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Front brake question/issue


kalali

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1999 R1100R with 16000 miles, the front brake lever gets a little spongy with somewhat reduced travel and somehow causes the brake light to come on intermittently. I hear the brake tick sound at the mater cylinder when I apply the brake but it doesn't trigger the light right away when the lever feels spongy. I initially thought this only happened after/during a ride but it can also happen before a ride. In fact that's how I discovered the issue with the brake light. Thinking there's air trapped in the system, I went ahead and flushed the front brake fluid to make sure there's no air in the system. Fortunately the PO has installed Speed Bleeder on the front brakes so was really simple and only took 30 minutes. Tried the brake - bike cold with engine off, and after a few applications of the lever it felt exactly as before - spongy and brake light coming on intermittently. In my experience, bleeding usually fixes these symptoms so was just wondering of anyone else has run into this

and how they addressed it. The rear brake works perfectly. Thanks in advance.

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1999 R1100R with 16000 miles, the front brake lever gets a little spongy with somewhat reduced travel and somehow causes the brake light to come on intermittently..

 

Afternoon kalali

 

Something conflicting here-- As a rule when the brakes get spongy the lever travel GETS LONGER (not reduced travel)

 

Your brake light issue is more than likely the little (mechanical) switch that is activated by lever movement (not brake pressure). (you can buy a generic switch from electronics store & solder it into your wires--or buy a new BMW switch & replace it back to the pigtail connector)

 

I'm not sure what your brake mushiness is but on a bike as old as yours it is usually degrading brake hoses (hoses get spongy)

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Hi dirtrider, sorry perhaps spongy was a poor choice of word. What I meant to say was the brake lever gets firmer with less travel almost like when you pump the lever after bleeding. You answered my main question which was essentially the hydraulics are not related to the electrical switch and that's something I can address separately. As for the brake lines, the PO already replaced the rear lines with braided SS lines and fronts are next on my to-do list. Thanks again.

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Hi dirtrider, sorry perhaps spongy was a poor choice of word. What I meant to say was the brake lever gets firmer with less travel almost like when you pump the lever after bleeding. You answered my main question which was essentially the hydraulics are not related to the electrical switch and that's something I can address separately. As for the brake lines, the PO already replaced the rear lines with braided SS lines and fronts are next on my to-do list. Thanks again.

 

Evening kalali

 

The brake lever getting firmer as you pump it is pretty normal on a disk brake motorcycle. That probably limits the brake lever travel just enough not trigger the brake switch. (that limited travel won't happen during riding)

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Or, a failing hose could be preventing the fluid from pressurizing the caliper. I would replace the hoses with new stainless lines and then review the brake operation again.

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I looked around but the options for replacement SS lines for bikes with ABS are limited to only Spiegler and even more so, its limited to the entire system, front and rear, and I already have SS line in the rear. Hate to spend $225 (the only price/option I saw on the Spiegler site) and not use the rear line. Anyone has any leads on a front set - 4 lines for ABS bikes, sold separately? Appreciate any input. I checked Galfer as well and they no longer have a kit for front brakes for ABS equipped bikes.

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I looked around but the options for replacement SS lines for bikes with ABS are limited to only Spiegler and even more so, its limited to the entire system, front and rear, and I already have SS line in the rear. Hate to spend $225 (the only price/option I saw on the Spiegler site) and not use the rear line. Anyone has any leads on a front set - 4 lines for ABS bikes, sold separately? Appreciate any input. I checked Galfer as well and they no longer have a kit for front brakes for ABS equipped bikes.

 

Evening Kalali

 

 

I imagine that some of the brake line supply companies are a little gun-shy since BMW published a service bulletin on NOT installing steel or steel-flex brake lines on ABS-2 & I-ABS bikes that didn't originally come with them. (changing brake line expansion/volume changes the ABS calibration)

 

Some riders do install steel brake lines & have no complaints. On dry road ABS braking you probably wouldn't tell any difference in ABS braking performance. On slippery roads or slick wet roads there is a chance the ABS won't react properly & might allow enough wheel lock up to allow wheel stability issues & even lose traction enough to de-stabilize the bike & cause a bike-drop at speed.

 

Sorry I can't post BMW service bulletins here as they are protected BMW proprietary info--

 

Below is a little part of the BMW bulletin as it applies to your bike's ABS-2 brakes--

 

 

 

 

 

"2. Vehicles with ABS 2

 

In vehicles with ABS2, installation of steel or steel-flex lines in the wheel circuit (between pressure modulator and brake caliper) affects ABS regulation, which modulates pressure based on change of volume in wheel circuit. That is, due to a different volume-to-pressure characteristic of the lines, the same change in volume will correspond to a different brake pressure. This changes the control levels of the ABS control.

 

"BMW does not approve of installation of steel-flex lines in wheel circuit.

 

Hint: Installation of steel-flex brake line between hand controls and ABS Modulator can cause a change in the brake feel; however, BMW sees no safety-related limitations with regard to the brake function"

 

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