BMW K1200, K1300, and K1600 Forum banner

Front end vibration and brake pulsing

4K views 14 replies 6 participants last post by  Eric Woerner 
#1 ·
Hello chums - I have a diagnostic question about the front end of a 2006 1200GT.
About 3/4 of the way through a 1500 mi trip in to the Catskills and around, we (my spouse was the passenger for the first time) found the front tire was starting to show the cords on a Road Pilot 3. It was Labor Day weekend. No way finding a tire and getting it serviced on Saturday night, in the Catskills. I swear the tire was fine before we left.
Before we left, I had been noticing shaking / pulsing from the front brake when braking at 30+ mph and I checked the pads. The pads on the right inside pad was definitely getting hit harder than the others. So I installed 4 new EBC HH pads and bled the front brakes etc.
Decided to go anyway because I didn't want to lose the $1000 in hotel reservations.
Anywho, brakes were still pulsing all the way thru to home. It felt like I had a warped rotor. I know, I know, it isn't probably a warped rotor.
Thankfully got home, replaced the front tire and now I feel a front end wobble at slow speeds and vibration at higher speeds.

My first thought that maybe it wasn't balanced right. But would bad balance show itself as a wobble at slow speeds?
Bent rim? Anyone that commutes to work in Michigan can attest to the road conditions here and I have hit a couple potholes (pits to hell) that scared the crap out of me. Nevermind the mini-mountain speed bumps because the heaving of the concrete here.

The two problems may not even be related.

Any ideas of where to start would be great.

PS. if it is the rim, what other models can I steal from that fits the K1200? I was thinking RS of the same vintage.
 
See less See more
#2 ·
Eric

One problem might be the ball-joint on the front Hossack suspension. It can tighten and get 'notchy' or even feel loose, especially if you've hit a few big potholes - I can't tell you the number of times I stopped and got off my 2005 K1200S convinced that I'd got a puncture. The difference in front end feel on my 2015 K1300S is so much better.

I guess you could test this by putting the bike on the main-stand, getting a pillion on to push the back end down and grab those lower 'fork' legs to feel for tightness or play.

Hope you get sorted, David
 
#4 ·
Could be a number of things going on here. What tire did you replace the old one with? Some tires can induce a slow weave and this has been well documented, in particular on the previous generation bricks. Did you sort the pulsing brakes? Replacing the pads is not a fix or even a bandaid for the problem. You need to be sure none of the pistons are sticking. If one rotor is hotter than the other there is a very good chance this is (one of) your problems. If the brakes get very hot and you come to a standstill and leave the brake lever pulled, heat from the pads is trapped against the rotor and may leave very small deposits of pad material on the surface of the very hot rotor. This will then feel like a warped rotor, and if you have a sticking piston or two, the problem gets worse. The fix is to give the rotors a very good rub down with Emory paper or wet and dry sand paper. Start with a coarse grade, say around 320 and work up to 1000 with plenty of soapy water. The pistons in the callipers need to be thoroughly cleaned (DON’T use brake clean products as they react with the piston brake seals. A tooth brush and warm soapy water works well enough although you can use other products. You should do this every time are fitting new pads or undertaking a brake fluid change. Personally I would remove the wheel from the bike and remove the rotors from the wheel so you can give everything a thorough inspection.
 
  • Like
Reactions: Capt howdy
#5 ·
Check your wheel bearings too. Check by either removing the wheel and stick a finger in the bearing and rotate it. Should be perfectly smooth and no other movement than rotating. Or, not as easy, block bike on stand so wheel is off the ground and grab it with two hands opposite of each other. Try to move the wheel and carefully look at the wheel axle joint. Two of your symptoms are covered in failed wheel bearings.
I use scotch brite on brake rotors along with spray brake cleaner.
PR3's are notorious for looking okay but worn out. Move on to PR5's or something else.
Wheel carrier ball joint failure is presented by the symptom of the front end weaving at 25 or 30 mph. Gets worse if you ignore it and you find your bike changing paths in corners.
 
#9 ·
So, a year and a half later, I finally am getting around to fixing the problem. Probably only put another 200 miles on the bike since then because of the pandemic.
Going over the discs looks like on both there is definite areas on both there's still a little rust and I could feel the pads rubbing a little when I had the front wheel off the ground.
Took the wheel off and the bearings are really hard to turn. There doesn't seem to be any play, but harder than heck to turn them. So I'm guessing I need new bearings.
Oh yeah, and clean the discs up.
Thanks to everybody for their expertise.
Cheers,
Red
 
#10 ·
The bearings may be pressed tight against the inner space tube. Makes them hard to turn. If smooth when you do turn them okay. I've taken hard steel Vessel pliers and put them into the bearing hole to grab the inner race just to move and check for smoothness. You need to clean your brake disks with either scotch guard pad with brake spray solvent very well on both sides or something like 280 grit wet dry sandpaper and same solvent. Don't make a mess out of it by getting solvent into the bearing cavity. This is something to be done each time new pads go on or when ever some pulsing crops up.
Yes the disks can be warped but more often than not it is just dirty disks.
common pad find in most hardware stores.
 
#12 ·
You need to do some serious cleaning there and if you have an 8mm thread chaser that too. No antisieze. New bolts come with a red thread lock on them from the factory. Do not use loctite red here you will distroy the threads next removal. Use some Loctite 242 (blue). Have no clue what your plastic washer might be but it is not in the parts diagram. Are your brake pads wearing equally?
 
#13 ·
Would a 8mm tap work as a thread chaser?
I have Loctite blue and I'll measure one of the other washers/shims with my calipers to see what it's supposed to be. Brakes are wearing how I'd expect them to, inside pads are a little more warn. The rotors seem to have a section that the brakes aren't clamping as hard (a little surface rust). My guess is that plastic "washer" was crushed and not supporting the rotor as it should, causing the "pulsing" and uneven wear across the rotor?
Anywho, I'll respond back here after I clean everything up and get it back together.
Really appreciate the guidance.
Cheers,
Red
 
#14 · (Edited)
Your thoughts sound reasonable. There is no way you can torque down on a plastic washer and have it equal in all the bolt positions. It is not in the parts diagram and I suggest you not use anything like it until some specific confirmation. Yes a tap will work but it tends to cut metal out that it meets up with . A chaser just pushes things around ( wonder the merits of that but have been using them for years). I have made chasers out of a bolt the same size and pitch by grinding a groove down one side. I ask about your wear pattern to see if the calipers are basically centered on your rotors. I would personally clean up things carefully and not put in anything to stand the rotors off the mounting position. Some blue loctite and the stock torque. Clean the fasteners too.
I'm thinking your disk wobble is possible those plastic washers someone put in there just like you.

Not relevant to this conversation but I'm super pissed at an add that keeps coming up while trying to type that covers the field and has no delete ability. This is too much. Attention owners.

One thing about using a tap to chase a valuable thread is that you have to make sure you are straight and true. Easy to start a new thread that is off a couple of degrees.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top