Brake pedal sticks; brake light stays on

[Rex R]

Like the subject line says the brake pedal sticks (04 1150RT) causing the brake lights to remain on. Quick diagnosis tells me that when the brake pedal is intentionally, definitively pressed, the pedal returns to its normal position and the brake lights turn off. However, if the pedal is pressed ever-so-lightly, just barely enough to activate the brake light switch, then the light stays on. A firmer touch on the brake pedal will then allow it to return to its normal position.

 

Have never r/r the brake switch on an oilhead, but I'm thinking that the linkage may need a cleaning/lube and/or the switch might need a cleaning.

 

Any suggestions? Dirtrider? You seem to be one of our resident gurus.

 

Thanks to everyone who takes the time to read the question and consider it, even if you have no suggestions to offer.

[Selden]

I don't know if the rear brake light switch design is the same on the R1150RT, but on the R1100, there is a fair amount of freedom of movement in the area around the switch. I found that I could loosen the screw that holds the switch to the side plate, and rotate the switch for more positive interaction with the brake pedal. You might also remove the pivot bolt for the brake lever, clean, and grease the bushing.

[Galactic Greyhound]

If the rear brake pedal switch is the same as on the R1100's, then on the brake pedal is a screw stop which contacts the micro-switch plate arm against the underside of the RH footplate to switch off the rear brake light.

 

I had the problem of a flickering rear brake light for a long time. This was eventually traced to fatigue of the micro-switch plate arm such that the switch was only just being held off when the brake pedal was released but would activate if the bike hit a bump.

 

The remedy I used was to carefully bend the metal micro-switch plate arm just enough to maintain a positive 'off'. Only a minute adjustment was required around the plate 'foot' area which is contacted by the screw stop.

[dirtrider]

 

Afternoon Rex

 

The rear brake switch adjustment on the 1150RT is a bit complex. Kind of a funny leaf type switch. The I-ABS system on the 1150 needs a precise switch & blow-by setting as that also controls ABS pump initiation vs system pressure. (it needs to be correct)

 

In any case you first need to adjust the piston rod blow-by clearance as that controls the pedal return to contact the brake light switch leaf. Then move on to do the actual switch adjustment.

 

See link.. Then study the process, then ask questions if you have any.

 

 

 

Rear brake switch adjust

[Rex R]

 

 

See link.. Then study the process, then ask questions if you have any.

 

 

 

Rear brake switch adjust

 

 

Yeah, I have a question: Why can't ANYTHING be simple on these bikes???!! It's like Scotty said in some Star Trek movie (I think it was Star Trek LXXVIII) "The more they over-think the plumbing, the easier it is to stop up the drain."

 

Seriously, tho. Thanks, D-rider, for the info and posting a scan of the relevant pages from the service manual. I actually have that one on my harddrive as well as a few other repair manuals on paper, but it's nice of you to go the extra mile to find the page and post the link.

 

Thanks to Selden and Greyhound too.

[Bologna]

Thanks D.R. I think I will check this on mine!

 

[Rex R]

Okay Dirt, I actually have a couple of real questions. (easy ones, too.) What type of grease is Shell Retinax A? White lithium? Moly lube? Wheel bearing? What commonly available grease can substitute for Retinax? And the "colored sealing lacquer"? What is that? At first I thought they were referring to loctite, but the use and application is different. Can you recommend a brand.

 

Any tips for removing the pedal without losing the torsion spring? Looks like it would be a lot easier if I had a lift and could work with the pedal at eye level, but I don't have one so unless I dig a trench can't working on it at eye level ain't gonna happen. That sucker looks like it's just dying to fly away during removal and if I managed not to lose it, is there a trick to compressing it for re-installation?

 

thanks.

 

[dirtrider]

Morning Rex

 

 

Once you remove the link & clevis that hooks the pedal to the master cylinder then loosen the pivot bolt the pedal can be more easily worked with.

 

I haven't had any problem with that spring popping off. You just need to unhook it as you go. It does help to have the bike on a lift table so you can see better & have better access.

 

On the grease question. I just use a heavy duty chassis

LC-2 Grease.

 

As to the sealing lacquer?-- I just use a bit of Loc-Tite (either 222 low strength or even 242 mid strength). If I have it handy I like the 222 as it will seal the threads & prevent movement but still come loose easily if needed). Most people don't have 222 at hand so blue 242 (or similar) will also work.

 

Added: before starting be sure mark the pedal position to the little stub shaft it mounts to so you can get the index back to where it was at re-assembly.

 

 

[Rex R]

I finally took the time to address this issue. And it took far less time than I thought it would. Thanks to everyone esp. Dirtrider and Selden. I removed the brake pedal and cleaned and greased the bushing, re-assembled and now no sticking brake pedal/switch/light.

 

Tomorrow I'm going to check the clearances just to make sure they're within specs.

 

You were right dirtrider, r&r the pedal and torsion spring is easier than I thought. The spring is under far less tension than I expected and it was much easier to work free and re-install than I predicted.

 

How did anything get done before Al Gore invented the internet?

 

Be safe everyone

[Rex R]

Hi guys,

 

I have a few follow-up questions (You listening, Dirtrider?)

 

The brake pedal is sooooo sensitive and so light now that if I rest my foot on it at all, I turn on the brake lights. Is this normal for the 1150RTs? I bought it used and maybe before all this a little dirt and wear in the bushing provided just enogh resistance that I could lightly rest my foot on the pedal without activating the lights. But now that I've cleaned and lubed it, it's like trying to touch a soap bubble with breaking it.

 

I can't seem to adjust the clearances to within BMW specs. When checking the blow-by clearance, even a .15mm feeler doesn't leave any play. After releasing the brake pedal with the feeler gauge in place, I can slide out the feeler and watch the brake pedal snap back to its resting position.

 

I lowered the adjusting screw to the low end of specs (13.1mm) and turned the piston rod to maximize play, but .15mm still seems too much.

 

After making the above adjustments, the brake light switch won't switch off with a .90mm feeler (per specs). Have to go down to a .45mm feeler to get the brake light to switch off. Dont want to remove the side plate to access the adjustment screw when the blow-by clearance is still out of spec.

 

any ideas why I'm at the end of the adjustment range and still dont have the proper clearance?

 

Thanks and have a good Sat night everyone

[tallman]

On all my BMW's touching pedal activated brake light.

I never "rested" foot on it.

YMMV

[dirtrider]

Afternoon Rex

 

The 1150RT (I-ABS) system uses a servo pump to assist braking & give a quick response ABS activation so it is necessary for the pump to come on at the very start of pedal movement so the pump is on as the pedal pressure increases. So early activation is about the norm.

 

As far as adjusting yours?--just do the best you can to get it as close to the book settings as possible (you might have to access the switch to do so).