K11 Owners Group

OldJerry · Joined: 22 May 2010 Posts: 21 Location: West Michigan

I just replaced the front brake pads on my 97 KLT ( it only has 35,000 miles). When I finished, I found the left caliper wasn't fully releasing .... left brake was dragging badly. Was going to pull the caliper ..... removed the rubber brake line going to the caliper and found it plugged with "gooey rubber type stuff". Also the "banjo bolt" where the left line connects to the "T" above the front fender was full of black rubbery "gook". In short .... the rubber brake lines were SHOT. Luckily ... there is a shop near me that makes custom brake hoses. He fixed me up. He also said the brake hoses should be replaced much more frequently than they are. He says they deteriorate from the inside. Now, I know he sells brake hoses ..... but these really were soft and bad on the inside. I bought this bike used, so I don't know the history ..... but I flushed the brake fluids about 4K miles ago. I am sure most of you know more about brakes than I do ..... but if you have any doubts about those rubber brake hoses ..... replace them and save yourself some trouble on the road.
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1997 K1100-LT
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Flying Duck · Posted: Fri Jul 30, 2010 9:27 pm Post subject:

Yeah, the K75 with a K1100 front end I just finished has a sticky left caliper too. Looks like I'll have to pull it all apart and inspect the lines. I hate brake work - mostly because brake fluid is the spawn of Satan.
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93 LT (x2)
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Scott_Anderson · Posted: Sat Jul 31, 2010 8:16 am Post subject:

I'm thinking I am having a caliper sticking as well.
When I got back from SD I needed to replace the pads on the right side caliper as they were verrrrry thin. Not metal to metal, but close enough.
The left side ones were still better than 50% good. Makes me think it's not traveling. I put new brake lines on it last year and flushed them this spring.
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1995 K1100LT 0302044
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1997 K1100LT 0302488(R.I.P.)
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Ernie-NH · Posted: Sat Jul 31, 2010 10:08 am Post subject:

Good morning all...

The "gooey" stuff inside the brake lines is a reverted EPDM or EPM polymer. Brake hoses are a combination of "first" extruded EPDM ( ethylenepropylenediene ) onto a PTFE solid core which is later removed. The first extrusion is then wrapped with wire or nylon braid and over extruded once again using an HNBR ( hydroginated Nitrile ) for resistance to sunlight, under-hood ozone, and transient engine oils etc... In the course of its useful life, water (plus dissolved road contaminants ) enters into the brake system through the hose end fittings which are only crimped on and NOT bonded to the hose itself. This entrained water slowly breaks down to form acids within the system and it is these acids which cause the reversion of the innermost layer of EPDM resulting in the "goo" in/about the fittings. In fact, the brake fluid itself will also eventualy break down...but since the brake system is basically a 'no flow' system, the deterioration is concentrated in/near the fittings themselves.

During my working years in research of elastomerics, I have seen examples of all kinds of brake failure due to contaminated fluid and faulty fittings. Even though brake hose assemblies are tested 100% for pressure and flex at the factory level, long term lab testing of production samples still yields apx. 2% failure rate. This is true whether the hose assembly comes from Bendix, Lucas-Girling, Brembo or Teves.... I expect the same is true for 'high end' custom hoses, but I have no experience in this area, only OEM and after-market.

That's my $.02 , but I did want to share what I know about the subject. However, it is one of the reasons I change brake fluid every 24 months. A recommendation also made by ATE ( Teves ) who was one of my working partners.

very best regards all...........// Ernie-NH
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Jim · Posted: Sat Jul 31, 2010 12:47 pm Post subject:

Thanks, Ernie. I wasn't aware of all the technical stuff, but I am aware of what can happen when the system gets contaminated, or there are component failures.

I change brake fluid every year.
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Jim
1997 K1100LTSE 94,000 - still has gremlins!
1995 R100RT Classic 16,650 crashed - repaired!
1992 K75RTP 46,000

"We shall not all die, but we shall all be changed."

abreeze · Posted: Sat Jul 31, 2010 3:34 pm Post subject:

Jim · Posted: Sat Jul 31, 2010 11:49 pm Post subject:

Replaced the brake lines when the bike was 4 - 6 years old or so - I think. I don't know how long the newer lines should last. I'll call Spiegler and see what they say.
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Jim
1997 K1100LTSE 94,000 - still has gremlins!
1995 R100RT Classic 16,650 crashed - repaired!
1992 K75RTP 46,000

"We shall not all die, but we shall all be changed."