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damian7h
Joined: 23 Sep 2012 Posts: 14 Location: London
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Posted: Sat Nov 17, 2012 11:42 am Post subject: My back brake failed whilst filtering! |
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Hello fellow K11 owners, I have a 95 K1100 RS.
I was happy filtering along a 2 mile stretch of bad traffic when suddenly the back brake totally went to the bottom! Not a nice feeling , luckily I was almost at the end of the traffic queue.
The front brake was ok so I continued my journey.
After a few minutes on the open road I tested the back brake and slowly it starting working again after a few tries.
FYI: I only use my back brake at very low speeds, or to aid the breaking during a well planned stop. But most of the time I only use the front brake.
This morning I visually checked the caliper and can't find nothing out of the ordinary. There are no leaks of fluid, the caliper is well attached, the pads are in reasonable condition and the foot brake lever is in good condition too.
Any suggestions?
Should I replace the lot: pads, cylinder, hoses, fluid?
I appreciate any suggestions,
Cheers,
Damian _________________ K1100 RS 1995 |
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Scott_Anderson Site Admin
Joined: 05 Sep 2006 Posts: 3119 Location: Central Iowa, USA
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Posted: Sat Nov 17, 2012 12:54 pm Post subject: |
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I moved the post here to Tech so it will get more views and replies.
I'd suggest 1st check your fluid levels and/or replace the fluid and flush the system if you haven't had it done recently. Sounds as if you may be a tad bit low.
2nd thing to check would be the seals in the foot brake master cylinder. Check for a clean bore and no "grunge" packed around the seals.
Whatever you do do, don't muck with the pedal travel stops. _________________ Ride safe.
1995 K1100LT 0302044
1997 R1100RT ZC62149
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.) |
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DLBass Mad Brick Rider
Joined: 29 Jul 2010 Posts: 93 Location: Desborough UK
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Posted: Sat Nov 17, 2012 5:04 pm Post subject: |
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Fluid level???
If that's OK, change the fluid. Its got too much water in it and you boiled it up while filtering _________________ There is only now, yesterday is gone and is unchangeable, tomorrow is uncertain. Live in the moment. |
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Blackk
Joined: 12 Nov 2012 Posts: 7
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Posted: Sat Nov 17, 2012 5:18 pm Post subject: |
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Check disc temperature after a ride without using it.
Sounds like some temp related fadding.
B _________________ 1992 K 1100 LT 68000km. |
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Duc750
Joined: 01 Mar 2012 Posts: 11
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Posted: Sat Nov 17, 2012 7:37 pm Post subject: |
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Drag the back brake less. Check you're not resting the toe of your boot on it by mistake and change the fluid. It just faded through heat. That's basically caused by one of two things, bad technique or bad maintenance |
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quaddawg Big Brick Rider
Joined: 18 Jul 2012 Posts: 64 Location: Cincinnati, Ohio
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Posted: Sun Nov 18, 2012 8:14 am Post subject: |
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If the brake lever went to the bottom, then I highly doubt it's just brake fading. Sounds like a master cylinder that's leaking past the seal slightly.
I'd rebuild the rear master, or at least inspect it really well. _________________ I am: Andrew Stanford
My shop, my passion:
www.stanfordmotorsports.com
Cincinnati, Ohio
1993 K1100lt touring
106K miles on the clock and rising |
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Duc750
Joined: 01 Mar 2012 Posts: 11
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Posted: Sun Nov 18, 2012 8:26 am Post subject: |
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If a seal is gone, its gone, it can't fix itself while riding |
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quaddawg Big Brick Rider
Joined: 18 Jul 2012 Posts: 64 Location: Cincinnati, Ohio
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Posted: Sun Nov 18, 2012 3:41 pm Post subject: |
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Nope, not true. Have been doing this for close to 35 years (bike shop ownership and mechanic work) , have seen slightly leaky umbrella seals that will bypass leak when lightly pressing brake, but will seal when agressivly pumping, or braking.
Fade usually won't allow pedal to go to limit, unless you have been boiling the fluid, and you won't do that whilst filtering at low speeds. Fade is more like push the pedal and nothing happens, at least in my experience.
If you read his description, it says it started working again after applying it several times, this does not describe fade, fade would go away if you stayed off the brake, and allowed system to cool, not by applying it several times.
I still put my money on the master cylinder.
That being said, I have been wrong before... haha... I think... hard to remember.. (kidding) _________________ I am: Andrew Stanford
My shop, my passion:
www.stanfordmotorsports.com
Cincinnati, Ohio
1993 K1100lt touring
106K miles on the clock and rising |
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Duc750
Joined: 01 Mar 2012 Posts: 11
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Posted: Sun Nov 18, 2012 4:29 pm Post subject: |
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We'll see. It apparently came back after a few minutes on the opoen road which says to me progressive cooling of the brake.
The problem (I find) with the K is its quite easy to catch the brake pedal with your toe and just drag it a little bit. Its particularly easy when on and off the brake in traffic.
I've had exactly the same on mine (my daily ride is 65 miles each way to work. 15 of that is filtering. BMW brake fluid also seems to be particularly vbad for fade resistence too. The best dot 4 I've ever used for fade is red line. That's what we used to use for endurance racing |
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Tim (Midland Section) Flying Brick Rider
Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Sun Nov 18, 2012 6:37 pm Post subject: |
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It could be both M/cyl & boiling, I have had both during 60K miles of K ownership. As the fluid is in need of changing, it would be silly not to strip & clean the master cylinder. IMHO there is a ring of dried fluid or crud (tech term) making the piston slow to return & therefore during filtering not allowing the cylinder to refill or release the brakes properly. Essentially what Scott said in the second post.
Damian, pull back the rubber at the front end of the cylinder, see if it's wet with fluid. Order a repair kit. 34 31 2 311 064.
If it's done 40K or more order one anyway, unless you know when it was last changed.
Best fluid is DOT 5.1 NOT DOT 5 http://en.wikipedia.org/wiki/DOT_5 explains.
HTH _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
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chas Brick Rider
Joined: 21 Jul 2008 Posts: 37 Location: Helsinki, Finland
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Posted: Sat Nov 24, 2012 10:01 am Post subject: |
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I have a similar problem with my '93 RS. I took the rear caliper off to check the pads, inadvertantly loosening the bolts holding the caliper halves together. I tightened those bolts again, and after undoing the correct ones(!), realised the pads were OK. Now I have no rear brake i.e. the brake pedal goes right down with no resistance, and some fluid leaked out. Seals?
The brake was working before, although the pedal felt stiff.
Is replacing the seals difficult, and what about bleeding the brakes afterwards? The bike has ABS1.
Update: just checked the fluid level - it's empty!
One more question - do I need a Torx wrench to remove the master cylinder if needed? |
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Inge K. Flying Brick Rider
Joined: 30 Apr 2011 Posts: 458 Location: Norway
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Posted: Sat Nov 24, 2012 12:04 pm Post subject: |
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Hi Chas!
Between the calipper halves it`s a o-ring which probably have come out of position when you did loosen the wrong bolts.
But you could be lucky, and only got air into the system.................
If your brake pads have been soaked with brake fluid, I would recommend you to change them............as the brake fluid would disolve the glue between the friction material and backing plates.
Inge K. |
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chas Brick Rider
Joined: 21 Jul 2008 Posts: 37 Location: Helsinki, Finland
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Posted: Sat Nov 24, 2012 4:05 pm Post subject: |
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Inge K. wrote: | Hi Chas!
Between the calipper halves it`s a o-ring which probably have come out of position when you did loosen the wrong bolts.
But you could be lucky, and only got air into the system.................
If your brake pads have been soaked with brake fluid, I would recommend you to change them............as the brake fluid would disolve the glue between the friction material and backing plates.
Inge K. |
Good point. But I only started to loosen the bolts, and I didn't see any fluid leaking from the caliper.
And I now have a working brake - I bled the modulator then the caliper, and I have pressure again. There must be a leak from the master cylinder though, as the reservoir was empty and the rubber boot on the master cylinder had old fluid in it.
I'll take the bike out tomorrow, and check for leaks after a ride. If it's leaking again, I'm tempted to buy a complete master cylinder, as they only cost £100, compared to £40 for an overhaul kit (from Motorworks).
Any tips on replacing the master cylinder, anyone?
P.S. My original post should have said 'some fluid leaked from the master cylinder' (when I pressed the pedal). |
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Tim (Midland Section) Flying Brick Rider
Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Sat Nov 24, 2012 6:26 pm Post subject: |
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As I said in post #10
Damian, pull back the rubber at the front end of the cylinder, see if it's wet with fluid. Order a repair kit. 34 31 2 311 064.
That, Chas, is why your Reservoir was empty.
Luckily for me, Mr MOT man noticed mine I should have been better than that! _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
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chas Brick Rider
Joined: 21 Jul 2008 Posts: 37 Location: Helsinki, Finland
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Posted: Mon Nov 26, 2012 5:37 am Post subject: |
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Tim (Midland Section) wrote: | As I said in post #10
Damian, pull back the rubber at the front end of the cylinder, see if it's wet with fluid. Order a repair kit. 34 31 2 311 064.
That, Chas, is why your Reservoir was empty.
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Not quite! I've just discovered that the hose to the caliper is squirting out fluid So perhaps the 'slight' leak from the m/c wasn't responsible, but I've ordered a new one, plus 2 Goodrich hoses. And the reservoir to m/c hose, just in case. |
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chas Brick Rider
Joined: 21 Jul 2008 Posts: 37 Location: Helsinki, Finland
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Posted: Tue Dec 18, 2012 10:06 am Post subject: Leaking master cylinder/split hose update |
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Fitted a new master cylinder plus Goodrich hoses. Everything fitted, despite the master cylinder having a different connector i.e. the original was a 'straight' fit (US spec), as opposed to a right-angle connection.
All I need to do now is sort out a slight leak from the master cylinder banjo bolt Perhaps the new washers are lesser quality? I'll try annealing the old ones. |
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damian7h
Joined: 23 Sep 2012 Posts: 14 Location: London
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Posted: Sat Jan 05, 2013 12:47 pm Post subject: |
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Thanks for all your advice fellow K11 owners!
I stopped riding for a few weeks... but back on riding the K now.....
I followed Tim advise about pulling back the rubber from the cylinder and checked for fluid but I don't see any evidence of a leak.
So I am going to change the fluid as I suspect it is quite old (looks dirty/dark on the reservoir).
Never replaced the fluid so I'll be following this guide that I found on the web, different model but the concept seems to be there:
http://advwisdom.hogranch.com/Wisdom/service_abs3.pdf
Thanks again All!
Damian _________________ K1100 RS 1995 |
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Duc750
Joined: 01 Mar 2012 Posts: 11
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Posted: Sat Jan 05, 2013 1:11 pm Post subject: |
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Damian, follow that guide if you want but its not for your abs system. I believe that one is for iabs or abs 3. You will have either abs 1 or 2. If you get a haynes for the bike it tells you how to do it or download the bmw workshop manual from the web |
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chas Brick Rider
Joined: 21 Jul 2008 Posts: 37 Location: Helsinki, Finland
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Posted: Sun Jan 06, 2013 5:00 am Post subject: |
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I just used a bleed pipe with non-return valve, and did the ABS modulator then the rear caliper, then repeated. And when the system had presuure, the hose to the caliper split! So check carefully for leaks. |
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AUSBRICK Mad Brick Rider
Joined: 18 May 2007 Posts: 119 Location: MELBOURNE AUSTRALIA
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Posted: Fri Feb 08, 2013 2:47 am Post subject: |
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Almost certainly overheating as Duc 750 suggests , Iv'e had this happen many times on my 1100 lt when decending on long downhills with twisties if you use the rear a little too much it overheats and the peddle will go all the way to the stop with nothing . I think the fluid boils , the peddle returns after some fast running with no braking as it cools down.It doesn't take much on these ks for this to happen as the rear disc is poorly vented .I have tried a few scoops to get more air onto it but nothing has worked yet. Has also happened when I have accidently rested my foot on the pedal slightly which sounds like what might have caused your problem. Cheers Brick _________________ 92k1100 lt with sidecar. 93K1100 CAFE..86K75C.95 k1100lt |
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