While coming to a full stop I.e. at a red light, downshift to 1st, the pull in the clutch lever to disengage the transmission before applying brake to full stop. I'd expect engine braking to stop as soon as the clutch lever is pulled, but it takes sometimes three or four seconds for the resistance to completely go away so that the bike can roll freely as If it were in neutral.

I don't know if this is just a worn or frayed cable -- I've had cables snap on me before and remember that this behavior was a precursor. I have a new cable and will install soon -- it's a serious PITA on ABS K75s because the ABS modulator blocks access to the hole the cable threads thru and it's impossible to nurse the rubber booty through the hole without taking some stuff off. Anyway -- I'm bringing this up now because I didn't inspect anything but the clutch disk -- everything else seems pretty beefy in the clutch assembly except the large metal o-ring and maybe the spring itself. Ive heard the metal o-ring can flatten out with time but mine seemed intact. So the question is -- how does one inspect the spring and other parts to determine if they're ok?

[F14CRAZY]

Oh yeah, that boot is a pain to get through the hole. I should probably spray some silicon on it or something because I'm afraid of it tearing from the necessary force

[Motorhobo]

Definitely put some slippery on it. It is easy to tear but it can be done without tearing. It has sections like an accordion. You have to nurse the first couple of sections thru -- I usually push thru section at a time with fingers while pulling gently from the other side with small curve-tip needlenose. Once the second section is thru and you can get fingers around it continue section by section with just fingers on both ends. That's why you need full access with both hands to both sides and that's not possible with the abs unit on -- best with rear wheel off too, IMO. Not something I'd want to do on the road...that's why Chris Harris recommends replacing cable with every clutch spline lube.

Having said that, the new OEM clutch cables look like a redesign -- the one I got last week looks like it will last a very long time. There's also a little sleeve for $1.50 they sell with it now, looks like it's to protect the ball at the lever end...almost $50 for the frackin thing so it _better_ last a long time! At least 3 clutch spline lubes...so that means getting that booty in and out three more times...better get your technique down pat now  :2thumbup:

[F14CRAZY]

Did the job today. It started to downpour as I was picking up my tools so I didn't get to go for a test ride, aside from riding the bike into the garage a few feet from where I worked on it. Definitely will have to adjust the clutch cable but it moved the bike and disengaged  :yes

As you can see, the splines were just about shot:



Side by side:



Transmission splines still look pretty good though

BUT...

Lately I've noticed this (video taken prior to disc replacement today):

Post

(Should be able to click the link and see the video hosted on my Facebook, without being a user of friending me. Let me know if it's not working)

Again, I haven't test ridden the bike with the new disc but the intermittent knocking noise seems to have gone away. Could that have been due to the bad splines?

[Elipten]

Those spline are well worn!.