Rear brake pedal... seems very low, not doing much. 1988 K100lt

[geo]

Hi all..  I finally got my 1988 K100lt out for a ride. I purchased the bike last year.  I had only ridden it home prior to that.  Well the rear brake pedal seems to be very low.  I have to take my foot off the peg, to push down enough on it to actually have it begin to stop bike.  Looks fine , not bent or anything.  But I have to push all the way down, and then it does not do much stopping.  The rear disk looks fine and there are no strange sounds.  I am thinking bleed brakes, but was wondering if any other thoughts. This is my first BMW, but have been riding along time now.  Thanx for any info..

[Laitch]

Welcome, geo!
First, you need to inspect the brake pads to determine that they are still thick enough to meet specifications and replace them if they aren't before doing anything else. Do you have a Brick shop manual or rider's handbook? Both are downloadable from this site.

Does your Brick have ABS brakes? They have a dedicated bleeding sequence. Regardless, if the pads are ok, you should flush both the front and rear brake lines. That means pumping a few ounces of DOT4 brake fluid through each of them without letting the reservoirs get empty. The brake pedal should have more effect after that. Consider the flushing a temporary measure because BMW's rubber brake lines degrade after time and neglect; the interiors can collapse and seriously effect braking. Consider replacing them eventually.

Tell us how many miles are on the odometer and what you know about its history. Post a few photos of it.

[geo]

Thanx for the reply and info. Bike has 87k miles. Looks like we'll taken care of.  Guy says his uncle bought it new, and he bought off uncle. So I am third owner.   Seemed like he telling truth.   
Pads look OK as far as I can see. Gonna look closer. Then see about bleeding. See if that helps.  Might be awhile supposed to be 90 this next week. A bit too hot for me to function.
No pics yet. Gonna see about getting some. I do have manuals.   Do not have ABS.  How do you know ow when brake lines need to be replaced?   Probably won't hurt after all this time. Thanx again.

[Laitch]

How do you know when brake lines need to be replaced?

One symptom is that when you press the pedal or squeeze the lever there's resistance but not much braking. Rotting rubber is clogging the lines.    Of course, that symptom can also mean air in the brake line or the brake fluid has absorb too much water from air. Minimum brake pad thickness is 1.5mm (0.06"). Pull the pins and spring from each caliper, clean the the pins and spring then grease them lightly with silicone grease, lightly smear some silicone grease on the backs of the pads. Afterwards, flush the brake lines.

[geo]

Thank you for the extra info..appreciate it.

[frankenduck]

http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/rearbrakeadjust/rearbrakeadjust.htm

[geo]

Thank you. Will definitely look into this.