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Author Topic: Clutch disc K75s  (Read 7404 times)

Offline motorheadsdiygarage

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Clutch disc K75s
« on: October 15, 2016, 03:19:18 PM »
Has anybody tried cleaning the clutch disc if it is still within the wear limit? Mines slipping if I crack the throttle above 3500 rpm. Might be dirty or glazed. I'll know for sure when and if I open her up over the winter..... Brrrrr!!
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  • Near Montreal Canada
  • 1992 BMW K75S

Offline kennybobby

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  • Last of the True Southern Sweet Mullets and Squids
Re: Clutch disc K75s
« Reply #1 on: October 15, 2016, 03:32:38 PM »
Is your clutch cable out of range of adjustment--the free-play is taken up as the clutch wears to the point that the clutch cannot release fully, causing slippage such as you describe.
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Ridin' 87 K75S vin 1334,
Renchin' 86 75S vin 0061

Offline Martin

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Re: Clutch disc K75s
« Reply #2 on: October 15, 2016, 03:46:47 PM »
Brick clutches are pretty hardy I replaced mine at approximately 140,000 K's. I measured it against the old one and it showed no discernable wear. I only replaced it as I had to special order it, and it was ordered as a precaution when replacing a leaking rear main seal. New clutch 5.05 -5.55 mm wear limit 4.50 mm ( my clutch at replacement 5.4 mm ).  As per Kennybobby try adjusting first.
Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline F14CRAZY

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Re: Clutch disc K75s
« Reply #3 on: October 15, 2016, 05:02:45 PM »
If it's soaked and slipping I'd try soaking it in lacquer thinner overnight and scrubbing it with a brush.

I replaced my disc just because the hub splines were getting close to failing
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  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...

Offline Motorhobo

  • +25 years of K75
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Re: Clutch disc K75s
« Reply #4 on: October 15, 2016, 06:32:27 PM »
I just sprayed some degreaser on it, lightly sanded with 600 grit, spray, wipe clean, repeat three times. Worked for me but sounds to me like you may have an active grease spray problem in the bell housing. If your clutch is greased, it's coming from somewhere -- maybe rear main seal or bad clutch pushrod seal. Dripping fluid gets slung all over the place inside. I've had both seals fail, different times. No way to know which it is until you open it up and sniff the wetness. Yes...sniff the wetness...and I'm sure some wise ass is going to jump all over that one.
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1994/1995 K75 ABS Frankenbike: original engine 136k miles, frame from Gary Weaver (RIP), 173k miles -- Current Odometer: 198k miles
1994 K75 since 2013, 82,000 mi (19k mine) w/California Sidecar Friendship II Sidecar & Black Lab 'Miss B' - RIP

Past: 1974 Honda 550/4 (first bike), 1994 K75 (sold), 1995 K75 ABS (parts bike), Sidecar Dog & Best Bud 'Bo' - RIP

Offline Martin

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Re: Clutch disc K75s
« Reply #5 on: October 15, 2016, 06:53:13 PM »
Have you checked the weep hole for signs of leakage, an occasional drip should not effect the clutch.
Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline The Mighty Gryphon

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Re: Clutch disc K75s
« Reply #6 on: October 15, 2016, 06:54:24 PM »
Quote from: Motorhobo on October 15, 2016, 06:32:27 PM
No way to know which it is until you open it up and sniff the wetness. Yes...sniff the wetness...

You better not have any plans for being a future Republican presidential nominee...
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline motorheadsdiygarage

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Re: Clutch disc K75s
« Reply #7 on: October 15, 2016, 07:09:57 PM »
1. I haven't checked the weep hole. :mbird
2. I have 139700km.
3. When I open it up then I will know if the disc is still in spec or needs to be replaced.
4. I like the idea of cleaning and resurfacing the facing. :clap:
5. The clutch cable is adjusted in accordance with the manual with 5-6mm of play at the lever. :musicboohoo:
6. Can't wait to sniff the wetness..... :hehehe

I have a feeling that the friction surfaces are glazed or contaminated with lubricant (spline lube or engine oil). :musicboohoo:

I will probably open it up and at the same time replace the rear tire and do the spline lube. Fall is here and the weather changes fast so just a few rides left weather dependent by November I'll store the motobrick and my 325i until April. If I'm bored maybe I'll attack this slipping problem. On the to do list. :bmwsmile

Thanks Boys
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  • Near Montreal Canada
  • 1992 BMW K75S

Offline rbm

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Re: Clutch disc K75s
« Reply #8 on: October 16, 2016, 08:41:32 AM »
Quote from: motorheadsdiygarage on October 15, 2016, 07:09:57 PM
...
5. The clutch cable is adjusted in accordance with the manual with 5-6mm of play at the lever. :musicboohoo:
...
Should be 2-4mm free play at the clutch handle.  Is there 175mm of exposed cable length at the actuator arm end of the cable?  Did you check to make sure the adjustment screw resting against the clutch actuator rod is adjusted properly as well?
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  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline The Mighty Gryphon

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Re: Clutch disc K75s
« Reply #9 on: October 16, 2016, 09:16:22 AM »
Quote from: rbm on October 16, 2016, 08:41:32 AM
Should be 2-4mm free play at the clutch handle.  Is there 175mm of exposed cable length at the actuator arm end of the cable?  Did you check to make sure the adjustment screw resting against the clutch actuator rod is adjusted properly as well?

Typo: Exposed cable should be 75mm..
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline motorheadsdiygarage

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  • Posts: 42
Re: Clutch disc K75s
« Reply #10 on: October 16, 2016, 09:25:18 AM »
Quote from: rbm on October 16, 2016, 08:41:32 AM
Should be 2-4mm free play at the clutch handle.  Is there 175mm of exposed cable length at the actuator arm end of the cable?  Did you check to make sure the adjustment screw resting against the clutch actuator rod is adjusted properly as well?

I knew that this statement would get some attention when I wrote it. In some other research on this subject, I've read that this measurement is a personal feeling to some. I had the clutch cable play at the prescribed 2-4mm of play and opened it to 5mm to make sure that the cable wasn't a factor in the slippage. No change it feels the same and still slips at 3500 rpm if you're aggressive to accelerate. I know its the disc and not the cable (new cable). The cable end at the actuator arm is 75mm. I think you have a typo (175mm). I'll keep poking at the adjustment to satisfy the question.
Thanks for your input Robert.

Dave
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  • Near Montreal Canada
  • 1992 BMW K75S

Offline rbm

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Re: Clutch disc K75s
« Reply #11 on: October 16, 2016, 09:29:49 AM »
Ok, good to hear.  Yes, finger slip on typing the numbers.
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  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline kennybobby

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  • Last of the True Southern Sweet Mullets and Squids
Re: Clutch disc K75s
« Reply #12 on: October 16, 2016, 12:22:31 PM »
Quote from: motorheadsdiygarage on October 16, 2016, 09:25:18 AM
... I had the clutch cable play at the prescribed 2-4mm of play and opened it to 5mm to make sure that the cable wasn't a factor in the slippage.

It sounds like you have covered all the cable bases--one other thing to check is if the clutch release arm on the jenner is touching or hitting the muffler.
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Ridin' 87 K75S vin 1334,
Renchin' 86 75S vin 0061

Offline motorheadsdiygarage

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Re: Clutch disc K75s
« Reply #13 on: October 16, 2016, 12:28:45 PM »
No contact....

Thanks Dave
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  • Near Montreal Canada
  • 1992 BMW K75S

Offline motorheadsdiygarage

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Re: Clutch disc K75s
« Reply #14 on: October 16, 2016, 12:31:30 PM »
Quote from: The Mighty Gryphon on October 15, 2016, 06:54:24 PM
You better not have any plans for being a future Republican presidential nominee...

Canadian and no vote possible.... Its ashameful situation south of the border.. :musicboohoo:
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  • Near Montreal Canada
  • 1992 BMW K75S
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