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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Mntholler97703 on August 09, 2025, 09:39:18 PM

Title: Clutch arm too low to thread
Post by: Mntholler97703 on August 09, 2025, 09:39:18 PM

Hi. 
I removed and replaced my gear box because I had to rebuild the motor.  I mated the gear box to the transmission without problem but now my clutch arm is too low to thread the clutch cable to? I have backed out the adjustment screw and still no luck.   Any thoughts?   Thank you very much.  1985 K100

Title: Re: Clutch arm too low to thread
Post by: Mntholler97703 on August 09, 2025, 09:43:29 PM

I do have the correct amount of cable free ..

Title: Re: Clutch arm too low to thread
Post by: frankenduck on August 09, 2025, 09:51:46 PM

https://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/clutchadjust/clutchadjust.htm

Title: Re: Clutch arm too low to thread
Post by: Mntholler97703 on August 09, 2025, 10:05:41 PM

Thank you for posting.  Unfortunately,  even with 75 mm free cable and the adjustment screw backed out, I still do not get close enough to thread the clutch cable.

Title: Re: Clutch arm too low to thread
Post by: Laitch on August 10, 2025, 12:20:57 AM

Thanks for coming up with this weird condition, Mntholler! 103123 

Are you indicating that with the clutch arm adjustment bolt backed all the way out, the clutch arm still touches the clutch piston contact in the clutch boot?

Title: Re: Clutch arm too low to thread
Post by: Mntholler97703 on August 10, 2025, 12:35:25 AM

That is correct.  It bottoms out way too early.  I did not remove it when I detached the gear box. The gear box went back on very easily and didn't have any issues.  I just hope I can figure this out without disassembling it again.  Thanks

Title: Re: Clutch arm too low to thread
Post by: Laitch on August 10, 2025, 01:45:24 AM

That ain't right.  :laughing4-giggles: The clutch arm and the clutch boot have a fixed relationship. Even if the transmission weren't fully coupled, their relationship would be the same. If the clutch rod wasn't seated into the diaphragm spring it would push the clutch piston further outward into the boot. That would be indicated by the boot's accordion pleats being deformed by stretching.
Did you remove the clutch rod before decoupling the transmission from the engine?

Title: Re: Clutch arm too low to thread
Post by: Mntholler97703 on August 10, 2025, 07:59:51 AM

I did not

Title: Re: Clutch arm too low to thread
Post by: Laitch on August 10, 2025, 09:42:30 AM

Does the boot look stretched? Measure along the boot from the transmission to its tip where it contacts the arm and post the measurement here.

Title: Re: Clutch arm too low to thread
Post by: Duckbubbles on August 10, 2025, 10:24:09 AM

I would say that there is a problem with the clutch actuating rod somehow hanging up on the diaphram spring on the clutch or the end of the engine output shaft and not penetrating enough.  Probably through mis-alignment.

Frank

Title: Re: Clutch arm too low to thread
Post by: Mntholler97703 on August 10, 2025, 10:56:19 AM

This is my first K bike and I did not even realize there was supposed to be boot cover until after I had posted
  The boot cover is completely gone and it is just a spring.  I can shift the bike into gear by manually lifting the  shift lever, but the rod itself is very stiff to move. 

Title: Re: Clutch arm too low to thread
Post by: Mntholler97703 on August 10, 2025, 11:06:33 AM

Thank you for the feedback.  Im going to pull the gear box and explore.

Title: Re: Clutch arm too low to thread
Post by: Ingo on August 10, 2025, 11:09:22 AM

Probably bent the rod when pulling the gearbox off, don't ask how I  come up with that thought... now it's not centered on the diaphragm spring...
Try taking off the arm and pull out the push rod. Straighten if bent...

Title: Re: Clutch arm too low to thread
Post by: frankenduck on August 10, 2025, 01:39:09 PM

Quote from: Ingo on August 10, 2025, 11:09:22 AM

Probably bent the rod when pulling the gearbox off, don't ask how I  come up with that thought... now it's not centered on the diaphragm spring...
Try taking off the arm and pull out the push rod. Straighten if bent...

Did you manage to bend one? I'm surprised. Those are pretty hardened steel and despite my best efforts and abuse of them (unintentional) I have never managed to bend one on the dozens of K bikes I've dealt with.

Title: Re: Clutch arm too low to thread
Post by: Ingo on August 10, 2025, 02:08:31 PM

I sure did. It also was easy to straighten. This was a 1992 k1100...
I believe only the tip was hard steel.

Title: Re: Clutch arm too low to thread
Post by: Laitch on August 10, 2025, 05:55:07 PM

Quote from: Mntholler97703 on August 10, 2025, 10:56:19 AM

This is my first K bike and I did not even realize there was supposed to be boot cover until after I had posted.. . . I can shift the bike into gear by manually lifting the  shift lever, but the rod itself is very stiff to move.

Hold on there, partner.

First, get a new clutch piston, clutch rod, spring and boot from MaxBMW (https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51752&rnd=10232024). You need three of those parts and could need the clutch rod to work with the new style piston, also. But first realize this. The gears are shifted by means of compound leverage. One of those levers is your foot pivoting on your ankle. The others are the foot shifter pivoting on its axle from the transmission and the clutch arm relieving pressure on the pressure plate by pressing on the diaphragm spring. Your shifting the rod manually can't match the eifficiency of those three items together, so shifting manually would be stiff regardless of the rod's condition. Order those items and install them first. You could remove the transmission, sure.

What are the sources of the instructions you followed? You missed some critical elements, as you now realize.