K75 rear brake mystery - K-Bikes.com - Excellence in Motion
 
LinkBack Thread Tools Display Modes
post #1 of 8 (permalink) Old May 6th, 2010, 6:54 pm Thread Starter
Noob
 
K-rusty's Avatar
 
Join Date: May 2010
Location: Coldbrook, NS, Canada
Posts: 13
K75 rear brake mystery

It's an 1988 S model, and when I put it away for the snow season, everything was working like a top. It also had just passed a gov't safety inspection, which is required by law every two years.

My last ride last year was Dec. 12th, and I was back on the road Feb. 25th , so not a lot of down time really. That being said, for some reason, the rear brake seems very "weak" compared to what it was when I parked it in my dry, heated, garage. No one else has access to the bike.

I initially thought the pedal was traveling a tad too far down to engage, so I adjusted it up to a position that did not require me to use my heel. It changed nothing, still almost non existent. When rotating the wheel by hand, on the centre stand, and then applying the brake by hand, I could still fairly easily rotate the wheel. It does properly engage and disengage. The only other details I can think of, is that I am the third owner, and do not know when the brakes were last serviced, but the rotors seem fine, but the rear reservoir could probably use fresh dot4, as it a tad yellow-ish....but surely that couldn't cause that much fade...could it? And finally, I cannot find anywhere in the shop manual that mentions, or shows the recommended fluid level in the reservoir. It merely says the fluid will go down as the pads wear down. Mine is almost right to the top..which always seemed odd to me, but as I stated earlier, it worked fine.

Help and feedback would be greatly appreciated.
K-rusty is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old May 7th, 2010, 5:09 am
Member
 
Join Date: Mar 2009
Location: Clifton Beach, Tasmania, Australia
Posts: 95
If you are sure the pads are moving when you press the brake pedal I would be very inclined to change the fluid as it should be done every couple of years anyway and certainly won't hurt.

Otherwise it could be one or both pads sticking.

Phil Mars

1984 K100RT
phil_mars is offline  
post #3 of 8 (permalink) Old May 7th, 2010, 5:15 am Thread Starter
Noob
 
K-rusty's Avatar
 
Join Date: May 2010
Location: Coldbrook, NS, Canada
Posts: 13
Thanks for the reply Phil. Yes the pads are moving, as they do engage the rotor when I depress the brake lever. I tested this by putting it on the centre stand and testing them. You can also hear them engage. I will change the fluid as a "plan A" .
K-rusty is offline  
Sponsored Links
Advertisement
 
post #4 of 8 (permalink) Old Aug 18th, 2010, 4:52 am
Noob
 
Join Date: Jun 2010
Location: , , UK
Posts: 12
Quote:
Originally Posted by K-rusty
Thanks for the reply Phil. Yes the pads are moving, as they do engage the rotor when I depress the brake lever. I tested this by putting it on the centre stand and testing them. You can also hear them engage. I will change the fluid as a "plan A" .
Did you ever resolve this?

I seem to have near identical symptoms (and I have just changed the master cylinder).

Could it be a partially seized calliper?

Thanks, N
nikos is offline  
post #5 of 8 (permalink) Old Aug 18th, 2010, 5:49 am Thread Starter
Noob
 
K-rusty's Avatar
 
Join Date: May 2010
Location: Coldbrook, NS, Canada
Posts: 13
Mystery solved

Yes Nikos, I solved it. However, if you have already replaced the master cylinder, and yours still does not work properly, then I am baffled...unless your "new" master cylinder was a "reconditioned" unit, or from another bike. My issue was also with the master cylinder, but the OEM rebuild kit cured it. The lever was pushing on the plunger, but it was almost frozen. It got to the the point, where on my last depression of the brake pedal...after testing to see if the new pads and fluid helped, it almost seized. So in a nutshell, it works great now. I am guessing you checked and serviced your callipers when you changed your pads?
K-rusty is offline  
post #6 of 8 (permalink) Old Aug 18th, 2010, 6:58 am
Noob
 
Join Date: Jun 2010
Location: , , UK
Posts: 12
Hi K-Rusty

I changed the master cylinder because of a lot of pedal travel and brake fluid came out when I removed the dust cover. It all seemed OK (although bleeding was an issue). Then this morning I noticed zero braking effect and increased pedal travel. When I apply the brake on the centre stand there is some little resistance on the wheel and pumping it makes no difference. I did not touch the calliper as it seemed to be OK. I have however adjusted the operating pin a little so that the brake came on at about 1inch pedal travel (some say you should not to do this as it causes the brakes to drag?). Or has the new master cylinder given up the ghost?

N

Last edited by nikos; Aug 18th, 2010 at 7:07 am.
nikos is offline  
post #7 of 8 (permalink) Old Aug 18th, 2010, 7:26 am Thread Starter
Noob
 
K-rusty's Avatar
 
Join Date: May 2010
Location: Coldbrook, NS, Canada
Posts: 13
Well Nikos, I certainly am not a mechanic, but experience tells me you need to properly bleed the brakes. I also suspect, perhaps over filling of the brake resevoir? No fluid should spill over the top if it is filled to the correct indicated level...unless you depress the brake pedal while the cover is off and it is overfilled. It is also recommend you keep a sterile mechanical syringe, or turkey baster, to remove any excess from the resevoir during pad replacement, as new pads are, of course, thicker, and may push the fluid over the top of the resevoir. Sounds like a bleeding issue to me. And BTW, if you are using a Clymer manual, there are misprints, mistakes and ommisions, so be careful and cross-consult, other manuals, mechanics and forums. There is a reference to "blocking" the front brake lever in the rear brake section. Not uncommon for most aftermarket, translated manuals. It could mess you up, or confuse and frustrate those who are "by the book" and not familiar with mechanics. Of course, then one could argue that you should be seeing a professional, but I digress...I'd re-visit my bleeding procedure again. I hope I did not insult you...not my intention
K-rusty is offline  
post #8 of 8 (permalink) Old Aug 18th, 2010, 7:56 am
Noob
 
Join Date: Jun 2010
Location: , , UK
Posts: 12
Hi K-rusty

I did not detect any insults!


It's always good to share experiences and I take your point about the manuals - I look at 3, the Clymer , Haynes and the BMW K100LT one = common sense!

N
nikos 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
Absolutely the most detailed description of the K1200S I've come across... sinc K12/1300S 20 Jul 19th, 2014 9:04 am
Rear Brake Fix mjptexas K12/1300R/R-Sport 7 Sep 22nd, 2009 1:57 pm
Poor rear brake alanp K12/1300R/R-Sport 5 Jun 19th, 2009 9:20 am
1987 K100LT no abs, rear brake questions? Euripides Other K-Bikes Discussion 3 Aug 14th, 2007 9:58 am
BMW DOES HAVE A Fix for Rear Brake pedal Shelley K12/1300S 4 Mar 29th, 2007 12:17 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